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People can support abstract reasoning by using mental models with spatial simulations. Such models are employed when people represent elements in terms of ordered dimensions (e.g. who is oldest, Tom, Dick, or Harry). We test and find that the process of forming and using such mental models can influence the liking of its elements (e.g. Tom, Dick, or Harry). The presumed internal structure of such models (linear-transitive array of elements), generates variations in processing ease (fluency) when using the model in working memory (see the Symbolic Distance Effect, SDE). Specifically, processing of pairs where elements have larger distances along the order should be easier compared to pairs with smaller distances. Elements from easier pairs should be liked more than elements from difficult pairs (fluency being hedonically positive). Experiment 1 shows that unfamiliar ideographs are liked more when at wider distances and therefore easier to process. Experiment 2 replicates this effect with non-words. Experiment 3 rules out a non-spatial explanation of the effect while Experiments 4 offers a high-powered replication. Experiment 5 shows that the spatial effect spontaneously emerges after learning, even without a task that explicitly focuses on fluency. Experiment 6 employed a shorter array, but yielded no significant results.

Even though vision is considered the best suited sensory modality to acquire spatial information, blind individuals can form spatial representations to navigate and orient themselves efficiently in space. Consequently, many studies support the amodality hypothesis of spatial representations since sensory modalities other than vision contribute to the formation of spatial representations, independently of visual experience and imagery. However, given the high variability in abilities and deficits observed in blind populations, a clear consensus about the neural representations of space has yet to be established. To this end, we performed a meta-analysis of the literature on the neural correlates of spatial processing and navigation via sensory modalities other than vision, like touch and audition, in individuals with early and late onset blindness. An activation likelihood estimation (ALE) analysis of the neuroimaging literature revealed that early blind individuals and sighted controls activate the same neural networks in the processing of non-visual spatial information and navigation, including the posterior parietal cortex, frontal eye fields, insula, and the hippocampal complex. Furthermore, blind individuals also recruit primary and associative occipital areas involved in visuo-spatial processing via cross-modal plasticity mechanisms. The scarcity of studies involving late blind individuals did not allow us to establish a clear consensus about the neural substrates of spatial representations in this specific population. In conclusion, the results of our analysis on neuroimaging studies involving early blind individuals support the amodality hypothesis of spatial representations.

Even though vision is considered the best suited sensory modality to acquire spatial information, blind individuals can form spatial representations to navigate and orient themselves efficiently in space. Consequently, many studies support the amodality hypothesis of spatial representations since sensory modalities other than vision contribute to the formation of spatial representations, independently of visual experience and imagery. However, given the high variability in abilities and deficits observed in blind populations, a clear consensus about the neural representations of space has yet to be established. To this end, we performed a meta-analysis of the literature on the neural correlates of spatial processing and navigation via sensory modalities other than vision, like touch and audition, in individuals with early and late onset blindness. An activation likelihood estimation (ALE) analysis of the neuroimaging literature revealed that early blind individuals and sighted controls activate the same neural networks in the processing of non-visual spatial information and navigation, including the posterior parietal cortex, frontal eye fields, insula, and the hippocampal complex. Furthermore, blind individuals also recruit primary and associative occipital areas involved in visuo-spatial processing via cross-modal plasticity mechanisms. The scarcity of studies involving late blind individuals did not allow us to establish a clear consensus about the neural substrates of spatial representations in this specific population. In conclusion, the results of our analysis on neuroimaging studies involving early blind individuals support the amodality hypothesis of spatial representations.

Throughout their daily lives, animals and humans often switch between different behaviours. However, neuroscience research typically studies the brain while the animal is performing one behavioural task at a time, and little is known about how brain circuits represent switches between different behaviours. Here we tested this question using an ethological setting: two bats flew together in a long 135 m tunnel, and switched between navigation when flying alone (solo) and collision avoidance as they flew past each other (cross-over). Bats increased their echolocation click rate before each cross-over, indicating attention to the other bat1-9. Hippocampal CA1 neurons represented the bat's own position when flying alone (place coding10-14). Notably, during cross-overs, neurons switched rapidly to jointly represent the interbat distance by self-position. This neuronal switch was very fast-as fast as 100 ms-which could be revealed owing to the very rapid natural behavioural switch. The neuronal switch correlated with the attention signal, as indexed by echolocation. Interestingly, the different place fields of the same neuron often exhibited very different tuning to interbat distance, creating a complex non-separable coding of position by distance. Theoretical analysis showed that this complex representation yields more efficient coding. Overall, our results suggest that during dynamic natural behaviour, hippocampal neurons can rapidly switch their core computation to represent the relevant behavioural variables, supporting behavioural flexibility.

BackgroundRapid 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).ObjectiveTo examine the accuracy and validity of the Brain Health Assessment (BHA) in detecting cognitive impairment in a Cuban population.MethodsIn 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.ResultsThe 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.ConclusionThe 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.

Дисертаційна робота присвячена використанню просторової обробки сигналів по сферичному фазовому фронту ЕМХ для вирішення актуальної науково-технічної задачі – визначення координат (пеленга та дальності) для ДРВ проміжної зони та просторової селекції сигналу обраного ДРВ на фоні сигналів інших ДРВ. У роботі розроблено фазовий метод пеленгації та удосконалено метод пеленгації Кейпона, які відповідно дозволяють визначати координати місцеположення для одного та декількох ДРВ проміжної зони по сферичному фронту ЕМХ. Удосконалено метод просторової селекції сигналів, що дозволяє по сферичності фазових фронтів ЕМХ розділяти один від одного сигнали з ідентичними поляризаційно-частотними характеристиками від кількох ДРВ, в тому числі й при співпадінні їх пеленгів, але за наявності рознесення за дальністю розташування ДРВ. На основі запропонованих методів представлено технічні рішення з побудови фазових радіопеленгаторів та систем просторової селекції сигналів. Проведено експериментальне дослідження, яке в лабораторних умовах підтвердило можливість здійснення просторової селекції сигналу по сферичному фронту ЕМХ від обраного ДРВ проміжної зони на фоні сигналів від інших ДРВ.

Дисертаційна робота присвячена використанню просторової обробки сигналів по сферичному фазовому фронту ЕМХ для вирішення актуальної науково-технічної задачі – визначення координат (пеленга та дальності) для ДРВ проміжної зони та просторової селекції сигналу обраного ДРВ на фоні сигналів інших ДРВ. У роботі розроблено фазовий метод пеленгації та удосконалено метод пеленгації Кейпона, які відповідно дозволяють визначати координати місцеположення для одного та декількох ДРВ проміжної зони по сферичному фронту ЕМХ. Удосконалено метод просторової селекції сигналів, що дозволяє по сферичності фазових фронтів ЕМХ розділяти один від одного сигнали з ідентичними поляризаційно-частотними характеристиками від кількох ДРВ, в тому числі й при співпадінні їх пеленгів, але за наявності рознесення за дальністю розташування ДРВ. На основі запропонованих методів представлено технічні рішення з побудови фазових радіопеленгаторів та систем просторової селекції сигналів. Проведено експериментальне дослідження, яке в лабораторних умовах підтвердило можливість здійснення просторової селекції сигналу по сферичному фронту ЕМХ від обраного ДРВ проміжної зони на фоні сигналів від інших ДРВ., The thesis is devoted to the spatial signal processing application by the shape of the electromagnetic wave phase front in radio engineering systems for solving actual scientific problems: determination of location coordinates and spatial signal selection of radio sources located in one or different regions, including the case of angular coordinates coincidence of the radiation sources. The aim of the dissertation is to increase the efficiency of the radio sources positions determining located in the intermediate-field region and their spatial selection by developing and improving phase direction finding methods, as well as the method of spatial filtering, mathematical models of which take into account the sphericity of the electromagnetic wave phase front. The following new scientific results are obtained in the thesis: 1. Рhase method of a radio source direction finding was developed for the first time, where the sphericity of an electromagnetic wave phase front for the mathematical model of which is taken into account. This phase method allows to determine the bearing aangle and distance for one radio source located in the intermediate-field region. 2. The Capon’s method of direction finding was improved by entering the mathematical model of electromagnetic wave with the spherical phase front instead of the flat phase front model in the antenna array steering vector, which allows to determine the bearing angle and distance for several radio sources located in the intermediate-field region. 3. Spatial signal filtering method was improved by using direction finding method of several radio sources to obtain information about the spatial position of this radio sources. The method allows to separate from each other signals with identical polarization and frequency characteristics from several radio sources by the sphericity of the electromagnetic waves phase fronts, including the case when their bearing angles are equal. The practical significance of the thesis is tha, Диссертационная работа посвящена использованию пространственной обработки сигналов по сферическому фазовому фронту ЭМВ для решения актуальной научно-технической задачи – определения координат (пеленга и дальности) для ИРИ промежуточной зоны и пространственной селекции сигнала выбранного ИРИ на фоне сигналов от других ИРИ. В работе разработаны фазовый метод пеленгации и усовершенствован метод пеленгации Кейпона, которые соответственно позволяют определять координаты местоположения для одного и нескольких ИРИ промежуточной зоны по сферическому фронту ЭМВ. Усовершенствован метод пространственной селекции сигналов, позволяющий по сферичности фазовых фронтов ЭМВ разделять друг от друга сигналы с идентичными поляризационно-частотными характеристиками от нескольких ИРИ, в том числе и при совпадении их пеленгов, но при наличии разнесения по дальности расположения ИРИ. На основе предложенных методов представлены технические решения по построению фазовых радиопеленгаторов и систем пространственной селекции сигналов. Проведено экспериментальное исследование, которое в лабораторных условиях подтвердило возможность осуществления пространственной селекции сигнала по сферическому фронту ЭМВ от выбранного ИРИ промежуточной зоны на фоне сигналов от других ИРИ.

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.

BackgroundGenetic factors have been suggested to affect the efficacy of working memory training. However, few studies have attempted to identify the relevant genes.MethodsIn this study, we first performed a randomized controlled trial (RCT) to identify brain regions that were specifically affected by working memory training. Sixty undergraduate students were randomly assigned to either the adaptive training group (N = 30) or the active control group (N = 30). Both groups were trained for 20 sessions during 4 weeks and received fMRI scans before and after the training. Afterward, we combined the data from the 30 participants in the RCT study who received adaptive training with data from 71 additional participants who also received the same adaptive training but were not part of the RCT study (total N = 101) to test the contribution of the COMT Val158/108Met polymorphism to the interindividual difference in the training effect within the identified brain regions.ResultsIn the RCT study, we found that the adaptive training significantly decreased brain activation in the left prefrontal cortex (TFCE-FWE corrected p = .030). In the genetic study, we found that compared with the Val allele homozygotes, the Met allele carriers' brain activation decreased more after the training at the left prefrontal cortex (TFCE-FWE corrected p = .025).ConclusionsThis study provided evidence for the neural effect of a visual-spatial span training and suggested that genetic factors such as the COMT Val158/108Met polymorphism may have to be considered in future studies of such training.

Human adults are faster to respond to small/large numerals with their left/right hand when they judge the parity of numerals, which is known as the SNARC (spatial-numerical association of response codes) effect. It has been proposed that the size of the SNARC effect depends on response latencies. The current study introduced a perceptual orientation task, where participants were asked to judge the orientation of a digit or a frame surrounding the digit. The present study first confirmed the SNARC effect with native Chinese speakers (Experiment 1) using a parity task, and then examined whether the emergence and size of the SNARC effect depended on the response latencies (Experiments 2, 3, and 4) using a perceptual orientation judgment task. Our results suggested that (a) the automatic processing of response-related numerical-spatial information occurred with Chinese-speaking participants in the parity task; (b) the SNARC effect was also found when the task did not require semantic access; and (c) the size of the effect depended on the processing speed of the task-relevant dimension. Finally, we proposed an underlying mechanism to explain the SNARC effect in the perceptual orientation judgment task.

INTRODUCTION: Previous research has identified a relationship between hearing loss and cognitive impairment/dementia in older adults, however this research has primarily focused on measures of sensorineural hearing loss (SNHL). Central Auditory Processing (CAP), an ability which decreases with increasing age, is recognised as important for understanding speech in background noise, but is not routinely considered in audiological assessment or hearing-cognition research. Yet, some studies have provided evidence that poorer performance on some measures of CAP ability significantly relate to reduced cognitive function and/or increased likelihood of dementia diagnosis. Although there is no known treatment for cognitive impairment, hearing impairment is to some extent treatable with hearing aids (HAs). OBJECTIVES: This study aimed to examine the relationship between hearing impairment and cognitive impairment by assessing both peripheral hearing loss and CAP ability. Additionally, this research aimed to investigate how hearing, cognition and personal factors influence HA outcomes (uptake/use/benefit) in older adults. DESIGN: Experimental study design with 85 older adults between the ages of 60.33 and 80.08 (m =70.23, SD = 5.17). SNHL was assessed using Pure Tone Audiometry (PTA), the Listening in Spatialised noise-Sentences (LiSN-S) test and Dichotic Digits Test. Cognition was measured using the Cogstate Brief Battery. Personal factors were recorded from participant’s answers on a series of take-home questionnaires. Hearing aid benefit and use was subjectively reported at three- and six-months post HA fitting. RESULTS: Results for three of the four LiSN-S conditions shared a significant correlation with at least one cognitive measure, and SNHL was also significantly related to two cognitive domains (attention and executive function) in this cohort. Those who decided to use HAs had significantly poorer hearing as measured by both PTA and the LiSN-S test, and those with poo

Human adults are faster to respond to small/large numerals with their left/right hand when they judge the parity of numerals, which is known as the SNARC (spatial-numerical association of response codes) effect. It has been proposed that the size of the SNARC effect depends on response latencies. The current study introduced a perceptual orientation task, where participants were asked to judge the orientation of a digit or a frame surrounding the digit. The present study first confirmed the SNARC effect with native Chinese speakers (Experiment 1) using a parity task, and then examined whether the emergence and size of the SNARC effect depended on the response latencies (Experiments 2, 3, and 4) using a perceptual orientation judgment task. Our results suggested that (a) the automatic processing of response-related numerical-spatial information occurred with Chinese-speaking participants in the parity task; (b) the SNARC effect was also found when the task did not require semantic access; and (c) the size of the effect depended on the processing speed of the task-relevant dimension. Finally, we proposed an underlying mechanism to explain the SNARC effect in the perceptual orientation judgment task.

BackgroundGenetic factors have been suggested to affect the efficacy of working memory training. However, few studies have attempted to identify the relevant genes.MethodsIn this study, we first performed a randomized controlled trial (RCT) to identify brain regions that were specifically affected by working memory training. Sixty undergraduate students were randomly assigned to either the adaptive training group (N = 30) or the active control group (N = 30). Both groups were trained for 20 sessions during 4 weeks and received fMRI scans before and after the training. Afterward, we combined the data from the 30 participants in the RCT study who received adaptive training with data from 71 additional participants who also received the same adaptive training but were not part of the RCT study (total N = 101) to test the contribution of the COMT Val158/108Met polymorphism to the interindividual difference in the training effect within the identified brain regions.ResultsIn the RCT study, we found that the adaptive training significantly decreased brain activation in the left prefrontal cortex (TFCE-FWE corrected p = .030). In the genetic study, we found that compared with the Val allele homozygotes, the Met allele carriers' brain activation decreased more after the training at the left prefrontal cortex (TFCE-FWE corrected p = .025).ConclusionsThis study provided evidence for the neural effect of a visual-spatial span training and suggested that genetic factors such as the COMT Val158/108Met polymorphism may have to be considered in future studies of such training.

Theoretical and computational models such as transfer-appropriate processing (TAP) and global matching models have emphasized the encoding-retrieval interaction of memory representations in generating false memories, but relevant neural mechanisms are still poorly understood. By manipulating the sensory modalities (visual and auditory) at different processing stages (learning and test) in the Deese-Roediger-McDermott task, we found that the auditory-learning visual-test (AV) group produced more false memories (59%) than the other three groups (42∼44%) [i.e., visual learning visual test (VV), auditory learning auditory test (AA), and visual learning auditory test (VA)]. Functional imaging results showed that the AV group's proneness to false memories was associated with (i) reduced representational match between the tested item and all studied items in the visual cortex, (ii) weakened prefrontal monitoring process due to the reliance on frontal memory signal for both targets and lures, and (iii) enhanced neural similarity for semantically related words in the temporal pole as a result of auditory learning. These results are consistent with the predictions based on the TAP and global matching models and highlight the complex interactions of representations during encoding and retrieval in distributed brain regions that contribute to false memories.

Beta and gamma frequency neuronal oscillations have been implicated in top-down and bottom-up attention. In this study, we used rhythmic TMS to modulate ongoing beta and gamma frequency neuronal oscillations in frontal and parietal cortex while human participants performed a visual search task that manipulates bottom-up and top-down attention (single feature and conjunction search). Both task conditions will engage bottom-up attention processes, although the conjunction search condition will require more top-down attention. Gamma frequency TMS to superior precentral sulcus (sPCS) slowed saccadic RTs during both task conditions and induced a response bias to the contralateral visual field. In contrary, beta frequency TMS to sPCS and intraparietal sulcus decreased search accuracy only during the conjunction search condition that engaged more top-down attention. Furthermore, beta frequency TMS increased trial errors specifically when the target was in the ipsilateral visual field for the conjunction search condition. These results indicate that beta frequency TMS to sPCS and intraparietal sulcus disrupted top-down attention, whereas gamma frequency TMS to sPCS disrupted bottom-up, stimulus-driven attention processes. These findings provide causal evidence suggesting that beta and gamma oscillations have distinct functional roles for cognition.

Theoretical and computational models such as transfer-appropriate processing (TAP) and global matching models have emphasized the encoding-retrieval interaction of memory representations in generating false memories, but relevant neural mechanisms are still poorly understood. By manipulating the sensory modalities (visual and auditory) at different processing stages (learning and test) in the Deese-Roediger-McDermott task, we found that the auditory-learning visual-test (AV) group produced more false memories (59%) than the other three groups (42∼44%) [i.e., visual learning visual test (VV), auditory learning auditory test (AA), and visual learning auditory test (VA)]. Functional imaging results showed that the AV group's proneness to false memories was associated with (i) reduced representational match between the tested item and all studied items in the visual cortex, (ii) weakened prefrontal monitoring process due to the reliance on frontal memory signal for both targets and lures, and (iii) enhanced neural similarity for semantically related words in the temporal pole as a result of auditory learning. These results are consistent with the predictions based on the TAP and global matching models and highlight the complex interactions of representations during encoding and retrieval in distributed brain regions that contribute to false memories.

ObjectivesThe aim of this study was to identify whether the three main primary progressive aphasia (PPA) variants would show differential profiles on measures of visuospatial cognition. We hypothesized that the logopenic variant would have the most difficulty across tasks requiring visuospatial and visual memory abilities.MethodsPPA patients (n=156), diagnosed using current criteria, and controls were tested on a battery of tests tapping different aspects of visuospatial cognition. We compared the groups on an overall visuospatial factor; construction, immediate recall, delayed recall, and executive functioning composites; and on individual tests. Cross-sectional and longitudinal comparisons were made, adjusted for disease severity, age, and education.ResultsThe logopenic variant had significantly lower scores on the visuospatial factor and the most impaired scores on all composites. The nonfluent variant had significant difficulty on all visuospatial composites except the delayed recall, which differentiated them from the logopenic variant. In contrast, the semantic variants performed poorly only on delayed recall of visual information. The logopenic and nonfluent variants showed decline in figure copying performance over time, whereas in the semantic variant, this skill was remarkably preserved.ConclusionsThis extensive examination of performance on visuospatial tasks in the PPA variants solidifies some previous findings, for example, delayed recall of visual stimuli adds value in differential diagnosis between logopenic variant PPA and nonfluent variant PPA variants, and illuminates the possibility of common mechanisms that underlie both linguistic and non-linguistic deficits in the variants. Furthermore, this is the first study that has investigated visuospatial functioning over time in the PPA variants. (JINS, 2018, 24, 259-268).

The basis for how we represent temporal intervals in memory remains unclear. One proposal, the mental time line theory (MTL), posits that our representation of temporal duration depends on a horizontal mental time line, thus suggesting that the representation of time has an underlying spatial component. Recent work suggests that the MTL is a learned strategy, prompting new questions of when and why MTL is used to represent temporal duration, and whether time is always represented spatially. The current study examines the hypothesis that the MTL may be a time processing strategy specific to centrally-located stimuli. In two experiments (visual eccentricity and prismatic adaptation procedures), we investigated the magnitude of the rightward bias, an index of the MTL, in central and peripheral space. When participants performed a supra-second temporal interval reproduction task, we observed a rightward bias only in central vision (within 3° visual angle), but not in the peripheral space (approximately 6-8° visual angle). Instead, in the periphery, we observed a leftward bias. The results suggest that the MTL may be a learned strategy specific to central space and that strategies for temporal interval estimation that do not depend on MTL may exist for stimuli perceived peripherally.

Psychophysical inferences about the neural mechanisms supporting spatial vision can be undermined by uncertainties introduced by optical aberrations and fixational eye movements, particularly in fovea where the neuronal grain of the visual system is fine. We examined the effect of these preneural factors on photopic spatial summation in the human fovea using a custom adaptive optics scanning light ophthalmoscope that provided control over optical aberrations and retinal stimulus motion. Consistent with previous results, Ricco's area of complete summation encompassed multiple photoreceptors when measured with ordinary amounts of ocular aberrations and retinal stimulus motion. When both factors were minimized experimentally, summation areas were essentially unchanged, suggesting that foveal spatial summation is limited by postreceptoral neural pooling. We compared our behavioral data to predictions generated with a physiologically-inspired front-end model of the visual system, and were able to capture the shape of the summation curves obtained with and without pre-retinal factors using a single postreceptoral summing filter of fixed spatial extent. Given our data and modeling, neurons in the magnocellular visual pathway, such as parasol ganglion cells, provide a candidate neural correlate of Ricco's area in the central fovea.

INTRODUCTION: One of the most common childhood ear pathologies is otitis media with effusion. The immediate impacts of otitis media are well known, and include fluctuating conductive hearing loss and impaired speech intelligibility. A more subtle influence, present years after the otitis media clears, includes disruptions to binaural cue processing, specifically, the cues that arise when there are differences in the signal arriving at each ear. It is the processing of these difference cues that allows a listener to follow speech in noisy environments and, if compromised in school-age children, may have negative ramifications on classroom listening and academic performance. There is a recognised link between otitis media in early childhood and impaired processing of binaural cues in subsequent years (i.e. longer-term). However, the mechanisms influencing this reported association are yet to be fully explored. OBJECTIVES: This thesis examined the implications of early conductive hearing loss (associated with otitis media) on longer-term binaural processing, at a behaviourally measurable level, and at the level of an auditory evoked potential. DESIGN: Binaural listening ability was determined using standard clinical assessment measures in school-age children with clinical histories documenting hearing and middle-ear status throughout early childhood. Additionally, an evoked potential measure was used as an objective measure of binaural processing ability, with comparisons made between the electrophysiological measure and a behavioural correlate pre- and post-auditory training. RESULTS: The two most important contributions made by this doctoral project were 1) the established relationship between an otitis media related conductive hearing loss history in the first four years of life and reduced spatial processing ability at school-age, and 2) the findings that suggest spatial processing is not completely dependent upon the activity at the subcortical centres. IMPLICATIO

An individual’s socio-economic status can increase their vulnerability to, and ability to prepare for and recover in the aftermath of a disaster. People from low socio-economic (LSE) backgrounds often face greater disaster risks, but are least prepared for disaster events due to a number of factors including a lack of housing affordability, low income and literacy levels. While there is an established relationship between a person’s socio-economic status and disaster vulnerability, very little is understood about the disaster information seeking needs and preferences of LSE population groups and how this affects their levels of disaster awareness. This paper addresses this gap through a comparative study of LSE and non-LSE population groups to identify key disaster information sources and how it shapes levels of disaster awareness. A survey of 224 residents was conducted, and multivariate regression analysis of both LSE and non-LSE respondents revealed a trend of disaster passivity in both population groups. English language proficiency, occupation, familiarity with the local environment are the most important factors influencing disaster awareness among the LSE population groups. For non-LSE population groups, disaster awareness is gender-dependent with females showing higher levels of awareness. Overall, television was the most trusted information source regardless of socio-economic status. The results provide a better understanding of the underlying impact of socio-economic status on disaster awareness and information seeking behaviour, which can assist practitioners and policy makers in making informed decisions on disaster mitigation strategies to reduce the disaster risk vulnerability of targeted population groups.

The basis for how we represent temporal intervals in memory remains unclear. One proposal, the mental time line theory (MTL), posits that our representation of temporal duration depends on a horizontal mental time line, thus suggesting that the representation of time has an underlying spatial component. Recent work suggests that the MTL is a learned strategy, prompting new questions of when and why MTL is used to represent temporal duration, and whether time is always represented spatially. The current study examines the hypothesis that the MTL may be a time processing strategy specific to centrally-located stimuli. In two experiments (visual eccentricity and prismatic adaptation procedures), we investigated the magnitude of the rightward bias, an index of the MTL, in central and peripheral space. When participants performed a supra-second temporal interval reproduction task, we observed a rightward bias only in central vision (within 3° visual angle), but not in the peripheral space (approximately 6-8° visual angle). Instead, in the periphery, we observed a leftward bias. The results suggest that the MTL may be a learned strategy specific to central space and that strategies for temporal interval estimation that do not depend on MTL may exist for stimuli perceived peripherally.

Psychophysical inferences about the neural mechanisms supporting spatial vision can be undermined by uncertainties introduced by optical aberrations and fixational eye movements, particularly in fovea where the neuronal grain of the visual system is fine. We examined the effect of these preneural factors on photopic spatial summation in the human fovea using a custom adaptive optics scanning light ophthalmoscope that provided control over optical aberrations and retinal stimulus motion. Consistent with previous results, Riccos area of complete summation encompassed multiple photoreceptors when measured with ordinary amounts of ocular aberrations and retinal stimulus motion. When both factors were minimized experimentally, summation areas were essentially unchanged, suggesting that foveal spatial summation is limited by postreceptoral neural pooling. We compared our behavioral data to predictions generated with a physiologically-inspired front-end model of the visual system, and were able to capture the shape of the summation curves obtained with and without pre-retinal factors using a single postreceptoral summing filter of fixed spatial extent. Given our data and modeling, neurons in the magnocellular visual pathway, such as parasol ganglion cells, provide a candidate neural correlate of Riccos area in the central fovea.

During active sensation, sensors scan space in order to generate a representation of the outside world. However, since spatial coding in sensory systems is typically addressed by measuring receptive fields in a fixed, sensor-based coordinate frame, the cortical representation of scanned space is poorly understood. To address this question, we probed spatial coding in the rodent whisker system using a combination of two-photon imaging and electrophysiology during active touch. We found that surround whiskers powerfully transform the cortical representation of scanned space. On the single-neuron level, surround input profoundly alters response amplitude and modulates spatial preference in the cortex. On the population level, surround input organizes the spatial preference of neurons into a continuous map of the space swept out by the whiskers. These data demonstrate how spatial summation over a moving sensor array is critical to generating population codes of sensory space.

The medial entorhinal cortex (mEC) has been identified as a hub for spatial information processing by the discovery of grid, border, and head-direction cells. Here we find that in addition to these well-characterized classes, nearly all of the remaining two-thirds of mEC cells can be categorized as spatially selective. We refer to these cells as nongrid spatial cells and confirmed that their spatial firing patterns were unrelated to running speed and highly reproducible within the same environment. However, in response to manipulations of environmental features, such as box shape or box color, nongrid spatial cells completely reorganized their spatial firing patterns. At the same time, grid cells retained their spatial alignment and predominantly responded with redistributed firing rates across their grid fields. Thus, mEC contains a joint representation of both spatial and environmental feature content, with specialized cell types showing different types of integrated coding of multimodal information.

The oblique effect-poorer performance when contours are in oblique meridians-is here extended from the discrimination of line-orientation to the tilt illusion and to the detection and contextual induction of curvature. The distinction is made between a contour's susceptibility to contextual perturbation and its capacity to induce such perturbation, for which the oblique effect is only about one half. That the cardinal/oblique superiority is retained for the orientation of illusory borders and for the implicit orientation of shapes lacking explicit rectilinear delineation has implications for its neural substrate. To the extent that a geometrical-visual illusion, such as Poggendorff's or Hering's, depends on interaction in the domain of contour orientation, it manifests a corresponding orientational anisotropy. On the other hand, visual functions that govern whether and how well a boundary is visible are invariant with orientation.

Context: The aim was to further understand the heterogeneity of developmental dyscalculia (DD). Utilizing four children (8-9 year-old) performance was contrasted against predominant hypotheses of DD. Case report: Despite showing similar mathematical deficits, these children showed remarkable interindividual variability regarding cognitive profile and deficits. Two cases were consistent with the approximate number system deficit account, and the general magnitude-processing deficit account. One case had an access deficit in combination with a general cognitive deficit. One cases suffered from general cognitive deficits only. Conclusions: The results showed that DD cannot be attributed to a single explanatory factor. These findings support a multiple deficits account of DD and suggest that some cases have multiple deficits, whereas other cases have a single deficit. We discuss a previously proposed distinction between primary DD and secondary DD, and suggest hypotheses of dysfunctional neurocognitive correlates responsible for the displayed deficits., Funding agencies: Swedish Research Council for Health, Working Life and Welfare [2008-0238, 2010-0078]

The oblique effect-poorer performance when contours are in oblique meridians-is here extended from the discrimination of line-orientation to the tilt illusion and to the detection and contextual induction of curvature. The distinction is made between a contour's susceptibility to contextual perturbation and its capacity to induce such perturbation, for which the oblique effect is only about one half. That the cardinal/oblique superiority is retained for the orientation of illusory borders and for the implicit orientation of shapes lacking explicit rectilinear delineation has implications for its neural substrate. To the extent that a geometrical-visual illusion, such as Poggendorff's or Hering's, depends on interaction in the domain of contour orientation, it manifests a corresponding orientational anisotropy. On the other hand, visual functions that govern whether and how well a boundary is visible are invariant with orientation.

Human communication frequently takes place in noisy environments. In these environments, successful understanding of speech is dependent on an individual’s ability to extract and use spatial cues for separating speech from distracting noise. When speech and noise are separated spatially, the speech reception threshold (SRT) is reduced, and this is referred to in the literature as spatial release from masking (SRM). SRM is in most part due to acoustic cues arising from the differences in time and intensity of signals arriving at each of our two ears (i.e. interaural time (ITD) and interaural level (ILD) differences). ITDs and ILDs have in general been investigated through psychoacoustic studies. However, the electrophysiological correlates of these acoustic cues have only been investigated individually. For this reason, a novel experiment was designed to investigate the effect of spatial separation on the detection of target sound in competition with distractor stimuli in a more realistic experimental environment in which both ITD and ILD cues were present. The primary aim of this thesis was to determine whether it is possible to identify a neural representation of SRM in the electrophysiological responses recorded from either the brainstem or auditory cortex, or both, using experimental stimuli conveying ILD and ITD cues. This research was conducted in two primary studies. The first study investigated whether the frequency-following response (FFR) in response to the fundamental frequency (F0) of a speech sound could be used to demonstrate SRM at different signal-to-noise ratios (SNRs), and what role of attentional mechanisms might play in spatial processing. FFRs were recorded in eighteen normally hearing participants. Participants were presented through headphones with a synthesized steady-state vowel /u/ with an F0 of 110 Hz and a 250 ms duration at 60 dB SPL. This vowel was labelled as the target stimulus. To be able to measure the effects of attention, a deviant

Many everyday activities require coordination and monitoring of multiple deadlines. One way to handle these temporal demands might be to represent future goals and deadlines as a pattern of spatial relations. We examined the hypothesis that spatial ability, in addition to executive functioning, contributes to individual differences in multitasking. Participants completed a multitasking session in which they monitored four digital clocks running at different rates. We predicted and found that individual differences in spatial ability and executive functions were independent predictors of multiple-task performance. Individual differences in spatial ability were also selectively related to multiple-task performance, as only coordinate spatial processing, but not categorical, predicted multitasking, even beyond executive functioning and numeracy. Furthermore, males outperformed females in spatial ability and multitasking and these sex differences generalized to a complex simulation of everyday multitasking. Menstrual changes moderated these effects in that sex differences in coordinate spatial processing and multitasking were observed between males and females in the luteal phase of the menstrual cycle, but not between males and females at menses. Overall, these findings suggest that multiple task performance reflects independent contributions of spatial ability and executive functioning. Furthermore, our results support the distinction of categorical vs. coordinate spatial processing, and suggest that these two basic relational processes are selectively affected by female sex hormones and differentially effective in transforming and handling temporal patterns as spatial relations in the context of multitasking.

We often need to monitor and coordinate multiple deadlines. One way to handle these temporal demands might be to represent future deadlines as a pattern of spatial relations. More specifically, we tested the hypothesis that multitasking reflects selective effects of coordinate (i.e., metric) relational processing. Participants completed two multitasking sessions under concurrent processing demands of coordinate versus categorical spatial information. We expected and observed that multitasking impairs concurrent coordinate, rather than categorical, spatial processing. In Experiment 1, coordinate-task performance was selectively decreased, while multitasking performance was equal under both load conditions. When emphasizing equal (primary/secondary) task-importance in Experiment 2, it was only multitasking performance that was selectively reduced under the coordinate-load condition. Thus, effective multitasking may partly reflect coordinate-relational processing.

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, the degree of neural overlap across several dimensions has yet to be established, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional resonance imaging (fMRI) study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex, inferior frontal gyrus and frontal eye-fields. Together with previous research highlighting IPS, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest., Funding Agencies|Swedish Council for Working Life and Social Research [2010-0078]

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, the degree of neural overlap across several dimensions has yet to be established, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional resonance imaging (fMRI) study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex, inferior frontal gyrus and frontal eye-fields. Together with previous research highlighting IPS, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest., Funding Agencies|Swedish Council for Working Life and Social Research [2010-0078]

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, the degree of neural overlap across several dimensions has yet to be established, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional resonance imaging (fMRI) study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex, inferior frontal gyrus and frontal eye-fields. Together with previous research highlighting IPS, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest., Funding Agencies|Swedish Council for Working Life and Social Research [2010-0078]

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, the degree of neural overlap across several dimensions has yet to be established, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional resonance imaging (fMRI) study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex, inferior frontal gyrus and frontal eye-fields. Together with previous research highlighting IPS, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest., Funding Agencies|Swedish Council for Working Life and Social Research [2010-0078]

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, the degree of neural overlap across several dimensions has yet to be established, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional resonance imaging (fMRI) study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex, inferior frontal gyrus and frontal eye-fields. Together with previous research highlighting IPS, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest., Funding Agencies|Swedish Council for Working Life and Social Research [2010-0078]

Retinal topography maps are a widely used tool in vision science, neuroscience, and visual ecology, providing an informative visualization of the spatial distribution of cell densities across the retinal hemisphere. Here, we introduce Retina, an R package for computational mapping, inspection of topographic model fits, and generation of average maps. Functions in Retina take cell count data obtained from retinal wholemounts using stereology software. Accurate visualizations and comparisons between different eyes have been difficult in the past, because of deformation and incisions of retinal wholemounts. We account for these issues by incorporation of the R package Retistruct, which results in a retrodeformation of the wholemount into a hemispherical shape, similar to the original eyecup. The maps are generated by thin plate splines, after the data were transformed into a two-dimensional space with an azimuthal equidistant plot projection. Retina users can compute retinal topography maps independent of stereology software choice and assess model fits with a variety of diagnostic plots. Functionality of Retina also includes species average maps, an essential feature for interspecific analyses. The Retina package will facilitate rigorous comparative studies in visual ecology by providing a robust quantitative approach to generate retinal topography maps.

Visuospatial processing is a commonly assessed neurocognitive domain with deficits linked to dysfunction in right posterior regions of the brain. With the growth of large-scale clinical research studies, there is an increased need for efficient and scalable assessments of neurocognition, including visuospatial processing. The purpose of the current study was to use a novel method that combines item response theory (IRT) and computerized adaptive testing (CAT) approaches to create an abbreviated form of the computerized Penn Line Orientation Test (PLOT). The 24-item PLOT was administered to 8,498 youths (aged 8-21 years) as part of the Philadelphia Neurodevelopmental Cohort study and, by Web-based data collection, in an independent sample of 4,593 adults from Great Britain as part of a TV documentary. IRT-based CAT simulations were used to select the best PLOT items for an abbreviated form by performing separate simulations in each group and choosing only items that were selected as useful (i.e., high item discrimination and in the appropriate difficulty range) in at least 1 of the simulations. Fifteen items were chosen for the final, short form of the PLOT, indicating substantial agreement among the models in how they evaluated each item's usefulness. Moreover, this abbreviated version performed comparably to the full version in tests of sensitivity to age and sex effects. This abbreviated version of the PLOT cuts administration time by 50% without detectable loss of information, which points to its feasibility for large-scale clinical and genomic studies.

Humans perceive a stable average intensity image without flicker artifacts when a television or monitor updates at a sufficiently fast rate. This rate, known as the critical flicker fusion rate, has been studied for both spatially uniform lights, and spatio-temporal displays. These studies have included both stabilized and unstablized retinal images, and report the maximum observable rate as 50-90 Hz. A separate line of research has reported that fast eye movements known as saccades allow simple modulated LEDs to be observed at very high rates. Here we show that humans perceive visual flicker artifacts at rates over 500 Hz when a display includes high frequency spatial edges. This rate is many times higher than previously reported. As a result, modern display designs which use complex spatio-temporal coding need to update much faster than conventional TVs, which traditionally presented a simple sequence of natural images.

The ability to self-localize and navigate in both stable and changing environments is crucial for the survival of many species. Research conducted on the non-human mammalian hippocampus and surrounding brain structures has uncovered several classes of spatial related cells. These cells provide the rest of the brain with knowledge of the animal’s location and direction—knowledge that is subsequently used in spatial navigation. This thesis provides an overview of three types of cells underlying this ability in rodents. First, place cells located in the hippocampus encode the animal’s specific location in the environment. Second, head direction cells found throughout the Papez circuit convey the angular direction of the animal’s head. Last, grid cells in the medial entorhinal cortex generate a regular triangular grid spanning the entire explored setting. The focus of this review lies on the most salient features of these types of cells. It is also considered how the cells respond to manipulations of external and internal information, as well as how different lesions affect their activity.

The relationship between stimulus-dependent and task-dependent activations in human auditory cortex (AC) during pitch and location processing is not well understood. In the present functional magnetic resonance imaging study, we investigated the processing of task-irrelevant and task-relevant pitch and location during discrimination, n-back, and visual tasks. We tested three hypotheses: (1) According to prevailing auditory models, stimulus-dependent processing of pitch and location should be associated with enhanced activations in distinct areas of the anterior and posterior superior temporal gyrus (STG), respectively. (2) Based on our previous studies, task-dependent activation patterns during discrimination and n-back tasks should be similar when these tasks are performed on sounds varying in pitch or location. (3) Previous studies in humans and animals suggest that pitch and location tasks should enhance activations especially in those areas that also show activation enhancements associated with stimulus-dependent pitch and location processing, respectively. Consistent with our hypotheses, we found stimulus dependent sensitivity to pitch and location in anterolateral STG and anterior planum temporale (PT), respectively, in line with the view that these features are processed in separate parallel pathways. Further, task-dependent activations during discrimination and n-back tasks were associated with enhanced activations in anterior/posterior STG and posterior STG/inferior parietal lobule (IPL) irrespective of stimulus features. However, direct comparisons between pitch and location tasks performed on identical sounds revealed no significant activation differences. These results suggest that activations during pitch and location tasks are not strongly affected by enhanced stimulus dependent activations to pitch or location. We also found that activations in PT were strongly modulated by task requirements and that areas in the inferior parietal lobule (IPL) showed

The ability to self-localize and navigate in both stable and changing environments is crucial for the survival of many species. Research conducted on the non-human mammalian hippocampus and surrounding brain structures has uncovered several classes of spatial related cells. These cells provide the rest of the brain with knowledge of the animal’s location and direction—knowledge that is subsequently used in spatial navigation. This thesis provides an overview of three types of cells underlying this ability in rodents. First, place cells located in the hippocampus encode the animal’s specific location in the environment. Second, head direction cells found throughout the Papez circuit convey the angular direction of the animal’s head. Last, grid cells in the medial entorhinal cortex generate a regular triangular grid spanning the entire explored setting. The focus of this review lies on the most salient features of these types of cells. It is also considered how the cells respond to manipulations of external and internal information, as well as how different lesions affect their activity.

Recent studies have reported that early right anterior negativity (ERAN) is elicited by harmonic irregularity in Western tonal music. We assumed that tonal hierarchy-as the basic structure for harmony processing-is expressed as a mental representation with spatial specificity. In this study, we examined whether this assumption was appropriate by investigating the effect of a mental rotation task on ERAN. If the representation of tonal hierarchy has a spatial structure, mental rotation of the structure will decrease the amplitude of ERAN. Twelve adult participants took part in the experiment, which comprised three task conditions (mental rotation, reading, and control). Event-related potentials to cadenzas including the Neapolitan sixth chord as the deviated tone were recorded under each condition. Results showed a decrease of ERAN amplitude in the mental rotation task, suggesting a relationship between spatial processing and the establishment of tonal hierarchy. Further research is necessary to confirm distinguish whether the effect is attentional or task specific.

Visuospatial processing is a commonly assessed neurocognitive domain with deficits linked to dysfunction in right posterior regions of the brain. With the growth of large-scale clinical research studies, there is an increased need for efficient and scalable assessments of neurocognition, including visuospatial processing. The purpose of the current study was to use a novel method that combines item response theory (IRT) and computerized adaptive testing (CAT) approaches to create an abbreviated form of the computerized Penn Line Orientation Test (PLOT). The 24-item PLOT was administered to 8,498 youths (aged 8-21 years) as part of the Philadelphia Neurodevelopmental Cohort study and, by Web-based data collection, in an independent sample of 4,593 adults from Great Britain as part of a TV documentary. IRT-based CAT simulations were used to select the best PLOT items for an abbreviated form by performing separate simulations in each group and choosing only items that were selected as useful (i.e., high item discrimination and in the appropriate difficulty range) in at least 1 of the simulations. Fifteen items were chosen for the final, short form of the PLOT, indicating substantial agreement among the models in how they evaluated each item's usefulness. Moreover, this abbreviated version performed comparably to the full version in tests of sensitivity to age and sex effects. This abbreviated version of the PLOT cuts administration time by 50% without detectable loss of information, which points to its feasibility for large-scale clinical and genomic studies.

Humans perceive a stable average intensity image without flicker artifacts when a television or monitor updates at a sufficiently fast rate. This rate, known as the critical flicker fusion rate, has been studied for both spatially uniform lights, and spatio-temporal displays. These studies have included both stabilized and unstablized retinal images, and report the maximum observable rate as 50-90 Hz. A separate line of research has reported that fast eye movements known as saccades allow simple modulated LEDs to be observed at very high rates. Here we show that humans perceive visual flicker artifacts at rates over 500 Hz when a display includes high frequency spatial edges. This rate is many times higher than previously reported. As a result, modern display designs which use complex spatio-temporal coding need to update much faster than conventional TVs, which traditionally presented a simple sequence of natural images.

Previous research has shown that interacting with natural environments vs. more urban or built environments can have salubrious psychological effects, such as improvements in attention and memory. Even viewing pictures of nature vs. pictures of built environments can produce similar effects. A major question is: What is it about natural environments that produces these benefits? Problematically, there are many differing qualities between natural and urban environments, making it difficult to narrow down the dimensions of nature that may lead to these benefits. In this study, we set out to uncover visual features that related to individuals' perceptions of naturalness in images. We quantified naturalness in two ways: first, implicitly using a multidimensional scaling analysis and second, explicitly with direct naturalness ratings. Features that seemed most related to perceptions of naturalness were related to the density of contrast changes in the scene, the density of straight lines in the scene, the average color saturation in the scene and the average hue diversity in the scene. We then trained a machine-learning algorithm to predict whether a scene was perceived as being natural or not based on these low-level visual features and we could do so with 81% accuracy. As such we were able to reliably predict subjective perceptions of naturalness with objective low-level visual features. Our results can be used in future studies to determine if these features, which are related to naturalness, may also lead to the benefits attained from interacting with nature.

In line bisection right-brain-damaged patients with left spatial neglect show a rightward deviation, with respect to the line's physical center. In word bisection ortho-phonological features of the stimulus' final (right-sided) part modulate performance of both patients and healthy participants (Veronelli, Vallar, Marinelli, Primativo, & Arduino, 2014). We investigated the role of linguistic factors in sentence bisection, in patients with and without neglect, and control participants. The effects of information in the right-sided part of the sentence (Experiment #1), and of lexical and syntactic violations (Experiment #2) were assessed. Neglect patients showed an overall rightward bias, larger than those of patients without neglect and controls. The neglect patients' bias was modulated by stimulus type, decreasing from lines, to letter strings and to all types of sentences. In sum, in visuo-manual sentence bisection a basic linguistic mechanism, such as sentence readability, brings about a more leftward appreciation of the stimulus, reducing the neglect patients' rightward bias.

Відображені теоретичні результати ефективності застосування оптимальної просторової обробки двох радіосигналів на приймальній стороні радіолінії бездротової телекомунікаційної системи при дискримінації радіосигналів двох передавачів, що працюють одночасно на одній частоті й тому самому виді поляризації по кривизні фронту електромагнітної хвилі, отримані на основі аналізу коефіцієнта ослаблення корисного сигналу, коефіцієнта придушення завади й відношення сигнал/(завада+шум)., Introduction. The effectiveness of the theoretical results of optimal spatial processing ot-wo radio signals at the receiving side of wireless communication system with two radio signals which operating simultaneously on the same frequency and same polarization using the curvature of the electromagnetic waves phase front produced on the basis of analysis of attenuation signal coefficient, interference rate suppression and signal-to-noise ratio are shown. Formulation of the problem. Initial data and wireless communication system configuration for research are described. Simulation results. Signal-of-interest attenuation index and signal-to-interference plus noise parameter calculation for sparse linear antenna array (SLAA) are presented. Conclusions. There is relationship between parameters of transmit and receive SLAA for optimal spatial signal processing in the wireless communication system., Расчёт показателей эффективности оптимальной пространственной обработки сигналов для радиолинии стационарной беспроводной телекоммуникационной системы. Отображены теоретические результаты эффективности применения оптимальной пространственной обработки двух радиосигналов на приёмной стороне радиолинии беспроводной телекоммуникационной системы при дискриминации радиосигналов двух передатчиков, работающих одновременно на одной частоте и одном и том же виде поляризации по кривизне фронта электромагнитной волны, полученные на основе анализа коэффициента ослабления полезного сигнала, коэффициента подавления помехи и отношения сигнал/(помеха+шум).

Відображені теоретичні результати ефективності застосування оптимальної просторової обробки двох радіосигналів на приймальній стороні радіолінії бездротової телекомунікаційної системи при дискримінації радіосигналів двох передавачів, що працюють одночасно на одній частоті й тому самому виді поляризації по кривизні фронту електромагнітної хвилі, отримані на основі аналізу коефіцієнта ослаблення корисного сигналу, коефіцієнта придушення завади й відношення сигнал/(завада+шум).

Change blindness, the surprising inability of people to detect significant changes between consecutively-presented visual displays, has recently been shown to affect tactile perception as well. Visual change blindness has been observed during saccades and eye blinks, conditions under which people's awareness of visual information is temporarily suppressed. In the present study, we demonstrate change blindness for suprathreshold tactile stimuli resulting from the execution of a secondary task requiring bodily movement. In Experiment 1, the ability of participants to detect changes between two sequentially-presented vibrotactile patterns delivered on their arms and legs was compared while they performed a secondary task consisting of either the execution of a movement with the right arm toward a visual target or the verbal identification of the target side. The results demonstrated that a motor response gave rise to the largest drop in perceptual sensitivity (as measured by changes in d′) in detecting changes to the tactile display. In Experiment 2, we replicated these results under conditions in which the participants had to detect tactile changes while turning a steering wheel instead. These findings are discussed in terms of the role played by bodily movements, sensory suppression, and higher order information processing in modulating people's awareness of tactile information across the body surface. © 2009 Elsevier Inc.