Visuospatial Processing Deficits Research Articles

QOL-35. ANALYSIS ON THE EVOLUTIONARY PATTERN OF COGNITIVE FUNCTIONS IN CHILDREN ON FOLLOW-UP FOR BRAIN TUMORS

Abstract BACKGROUND Long-term cognitive sequelae of paediatric brain tumors are of increasing interest. The role of histology and surgery remains still unclear. Our study aimed to evaluate children cognitive functioning before and after brain tumors surgery, and at the end of additional treatments. METHODS New diagnoses of paediatric primary brain tumors were prospectively assessed. Neurocognitive evaluations were performed at diagnosis (T0), within 7-10 days from surgery (T1) and 12-18 months after the end of treatments (T2). Language, learning and memory, attention, executive functions, visuo-constructional and sensorimotor skills were evaluated at T0 and T1, Intelligent Quotient (IQ) was explored at T0 and T2. RESULTS Twenty-five patients (M:F=15:10, mean age 10.9±3.4 years) were enrolled between January 2019 and December 2022. In comparison to normal values (>7.0), at baseline patients showed major deficits in narrative memory (6.6±3.7, p<0.001) and visuo-spatial memory (copy design tasks: general 6.8±3.9, p<0.001, specific 6.2±3.3, p<0.001, motor 5.2±3.2, p<0.001). At T1 assessment, significant deficits remained in narrative memory (6.2±3.3, p<0.001) and visual-motor coordination (copy design tasks: specific 5.9±3.0, p<0.001 and motor 4.8±4.3 p<0.001); attention and visual-constructional abilities significantly improved (p=0.04 and p=0.001). On the visual construction test, children with high-grade histology scored lower than the low-grade group (Rey- Osterrieth complex figure-copy 5.1±4.4 vs 11.0±4.3; p=0.019). At T2 evaluation children showed persistent deficits in visuo-spatial processing and a possible decline in IQ scores, with lower scores compared with T0 (93 vs 100, p=0.05). CONCLUSIONS Children with brain tumors may present several neuropsychological impairments at diagnosis, particularly those with high-grade diseases. Surgery may have a positive effect on the recovery of some cognitive functions. However, cognitive decline may worsen over time. Baseline and periodic neurocognitive evaluations should be encouraged to identify functional difficulties and to develop a tailored treatment approach for the patient.

Language uncovers visuospatial dysfunction in posterior cortical atrophy: a natural language processing approach.

Posterior Cortical Atrophy (PCA) is a syndrome characterized by a progressive decline in higher-order visuospatial processing, leading to symptoms such as space perception deficit, simultanagnosia, and object perception impairment. While PCA is primarily known for its impact on visuospatial abilities, recent studies have documented language abnormalities in PCA patients. This study aims to delineate the nature and origin of language impairments in PCA, hypothesizing that language deficits reflect the visuospatial processing impairments of the disease. We compared the language samples of 25 patients with PCA with age-matched cognitively normal (CN) individuals across two distinct tasks: a visually-dependent picture description and a visually-independent job description task. We extracted word frequency, word utterance latency, and spatial relational words for this comparison. We then conducted an in-depth analysis of the language used in the picture description task to identify specific linguistic indicators that reflect the visuospatial processing deficits of PCA. Patients with PCA showed significant language deficits in the visually-dependent task, characterized by higher word frequency, prolonged utterance latency, and fewer spatial relational words, but not in the visually-independent task. An in-depth analysis of the picture description task further showed that PCA patients struggled to identify certain visual elements as well as the overall theme of the picture. A predictive model based on these language features distinguished PCA patients from CN individuals with high classification accuracy. The findings indicate that language is a sensitive behavioral construct to detect visuospatial processing abnormalities of PCA. These insights offer theoretical and clinical avenues for understanding and managing PCA, underscoring language as a crucial marker for the visuospatial deficits of this atypical variant of Alzheimer's disease.

Remote digital cognitive assessment reveals cognitive deficits related to hippocampal atrophy in autoimmune limbic encephalitis: a cross-sectional validation study

Autoimmune limbic encephalitis (ALE) is a neurological disease characterised by inflammation of the limbic regions of the brain, mediated by pathogenic autoantibodies. Because cognitive deficits persist following acute treatment of ALE, the accurate assessment of long-term cognitive outcomes is important for clinical assessments and trials. However, evaluating cognition is costly and an unmet need exists for validated digital methods. In this cross-sectional validation study, we investigated whether a remote digital platform could identify previously characterised cognitive impairments in patients with chronic ALE and whether digital metrics would correlate with standard neuropsychological assessment and hippocampal volume. Patients with ALE who had a chronic and stable presentation and received a clinical diagnosis of ALE were recruited for this study. The cognitive performance of 21 patients with ALE and 54 age-matched healthy controls - enrolled via the University of Oxford (UK) Cognitive Neurology Lab testing programme - was assessed with a battery of 12 cognitive tasks from the Cognitron online platform. The platform was optimised with National Institute for Health and Care Research (NIHR) support to be deliverable remotely to elderly and patient groups. The primary outcome measure was behavioural performance and corresponding neuroimaging and neuropsychological assessment metrics. Between February 15, 2021, and April 21, 2022, 21 patients with ALE (mean age 63.01 years, 14 males) and 54 healthy controls (mean age 65.56 years, 23 males) completed the digital cognitive assessment. Patients with ALE performed significantly worse in memory, visuospatial abilities, executive function, and language. No impairments in digit & spatial span, target detection (attention) and emotion discrimination were observed. The global score on the online cognitive tasks correlated significantly with the established Addenbrooke's Cognitive Examination III (ACE) pen-and-paper test. Deficits in visuospatial processing and language were identified in ALE compared to controls using remote digital testing but not using the ACE, highlighting higher sensitivity of computerised testing to residual cognitive impairment. Finally, the hippocampal volumes of patients with ALE and healthy controls correlated with online cognitive scores. These findings demonstrate that subtle cognitive deficits in patients with chronic ALE, who often show full recovery in measures of disability and dependence on daily activities, are detectable using a remote online platform, which also relates to hippocampal atrophy. Such methods may facilitate the characterisation of cognitive profiles in complex neurological diseases. Future longitudinal studies designed to assess the utility of such digital methods for further clinical characterisation are needed. The Wellcome Trust, Medical Research Council, National Institute for Health Research, Rhodes Scholarship, and the Berrow Foundation Scholarship.

Altered neural oscillations underlying visuospatial processing in cerebral visual impairment.

Visuospatial processing deficits are commonly observed in individuals with cerebral visual impairment, even in cases where visual acuity and visual field functions are intact. Cerebral visual impairment is a brain-based visual disorder associated with the maldevelopment of central visual pathways and structures. However, the neurophysiological basis underlying higher-order perceptual impairments in this condition has not been clearly identified, which in turn poses limits on developing rehabilitative interventions. Using combined eye tracking and EEG recordings, we assessed the profile and performance of visual search on a naturalistic virtual reality-based task. Participants with cerebral visual impairment and controls with neurotypical development were instructed to search, locate and fixate on a specific target placed among surrounding distractors at two levels of task difficulty. We analysed evoked (phase-locked) and induced (non-phase-locked) components of broadband (4-55 Hz) neural oscillations to uncover the neurophysiological basis of visuospatial processing. We found that visual search performance in cerebral visual impairment was impaired compared to controls (as indexed by outcomes of success rate, reaction time and gaze error). Analysis of neural oscillations revealed markedly reduced early-onset evoked theta [4-6 Hz] activity (within 0.5 s) regardless of task difficulty. Moreover, while induced alpha activity increased with task difficulty in controls, this modulation was absent in the cerebral visual impairment group identifying a potential neural correlate related to deficits with visual search and distractor suppression. Finally, cerebral visual impairment participants also showed a sustained induced gamma response [30-45 Hz]. We conclude that impaired visual search performance in cerebral visual impairment is associated with substantial alterations across a wide range of neural oscillation frequencies. This includes both evoked and induced components suggesting the involvement of feedforward and feedback processing as well as local and distributed levels of neural processing.

Resting State Dynamic Reconfiguration of Spatial Attention Cortical Networks and Visuospatial Functioning in Non-Verbal Learning Disability (NVLD): A HD-EEG Investigation.

Nonverbal learning disability (NVLD) is a neurodevelopmental disorder characterized by deficits in visuospatial processing but spared verbal competencies. Neurocognitive markers may provide confirmatory evidence for characterizing NVLD as a separate neurodevelopmental disorder. Visuospatial performance and high-density electroencephalography (EEG) were measured in 16 NLVD and in 16 typically developing (TD) children. Cortical source modeling was applied to assess resting-state functional connectivity (rs-FC) in spatial attention networks (dorsal (DAN) and ventral attention networks (VAN)) implicated in visuospatial abilities. A machine-learning approach was applied to investigate whether group membership could be predicted from rs-FC maps and if these connectivity patterns were predictive of visuospatial performance. Graph theoretical measures were applied to nodes inside each network. EEG rs-FC maps in the gamma and beta band differentiated children with and without NVLD, with increased but more diffuse and less efficient functional connections bilaterally in the NVLD group. While rs-FC of the left DAN in the gamma range predicted visuospatial scores for TD children, in the NVLD group rs-FC of the right DAN in the delta range predicted impaired visuospatial performance, confirming that NVLD is a disorder with a predominant dysfunction in right hemisphere connectivity patterns.

Cannabis use impacts pre-stimulus neural activity in the visual cortices of people with HIV.

People with HIV (PWH) use cannabis at a higher rate than the general population, but the influence on neural activity is not well characterized. Cannabis use among PWH may have a beneficial effect, as neuroinflammation is known to be a critical problem in PWH and cannabis use has been associated with a reduction in proinflammatory markers. Thus, it is important to understand the net impact of cannabis use on brain and cognitive function in PWH. In this study, we collected magnetoencephalographic (MEG) brain imaging data on 81 participants split across four demographically matched groups (i.e., PWH using cannabis, controls using cannabis, non‐using PWH, and non‐using controls). Participants completed a visuospatial processing task during MEG. Time–frequency resolved voxel time series were extracted to identify the dynamics of oscillatory and pre‐stimulus baseline neural activity. Our results indicated strong theta (4–8 Hz), alpha (10–16 Hz), and gamma (62–72 Hz) visual oscillations in parietal–occipital brain regions across all participants. PWH exhibited significant behavioral deficits in visuospatial processing, as well as reduced theta oscillations and elevated pre‐stimulus gamma activity in visual cortices, all of which replicate prior work. Strikingly, chronic cannabis use was associated with a significant reduction in pre‐stimulus gamma activity in the visual cortices, such that PWH no longer statistically differed from controls. These results provide initial evidence that cannabis use may normalize some neural aberrations in PWH. This study fills an important gap in understanding the impact of cannabis use on brain and cognitive function in PWH.

Prevalence and Cognitive Profiles of Children With Comorbid Literacy and Motor Disorders

There is a high prevalence of comorbidity between neurodevelopmental disorders. Contemporary research of these comorbidities has led to the development of multifactorial theories of causation, including the multiple deficit model (MDM). While several combinations of disorders have been investigated, the nature of association between literacy and motor disorders remains poorly understood. Comorbid literacy and motor disorders were the focus of the two present studies. In Study 1, we examined the prevalence of comorbid literacy and motor difficulties relative to isolated literacy and motor difficulties in a community sample (N = 605). The prevalence of comorbidity was five times greater than expected by chance alone, implying some relationship between difficulties. In Study 2, we examined the cognitive profiles of children with literacy and motor disorders amongst a subsample of children from Study 1 (N = 153). Children with literacy disorder had deficits in phonological processing, selective attention, and memory whilst children with motor disorder had deficits in visuospatial processing and memory, suggesting the disorders should be considered to have both independent and shared (memory) cognitive risk factors. Children with comorbid literacy and motor disorder demonstrated an additive combination of these deficits. Together, these findings are consistent with predictions from the MDM.

Brain Tumors in NF1 Children: Influence on Neurocognitive and Behavioral Outcome

Neurofibromatosis type-1 (NF1) is a monogenic tumor-predisposition syndrome creating a wide variety of cognitive and behavioral abnormalities, such as decrease in cognitive functioning, deficits in visuospatial processing, attention, and social functioning. NF1 patients are at risk to develop neurofibromas and other tumors, such as optic pathway gliomas and other tumors of the central nervous system. Few studies have investigated the impact of an additional diagnosis of brain tumor on the cognitive outcome of children with NF1, showing unclear results and without controlling by the effect of surgery, radio- or chemotherapy. In the present mono-institutional study, we compared the behavioral and cognitive outcomes of 26 children with neurofibromatosis alone (NF1) with two age-matched groups of 26 children diagnosed with NF1 and untreated optic pathway glioma (NF1 + OPG) and 19 children with NF1 and untreated other central nervous system tumors (NF1 + CT). NF1 + CT and NF1 + OPG showed significantly impaired cognitive abilities compared to NF1 group, with weaknesses in visuo-spatial abilities, visual scanning and verbal working memory, while general verbal abilities are preserved. Moreover, NF1 + OPG patients present more frequent internalizing problems and increased oppositional-deviant behaviors. These results suggest that the co-diagnosis of a brain tumor in NF1 children may partially worsen the cognitive and emotional outcome.

Mental rotation task in bipolar disorder.

Bipolar disorder (BD) significantly affects level of cognitive and motor functioning. Studies on cognitive function in BD shows i.a. deficits in visuospatial processing and visuospatial memory. However, studies have not used Mental Rotation Task to evaluate these functions so far. Our aim is to introduce this method to assess abovementioned deficits in euthymic BD patients. 31 euthymic BD patients and 27 healthy volunteers matched for age and years of education were recruited. All participants performed digital version of Mental Rotation Task. In this task, participants were asked to compare two figures rotated against each other and declare its similarity or difference indicating whether the figures are identical or whether they constitute their own mirror image. The test revealed significantly longer reaction times in the group of BD patients when images were rotated by - 90, - 45, 45, 90 degrees, or not rotated at all. There was no significant difference in condition of - 135, 135 or 180 degrees. The accuracy rate was significantly lower in the patient group than in the control group for the entire test and in each condition. The correlation between the average response time and the accuracy rate turned out to be insignificant. Our results are consistent with studies presenting visuospatial deficits in bipolar disorder. In this study we show for the first time that mental rotation deficits are present in euthymic state of BD patients.

Role of the left hemisphere in visuospatial working memory.

Visuospatial processing deficits are typically associated with damage to the right hemisphere. However, deficits on spatial working memory have been reported among some individuals with focal left hemisphere damage (LHD). It has been suggested that the left hemisphere may play a role in such non-verbal working memory tasks due to the use of subvocal, verbally-mediated strategies. The current study investigated the role of the left hemisphere in spatial working memory by testing spatial span performance, both forward and backward, in a large group of individuals with a history of left hemisphere stroke. Our first aim was to establish whether individuals with LHD are indeed impaired on spatial span tasks using standardized span tasks with published normative data. Our second aim was to identify the role that language plays in supporting spatial working memory by comparing LHD individuals with and without aphasia, and by relating spatial span performance to performance on a series of language measures. Our third aim was to identify left hemisphere brain regions that contribute to spatial working memory using voxel-based lesion symptom mapping (VLSM), a whole-brain statistical approach that identifies regions critical to a particular behavior on a voxel-by-voxel basis. We found that 28% of individuals with LHD performed in the clinically-impaired range on forward spatial span and 16% performed in the clinically-impaired range on backward spatial span. There were no significant differences in performance between individuals with and without aphasia, and there were no correlations between spatial span performance and language functions such as repetition and comprehension. The VLSM analysis showed that backward spatial span was associated with a left fronto-parietal network consisting of somatosensory cortex, the supramarginal gyrus, lateral prefrontal cortex, and the frontal eye fields. Regions identified in the VLSM analysis of forward spatial span did not reach the conservative statistical threshold for significance. Overall, these results suggest that spatial working memory, as measured by spatial span, can be significantly disrupted in a subset of individuals with LHD whose lesions infringe on a network of regions in the left hemisphere that have been implicated in domain-general working memory and attentional control mechanisms.

The nature of social cognitive deficits in children and adults with Klinefelter syndrome (47,XXY).

About 1 in 650 boys are born with an extra X chromosome (47,XXY or Klinefelter syndrome). 47,XXY is associated with vulnerabilities in socio-emotional development. This study was designed to assess types of cognitive deficits in individuals with 47,XXY that may contribute to social-emotional dysfunction, and to evaluate the nature of such deficits at various levels: ranging from basic visuospatial processing deficits, impairments in face recognition (FR), to emotion expression impairments. A total of 70 boys and men with 47,XXY, aged 8 to 60 years old, participated in the study. The subtests feature identification, FR and identification of facial emotions of the Amsterdam Neuropsychological Tasks were used. Level of intellectual functioning was assessed with the child and adult versions of the Wechsler Intelligence Scales. Reaction time data showed that in the 47,XXY group, 17% had difficulties in visuospatial processing (no social load), 26% had difficulties with FR (medium social load) and an even higher number of 33% had difficulties with facial expressions of emotions (high-social load). Information processing impairments increased as a function of "social load" of the stimuli, independent of intellectual functioning. Taken together, our data suggest that on average individuals with XXY may have more difficulties in information processing when "social load" increases, suggesting a specific difficulty in the higher-order labeling and interpretation of social cues, which cannot be explained by more basic visuospatial perceptual skills. Considering the increased risk for social cognitive impairments, routine assessment of social cognitive functioning as part of neuropsychological screening is warranted.

Getting Lost Behavior in Patients with Mild Alzheimer's Disease: A Cognitive and Anatomical Model.

Getting lost behavior (GLB) in the elderly is believed to involve poor top-down modulation of visuospatial processing, by impaired executive functions. However, since healthy elderly and elderly with Alzheimer's disease (AD) experience a different pattern of cognitive decline, it remains unclear whether this hypothesis can explain GLB in dementia. We sought to identify whether poor executive functions and working memory modulate the relationship between visuospatial processing and prevalence of GLB in healthy elderly and patients with AD. Complementary to this, we explored whether brain regions critical for executive functions modulate the relationship between GLB and brain regions critical for visuospatial processing. Ninety-two participants with mild AD and 46 healthy age-matched controls underwent neuropsychological assessment and a structural MRI. GLB was assessed using a semistructured clinical interview. Path analysis was used to explore interactions between visuospatial deficits, executive dysfunction/working memory, and prevalence of GLB, in AD and controls independently. For both healthy controls and patients with mild AD, visuospatial processing deficits were associated with GLB only in the presence of poor working memory. Anatomically, GLB was associated with medial temporal atrophy in patients with mild AD, which was not strengthened by low frontal gray matter (GM) volume as predicted. Instead, medial temporal atrophy was more strongly related to GLB in patients with high frontal GM volumes. For controls, GLB was not associated with occipital, parietal, medial temporal, or frontal GM volume. Cognitively, a top-down modulation deficit may drive GLB in both healthy elderly and patients with mild AD. This modulation effect may be localized in the medial temporal lobe for patients with mild AD. Thus, anatomical substrates of GLB in mild AD may not follow the typical top-down modulation mechanisms often reported in the healthy aging population. Implications advance therapeutic practices by highlighting the need to target both working memory and visuospatial deficits simultaneously, and that anatomical substrates of GLB may be disease specific.

EYE MOVEMENT BEHAVIOR IN EARLY ALZHEIMER'S DISEASE: THE IMPACT OF TIME AND STIMULI SIMILARITY AS A MEASURE OF COGNITIVE EFFORT

Research has been showing that oculomotor measurements can accurately detect higher-order cognitive deficits, namely in memory and visuospatial processing deficits (Rizzo et al., 2004; Garbutt et al., 2008; Crutcher et al., 2009). Literature has still failed to analyze the impact of cognitive effort in the eye movement behavior as a tool to distinguish healthy subjects from those with cognitive decline due to Alzheimer's disease. 26 age and education matched participants (6 AD, 10 MCI, 10 NC) were submitted to a computational task composed by a familiarization phase and a test phase. During the familiarization phase, participants were instructed to look at two initial images. After that, there was a variable time delay of 5 or 90 seconds. During the test phase, other two images were presented, one of them was identical to previously seen, the other was a new one. Subjects were instructed to select the novel image which was either similar or non similar to the familiar stimulus. Eye-movement bahavior was analyzed based on four main parameters: number of visits (VC), duration of visits (VD) number of fixations (FC), fixation duration (FD). Parameters were analyzed regarding diagnostic, stimuli similarity and time between trials. Stimuli similarity revealed significant interference in the following parameters: VC, PrFC, PrVD, PrVC. Stimuli similarity also had impact on eye-movement pattern when associated with time delay between the familiarization phase and the test phase (PrFD, PrFC, PrVC). Both the proportion of time fixated on the novel stimulus (PrFD) and the proportion of the number of visits on the novel stimulus (PrVC) were affected by the participants’ diagnosis, when combined with stimuli similarity and time delay, respectively.

Visuospatial processing in adolescents with critical congenital heart disease: Organization, integration, and implications for academic achievement

ABSTRACTAmong the most significant factors affecting quality of life in individuals with critical congenital heart disease (CCHD) are neurodevelopmental challenges, including deficits in visuospatial processing and academic achievement. Few studies have compared outcomes across CCHD subgroups, despite their significant differences in anatomy/physiology and medical/surgical courses. This study compared visuospatial processing abilities using the Developmental Scoring System for the Rey–Osterrieth Complex Figure (DSS-ROCF) across groups of adolescents with CCHD (d-transposition of the great arteries [TGA, n = 139], Tetralogy of Fallot [TOF, n = 68], single-ventricle cardiac anatomy requiring the Fontan operation [SVF, n = 145]) and a group of healthy controls (CTR, n = 111), and examined the validity of visuospatial processing in predicting concurrent academic outcomes. The CCHD subgroups were found to differ in Organization, ps < .001, Structural Accuracy, ps < .001, and Incidental Elements Accuracy scores, ps ≤ .008; the post hoc analyses show that the SVF group tended to underperform compared to the other CCHD groups. With respect to academic skills, all CCHD groups scored lower than the CTR group, ps ≤ .007; however, the CCHD groups were not different from each other, ps > .23. The regression results showed that the DSS-ROCF Style rating (reflecting integration) accounted for a small yet statistically significant portion of unique variance in “assembled” academic outcomes, over and above the variance already accounted for by DSS-ROCF Organization, p < .01. These findings support the need for comprehensive neuropsychological assessment and monitoring of children and adolescents with CCHD, as well as targeted intervention for organization and integration deficits that may increase their risk for academic underachievement.

Emotion knowledge, emotion regulation, and psychosocial adjustment in children with nonverbal learning disabilities

ABSTRACTNonverbal learning disability is a childhood disorder with basic neuropsychological deficits in visuospatial processing and psychomotor coordination, and secondary impairments in academic and social-emotional functioning. This study examines emotion recognition, understanding, and regulation in a clinic-referred group of young children with nonverbal learning disabilities (NLD). These processes have been shown to be related to social competence and psychological adjustment in typically developing (TD) children. Psychosocial adjustment and social skills are also examined for this young group, and for a clinic-referred group of older children with NLD. The young children with NLD scored lower than the TD comparison group on tasks assessing recognition of happy and sad facial expressions and tasks assessing understanding of how emotions work. Children with NLD were also rated as having less adaptive regulation of their emotions. For both young and older children with NLD, internalizing and externalizing problem scales were rated higher than for the TD comparison groups, and the means of the internalizing, attention, and social problem scales were found to fall within clinically concerning ranges. Measures of attention and nonverbal intelligence did not account for the relationship between NLD and Social Problems. Social skills and NLD membership share mostly overlapping variance in accounting for internalizing problems across the sample. The results are discussed within a framework wherein social cognitive deficits, including emotion processes, have a negative impact on social competence, leading to clinically concerning levels of depression and withdrawal in this population.

Visuospatial Processing Deficits Linked to Posterior Brain Regions in Premanifest and Early Stage Huntington's Disease.

Visuospatial processing deficits have been reported in Huntington's disease (HD). To date, no study has examined associations between visuospatial cognition and posterior brain findings in HD. We compared 119 premanifest (55> and 64<10.8 years to expected disease onset) and 104 early symptomatic (59 stage-1 and 45 stage-2) gene carriers, with 110 controls on visual search and mental rotation performance at baseline and 12 months. In the disease groups, we also examined associations between task performance and disease severity, functional capacity and structural brain measures. Cross-sectionally, there were strong differences between all disease groups and controls on visual search, and between diagnosed groups and controls on mental rotation accuracy. Only the premanifest participants close to onset took longer than controls to respond correctly to mental rotation. Visual search negatively correlated with disease burden and motor symptoms in diagnosed individuals, and positively correlated with functional capacity. Mental rotation ("same") was negatively correlated with motor symptoms in stage-2 individuals, and positively correlated with functional capacity. Visual search and mental rotation were associated with parieto-occipital (pre-/cuneus, calcarine, lingual) and temporal (posterior fusiform) volume and cortical thickness. Longitudinally, visual search deteriorated over 12 months in stage-2 individuals, with no evidence of declines in mental rotation. Our findings provide evidence linking early visuospatial deficits to functioning and posterior cortical dysfunction in HD. The findings are important since large research efforts have focused on fronto-striatal mediated cognitive changes, with little attention given to aspects of cognition outside of these areas. (JINS, 2016, 22, 595-608).

Nature and origins of mathematics difficulties in very preterm children: a different etiology than developmental dyscalculia

Children born very preterm (<32 wk) are at high risk for mathematics learning difficulties that are out of proportion to other academic and cognitive deficits. However, the etiology of mathematics difficulties in very preterm children is unknown. We sought to identify the nature and origins of preterm children's mathematics difficulties. One hundred and fifteen very preterm children aged 8-10 y were assessed in school with a control group of 77 term-born classmates. Achievement in mathematics, working memory, visuospatial processing, inhibition, and processing speed were assessed using standardized tests. Numerical representations and specific mathematics skills were assessed using experimental tests. Very preterm children had significantly poorer mathematics achievement, working memory, and visuospatial skills than term-born controls. Although preterm children had poorer performance in specific mathematics skills, there was no evidence of imprecise numerical representations. Difficulties in mathematics were associated with deficits in visuospatial processing and working memory. Mathematics difficulties in very preterm children are associated with deficits in working memory and visuospatial processing not numerical representations. Thus, very preterm children's mathematics difficulties are different in nature from those of children with developmental dyscalculia. Interventions targeting general cognitive problems, rather than numerical representations, may improve very preterm children's mathematics achievement.

Face and location processing in children with early unilateral brain injury

Human visuospatial functions are commonly divided into those dependent on the ventral visual stream (ventral occipitotemporal regions), which allows for processing the ‘what’ of an object, and the dorsal visual stream (dorsal occipitoparietal regions), which allows for processing ‘where’ an object is in space. Information about the development of each of the two streams has been accumulating, but very little is known about the effects of injury, particularly very early injury, on this developmental process. Using a set of computerized dorsal and ventral stream tasks matched for stimuli, required response, and difficulty (for typically-developing individuals), we sought to compare the differential effects of injury to the two systems by examining performance in individuals with perinatal brain injury (PBI), who present with selective deficits in visuospatial processing from a young age. Thirty participants (mean=15.1years) with early unilateral brain injury (15 right hemisphere PBI, 15 left hemisphere PBI) and 16 matched controls participated. On our tasks children with PBI performed more poorly than controls (lower accuracy and longer response times), and this was particularly prominent for the ventral stream task. Lateralization of PBI was also a factor, as the dorsal stream task did not seem to be associated with lateralized deficits, with both PBI groups showing only subtle decrements in performance, while the ventral stream task elicited deficits from RPBI children that do not appear to improve with age. Our findings suggest that early injury results in lesion-specific visuospatial deficits that persist into adolescence. Further, as the stimuli used in our ventral stream task were faces, our findings are consistent with what is known about the neural systems for face processing, namely, that they are established relatively early, follow a comparatively rapid developmental trajectory (conferring a vulnerability to early insult), and are biased toward the right hemisphere.

Deficits in visuospatial processing contribute to quantitative measures of freezing of gait in Parkinson’s disease

Objectives: The aim of this study was to investigate whether an objective measure of freezing of gait (FOG) using a validated alternating stepping in place (SIP) task, is related to executive and/or visuospatial cognitive impairment in Parkinson’s disease (PD). Methods: We studied prospectively 30 PD subjects with the Unified Parkinson’s Disease Rating Scale (UPDRS) III, the FOGq, Trail Making Test Part B (TMTB), Wisconsin Card Sorting, Initiation/Perseveration, Matrix Reasoning (MR) and Block Design (BD). PD subjects performed three, 100s trials of alternative SIP while standing on two force platforms to assess the number and duration of freezing episodes (FE), SIP rhythmicity and symmetry. Results: Freezers had larger cycle asymmetry and arrhythmicity than non-freezers (P<0.05). Performance on BD and MR tests differentiated freezers from non-freezers (P<0.04; P=0.001, respectively). BD performance negatively correlated with the FOGq total (P<0.05), the number and duration of FE (P<0.01), SIP arrhythmicity and asymmetry (P=0.01, P<0.05). MR performance negatively correlated with all FOGq #3 and total as well as SIP FE metrics (P⩽0.01), except for SIP asymmetry. Conclusion: Deficits in visuospatial perception and reasoning not in executive function differentiated freezers from non-freezers. Deficits in visuospatial processing negatively correlated with all SIP freeze metrics, whereas deficits in executive function were only correlated with SIP arrhythmicity, the FOGq total and the duration of freezing episodes. These results suggest that deficits in visuospatial processing to perform a motor task contribute to FOG and that different cognitive deficits may contribute to different aspects of freezing in PD. This is the first study to our knowledge that has compared metrics of freezing to cognitive tasks in the visuospatial and visual reasoning domains.

The relationship between pitch and space in congenital amusia

Congenital amusia manifests as a lifelong difficulty in making sense of musical sound. The extent to which this disorder is accompanied by deficits in visuo-spatial processing is an important question, bearing on the issue of whether pitch processing draws on supramodal spatial representations. The present study assessed different aspects of visuo-spatial processing with a range of tasks (Shepard–Metzler Mental Rotation, Corsi Blocks Task, Visual Patterns Test) in 14 amusics and matched controls. The absence of a group difference on any of these tasks fails to support a previous claim that the disorder is strongly related to deficits in spatial processing. However, a subgroup of amusics, with significantly elevated thresholds on a pitch direction discrimination task relative to the rest of the group, were slower, but equally accurate, at Mental Rotation. This finding is discussed in relation to the nature of supramodal representations of contour and strategies for dynamic mental transformation.