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The Developmental Topographical Disorientation (DTD) is a pathological condition that impairs an individual’s ability to orient in space, even in the most familiar environments. It is a lifelong selective condition in individuals without brain damage or without impaired general cognitive functions. Here, we aimed at characterizing 54 individuals with DTD identified in a previous study, aged between 18 and 35 years and assessed through a 4-year-long online survey. To this purpose, we compared them with 54 matched healthy participants. We described the demographics, sense of direction, town knowledge, navigational strategies, left-right confusion as well as agnosic disorders (for landmarks, faces and objects). This novel study attempts to characterize the phenotype of DTD, providing an important contribution to the worldwide definition of a condition that was first described only 13 years ago, but which, considering the growing number of cases complaining of the disorder, deserves continuous and increasing attention.

Patients with lesions in the posterior cingulate gyrus (PCG), including the retrosplenial cortex (RSC) and posterior cingulate cortex (PCC), cannot navigate in familiar environments, nor draw routes on a 2D map of the familiar environments. This suggests that the topographical knowledge of the environments (i.e., cognitive map) to find the right route to a goal is represented in the PCG, and the patients lack such knowledge. However, theoretical backgrounds in neuronal levels for these symptoms in primates are unclear. Recent behavioral studies suggest that human spatial knowledge is constructed based on a labeled graph that consists of topological connections (edges) between places (nodes), where local metric information, such as distances between nodes (edge weights) and angles between edges (node labels), are incorporated. We hypothesize that the population neural activity in the PCG may represent such knowledge based on a labeled graph to encode routes in both 3D environments and 2D maps. Since no previous data are available to test the hypothesis, we recorded PCG neuronal activity from a monkey during performance of virtual navigation and map drawing-like tasks. The results indicated that most PCG neurons responded differentially to spatial parameters of the environments, including the place, head direction, and reward delivery at specific reward areas. The labeled graph-based analyses of the data suggest that the population activity of the PCG neurons represents the distance traveled, locations, movement direction, and navigation routes in the 3D and 2D virtual environments. These results support the hypothesis and provide a neuronal basis for the labeled graph-based representation of a familiar environment, consistent with PCG functions inferred from the human clinicopathological studies.

Reading and interpreting a map represents an essential part of daily life, enabling appropriate orientation and navigation through space. Based on the idea that perceptual analogical reasoning is critical in aligning the spatial structure of the map with the spatial structure of the space and given the critical role of language, especially spatial language, in encoding and establishing spatial relations among elements in the environment, the present study investigated the joint contribution of perceptual analogical reasoning and spatial language in map reading. The study was conducted with 56 typically developing 4- to 6-year-old children, and the results indicated that perceptual abstract reasoning affected map reading through the mediating effect of spatial language. These findings yielded theoretical and practical implications regarding the role of perceptual abstract reasoning and spatial language in shaping map-reading abilities in the early stages of life, highlighting that domain-specific language competencies are necessary to improve the encoding of spatial relations, to establish object correspondences, and to ensure successful navigation. Limitations and future research directions were discussed. [ABSTRACT FROM AUTHOR]

The Developmental Topographical Disorientation (DTD) is a pathological condition that impairs an individual's ability to orient in space, even in the most familiar environments. It is a lifelong selective condition in individuals without brain damage or without impaired general cognitive functions. Here, we aimed at characterizing 54 individuals with DTD identified in a previous study, aged between 18 and 35 years and assessed through a 4-year-long online survey. To this purpose, we compared them with 54 matched healthy participants. We described the demographics, sense of direction, town knowledge, navigational strategies, left-right confusion as well as agnosic disorders (for landmarks, faces and objects). This novel study attempts to characterize the phenotype of DTD, providing an important contribution to the worldwide definition of a condition that was first described only 13 years ago, but which, considering the growing number of cases complaining of the disorder, deserves continuous and increasing attention. [ABSTRACT FROM AUTHOR]

Allochiria refers to the mislocation of stimuli to the corresponding position on the opposite side of the body or hemispace. It is most often, although not exclusively, reported in the tactile modality and typically in association with unilateral neglect. We describe a patient presenting with a 2-year history of topographical disorientation without other cognitive complaints. We conducted a systematic exploration of his topographical problems to identify their cognitive substrate. Standard neuropsychological examination revealed no abnormalities. Notably, he performed well on perceptual, spatial, and constructional tasks. No signs of neglect were elicited. A tailored battery of tests was administered, involving road maps and landmarks, and designed to replicate the situations in which he experienced symptoms. The experimental tests showed no evidence of topographical agnosia or amnesia for landmarks and their spatial relationships and no hemispatial neglect. Nevertheless, the patient exhibited a systematic tendency to translocate topographical landmarks sited on the left to the right side. The phenomenon, consistent with representational allochiria, occurred exclusively for topographical landmarks, and was present along both personally familiar and new learned routes. Over the next two years more widespread visuoperceptual and spatial deficits emerged, with Balint and Gerstmann syndromes. Functional imaging revealed hypoperfusion of the occipito-parietal regions and amyloid PET the presence of amyloid plaques. A diagnosis was made of posterior cortical atrophy, the visual variant of Alzheimer's Disease. To our knowledge this is the first case of topographical disorientation presenting with selective representational allochiria and the first report of allochiria as an early sign of posterior cortical atrophy. The case sheds light on the cognitive basis of allochiria and on a puzzling clinical presentation of neurodegenerative brain disease. [ABSTRACT FROM AUTHOR]

• We report 2 persisting topographical disorientation (TD) cases post stroke. • The lesion in the retrosplenial region was left-side, atypical for causing TD. • No other deficits affecting TD were detected, implying pure heading disorientation. • Impairments in reconstructing and integrating egocentric & allocentric inferences. • Left retrosplenial region can cause pure long-lasting heading disorientation. Topographical disorientation is linked to lesions in the right hemisphere and typically resolves within a few months post-stroke. Persistent topographical disorientation is uncommon and frequently accompanied by impairments in visual memory, complicating the analysis of the underlying mechanisms. Herein, we report two cases of sustained pure topographical disorientation following cerebral hemorrhages in the left retrosplenial region. The patients exhibited disorientation in both familiar and unfamiliar settings, attributable to heading disorientation, a deficit in determining the directional relationship between one's current position and a target location or external frames. The patients struggled with reconstructing large-scale spatial frameworks and integrating new egocentric and allocentric perspectives upon changes in body orientation. There were no landmark agnosia, egocentric disorientation, or anterograde disorientation. Although mild verbal memory deficits were observed, no other cognitive impairments, including visual memory deficits, were detected. Our findings imply that lesions confined to the left retrosplenial region can induce enduring heading disorientation and suggest a significant role for this area in processing and integrating spatial information necessary for large-scale navigation. Clarifying the features of topographical disorientation will significantly impact the therapeutic approaches, enhancing the quality of life for affected patients by restoring their independence and mobility. [ABSTRACT FROM AUTHOR]

Reading and interpreting a map represents an essential part of daily life, enabling appropriate orientation and navigation through space. Based on the idea that perceptual analogical reasoning is critical in aligning the spatial structure of the map with the spatial structure of the space and given the critical role of language, especially spatial language, in encoding and establishing spatial relations among elements in the environment, the present study investigated the joint contribution of perceptual analogical reasoning and spatial language in map reading. The study was conducted with 56 typically developing 4- to 6-year-old children, and the results indicated that perceptual abstract reasoning affected map reading through the mediating effect of spatial language. These findings yielded theoretical and practical implications regarding the role of perceptual abstract reasoning and spatial language in shaping map-reading abilities in the early stages of life, highlighting that domain-specific language competencies are necessary to improve the encoding of spatial relations, to establish object correspondences, and to ensure successful navigation. Limitations and future research directions were discussed.

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. [ABSTRACT FROM AUTHOR]

Background: Topographical disorientation (TD) refers to a particular condition which determines the loss of spatial orientation, both in new and familiar environments. TD and spatial memory impairments occur relatively early as effect of cognitive decline in aging, even in prodromal stages of dementia, namely mild cognitive impairment (MCI). Aims: (a) To show that components linked to the recall of familiar spatial knowledge are relatively spared with respect to the learning of unfamiliar ones in normal aging, while they are not in MCI, and (b) to investigate gender differences for their impact on egocentric and allocentric frames of reference. Method: Forty young participants (YC), 40 healthy elderly participants (HE), 40 elderly participants with subjective memory complaints (SMC), and 40 elderly with probable MCI were administered with egocentric and allocentric familiar tasks, based on the map of their hometown, and with egocentric and allocentric unfamiliar tasks, based on new material to be learned. A series of general linear models were used to analyze data. Results: No group differences were found on egocentric task based on familiar information. MCI performed worse than the other groups on allocentric tasks based on familiar information (YC = HE = SMC > MCI). Significant differences emerged between groups on egocentric and allocentric tasks based on unfamiliar spatial information (YC > HE = SMC > MCI). A gender difference was found, favoring men on allocentric unfamiliar task. Conclusion: Familiarity of spatial memory traces can represent a protective factor for retrospective components of TD in normal aging. Conversely, using newly learned information for assessment may lead to overestimating TD severity. [ABSTRACT FROM AUTHOR]

Difficulty in navigating in a well-known environment (i.e., topographical disorientation) is an incapacitating syndrome. Despite the relatively high frequency after a right cerebral lesion, there is currently a dearth of neuropsychological tests to assess it. We propose a completely new test, the third in a battery of three, which assesses perspective taking, a crucial process in spatial orientation. In this test, inspired from Piaget and Inhelder Three Mountains, the subject must imagine a change in perspective in two conditions: after a rotational or a linear displacement. This task was proposed to 63 patients with a right cerebral lesion and a control group (N = 112). Results show that a right cerebral lesion impairs perspective taking, more specifically when rotation is involved. In addition, the pattern of responses in patients indicates that they have a general deficit in the ability of decentering. Furthermore, we established preliminary normative data taking into account the effect of age and education (there was no effect of gender) on performance. These data indicate that this new test is a good tool in clinical practice for assessing spatial orientation and determining more precisely the symptoms underlying topographical disorientation. [ABSTRACT FROM AUTHOR]

Background: Topographical disorientation is one of the early symptoms of Alzheimer's disease (AD). The nature of this symptom, however, remains unclear. Objective: The aim of the study was to investigate egocentric and allocentric spatial cognition in patients with amnestic mild cognitive impairment (aMCI) and early AD. Participants and Methods: The participants consisted of normal healthy volunteers (n = 23), patients with aMCI (n = 26), and patients with early AD (n = 22). We administered the card placing test (CPT), in which a subject was required to recreate an array of 3 cards, each of which was randomly placed on 8 grids around the individual, before (part A) and after (part B) the individual's rotation. With this design, the CPT can reveal an individual's ability to represent spatial information either egocentrically (CPT-A) or allocentrically (CPT-B). A qualitative analysis of errors in performing the CPT was also conducted. Results: Compared with the controls, the aMCI patients showed significantly poorer CPT-B performance, while there was no significant difference in CPT-A performance between these 2 groups. In contrast, the AD patients demonstrated significantly poorer performance on both the CPT-A and CPT-B than the controls and aMCI patients. There was no significant difference in the profile of errors on the CPT-B between the controls and aMCI patients, whereas there was a notable difference in those on the CPT-A between the controls and AD patients and the aMCI and AD patients. Conclusion: Allocentric spatial cognition is selectively impaired in aMCI patients, while an egocentric spatial cognition is additionally impaired in AD patients. [ABSTRACT FROM AUTHOR]

Background and objective: In a landmark publication, O'Keefe & Dostrovsky (1971) presented a model for spatial navigation in the rat, the cognitive map theory. In this theory they proposed that the processing and storage of spatial information for spatial navigation takes place in the hippocampus. The theory was extended to include the contribution of the grid cells in the medial entorhinal cortex (Hafting et al. 2005). The cognitive map theory has been widely applied to spatial navigation in humans as well as rats. In this paper, an alternative theory is proposed in which spatial processing takes place in the right parieto-temporo-occipital area in humans, and that damage to this area causes a fragmentation in the sense of space, affecting the recall of both visual and tactile spatial information. Method: A group of eight subjects with damage to the right parieto-temporo-occipital area and a fragmented sense of space was assessed on tests of spatial navigation and memory and the results were compared with a group of patients with damage to the right hippocampus. Other comparison groups included left and right hemisphere subjects with normal spatial functioning. Results: The results suggest that, in the human, damage to the right parieto-temporo-occipital area causes a fragmentation in the sense of space, as well as an impaired memory for spatial material in both the visual and tactile modalities. These results support a model of spatial navigation in which the integrity of the right parieto-temporo-occipital area, and not the right hippocampus, is a necessary condition for the processing of spatial information in humans. An alternative explanation for the functioning of the right hippocampus is also presented. [ABSTRACT FROM AUTHOR]

Topographical disorientation (TD) in novel environments is considered to be a part of anterograde amnesia. A 56-year-old woman presented with pure TD only in novel environments following limbic encephalitis. She could not remember directions inside the hospital on weekly outpatient visits; however, her verbal and visual anterograde memories were normal. In the test of learning photographs of scenes, faces, and objects, only her scores for landscapes were worse than those in healthy controls. These findings suggested that her TD specific to landscapes and directions in novel environments was caused by category-specific memory impairment related to bilateral hippocampal and parahippocampal dysfunction. [ABSTRACT FROM AUTHOR]

Several neuropsychological case studies report brain-damaged individuals with concurrent impairments in face recognition (i.e., prosopagnosia) and topographical orientation. Recently, individuals with a developmental form of topographical disorientation have also been described, and several case reports of individuals with developmental prosopagnosia provide anecdotal evidence of concurrent navigational difficulties. Clearly, the co-occurrence of these difficulties can exacerbate the negative psychosocial consequences associated with each condition. This paper presents the first detailed case report of an individual (FN) with developmental prosopagnosia alongside difficulties in topographical orientation. FN's performance on an extensive navigational battery indicated that she primarily has difficulties in the formation and retrieval of cognitive maps. We then evaluated the effectiveness of a short-term virtual reality training programme and found that she is able to form a cognitive map of a particular environment following intense overlearning. Surprisingly, FN's performance on a face recognition task also improved following training. While the latter finding was unexpected and requires further exploration, the training programme reported here may help to alleviate some of the compounded negative psychosocial consequences that are associated with difficulties in finding both locations and people. [ABSTRACT FROM AUTHOR]

Topographical disorientation (TD) refers to navigational impairment as an effect of aging or brain damage. Decreases in navigational performance with aging are more due to deficits in the ability to mentally represent space in an object-centered (allocentric) than in a self-centered (egocentric) format. Familiarity/remoteness of spatial memory traces can represent a protective factor for TD in aging. Conversely, using newly learned information for assessment may lead to overestimating TD severity as it combines two contributing factors: heading (allocentric) disorientation and anterograde agnosia. A supplementary evaluation of TD with aging according to ecological spatial tasks is recommended. The core tasks should focus on landmark positioning, both on a blind map (allocentric) and along a route (egocentric) of the hometown so as to disentangle spatial memory for familiar/remote information from decline due to recent encoding of information. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Topographical disorientation is defined as the inability to recognize familiar or unfamiliar environments. While its slowly progressive development is a common feature of neurodegenerative processes like Alzheimer's dementia, acute presentations are less frequent and mostly caused by strategic lesions within the cerebral navigation network. Depending on the lesion site, topographical disorientation can originate from deficits in landmark recognition and utilization for route planning (egocentric navigation deficit), or disturbance of an overarching cognitive map of the spatial environment (allocentric navigation deficit). However, objective measurements of spatial navigation performance over time are largely missing in patients with topographical disorientation. Methods: We here report a 55‐year‐old patient with acute topographical disorientation as the single symptom of right‐sided hippocampal hemorrhage and present quantitative gaze‐monitoring head camera‐based analyses of his path‐finding strategy and visual exploration behavior in a real space navigation paradigm. Results: The patient exhibited severe allocentric and also egocentric navigation deficits during the acute phase, shown by higher error rates at finding target items. In addition, he showed a more extensive use of search saccades toward, and fixations on, landmarks that could potentially serve as spatial cues. These deficits had been completely compensated for after four months, when the patient performed unremarkably in the real space navigation task, and used even more strongly allocentric path optimization strategies than age‐matched controls. Conclusions: This case report highlights the integral function and right‐sided dominance of the hippocampal formation in the cerebral navigation network in humans. It shows that the cognitive map can be restored completely despite a residual hippocampal lesion, which illustrates the enormous plasticity of the cerebral navigation network in humans. [ABSTRACT FROM AUTHOR]

Objective: Landmark agnosia is a rare type of navigation impairment, for which various definitions have been presented. From a clinical as well as theoretical perspective, consensus on the characteristics of landmark agnosia would be valuable. In the current study we review the literature concerning landmark agnosia and present a new case study. Existing literature highlights the importance of examining familiar as well as novel landmark processing and substantial variation in performance patterns of individual patients. Method: We performed a case study with patient KS, a 53-year-old male, suffering from landmark agnosia, making use of elaborate neuropsychological screening and virtual reality-based tests of navigation ability. Results: Our extensive examination of his impairment shows that landmark agnosia can be very narrow; in KS it is restricted to recognition of newly learned landmarks only. Also, he has no trouble recognizing familiar landmarks that are not part of a navigated route. Conclusions: The literature review shows that the right temporal lobe, and the right hippocampus in particular are the main lesion sites for landmark agnosia. Furthermore, our case study substantiates that this disorder can occur for both familiar and novel landmarks, and can affect novel landmarks in isolation from familiar landmarks. Moreover, it can occur in isolation from problems with processing route information. [ABSTRACT FROM AUTHOR]

Topographical disorientation (TD) has not been as extensively studied as other frequent manifestations of Alzheimer's disease (AD). OBJECTIVE: To verify the occurrence of TD and to identify the neuropsychological dysfunctions associated with TD in AD. METHOD: Thirty patients with probable AD, their caregivers and 30 subjects without dementia (controls) were interviewed with a questionnaire and evaluated with tests related to topographical orientation. RESULTS: AD patients, even those with mild dementia, differ from controls in the questionnaire on topographical orientation and in most neuropsychological tests except for tests of spatial working memory, point localization, three dimension and nonsense figure copy. When the performances in the neuropsychological tests of patients with mild or moderate dementia were compared, only landmark recognition and route description were more impaired in moderate dementia. CONCLUSION: TD occurs even in mild dementia of AD, a finding apparently not explained by the impairments of more elementary spatial functions.Desorientação topográfica (DT) não tem sido tão exaustivamente estudada quanto outros sintomas frequentes da doença de Alzheimer (DA). OBJETIVO: Verificar a ocorrência de DT e identificar as disfunções neuropsicológicas associadas com a DT na DA. Método: Trinta pacientes com DA provável, seus cuidadores e trinta sujeitos sem demência (controles) foram entrevistados com um questionário e testes relacionados à orientação topográfica. RESULTADOS: Pacientes com DA, mesmo aqueles com demência leve, diferiram dos controles no questionário de orientação topográfica e na maioria dos testes neuropsicológicos, exceto nos testes memória operacional espacial, localização de pontos, cópia de figuras sem sentido e de figura em três dimensões. Quando os desempenhos de pacientes com demência leve ou moderada foram comparados, apenas os testes de reconhecimento de marcos e descrição de rotas foram mais comprometidos na demência moderada. CONCLUSÃO: DT ocorre mesmo na demência leve da DA, um achado aparentemente não explicado pelo comprometimento das funções espaciais mais elementares.

Lesions of the medio-parietal lobes are linked with topographical and temporal disorientation, and are of interest to understanding mental time. We examined a 39-year-old man who worked as a driving instructor before cerebral hemorrhage, and followed his case for 8 years including neuropsychological testing and brain imaging. The patient had mild anterograde episodic amnesia, but no semantic amnesia. He felt that time passed too quickly, and developed a compulsive routine to compensate, although he was able to count time at a normal speed. Furthermore, he was unable to accurately sketch the layout of his house and to make a cross-reference type timetable for the future. Brain magnetic resonance imaging showed lesions of the left anterior-posterior cingulate gyrus, and N-isopropyl-[123I] p-iodoamphetamine single-photon emission computed tomography showed decreased blood flow mainly of the left medio-parietal lobe. [ABSTRACT FROM AUTHOR]

Silent focal ischemic mini infarcts in the brain are thought to cause no clinically overt symptoms. Some populations of hippocampal cells are particularly sensitive to ischemic events, however, rendering hippocampal functions especially vulnerable to ischemia-induced deficits. The present study investigated whether an otherwise silent ischemic mini infarct in the hippocampus (HPC) can produce impairments in spatial performance in rats. Spatial performance was assessed in the ziggurat task (ZT) using a 10-trial spatial learning protocol for four days prior to undergoing hippocampal ischemic lesion or sham surgery. Hippocampal silent ischemia was induced by infusion of endothelin-1 (ET-1), a potent vasoconstrictor, into either the dorsal or the ventral hippocampus (dHPC and vHPC). When tested postoperatively in the ZT using a standard testing protocol for eight days, rats with hippocampal lesions exhibited no spatial deficit. Although spatial learning and memory in the ZT were not affected by the ET-1-induced silent ischemia, rats with dHPC stroke showed more returns when navigating the ZT as opposed to the vHPC rats. Comparison of region-specific HPC lesions in the present study indicated that dorsal hippocampal function is critically required for topographic orientation in a complex environment. Topographic disorientation as reflected by enhanced return behaviours may represent one of the earliest predictors of cognitive decline after silent ischemic insult that may be potentially traced with sensitive clinical examination in humans.

A right posterior cerebral lesion can lead to an inability to orient and can consequently interfere with daily-life autonomy. Despite the wide literature about navigation abilities, it is still difficult to assess topographical disorientation (TD) because of the interindividual specificity of spatial knowledge and the diversity of symptoms. We describe here a set of new tests evaluating spatial cognition in a patient with TD presenting difficulties in navigating inside the hospital and in his hometown more than 3 years after his diffuse ischemic right Sylvian stroke. These tests assess mental imagery (global and specifically spatial imagery), perspective change, and the ability to recall spatial relations in familiar environments. The evaluation revealed difficulties with all the tests (but not in global mental imagery) in this patient when compared with matched controls. Hence, these new tests seem specific and affected by a right hemispheric lesion. The observed deficits can explain, at least partially, the spatial orientation difficulties experienced by this patient in the hospital and familiar environments. In conclusion, these tests could be appropriate tools for the assessment of visuospatial and spatial processes. [ABSTRACT FROM PUBLISHER]

In the present study, we used single- and dual-task conditions to investigate the nature of topographical working memory to better understand what type of task can hamper performance during navigation. During dual-task conditions, we considered four different sources of interference: motor (M), spatial motor (SM), verbal (i.e. articulatory suppression AS) and spatial environmental (SE). In order to assess the nature of topographical working memory, we used the Walking Corsi Test, asking the participants to perform two tasks simultaneously (M, SM, AS and SE). Our results showed that only spatial-environmental interference hampers the execution of a topographical working memory task, suggesting a task-domain-specific effect. We also found general gender differences in the topographical working memory capabilities: men were more proficient than women, regardless of the type of interferences. However, like men, women performed worse when a spatial-environmental interference was present. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine whether an egocentric topographical working memory (WM) deficit is present in the early stages of Alzheimer's disease (AD) with respect to other forms of visuospatial WM. Further, we would investigate whether this deficit could be present in patients having AD without topographical disorientation (TD) signs in everyday life assessed through an informal interview to caregivers. Seven patients with AD and 20 healthy participants performed the Walking Corsi Test and the Corsi Block-Tapping Test. The former test requires memorizing a sequence of places by following a path and the latter is a well-known visuospatial memory task. Patients with AD also performed a verbal WM test to exclude the presence of general WM impairments. Preliminary results suggest that egocentric topographical WM is selectively impaired, with respect to visuospatial and verbal WM, even without TD suggesting an important role of this memory in the early stages of AD. [ABSTRACT FROM AUTHOR]

We describe behavioral and neuropsychological outcome of a patient (N.S.), who showed a bilateral paramedian thalamic ischemic lesion, with particular reference to the longitudinal evolution of topographical disorientation (TD) and confabulations. We report clinical neuropsychological/behavioral data over a 43-month follow-up. The results show early after the stroke a severe amnesic-confabulatory syndrome with dysexecutive deficits, associated with memory disorders both for visuo-spatial and verbal materials and TD both for known and new places. Behavioral disinhibition and anosognosia for cognitive deficits were also observed. All cognitive impairments have been recovered during the long-term follow-up. Bilateral paramedian thalamic infarcts often lead to severe and long-lasting neurological and cognitive impairments. Only a few cases showed good recovery. Our patient represents an interesting and uncommon case of bilateral paramedian thalamic syndrome with a significant neuropsychological recovery. [ABSTRACT FROM AUTHOR]

Silent focal ischemic mini infarcts in the brain are thought to cause no clinically overt symptoms. Some populations of hippocampal cells are particularly sensitive to ischemic events, however, rendering hippocampal functions especially vulnerable to ischemiainduced deficits. The present study investigated whether an otherwise silent ischemic mini infarct in the hippocampus (HPC) can produce impairments in spatial performance in rats. Spatial performance was assessed in the ziggurat task (ZT) using a 10-trial spatial learning protocol for 4 days prior to undergoing hippocampal ischemic lesion or sham surgery. Hippocampal silent ischemia was induced by infusion of endothelin-1 (ET-1), a potent vasoconstrictor, into either the dorsal or the ventral hippocampus (dHPC and vHPC). When tested postoperatively in the ZT using a standard testing protocol for 8 days, rats with hippocampal lesions exhibited no spatial deficit. Although spatial learning and memory in the ZT were not affected by the ET-1-induced silent ischemia, rats with dHPC stroke showed more returns when navigating the ZT as opposed to the vHPC rats. Comparison of region-specific HPC lesions in the present study indicated that dorsal hippocampal function is critically required for topographic orientation in a complex environment. Topographic disorientation as reflected by enhanced return behaviors may represent one of the earliest predictors of cognitive decline after silent ischemic insult that may be potentially traced with sensitive clinical examination in humans. [ABSTRACT FROM AUTHOR]

Purpose: This article provides a brief overview of the intervention strategies aimed at reducing spatial orientation disorders in elderly people with dementia. Methods: Eight experimental studies using spatial cues, assistive technology programs, reality orientation training, errorless learning technique, and backward chaining programs are described. They can be classified into two main approaches: restorative and compensatory, depending on whether they rely or not on residual learning ability, respectively. Results: A review of the efficacy of these intervention strategies is proposed. Results suggest that both compensatory and restorative approaches may be valuable in enhancing correct way-finding behavior, with various degrees of effectiveness. Some issues concerning (a) variability in participants' characteristics and experimental designs and (b) practicality of intervention strategies do not permit to draw a definite conclusion. Conclusions: Future research should be aimed at a direct comparison between these two strategies, and should incorporate an extensive neuropsychological assessment of spatial domain. [ABSTRACT FROM AUTHOR]

Developmental topographical disorientation (DTD) is the presence of navigational deficits in the context of normal intellectual ability and in the absence of any perinatal, neurological, or psychiatric disorder. As only three cases of DTD have been fully described thus far, we are still unable to draw definitive conclusions about its nature and relationship with other visuospatial competencies, such as mental rotation. The case of Mr. L.A., a 38-year-old man with no history of neurological or psychiatric disorders, sheds some light on these open questions. A neuropsychological assessment including IQ, memory, visuospatial, visuoconstructive, and navigational tests showed that Mr. L.A. has pure navigational deficits affecting both route knowledge and cognitive map processing. Unlike previously described cases of DTD, Mr. L.A. was not affected by any other visuospatial or visuoconstructive deficits. In a functional magnetic resonance imaging (fMRI) task involving the recall of route knowledge, Mr. L.A. showed activation in the occipital areas, involved in low-level perceptual analysis of the stimuli, and showed no activation in the areas activated in controls with regard to route knowledge. The present case suggests that different types of DTD exist, which are characterized by different navigational difficulties and anomalous/lacking functional brain activities in specific navigational networks. [ABSTRACT FROM PUBLISHER]