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Our experience of the world seems to unfold seamlessly in a unitary 3D space. For this to be possible, the brain has to merge many disparate cognitive representations and sensory inputs. How does it do so? I discuss work on two key combination problems: coordinating multiple frames of reference (e.g. egocentric and allocentric), and coordinating multiple sensory signals (e.g. visual and proprioceptive). I focus on two populations whose spatial processing we can observe at a crucial stage of being configured and optimised: children, whose spatial abilities are still developing significantly, and naïve adults learning new spatial skills, such as sensing distance using auditory cues. The work uses a model-based approach to compare participants’ behaviour with the predictions of alternative information processing models. This lets us see when and how—during development, and with experience—the perceptual-cognitive computations underpinning our experiences in space change. I discuss progress on understanding the limits of effective spatial computation for perception and action, and how lessons from the developing spatial cognitive system can inform approaches to augmenting human abilities with new sensory signals provided by technology.

ObjectiveTo determine the association between hypertensive disorders of pregnancy (HDP) and cognitive impairment 15 years after pregnancy, we measured cognitive performance in 115 women with a history of HDP and in 481 women with a previous normotensive pregnancy.MethodsThis was a nested cohort study embedded in a population-based prospective cohort from early pregnancy onwards. Cognitive function was assessed with cognitive tests 15 years after the index pregnancy (median 14.7 years, 90% range [13.9–16.1]). Cognitive performance was measured in different cognitive domains: executive function, processing speed, verbal memory, motor function, and visuospatial ability. A global cognition factor (g-factor) was derived from principal component analysis.ResultsOf the women with HDP, 80 (69.6%) had gestational hypertension (GH) and 35 (30.4%) had preeclampsia. Women with HDP had a lower g-factor than women with a previous normotensive pregnancy (mean −0.22, 90% range [−2.06−1.29]). HDP was negatively associated with the 15-word learning test: immediate recall (−0.25, 95% CI [−0.44 to −0.06]) and delayed recall (−0.30, 95% CI [−0.50 to −0.10]). Women with GH perform significantly worse on their 15-word learning test than women with a previous normotensive pregnancy.ConclusionA history of HDP is independently associated with poorer working memory and verbal learning 15 years after pregnancy. This association is mainly driven by women with GH. Clinicians and women who experienced HDP should be aware of this risk.

Our visual system is able to separate spatially intermixed objects into different categorical groups (e.g., berries and leaves) using the shape of feature distribution: Determining whether all objects belong to one or several categories depends on whether the distribution has one or several peaks. Despite the apparent ease of rapid categorization, it is a very computationally demanding task, given severely limited “bottlenecks” of attention and working memory capable of processing only a few objects at a time. Here, we tested whether this rapid categorical parsing is automatic or requires attention. We used the visual mismatch negativity (vMMN) ERP component known as a marker of automatic sensory discrimination. 20 volunteers (16 female, mean age—22.7) participated in our study. Loading participants’ attention with a central task, we observed a substantial vMMN response to unattended background changes of categories defined by certain length-orientation conjunctions. Importantly, this occurred in conditions where the distributions of these features had several peaks and, hence, supported categorical separation. These results suggest that spatially intermixed objects are parsed into distinct categories automatically and give new insight into how the visual system can bypass the severe processing restrictions and form rich perceptual experience.

SIGNIFICANCE This study suggests that Chinese newspaper characters are more legible than English newspaper letters. Characters in Chinese newspapers have higher acuity reserve than English newspapers. PURPOSE The purpose of this study was to evaluate visual demand and acuity reserve for Chinese newspapers in comparison with published data on U.S. newspapers. METHODS The test distances for visual acuity in Chinese clinical studies were reviewed systematically. Characters from different sections of newspapers printed in simplified Chinese were evaluated. The character height, frequency, and visual demand and acuity reserve of each newspaper section were determined for Chinese characters of the six different levels of complexity. RESULTS More than 70% of Chinese clinical studies measure near visual acuity at either 33 or 40 cm. The height of Chinese characters ranged from 1.95 to 3.28 mm across different sections of five newspapers compared with 1.0 to 2.0 mm for English letters. The frequency of Chinese characters from least to most complex ranged from 7 to 34% across 12 sections of one Chinese newspaper. The angular threshold across the six complexity levels of Chinese characters ranged from 4.62 to 5.93 arcmin (0.54 to 0.69 mm at 40-cm reading distance) with a weighted angular threshold of 5.18 arcmin compared with 3.37 arcmin (0.39 mm) for the English letters. For Chinese newspapers, at 40-cm reading distance, the acuity reserve for the smallest and largest median size was 3.55 and 4.61, respectively. CONCLUSIONS Chinese characters are larger than English characters in all newspaper sections newspapers by a factor of 1.60 to 2.34. Given that Chinese characters need to be 1.54 times larger than English letters to provide the same acuity reserve, on average, Chinese newspapers are more legible than U.S. English newspapers.

Objectives Latinos are 1.5 times as likely to develop Alzheimer’s dementia as non-Latino Whites. This health disparity may arise from multiple influences with culturally relevant factors receiving increasing attention. Models of acculturation stress the importance of considering acculturation-related factors within the context of socioenvironmental factors to better capture the Latino experience in the United States. Methods We measured 10 acculturation and contextually-related variables in 199 Latinos (age 69.7 years) without dementia participating in Rush Alzheimer’s Disease Center studies. We tested the relationship between these variables via Principal Component Analysis (PCA), then investigated how resulting components associated with level of and longitudinal change in global and domain-specific cognition using separate linear mixed-effects models adjusted for relevant confounders and their interactions with time. Results The PCA revealed a 3-factor unrotated solution (variance explained ~70%). Factor 1, representing acculturation-related aspects of nativity, language- and social-based acculturation, was positively associated with level, but not change, in global cognition, semantic memory, and perceptual speed. Factor 2, representing contextually-related socioenvironmental experiences of discrimination, social isolation, and social networks, was negatively associated with level of global cognition, episodic and working memory, and faster longitudinal decline in visuospatial ability. Factor 3 (familism only) did not associate with level or change in any cognitive outcome. Discussion Acculturation- and contextually-related factors differentiated from each other and differentially contributed to cognition and cognitive decline in older Latinos. Providers should query acculturation and lived experiences when evaluating cognition in older Latinos.

Contains fulltext : 219554.pdf (Publisher’s version ) (Closed access) Individuals with sequence-space synesthesia (SSS) perceive sequences like months, days and numbers in certain spatial arrangements. Several cognitive benefits have been associated with SSS, such as enhanced mental rotation, more vivid visual imagery and an advantage in spatial processing. The current study aimed to further investigate these cognitive benefits, focusing on spatial navigation skills, to explore if their enhanced sensitivity to spatial relations is reflected in enhanced navigational performance. Synesthetes were distinguished from controls by means of a questionnaire, a consistency test and drawings. A virtual Morris Water Maze (MWM) task with two allocentric and two egocentric navigation conditions was used to assess spatial navigation abilities. For the allocentric tasks, participants had to use object cues to find a hidden platform and for the egocentric tasks, they had to use their own position as a reference. Results showed that synesthetes performed significantly better compared to controls on the allocentric and egocentric tasks that reflected real life situations more accurately. However, this significant result was only found for the time taken to find the platform and not for the length of the path that was taken. In exploratory analyses, no significant relations were found between task performance and the specific features of the manifestation of each individual's synesthesia. Our hypothesis that synesthetes with the ability to mentally rotate their spatial arrangements would perform better on the allocentric task was not confirmed. Results add to the growing body of literature concerning the cognitive benefits of SSS and are consistent with the possibility that enhanced spatial navigation skills emerge from generally enhanced visuospatial abilities in SSS. 15 p.

BackgroundA mutation in C9orf72 constitute a cross-link between amyotrophic lateral sclerosis (ALS) and fronto-temporal dementia (FTD). At clinical manifestation, both patient groups may present with either cognitive impairment of predominantly behaviour or language (in FTD) or motor dysfunctions (in ALS).MethodsIn total, 36 non-symptomatic mutation carriers from ALS or FTD families were examined, including 21 subjects with C9orf72 and 15 with SOD1 mutations. Data were compared with 91 age-matched, education-matched and gender-matched healthy subjects (56 were first-degree relatives from ALS or FTD families, 35 with no known family history of ALS/FTD). MRI scanning for diffusion tensor imaging was performed to map fractional anisotropy (FA). Subjects performed an extensive neuropsychological assessment to address verbal fluency, language, executive, memory and visuospatial function. Measurements were repeated after 12 months.ResultsC9orf72 expansion carriers performed significantly worse in verbal fluency and non-verbal memory and presented with distinct alterations in structural white matter integrity indicated by lower FA values in inferior and orbitofrontal cortical areas compared with carriers of SOD1 mutations or healthy subjects. Loss of structural integrity was associated with decreased verbal fluency performance. White matter alterations and cognitive performance showed no changes over 12 months in all subjects.DiscussionReduced verbal fluency performance seems to be a distinct clinical feature of C9orf72 carriers before symptomatic disease onset without evidence for change over time in our cohort. The results support the emerging hypothesis of a general disorder in development in addition to neurodegeneration in C9orf72 carriers.

Much of what we know about object recognition arises from the study of isolated objects. In the real world, however, we commonly encounter groups of contextually-associated objects (e.g., teacup, saucer), often in stereotypical spatial configurations (e.g., teacup above saucer). Here we used EEG to test whether identity-based associations between objects (e.g., teacup-saucer vs. teacup-stapler) are encoded jointly with their typical relative positioning (e.g., teacup above saucer vs. below saucer). Observers viewed a 2.5Hz image stream of contextually-associated object pairs intermixed with non-associated pairs as every fourth image. The differential response to non-associated pairs (measurable at 0.625Hz in 28/37 participants), served as an index of contextual integration, reflecting the association of object identities in each pair. Over right occipitotemporal sites, this signal was larger for typically-positioned object streams, indicating that spatial configuration facilitated the extraction of the objects’ contextual association. This high-level influence of spatial configuration on object identity integration arose ∼320ms post stimulus onset, with lower-level perceptual grouping (shared with inverted displays) present at ∼130ms. These results demonstrate that contextual and spatial associations between objects interactively influence object processing. We interpret these findings as reflecting the high-level perceptual grouping of objects that frequently co-occur in highly stereotyped relative positions.

Objectives Visuospatial neglect (VSN) is a common cognitive disorder after stroke. The primary aim of this systematic review was to provide an overview of the impact of VSN in 3 aspects: (1) activities of daily living (ADL), (2) participation, and (3) caregiver burden. The second aim was to investigate the differences in studies focusing on populations with mean age Methods PubMed, EMBASE, Web of Science, Cochrane Library, Emcare, PsychINFO, Academic Search Premier and CENTRAL were searched systematically. Quality was assessed with the Mixed Methods Appraisal Tool. Results Of the 115 included studies, 104 provided outcomes on ADL, 15 on participation (4 studies with mean age ≥ 65), and 2 on caregiver burden (1 study with mean age ≥ 65). Quality assessment yielded scores ranging from 0 to 100%. VSN had a negative impact on ADL (i.e., independence during ADL and performance in self-care, household tasks, reading, writing, walking, wheelchair navigation) and participation (i.e., driving, community mobility, orientation, work). The impact of VSN on fulfilling social roles was unclear. VSN had a negative effect on caregiver burden. We found no clear age-related differences. Conclusions and implications VSN has a negative impact not only on patients’ independence but particularly on the performance of ADL. Despite the far fewer studies of VSN as compared with ADL, VSN also seems to hamper participation and increase caregiver burden, but further research is needed. Because of the large impact, VSN should be systematically and carefully assessed during rehabilitation. A considerable number of different instruments were used to diagnose VSN. Diagnosing VSN at more than one level [function (i.e., pen-and-paper test), activities, and participation] is strongly recommended. Consensus is needed on how to assess VSN and its negative impact for research and rehabilitation practice. Systematic review Registration No. PROSPERPO Registration No. CRD42018087483.

The present study investigated how response mode determines the specificity of control responsible for the congruency sequence effect (CSE), especially when conflict arises from spatial dimensions. Horizontal and vertical Simon tasks were presented in turn, while response mode (Experiment 1) or task-relevant stimulus dimension (Experiment 2) was manipulated. All responses were made by aimed movements to make the relative salience of the horizontal and vertical dimensions equivalent regardless of response mode. The confound-minimized CSEs were significant only when the two tasks shared the same response mode, which did not vary as a function of task-relevant stimulus dimension. This result suggests that response mode determines the scope of control, as it reconfigures the representations of the task-irrelevant spatial dimensions (i.e., the horizontal and vertical dimensions), which is corroborated by distributional analyses. This response mode-specific control was also consistently found for the horizontal and vertical arrow versions of flanker-compatibility tasks in Experiment 3, in which conflict does not directly arise from the response dimension. Furthermore, the current findings revealed that the CSEs were more evident in movement times than in initiation times, which provides new insight on how control inhibits the response activated by a task-irrelevant stimulus dimension, especially at a motor level.

Path integration plays a vital role in navigation: it enables the continuous tracking of one's position in space by integrating self-motion cues. Path integration abilities vary widely across individuals, and tend to deteriorate in old age. The specific causes of path integration errors, however, remain poorly characterized. Here, we combine tests of path integration performance in participants of different ages with an analysis based on the Langevin equation for diffusive dynamics, which allows us to decompose errors into distinct causes that can corrupt path integration computations. We show that, across age groups, the dominant error source is unbiased noise that accumulates with travel distance not elapsed time, suggesting that the noise originates in the velocity input rather than within the integrator. Age-related declines are primarily traced to a growth in this noise. These findings shed light on the contributors to path integration error and the mechanisms underlying age-related navigational deficits., Path integration abilities, important for spatial navigation, vary widely across individuals and deteriorate in old age. This work shows that path integration errors in general, as well as age-related path integration deficits, are mainly caused by accumulating noise in people’s velocity estimation.

OBJECTIVE To detail the characteristic traits of children with fetal alcohol spectrum disorders (FASDs) and maternal risk factors in a southeastern U.S. County. METHODS Independent samples were drawn from 2 different cohorts of first-grade students. All consented children (49.8%) were measured for height, weight, and head circumference, and those ≤ 25th centile entered the study along with a random sample drawn from all enrolled students. Study children were examined for physical growth, dysmorphology, and neurobehavior, and their mothers were interviewed. RESULTS Total dysmorphology scores discriminated well the physical traits of children across the FASD continuum: fetal alcohol syndrome (FAS) = 15.8, partial FAS (PFAS) = 10.8, alcohol-related neurobehavioral disorder (ARND) = 5.2, and typically developing controls = 4.4. Additionally, a neurobehavioral battery distinguished children with each FASD diagnosis from controls. Behavioral problems qualified more children for FASD diagnoses than cognitive traits. Significant proximal maternal risk variables were as follows: reports of prepregnancy drinking, drinking in any trimester, and comorbid use of other drugs in lifetime and during pregnancy, especially alcohol and marijuana (14.9% among mothers of children with FASD vs. 0.4% for controls). Distal maternal risks included reports of other health problems (e.g., depression), living unmarried with a partner during pregnancy, and a lower level of spirituality. Controlling for other drug use during pregnancy, having a child diagnosed with a FASD was 17.5 times greater for women who reported usual consumption of 3 drinks per drinking day prior to pregnancy than for nondrinking mothers (p

Nonverbal Learning Disability (NVLD) is characterized by deficits in visual-spatial, but not verbal, reasoning. Nevertheless, the functioning of the neural circuits supporting spatial processing have yet to be assessed in children with NVLD. We compared the resting state functional connectivity of a spatial brain network among children with NVLD, children with reading disorder (RD), and typically developing (TD) children. Seventy-five participants (7–15 years old) were included in the study (20 TD, 24 NVLD, and 31 RD). Group differences in global efficiency and functional connectivity among 12 regions comprising a previously defined spatial network were evaluated. Associations with behavior were explored. Global efficiency of the spatial network associated positively with spatial ability and inversely with socioemotional problems. Within the spatial network, associations between left posterior cingulate (PCC) and right retrosplenial cortical activity were reduced in children with NVLD relative to those without spatial deficits (RD and TD). Connectivity between left PCC and right posterior cerebellum (Crus I and II) was reduced in both groups of children with learning disabilities (NVLD and RD) relative to TD children. Functional connectivity of the spatial network was atypically associated with cognitive and socioemotional performance in children with NVLD. Identifying a neurobiological substrate for NVLD provides evidence that it is a discrete clinical entity and suggests targets for treatment.

Introduction: Persons with Alzheimer’s disease (AD) have profound impairment in wayfinding, potentially related to a deficit in visual attention and selection of relevant environmental information. This study sought to determine differences in visual attention to salient visual cues and nonsalient cues (building features) in older adults with and without AD during active wayfinding in a large-scale, virtual reality spatial task. Methods: Fifteen subjects (7 with AD and 8 controls without AD) were asked to find their way repeatedly during 10 trials in a virtual simulation of a senior retirement community. Subjects wore eye tracking glasses to capture visual fixations while wayfinding. The least square means (LSMs) and their standard errors (SEs) for percentage of fixations and duration of fixations on salient and nonsalient cues were estimated from the linear mixed effects models and compared by group (AD or control) and cue type. Results: The group by cue type interaction was significant for both percentage of fixations (F(1, 13) = 6.79, p = 0.02) and duration of fixations (F(1, 13) = 4.87, p = 0.04). The AD group had significantly lower percentages of fixations on salient cues, LSM = 57.91 (SE = 2.44), compared to controls, LSM = 66.40 (SE = 2.19); p = 0.03. Persons with AD had a higher percentage of fixations on building features, LSM = 31.65 (SE = 2.18), than controls, LSM = 24.54 (SE = 1.95); p = 0.02. Shorter durations of fixations on salient cues were experienced by the AD group, LSM = 38.89 (SE = 1.69), than the control group, LSM = 44.69 (SE = 1.55); p = 0.02. Discussion/Conclusion: Individuals with AD may have difficulty selecting relevant information for wayfinding as compared to normally aging individuals and attend more frequently than controls to irrelevant information. This may help explain the wayfinding difficulties seen in AD.

The Mini-Mental Examination for Children (MMC) is a widely used tool for assessing global cognitive deficits, however,is still unknown whether MMC is sensitive for investigating cognitive profiles associated with learning difficulties (LD). Objective: Here we investigate the feasibility of using the MMC for screening school-aged children with learning difficulties in spelling and math. Methods: The MMC and other neurophysiological tests were administered to a sample of 168 children, aged 7 to 12 years. The sample was subdivided into a Control group and LD group (Math Difficulties, Spelling Difficulties, Math and Spelling Difficulties). Diagnostic accuracy was assessed with ROC analysis. Convergent and divergent validity was assessed using correlation analysis. Results: Performance on the MMC was associated with nonverbal intelligence, age and school achievement. The LD group had significantly lower performance on the MMC than the Control group. Performance on the MMC discriminated LD children with a global accuracy of around 0.80. Associations between the MMC and the other neuropsychological variables were higher for finger gnosis (r=0.40) and generally higher for early elementary school grades. The MMC proved satisfactory for identifying LD children with good accuracy. Nonverbal intelligence, and perceptual/motor abilities play an important role in MMC performance. Conclusion: The MMC could be a useful instrument for screening children with LD. RESUMO Mini-exame mental para crianças (MMC) é uma ferramenta amplamente utilizada para avaliar déficits cognitivos globais, no entanto, ainda é desconhecido se a MMC é sensível para investigar perfis cognitivos associados a dificuldades de aprendizagem. Objetivo: Aqui nós investigamos a viabilidade de usar MMC para triagem de crianças em idade escolar com dificuldades de aprendizagem em ortografia e matemática. Métodos: MMC e outros testes neuropsicológicos foram administrados em uma amostra de 168 crianças de 7 a 12 anos de idade. A amostra foi subdividida em um Grupo Controle e um grupo LD (dificuldade na matemática, na escrita, ou na escrita e na matemática). A acurácia diagnóstica foi analisada através de uma análise de curva ROC. A validade convergente e divergente foi investigada através de análises de correlações. Resultados: A performance no MMC foi associada com a inteligência não verbal, idade e desempenho escolar. O grupo LD apresentou desempenho significativamente inferior ao Grupo Controle no MMC. A performance no MMC pôde identificar crianças LD com uma acurácia global em torno de 0.80. As associações entre MMC e outras variáveis neuropsicológicas foram maiores para gnosias digitais (r=0.40) e em geral, mais altas nas séries iniciais. O MMC se mostrou satisfatório para identificar crianças LD com uma boa acurácia. A inteligência não verbal, habilidades perceptivas/motoras tem um importante papel na performance no MMC. Conclusão: O MMC pode ser um instrumento útil para o rastreamento de crianças com LD.

Feedback in the brain is thought to convey contextual information that underlies our flexibility to perform different tasks. Empirical and computational work on the visual system suggests this is achieved by targeting task-relevant neuronal subpopulations. We combine two tasks, each resulting in selective modulation by feedback, to test whether the feedback reflected the combination of both selectivities. We used visual feature-discrimination specified at one of two possible locations and uncoupled the decision formation from motor plans to report it, while recording in macaque mid-level visual areas. Here we show that although the behavior is spatially selective, using only task-relevant information, modulation by decision-related feedback is spatially unselective. Population responses reveal similar stimulus-choice alignments irrespective of stimulus relevance. The results suggest a common mechanism across tasks, independent of the spatial selectivity these tasks demand. This may reflect biological constraints and facilitate generalization across tasks. Our findings also support a previously hypothesized link between feature-based attention and decision-related activity., Feedback modulates visual neurons, thought to help achieve flexible task performance. Here, the authors show decision-related feedback is not only relayed to task-relevant neurons, suggesting a broader mechanism and supporting a previously hypothesized link to feature-based attention.

Topographical disorientation is the impairment or inability to successfully navigate in three-dimensional space. Differing topographical disorientation syndromes have been associated with distinct lesion sites in the acquired brain injury (ABI) literature. This meta-analysis attempted to investigate the relationship between lesion location and dysfunctions in specific navigational abilities resulting in topographical disorientation in individuals with ABI, as measured by their performance on experimental and neuropsychological tests. It was expected that focal lesions would be associated with a specific navigational deficit in one ability, with relative sparing of other navigational abilities. Twenty-six papers met the inclusion criteria for the analysis. Results indicated that ABI populations performed worse on all measures of navigation, with moderate to large effect sizes. Dysfunctions in three core navigational skills were consistent with the available lesion studies: a feature/landmark processing unit, a spatial processing unit, and a spatial/feature binding and associative learning unit. A sequential processing model was created to attempt to best represent the transfer of information between these units and the process by which navigational knowledge is generated. The model was then used to assess the validity of existing models of navigation and topographical disorientation.

Reading causes widespread changes in the brain, but its effect on visual word representations is unknown. Learning to read may facilitate visual processing by forming specialized detectors for longer strings or by making word responses more predictable from single letters—that is, by increasing compositionality. We provided evidence for the latter hypothesis using experiments that compared nonoverlapping groups of readers of two Indian languages (Telugu and Malayalam). Readers showed increased single-letter discrimination and decreased letter interactions for bigrams during visual search. Importantly, these interactions predicted subjects’ overall reading fluency. In a separate brain-imaging experiment, we observed increased compositionality in readers, whereby responses to bigrams were more predictable from single letters. This effect was specific to the anterior lateral occipital region, where activations best matched behavior. Thus, learning to read facilitates visual processing by increasing the compositionality of visual word representations.

The human egocentric perception of approaching objects and the related perceptual processes have been of interest to researchers for several decades. This article gives a literature review on numerous studies that investigated the phenomenon when an object approaches an observer (or the other way around) with the goal to single out factors that influence the perceptual process. A taxonomy of metrics is followed by a breakdown of different experimental measurement methods. Thereinafter, potential factors affecting the judgment of approaching objects are compiled and debated while divided into human factors (e.g., gender, age, and driving experience), compositional factors (e.g., approaching velocity, spatial distance, and observation time), and technical factors (e.g., field of view, stereoscopy, and display contrast). Experimental findings are collated, juxtaposed, and critically discussed. With virtual-reality devices having taken a tremendous developmental leap forward in the past few years, they have been able to gain ground in experimental research. Therefore, special attention in this article is also given to the perception of approaching objects in virtual environments and put in contrast to the perception in reality.

SIGNIFICANCE Glaucoma has been shown to impair hazard detection ability and increase crash risk compared to controls. Differences in visual search behavior of the driving scene may explain these differences; however, there has been limited investigation of this issue with inconsistent findings. PURPOSE Through eye movement tracking of older drivers with glaucoma, we explored their visual search behavior in comparison with controls while performing the DriveSafe, a slide recognition test purported to predict fitness to drive. METHODS Thirty-one drivers with glaucoma (mean age, 71.7 ± 6.3 years; average better-eye mean defect,-3 dB; average worse-eye mean defect,-12 dB) and 25 age-matched controls underwent measurements of their visual acuity, contrast sensitivity, visual fields, and useful field of view (visual processing speeds). Participants' eye movements were recorded while they completed the DriveSafe test, which consists of brief presentations of static, real-world driving scenes containing various road users (pedestrians, bicycles, vehicles). Participants reported the types, positions, and direction of travel of road users in each image; the score was the total number of correctly reported items (maximum, 128). RESULTS Drivers with glaucoma had significantly worse DriveSafe scores (P = .03), fixated on road users for shorter durations (P < .001), and exhibited smaller saccades (P = .02) compared with controls. For all participants, longer fixation times on road users (P < .001) was the eye movement measure most strongly associated with better DriveSafe scores; this relationship was not significantly different between groups. Useful field-of-view divided attention was the strongest visual predictor of DriveSafe scores. CONCLUSIONS Eye movement changes in the glaucoma group may reflect increased difficulty in identifying relevant objects in the visual scene, which may be related to their lower DriveSafe scores. Given the DriveSafe's potential utility in assessing drivers with visual impairment before on-road testing, further investigations on how DriveSafe performance and eye movement patterns compare to those during on-road driving are warranted.

During reading, word recognition speed is influenced by the amount of orthographic overlap with surrounding words. The nature of this phenomenon is not understood: some theories attribute it to low-level visual operations (i.e., parafoveal feature detectors influencing foveal letter detectors), whereas other theories assume that orthographic processing (i.e., letter position coding and word activation) occurs across multiple words in parallel. To arbitrate between these theories, we used electroencephalography to reveal the time course of orthographic spatial integration in a lexical decision task. Foveal target words were flanked on each side by parafoveal words, manipulated across three conditions: repetition flankers (e.g. rock rock rock), unrelated flankers (step rock step) and a no-flanker condition. Linear mixed-effect models were constructed to analyze EEG data on a trial-by-trial basis. Word recognition was worse in the unrelated flanker condition than in the repetition and no-flanker conditions. This behavioral pattern was accompanied by increased negativity in the N250 and N400 windows, associated with the activation of sub-lexical and lexico-semantic representations, respectively. Crucially, the absence of effects prior to 200 ms post-stimulus onset provides evidence against the involvement of low-level visual processes. We conclude that orthographic spatial integration is driven by parallel processing of multiple words, which leads to the activation of a larger set of sub-lexical nodes and more difficult processing at the lexical level when those words are orthographically unrelated., Highlights • Words are recognized faster when they share many letters with surrounding words. • EEG measurements suggest that this effect unfolds 200 ms after stimulus onset. • The locus of effects contradicts the involvement of low-level visual processing. • Instead, the phenomenon appears to be driven by parallel orthographic processing.

The human PFC has been associated more with meta-perceptual as opposed to meta-memory decisions from correlational neuroimaging investigations. Recently, metacognitive abilities have also been shown to be causally dependent upon anterior and dorsal PFC in nonhuman primate lesion studies. Two studies, using postdecision wagering paradigms and reversible inactivation, challenged this meta-perceptual versus meta-memory notion and showed that dorsal and anterior prefrontal areas are associated with metamemory for experienced objects and awareness of ignorance, respectively. Causal investigations are important but scarce; nothing is known, for example, about the causal contributions of prefrontal subregions to spatial metamemory. Here, we investigated the effects of dorsal versus ventral PFC lesions on two-alternative forced-choice spatial discrimination tasks in male macaque monkeys. Importantly, we were rigorous in approach and applied three independent but complementary indices used to quantify individual animals' metacognitive ability (“Type II sensitivity”) by two variants of meta-d′/d′ and phi coefficient (φ). Our results were consistent across indices: while neither lesions to superior dorsolateral PFC nor orbitofrontal cortex impaired spatial recognition performance, only monkeys with superior dorsolateral PFC lesions were impaired in meta-accuracy. Together with the observation that the same orbitofrontal cortex lesioned monkeys were impaired in updating rule value in a Wisconsin Card Sorting Test analog, we therefore document a functional double-dissociation between these two PFC regions. Our study presents important causal evidence that other dimensions, namely, domain-specific processing (e.g., spatial vs nonspatial metamemory), also need considerations in understanding the functional specialization in the neural underpinnings of introspection. SIGNIFICANCE STATEMENT This study demonstrates macaque monkeys' metacognitive capability of introspecting its own memory success is causally dependent on intact superior dorsolateral prefrontal cortices but not the orbitofrontal cortices. Combining neurosurgical techniques on monkeys and state-of-the-art measures of metacognition, we affirm a critical role of the PFC in supporting spatial meta-recognition memory and delineate functional specificity within PFC for distinct elements of metacognition.

The animacy effect refers to enhanced memory for animate over inanimate items. In two studies, we examined whether this memory advantage generalises to source memory. A multinomial processing tree model was used to disentangle item recognition, source memory, and guessing processes. In Study 1, animate and inanimate words were presented at different spatial locations on the screen. Animacy was associated with enhanced source memory for the spatial locations of the items. In Study 2, pseudowords were associated with animate and inanimate properties. Replicating previous results, the pseudowords were better remembered when they were associated with animate properties than when they were associated with inanimate properties. What is more, participants had enhanced source memory for the association between the pseudowords and the animate properties. The results strengthen the idea that animate items are associated with richer mnemonic representations than inanimate items.

An arrow marker appearing in a field of view shifts the observer's attention in its indicated direction. On the other hand, the gaze of another individual not only shifts the observer's attention but also increases the likability of objects in the direction of their gaze. These effects occur even when the arrow markers or gaze cues are presented for very short periods so that the observer is unaware of them. To expand on the findings of previous studies, we conducted two experiments. In the first we examined the changes in likability and attentional shift induced by supraliminal and subliminal arrow markers, using 40 male and 40 female participants. We found, contrary to previous findings, that supraliminal arrow markers not only shifted the observers' attention but slightly increased object likability. On the other hand, subliminal arrow markers only shifted the observers' attention. The attentional shift was stronger for female than for male participants in the case of supraliminal, but not of subliminal, markers. The second experiment verified the changes in likability induced by supraliminal arrow markers and compared the effects with those of supraliminal gaze cues among 40 female participants. We found that the liking effect was observed for both arrow markers and gaze cues. However, both effects were small, and no significant difference was found between them. Overall, these results show that gender and individual differences have considerable impacts on cueing effects.

The aim of this study was to investigate how expert and novice learners integrate dynamic information from two types of representations, namely auditory description and arrow symbols. Participants were required to perform both recognition and recall tests and rate their invested mental effort after studying two representations in four different orders of presentation (audio → audio, arrow → arrow, arrow → audio, or audio → arrow). When the same representation is presented twice, the results demonstrated the superiority of the spatial representation over the verbal representation for novice learners. However, when comparing the representations, it was found that novice learners achieved higher levels of performance when they had received audio first and then arrows, while expert learners showed the same level of performance regardless of the sequence of representations. Implications for improving instructional design techniques aimed at the acquisition of temporal information are discussed.

In discrete aiming movements the task criteria of time-minimization to a spatial target (e.g., Fitts, 1954) and time-matching to a spatial-temporal goal (e.g., Schmidt et al., 1979) tend to produce different functions of the speed-accuracy trade-off. Here we examined whether the task-related movement speed-accuracy characteristics were due to differential space-time trade-offs in time-matching, velocity-matching and time-minimizing task goals. Twenty participants performed 100 aiming trials for each of 15 combinations of task-type (3) and space-time condition (5). The prevalence of the primary types of sub-movement (none, pre-peak, post-peak, undershooting and overshooting) was determined from the kinematics of the movement trajectory. There were comparable distributions of trajectory sub-movement profiles and space-time movement outcomes across the three tasks at the short movement duration that became increasingly dissimilar over decreasing movement velocity and increasing movement time conditions. Movement time was the most influential variable in mediating sub-movement characteristics and the spatial/temporal outcome accuracy and variability of discrete aiming tasks - a role that was magnified in the explicit task demands of time-matching. The time-matching and time-minimization task goals in discrete aiming induce qualitatively different control processes that progressively contribute beyond the minimal time conditions to task-specific space-time accuracy and variability characteristics of the respective movement speed-accuracy functions.

In the human cortex, event-related potentials (ERPs) are triggered in response to sensory, cognitive or motor stimuli. Due to the inherent difficulties of conducting invasive mechanistic studies in human subjects, little is known as to the precise neurophysiological mechanisms that lead to their manifestation. By contrast, although much is known about synaptic and neural mechanisms that underlie information processing in rodents, very few studies have addressed to what extent ERPs are comparable in rodents and humans. Here, we explored this by triggering ERPs in both species during the passive observation of visuospatial imagery, shown in an oddball-like manner, using an experimental design that was equivalent. Several ERP-components were identified in the rodent cohort, corresponding, for example, to the human P1, N1, and P2. ERPs that are likely to reflect a rodent N2 and P300 were also detected. Deviance, as well as repetition effects were evident in both species, whereby rodent ERPs displayed more immediate response alterations to repeated stimuli and humans showed more gradual response shifts. These results indicate that humans and rodents may implement similar strategies for the passive perception and initial processing of visuospatial imagery, despite clear differences in their sensory and cognitive capacities.

Even though we frequently execute saccades, we perceive the external world as coherent and stable. An important mechanism of trans-saccadic perception is spatial remapping: the process of updating information across eye movements. Previous studies have indicated a right hemispheric dominance for spatial remapping, which has been proposed to translate into enhanced trans-saccadic memory for locations that are remapped into the right compared to the left hemisphere in healthy participants. Previous study designs suffered from several limitations, however (i.e. multiple eye movements had to be made instead of one, fixations were not controlled for, and ceiling effects were likely present). We therefore compared accuracy of trans-saccadic memory for central items after left- versus rightward eye movements, and secondary, for items that were remapped within the left versus right visual field. Participants memorized the location of a briefly presented item, made one saccade, and subsequently decided in what direction the item had shifted. We used a staircase to adjust task difficulty. Bayesian repeated measures ANOVAs were used to compare between left versus right eye movements and items in the left versus right visual field. We found most evidence against directional differences in trans-saccadic memory (BF10=0.23). We found some evidence suggestive of enhanced trans-saccadic memory for items that were remapped within the left compared to the right visual field (BF10=4.00). The latter result could be explained by a leftward spatial attention bias. As such, the hypothesized right hemispheric dominance for spatial remapping does not result in asymmetric trans-saccadic memory capacities in healthy participants.

The entorhinal–hippocampal circuit is one of the earliest sites of cortical pathology in Alzheimer's disease (AD). Visuospatial memory paradigms that are mediated by the entorhinal–hippocampal circuit may offer a means to detect memory impairment during the early stages of AD. In this study, we developed a 4-min visuospatial memory paradigm called VisMET (Visuospatial Memory Eye-Tracking Task) that passively assesses memory using eye movements rather than explicit memory judgements. We had 296 control or memory-impaired participants view a set of images followed by a modified version of the images with either an object removed, or a new object added. Healthy controls spent significantly more time viewing these manipulations compared to subjects with mild cognitive impairment and AD. Using a logistic regression model, the amount of time that individuals viewed these manipulations could predict cognitive impairment and disease status with an out of sample area under the receiver–operator characteristic curve of 0.85. Based on these results, VisMET offers a passive, sensitive, and efficient memory paradigm capable of detecting objective memory impairment and predicting cognitive and disease status.

It has been previously shown that the interaction between vision and audition involves early sensory cortices. However, the functional role of these interactions and their modulation due to sensory impairment is not yet understood. To shed light on the impact of vision on auditory spatial processing, we recorded ERPs and collected psychophysical responses during space and time bisection tasks in sighted and blind participants. They listened to three consecutive sounds and judged whether the second sound was either spatially or temporally further from the first or the third sound. We demonstrate that spatial metric representation of sounds elicits an early response of the visual cortex (P70) which is different between sighted and visually deprived individuals. Indeed, only in sighted and not in blind people P70 is strongly selective for the spatial position of sounds, mimicking many aspects of the visual-evoked C1. These results suggest that early auditory processing associated with the construction of spatial maps is mediated by visual experience. The lack of vision might impair the projection of multi-sensory maps on the retinotopic maps used by the visual cortex.

When searching a target in a natural scene, it has been shown that both the target’s visual properties and similarity to the background influence whether and how fast humans are able to find it. So far, it was unclear whether searchers adjust the dynamics of their eye movements (e.g., fixation durations, saccade amplitudes) to the target they search for. In our experiment, participants searched natural scenes for six artificial targets with different spatial frequency content throughout eight consecutive sessions. High-spatial frequency targets led to smaller saccade amplitudes and shorter fixation durations than low-spatial frequency targets if target identity was known. If a saccade was programmed in the same direction as the previous saccade, fixation durations and successive saccade amplitudes were not influenced by target type. Visual saliency and empirical fixation density at the endpoints of saccades which maintain direction were comparatively low, indicating that these saccades were less selective. Our results suggest that searchers adjust their eye movement dynamics to the search target efficiently, since previous research has shown that low-spatial frequencies are visible farther into the periphery than high-spatial frequencies. We interpret the saccade direction specificity of our effects as an underlying separation into a default scanning mechanism and a selective, target-dependent mechanism.

When face was inverted, dynamic gaze cues could still effectively direct attention despite the disruption of configural face processing, but the static gaze cues could not. The present study investigated the role of the motion cue in the dynamic Gaze-Cueing Effect (GCE). With schematic and real faces, we employed the gaze-cueing paradigm to examine the differences among three kinds of cues (static gaze cue, dynamic gaze cue and motion cue) based on behavioral results and event-related potentials. Behavioral results revealed significant GCE in all conditions. In the schematic face group, the motion cue (two symmetrical dots shifting slightly to the side) induced a significantly smaller GCE than the dynamic gaze cues (two symmetrical dots moving within a rounded circle), while in the real face group, the motion cue (that is, the inverted-face gaze cue) remained a strong GCE compared with other conditions. With regard to the ERP results, we found the early directing attention negativity (EDAN), which was sensitive to voluntary cues (e.g. arrow cue) rather than gaze cue, in the schematic motion cue condition, but not in the inverted-face gaze cue condition. We supposed that the motion cue (real face) could activate the configural face processing even when the face is inverted. This finding supported that EDAN reflected a cue-triggered attention shift.

Location appears to play a vital role in binding discretely processed visual features into coherent objects. Consequently, it has been proposed that objects are represented for cognition by their spatiotemporal location, with other visual features attached to this location index. On this theory, the visual features of an object are only connected via mutual location; direct binding cannot occur. Despite supporting evidence, some argue that direct binding does take over according to task demands and when representing familiar objects. The current study was developed to evaluate these claims, using a brief memory task to test for contingencies between features under different circumstances. Participants were shown a sequence of three items in different colours and locations, and then asked for the colour and/or location of one of them. The stimuli could either be abstract shapes, or familiar objects. Results indicated that location is necessary for binding regardless of the type of stimulus and task demands, supporting the proposed structure. A follow-up experiment assessed an alternate explanation for the apparent importance of location in binding; eye movements may automatically capture location information, making it impossible to ignore and suggesting a contingency that is not representative of cognitive processes. Participants were required to maintain fixation on half of the trials, with an eye tracker for confirmation. Results indicated that the importance of location in binding cannot be attributed to eye movements. Overall, the findings of this study support the claim that location is essential for visual feature binding, due to the structure of object representations.

Background Children born preterm are at risk of visuospatial attention orienting and processing dysfunctions, which can be quantified early in life using visually-guided eye movement responses. Aims To identify the prevalence and perinatal risk factors for visuospatial attention orienting and processing dysfunctions in children born preterm of 1 year of corrected age (CA). Study design 123 children born between 26 and 33 weeks of gestation underwent a nonverbal visuospatial test at 1y CA, using an eye tracking-based paradigm. For the detected high-salient (cartoon and contrast), intermediate-salient (form and motion) and low-salient (color) stimuli, we quantified the reaction time to fixation (RTF). RTFs were compared to normative references from an age-matched control group (N = 38). The prevalence of perinatal risk factors (gestational age and weight, indices of neurological damage, overal sickness, respiratory failure, and retinopathy) was compared between the groups with normal and delayed RTFs. Results At 1y CA, the preterm group had 7–20% less detected stimuli than the control group, particularly for intermediate and low-salient stimuli. Compared to normative RTFs, modest delays were found for high-salient cartoon (in 19% of preterm children) and contrast (8%), intermediate-salient motion (23%) and form (21%), and low-salient color stimuli (8%). These children had a significantly higher prevalence of perinatal risk factors for respiratory failure and intraventricular hemorrhages. Conclusions Children born between 26 and 32 weeks have a modest risk (8–23%) of visuospatial attention and processing dysfunction. This warrants early monitoring and support of general visual development in preterm children at risk of respiratory distress and disrupted cerebral blood flow.

Purpose To detect visual field (VF) progression by analyzing spatial pattern changes. Methods We selected 12,217 eyes from 7360 patients with at least five reliable 24-2 VFs and 5 years of follow-up with an interval of at least 6 months. VFs were decomposed into 16 archetype patterns previously derived by artificial intelligence techniques. Linear regressions were applied to the 16 archetype weights of VF series over time. We defined progression as the decrease rate of the normal archetype or any increase rate of the 15 VF defect archetypes to be outside normal limits. The archetype method was compared with mean deviation (MD) slope, Advanced Glaucoma Intervention Study (AGIS) scoring, Collaborative Initial Glaucoma Treatment Study (CIGTS) scoring, and the permutation of pointwise linear regression (PoPLR), and was validated by a subset of VFs assessed by three glaucoma specialists. Results In the method development cohort of 11,817 eyes, the archetype method agreed more with MD slope (kappa: 0.37) and PoPLR (0.33) than AGIS (0.12) and CIGTS (0.22). The most frequently progressed patterns included decreased normal pattern (63.7%), and increased nasal steps (16.4%), altitudinal loss (15.9%), superior-peripheral defect (12.1%), paracentral/central defects (10.5%), and near total loss (10.4%). In the clinical validation cohort of 397 eyes with 27.5% of confirmed progression, the agreement (kappa) and accuracy (mean of hit rate and correct rejection rate) of the archetype method (0.51 and 0.77) significantly (P < 0.001 for all) outperformed AGIS (0.06 and 0.52), CIGTS (0.24 and 0.59), MD slope (0.21 and 0.59), and PoPLR (0.26 and 0.60). Conclusions The archetype method can inform clinicians of VF progression patterns.

Sensorimotor adaptation to wedge prisms can alter the balance of attention between left and right space in healthy adults, and improve symptoms of spatial neglect after stroke. Here we asked whether the orienting of spatial attention to visual stimuli is affected by a different form of sensorimotor adaptation that involves physical perturbations of arm movement, rather than distortion of visual feedback. Healthy participants performed a cued discrimination task before and after they made reaching movements to a central target. A velocity-dependent force field pushed the hand aside during each reach, and required participants to apply compensatory forces toward the opposite side. We used event-related potentials (ERPs) to determine whether electroencephalography (EEG) responses reflecting orienting (cue-locked N1) and disengagement (target-locked P1) of spatial attention are affected by adaptation to force fields. After adaptation, the cue-locked N1 was relatively larger for stimuli presented in the hemispace corresponding to the direction of compensatory hand force. P1 amplitudes evoked by invalidly cued targets presented on the opposite side were reduced. This suggests that force field adaptation boosted attentional orienting responses toward the side of hand forces, and impeded attentional disengagement from that side, mimicking previously reported effects of prism adaptation. Thus, remapping between motor commands and intended movement direction is sufficient to bias ERPs, reflecting changes in the orienting of spatial attention in the absence of visuo-spatial distortion or visuo-proprioceptive mismatch. Findings are relevant to theories of how sensorimotor adaptation can modulate attention, and may open new avenues for treatment of spatial neglect.

Representing multiple agents and their mutual relations is a prerequisite to understand social events. Using functional MRI on human adults, we show that visual areas dedicated to body-form and body-motion perception contribute to processing social events, by holding the representation of multiple moving bodies and encoding the spatial relations between them. In particular, seeing animations of human bodies facing and moving toward (vs. away from) each other, increased neural activity in the body-selective cortex (extrastriate body area -EBA) and posterior superior temporal sulcus for biological-motion perception (bm-pSTS). In those areas, representation of body postures and movements, as well as of the overall scene, was more accurate for facing-body (vs. non-facing body) stimuli. Effective connectivity analysis with Dynamic Causal Modeling revealed increased coupling between EBA and bm-pSTS during perception of facing-body stimuli. The attunement of human vision to multiple-body scenes involving perceptual cues of interaction such as face-to-face positioning and approaching behaviour, was further supported by the participants’ better performance in a match-to-sample task with facing-body vs. non-facing body stimuli. Thus, visuo-spatial cues of interaction in multiple-person scenarios affect the perceptual representation of body and body motion and, by promoting functional integration, streamline the process from body perception to action representation.

Listeners typically perceive a sound as originating from the direction of its source, even as direct sound is followed milliseconds later by reflected sound from multiple different directions. Early-arriving sound is emphasised in the ascending auditory pathway, including the medial superior olive (MSO) where binaural neurons encode the interaural-time-difference (ITD) cue for spatial location. Perceptually, weighting of ITD conveyed during rising sound energy is stronger at 600 Hz than at 200 Hz, consistent with the minimum stimulus rate for binaural adaptation, and with the longer reverberation times at 600 Hz, compared with 200 Hz, in many natural outdoor environments. Here, we computationally explore the combined efficacy of adaptation prior to the binaural encoding of ITD cues, and excitatory binaural coincidence detection within MSO neurons, in emphasising ITDs conveyed in early-arriving sound. With excitatory inputs from adapting, nonlinear model spherical bushy cells (SBCs) of the bilateral cochlear nuclei, a nonlinear model MSO neuron with low-threshold potassium channels reproduces the rate-dependent emphasis of rising vs. peak sound energy in ITD encoding; adaptation is equally effective in the model MSO. Maintaining adaptation in model SBCs, and adjusting membrane speed in model MSO neurons, ‘left’ and ‘right’ populations of computationally efficient, linear model SBCs and MSO neurons reproduce this stronger weighting of ITD conveyed during rising sound energy at 600 Hz compared to 200 Hz. This hemispheric population model demonstrates a link between strong weighting of spatial information during rising sound energy, and correct unambiguous lateralisation of a speech source in reverberation.

The ability to encode space is a crucial aspect of interacting with the external world. Therefore, this ability appears to be fundamental for the correct development of the capacity to integrate different spatial reference frames. The spatial reference frame seems to be present in all the sensory modalities. However, it has been demonstrated that different sensory modalities follow various developmental courses. Nevertheless, to date these courses have been investigated only in people with sensory impairments, where there is a possible bias due to compensatory strategies and it is complicated to assess the exact age when these skills emerge. For these reasons, we investigated the development of the allocentric frame in the auditory domain in a group of typically developing children aged 6–10 years. To do so, we used an auditory Simon task, a paradigm that involves implicit spatial processing, and we asked children to perform the task in both the uncrossed and crossed hands postures. We demonstrated that the crossed hands posture affected the performance only in younger children (6–7 years), whereas at 10 years of age children performed as adults and were not affected by such posture. Moreover, we found that this task’s performance correlated with age and developmental differences in spatial abilities. Our results support the hypothesis that auditory spatial cognition’s developmental course is similar to the visual modality development as reported in the literature.

Background: Rapid technological advances offer a possibility to develop cost-effective digital cognitive assessment tools. However, it is unclear whether these measures are suitable for application in populations from Low and middle-income countries (LMIC). Objective: To examine the accuracy and validity of the Brain Health Assessment (BHA) in detecting cognitive impairment in a Cuban population. Methods: In this cross-sectional study, 146 participants (cognitively healthy = 53, mild cognitive impairment (MCI) = 46, dementia = 47) were recruited at primary care and tertiary clinics. The main outcomes included: accuracy of the BHA and the Montreal Cognitive Assessment (MoCA) in discriminating between controls and cognitively impaired groups (MCI and dementia) and correlations between the BHA subtests of memory, executive functions, and visuospatial skills and criterion-standard paper-and-pencil tests in the same domains. Results: The BHA had an AUC of 0.95 (95% CI: 0.91–0.98) in discriminating between controls and cognitively impaired groups (MCI and dementia, combined) with 0.91 sensitivity at 0.85 specificity. In discriminating between control and MCI groups only, the BHA tests had an AUC of 0.94 (95% CI: 0.90–0.99) with 0.71 sensitivity at 0.85 specificity. Performance was superior to the MoCA across all diagnostic groups. Concurrent and discriminant validity analyses showed moderate to strong correlations between the BHA tests and standard paper-and-pencil measures in the same domain and weak correlations with standard measures in unrelated domains. Conclusion: The BHA has excellent performance characteristics in detecting cognitive impairment including dementia and MCI in a Hispanic population in Cuba and outperformed the MoCA. These results support potential application of digital cognitive assessment for older adults in LMIC.

The perirhinal cortex is situated on the border between sensory association cortex and the hippocampal formation. It serves an important function as a transition area between the sensory neocortex and the medial temporal lobe. While the perirhinal cortex has traditionally been associated with object coding and the “what” pathway of the temporal lobe, current evidence suggests a broader function of the perirhinal cortex in solving feature ambiguity and processing complex stimuli. Besides fulfilling functions in object coding, recent neurophysiological findings in freely moving rodents indicate that the perirhinal cortex also contributes to spatial and contextual processing beyond individual sensory modalities. Here, we address how these two opposing views on perirhinal cortex—the object‐centered and spatial‐contextual processing hypotheses—may be reconciled. The perirhinal cortex is consistently recruited when different features can be merged perceptually or conceptually into a single entity. Features that are unitized in these entities include object information from multiple sensory domains, reward associations, semantic features and spatial/contextual associations. We propose that the same perirhinal network circuits can be flexibly deployed for multiple cognitive functions, such that the perirhinal cortex performs similar unitization operations on different types of information, depending on behavioral demands and ranging from the object‐related domain to spatial, contextual and semantic information.

Neural components enabling flexible cognition and behavior are well-established, and depend mostly on proper intercommunication within the prefrontal cortex (PFC) and striatum. However, dense projections from the ventral hippocampus (vHPC) alter the functioning of the medial PFC (mPFC). Dysfunctional hippocampo-prefrontal connectivity negatively affects the integrity of flexible cognition, especially in patients with schizophrenia. In this study, we aimed to test the role of the vHPC and mPFC in a place avoidance task on a rotating arena using two spatial flexibility task variants - reversal learning and set-shifting. To achieve this, we inactivated each of these structures in adult male Long-Evans rats by performing bilateral local muscimol (a GABAA receptor agonist) injections. A significantly disrupted performance was observed in reversal learning in the vHPC-inactivated, but not in the mPFC-inactivated rats. These results confirm the notion that the vHPC participates in some forms of behavioral flexibility, especially when spatial cues are needed. It seems, rather unexpectedly, that the mPFC is not taxed in these flexibility tasks on a rotating arena.

Patients with posterior cortical atrophy (PCA-AD) show more severe visuospatial and perceptual deficits than those with typical AD (tAD). The aim of this study was to investigate whether functional alterations measured by electroencephalography can help understand the mechanisms that explain this clinical heterogeneity. 21-channel electroencephalography recordings of 29 patients with PCA-AD were compared with 29 patients with tAD and 29 controls matched for age, gender, and disease severity. Patients with PCA-AD and tAD both showed a global decrease in fast and increase in slow oscillatory activity compared with controls. This pattern was, however, more profound in patients with PCA-AD which was driven by more extensive slowing of the posterior regions. Alpha band functional connectivity showed a similar decrease in PCA-AD and tAD. Compared with controls, a less integrated network topology was observed in PCA-AD, with a decrease of posterior and an increase of frontal hubness. In PCA-AD, decreased right parietal peak frequency correlated with worse performance on visual tasks. Regional vulnerability of the posterior network might explain the atypical pattern of neurodegeneration in PCA-AD.

Among the techniques used to reduce spatial neglect's symptoms, left neck muscle vibration (NMV) is alluring because it does not require the patient's attentional co-operation. The aim of this study was to determine the type of NMV-associated feedback that induced the most intense and longest-lasting egocentric post-effects. Eighty-seven healthy individuals were randomly assigned to four intervention groups: "neck muscle vibration, blindfolded" (NMV), "neck muscle vibration with vision" (NMV + V), "neck muscle vibration and visual finger-pointing" (NMV + P), and "visual finger-pointing" (P). An eyes-closed finger-pointing subjective straight-ahead (SSA) test was carried out before the intervention, immediately afterwards, and 30 min afterwards. The results showed that only the NMV + P intervention induced a lasting leftward bias of SSA. In addition, the deviation reported in this intervention group differed significantly from those observed in the other interventions. The combination of visuo-haptic feedback and neck-somatosensory stimulation may enable a full, lasting intermodal recalibration, which could be potentiated by the attention level engaged during voluntary pointing. These outcomes highlighted that the NMV technique could easily integrate into routine occupational therapy sessions for treating various aspects of neglect disorders.

Summary Humans use rapid gaze shifts, known as saccades, to explore visual scenes. These movements yield abrupt luminance changes on the retina, which elicit robust neural discharges at fixation onsets. Yet little is known about the spatial content of saccade transients. Here, we show that saccades redistribute spatial information within the temporal range of retinal sensitivity following two distinct regimes: saccade modulations counterbalance (whiten) the spectral density of natural scenes at low spatial frequencies and follow the external power distribution at higher frequencies. This redistribution is a consequence of saccade dynamics, particularly the speed/amplitude/duration relation known as the main sequence. It resembles the redistribution resulting from inter-saccadic eye drifts, revealing a continuum in the modulations given by different eye movements, with oculomotor transitions primarily acting by regulating the bandwidth of whitening. Our findings suggest important computational roles for saccade transients in the establishment of spatial representations and lead to testable predictions about their consequences for visual functions and encoding mechanisms. Video Abstract Download : Download video (30MB)

Heading estimation from optic flow relies on the assumption that the visual world is rigid. This assumption is violated when one moves through a crowd of people, a common and socially important situation. The motion of people in the crowd contains cues to their translation in the form of the articulation of their limbs, known as biological motion. We investigated how translation and articulation of biological motion influence heading estimation from optic flow for self-motion in a crowd. Participants had to estimate their heading during simulated self-motion toward a group of walkers who collectively walked in a single direction. We found that the natural combination of translation and articulation produces surprisingly small heading errors. In contrast, experimental conditions that either present only translation or only articulation produced strong idiosyncratic biases. The individual biases explained well the variance in the natural combination. A second experiment showed that the benefit of articulation and the bias produced by articulation were specific to biological motion. An analysis of the differences in biases between conditions and participants showed that different perceptual mechanisms contribute to heading perception in crowds. We suggest that coherent group motion affects the reference frame of heading perception from optic flow.

In hearing individuals, vestibular and visuo-spatial functions seem to be functionally linked. Previous studies have suggested that congenitally deaf individuals are at a higher risk for vestibular problems, which in hearing adults have often been found to be associated with impairments in visuo-spatial processing. However, communicating in a sign language provides extensive practice in visuo-spatial processing, which might counteract negative effects of vestibular impairments. Here, we investigated whether the functional link between vestibular and visuo-spatial functions is mandatory, that is whether it is impenetrable to experience or context, or whether it is dependent on specific sensory and cognitive experiences. To this end, we tested a group of congenitally deaf native signers and a group of hearing nonsigners on mental rotation and balance tasks. Compared to hearing nonsigners, mental rotation was superior in the deaf signers in conditions crucial for sign language comprehension. By contrast, the balance performance of the group of deaf signers was impaired. While in the group of hearing nonsigners, balance skills correlated with mental rotation abilities, no such relationship was observed in the group of deaf signers. These results suggest that the link between vestibular and visuo-spatial functions is not fixed but can be altered or even cancelled out by certain sensory or cognitive experiences, such as the acquisition of a sign language.

Attentional tracking and working memory tasks are often performed better when targets are divided evenly between the left and right visual hemifields, rather than contained within a single hemifield (Alvarez & Cavanagh, 2005; Delvenne, 2005). However, this bilateral field advantage does not provide conclusive evidence of hemifield-specific control of attention and working memory, as it can be explained solely from hemifield-limited spatial interference at early stages of visual processing. If control of attention and working memory is specific to each hemifield, maintaining target information should become more difficult as targets move between the two hemifields. Observers in the present study maintained targets that moved either within or between the left and right hemifields, using either attention (Experiment 1) or working memory (Experiment 2). Maintaining spatial information was more difficult when target items moved between the hemifields compared to when target items moved within their original hemifields, consistent with hemifield-specific control of spatial attention and working memory. However, this pattern was not found for maintaining identity information (e.g., color) in working memory (Experiment 3). Together, these results provide evidence that control of spatial attention and working memory is specific to each hemifield, and that hemifield-specific control is a unique signature of spatial processing.

ObjectivesIn young adults, the ability to verbally recall instructions in working memory is enhanced if the sequences are physically enacted by the participant (self-enactment) or the experimenter (demonstration) during encoding. Here we examine the effects of self-enactment and demonstration at encoding on working memory performance in older and younger adults.MethodFifty young (18–23 years) and 40 older (60–89 years) adults listened to sequences of novel action-object pairs before verbally recalling them in the correct order. There were three different encoding conditions: spoken only, spoken + demonstration, and spoken + self-enactment. We included two different levels of difficulty to investigate whether task complexity moderated the effect of encoding condition and whether this differed between age groups.ResultsRelative to the spoken only condition, demonstration significantly improved young and older adults’ serial recall performance, but self-enactment only enhanced performance in the young adults, and this boost was smaller than the one gained through demonstration.DiscussionOur findings suggest that additional spatial-motoric information is beneficial for older adults when the actions are demonstrated to them, but not when the individual must enact the instructions themselves.

Declining auditory spatial processing is hypothesized to contribute to the difficulty older adults have detecting, locating, and selecting a talker from among others in noisy listening environments. Though auditory spatial processing has been associated with several cortical structures, little is known regarding the underlying white matter architecture or how age-related changes in white matter microstructure may affect it. The arcuate fasciculus is a target for understanding age-related differences in auditory spatial attention based on normative spatial attention findings in humans. Similarly, animal and human clinical studies suggest that the corpus callosum plays a role in the cross-hemispheric integration of auditory spatial information important for spatial localization and attention. The current investigation used diffusion imaging to examine the extent to which age-group differences in the identification of spatially cued speech were accounted for by individual differences in the white matter microstructure of the right arcuate fasciculus and the corpus callosum. Higher right arcuate and callosal fractional anisotropy (FA) predicted better segregation and identification of spatially cued speech across younger and older listeners. Further, individual differences in callosal microstructure mediated age-group differences in auditory spatial processing. Follow-up analyses suggested that callosal tracts connecting left and right pre-frontal and posterior parietal cortex are particularly important for auditory spatial processing. The results are consistent with previous work in animals and clinical human samples and provide a cortical mechanism to account for age-related deficits in auditory spatial processing. Further, the results suggest that both intrahemispheric and interhemispheric mechanisms are involved in auditory spatial processing.