Hemispheric preference in visuospatial processing: a complementary approach with fMRI and lesion studies

Impaired cognitive performance in older adults is associated with deficits in item memory and memory for object features

Amnestic mild cognitive impairment (aMCI) is associated with damage to the perirhinal/entorhinal cortex, and consequently, deficits in item/object memory. However, cognitive assessments commonly used to identify individuals with aMCI require a clinician to administer and interpret the test. We developed a novel self-administered global cognitive assessment, called the Cognitive Assessment via Keyboard (CAKe). To assess the relationship between CAKe performance and perirhinal/entorhinal cortex-dependent memory function, participants completed the CAKe, a feature source memory task, and a context memory task. During the memory tasks, participants studied line drawings with either a green or orange internal color (feature memory runs) or external color (context memory runs) and then classified each item as old and previously presented with a "green" or "orange" color, or "new". CAKe scores were correlated with item memory accuracies and source memory accuracies on both tasks. Participants with 'impaired' CAKe performance had worse item memory and worse feature source memory accuracies than those with 'normal' CAKe performance. These results demonstrate specific deficits in item memory and feature source memory and suggest that our assessments may be a valid predictor of aMCI memory deficits.

Identification of a novel link between adiposity and visuospatial perception

OBJECTIVE

Recent work has reported a negative association between BMI and performance on the Penn Line Orientation Task. To determine the reliability of this effect, a comprehensive assessment of visual function in individuals with healthy weight (HW) and those with overweight/obesity (OW/OB) was performed.

METHODS

Visual acuity/contrast, Penn Line Orientation Task, and higher-order visuospatial function were measured in 80 (40 with HW, 40 with OW/OB) case-control study participants. Adiposity, fasting glucose, hemoglobin A1c, diet, physical activity, and heart rate variability were also assessed. A subgroup of 22 participants plus 5 additional participants (n = 27) underwent functional magnetic resonance imaging scanning.

RESULTS

Compared with those with HW, individuals with OW/OB performed worse on tasks requiring judgments of line orientation. This effect was mediated by body fat percentage and was unrelated to other measures. Functional magnetic resonance imaging revealed a negative association between BMI and response in the primary visual cortex (V1) during line orientation judgment. Performance was unrelated to V1 response but positively correlated with response in a network of regions, including the lateral occipital cortex, when BMI was accounted for in the model.

CONCLUSIONS

These results demonstrate a selective deficit in line orientation perception associated with adiposity and blunted activation in the V1 that cannot be attributed to visual acuity and does not generalize to other visuospatial tasks.

Handedness did not affect motor skill acquisition by the dominant hand or interlimb transfer to the non-dominant hand regardless of task complexity level

Patients undergoing unilateral orthopedic or neurological rehabilitation have different levels of impairments in the right- or left-dominant hand. However, how handedness and the complexity of the motor task affect motor skill acquisition and its interlimb transfer remains unknown. In the present study, participants performed finger key presses on a numeric keypad at 4 levels of sequence complexities with each hand in a randomized order. Furthermore, they also performed motor sequence practice with the dominant hand to determine its effect on accuracy, reaction time, and movement time. The NASA-TLX at the end of each block of both testing and practice was used to confirm participants' mental workload related to sequence complexity. Both right- and left-handed participants performed the motor sequence task with faster RT when using their right hand. Although participants had increasing RT with increasing sequence complexity, this association was unrelated to handedness. Motor sequence practice produced motor skill acquisition and interlimb transfer indicated by a decreased RT, however, these changes were independent of handedness. Higher sequence complexity was still associated with longer RT after the practice, moreover, both right- and left-handed participants' RT increased with the same magnitude with the increase in sequence complexity. Similar behavioral pattern was observed in MT as in RT. Overall, our RT results may indicate left-hemisphere specialization for motor sequencing tasks, however, neuroimaging studies are needed to support these findings. On the other hand, handedness did not affect motor skill acquisition by the dominant hand or interlimb transfer to the non-dominant hand regardless of task complexity level.

Neuropsychiatric symptoms in a occipito-temporal infarction with remarkable long-term functional recovery

Posterior circulation infarctions (PCI) constitute 5-25% of ischemic strokes. PCI of the occipital lobe present with a panoply of symptoms including quadrantanopsia, topographical disorientation, and executive dysfunction. Long-term cognitive recovery after PCI is not well described. However, the adult brain is remarkably plastic, capable of adapting and remodeling. We describe a 43-year-old right-handed woman who complained of black spots in both eyes, headaches, photophobia, and a feeling she would faint. Initial neurological exam and a CT scan were normal; she was diagnosed with ocular migraine. A second neurological exam a week later showed left superior quadrantopsia; an MRI scan suggested right occipito-temporal infarct. In subsequent months, the patient complained of fatigue, quadrantanopsia, memory problems, and topographical disorientation. The patient participated in multi-modality treatment, and in self-directed arts projects and physical activities. Six years later, she reported noticeable improvements in cognition and daily functioning, which were documented on neurocognitive testing. Comparison between initial and subsequent MRIs using FreeSurfer 5.3 identified neuroplastic brain changes in areas serving similar functions to the areas injured from the stroke. The case illustrates the neuropsychiatric presentation after right occipito-temporal stroke, the value of formal and self-directed cognitive rehabilitation, the extended time to cognitive recovery, and the ability of the brain to undergo neuroplastic changes.

The oblique effect: The relationship between profiles of visuospatial preference, cognition, and brain connectomics in older adults

The oblique effect (OE) describes the visuospatial advantage for identifying stimuli oriented horizontally or vertically rather than diagonally; little is known about brain aging and the OE. We investigated this relationship using the Judgment of Line Orientation (JLO) in 107 older adults (∼age = 67.8 ± 6.6; 51% female) together with neuropsychological tests of executive functioning (EF), attention/information processing (AIP), and neuroimaging. Only JLO lines falling between 36-54° or 126-144° were considered oblique. To quantify the oblique effect, we calculated z-scores for oblique errors (zOblique = #oblique errors/#oblique lines), and similarly, horizontal + vertical line errors (zHV), and a composite measure of oblique relative to HV errors (zOE). Composite z-scores of EF and AIP reflected domains associated with JLO performance. Graph theory analysis integrated T1-derived volumetry and diffusion MRI-derived white matter tractography into connectivity matrices analyzed for select network properties. Participants produced more zOblique than zHV errors (p < 0.001). Age was not associated with zOE adjusting for sex, education, and MMSE. Similarly adjusted linear regression models revealed that lower EF was associated with a larger oblique effect (p < 0.001). Modular analyses of neural connectivity revealed a differential patterns of network affiliation that varied by high versus low group status determined via median split of zOblique and zHV errors, separately. Older adults exhibit the oblique effect and it is associated with specific cognitive processes and regional brain networks that may facilitate future investigations of visuospatial preference in aging.

The differential effect of background music on memory for verbal and visuospatial information

Background music is a part of our everyday activities. Considerable evidence suggests that listening to music while performing cognitive tasks may negatively influence performance. However, other studies have shown that it can benefit memory when the music played during the encoding of information is also provided during the retrieval of that information, in the so-called context dependent memory effect. Since controversial results may be attributed to the nature of the material to be memorized, the aim of the present study is to compare the potential effect of consistent background music on the immediate and long-term recall of verbal and visuospatial information. Experiment 1 showed that instrumental background music does not benefit nor decrease recall of a list of unrelated words, both at the immediate and the 48-hours-delayed tests. By contrast, Experiment 2 revealed that the same background music can impair immediate and therefore long-term memory for visuospatial information. Results are interpreted in terms of competition for neurocognitive resources, with tasks mostly relying on the same brain hemisphere competing for a limited set of resources. Hence, background music might impair visuospatial memory to a greater extent than verbal memory, in the context of limited capacity cognitive system. In conclusion, the nature of the material to be learnt must be considered to fully understand the effect of background music on memory.

Mind over motor mapping: Driver response to changing vehicle dynamics

Improvements in vehicle safety require understanding of the neural systems that support the complex, dynamic task of real-world driving. We used functional near infrared spectroscopy (fNIRS) and pupilometry to quantify cortical and physiological responses during a realistic, simulated driving task in which vehicle dynamics were manipulated. Our results elucidate compensatory changes in driver behavior in response to changes in vehicle handling. We also describe associated neural and physiological responses under different levels of mental workload. The increased cortical activation we observed during the late phase of the experiment may indicate motor learning in prefrontal-parietal networks. Finally, relationships among cortical activation, steering control, and individual personality traits suggest that individual brain states and traits may be useful in predicting a driver's response to changes in vehicle dynamics. Results such as these will be useful for informing the design of automated safety systems that facilitate safe and supportive driver-car communication.

The relationship between neuropsychological tests of visuospatial function and lobar cortical thickness

INTRODUCTION

Tests of visuospatial function are often administered in comprehensive neuropsychological evaluations. These tests are generally considered assays of parietal lobe function; however, the neural correlates of these tests, using modern imaging techniques, are not well understood. In the current study we investigated the relationship between three commonly used tests of visuospatial function and lobar cortical thickness in each hemisphere.

METHOD

Data from 374 patients who underwent a neuropsychological evaluation and MRI scans in an outpatient dementia clinic were included in the analysis. We examined the relationships between cortical thickness, as assessed with Freesurfer, and performance on three tests: Judgment of Line Orientation (JoLO), Block Design (BD) from the Fourth edition of the Wechsler Adult Intelligence Scale, and Brief Visuospatial Memory Test-Revised Copy Trial (BVMT-R-C) in patients who showed overall average performance on these tasks. Using a series of multiple regression models, we assessed which lobe's overall cortical thickness best predicted test performance.

RESULTS

Among the individual lobes, JoLO performance was best predicted by cortical thickness in the right temporal lobe. BD performance was best predicted by cortical thickness in the right parietal lobe, and BVMT-R-C performance was best predicted by cortical thickness in the left parietal lobe.

CONCLUSIONS

Performance on constructional tests of visuospatial function appears to correspond best with underlying cortical thickness of the parietal lobes, while performance on visuospatial judgment tests appears to correspond best to temporal lobe thickness. Future research using voxel-wise and connectivity techniques and including more diverse samples will help further understanding of the regions and networks involved in visuospatial tests.

The role of regional heterogeneity in age-related differences in functional hemispheric asymmetry: an fMRI study

Neuroimaging literature has documented age-related hemispheric asymmetry reduction in frontal regions during task performances. As most studies employed working memory paradigms, it is therefore less clear if this pattern of neural reorganization is constrained by working memory processes or it would also emerge in other cognitive domains which are predominantly lateralized. Using blocked functional magnetic resonance imaging (fMRI), the present study used a homophone judgment task and a line judgment task to investigate age-related differences in functional hemispheric asymmetry in language and visuospatial processing respectively. Young and older adults achieved similar task accuracy although older adults required a significantly longer time. Age-related functional hemispheric asymmetry reduction was found only in dorsal inferior frontal gyrus and was associated with better performance when the homophone condition was contrasted against fixation, and not line condition. Our data thus highlights the importance of considering regional heterogeneity of aging effects together with general age-related cognitive processes.

Functional hemispheric asymmetries during the planning and manual control of virtual avatar movements

Both hemispheres contribute to motor control beyond the innervation of the contralateral alpha motoneurons. The left hemisphere has been associated with higher-order aspects of motor control like sequencing and temporal processing, the right hemisphere with the transformation of visual information to guide movements in space. In the visuomotor context, empirical evidence regarding the latter has been limited though the right hemisphere’s specialization for visuospatial processing is well-documented in perceptual tasks. This study operationalized temporal and spatial processing demands during visuomotor processing and investigated hemispheric asymmetries in neural activation during the unimanual control of a visual cursor by grip force. Functional asymmetries were investigated separately for visuomotor planning and online control during functional magnetic resonance imaging in 19 young, healthy, right-handed participants. The expected cursor movement was coded with different visual trajectories. During planning when spatial processing demands predominated, activity was right-lateralized in a hand-independent manner in the inferior temporal lobe, occipito-parietal border, and ventral premotor cortex. When temporal processing demands overweighed spatial demands, BOLD responses during planning were left-lateralized in the temporo-parietal junction. During online control of the cursor, right lateralization was not observed. Instead, left lateralization occurred in the intraparietal sulcus. Our results identify movement phase and spatiotemporal demands as important determinants of dynamic hemispheric asymmetries during visuomotor processing. We suggest that, within a bilateral visuomotor network, the right hemisphere exhibits a processing preference for planning global spatial movement features whereas the left hemisphere preferentially times local features of visual movement trajectories and adjusts movement online.

Human Brain Mapping of Visual Script Familiarity between Phonological and Logographic Language: 3 T Functional MRI Study

Neurolinguistic circuitry for two different scripts of language, such as phonological scripts (PhonoS) versus logographic scripts (LogoS) (e.g., English versus Chinese, resp.), recruits segregated neural pathways according to orthographic regularity (OrthoR). The purpose of this study was to identify the effect of VSF for cortical representation according to different OrthoR to represent Hangul versus Hanja as PhonoS versus LogoS, respectively. A total of 24 right-handed, native Korean undergraduate students with the first language of PhonoS and the second language of LogoS were divided into high- or low-competent groups for L2 of LogoS. The implicit word reading task was performed using Hanja and Hangul scripts during functional magnetic resonance imaging (fMRI) acquisition. Fluctuations of fMRI BOLD signal demonstrated that the LogoS was associated with the ventral pathway, whereas PhonoS was associated with the dorsal pathway. By interaction analysis, compared with high-competent group, low-competent group showed significantly greater activation for Hanja than for Hangul reading in the right superior parietal lobule area and the left supplementary motor area, which might be due to neural efficiency such as attention and cognition rather than core neurolinguistic neural demand like OrthoR processing.

Cognitive Variability during Middle-Age: Possible Association with Neurodegeneration and Cognitive Reserve

Objective: Increased variability in cognition with age has been argued as an indication of pathological processes. Focusing on early detection of neurodegenerative disorders, we investigated variability in cognition in healthy middle-aged adults. In order to understand possible determinants of this variability, we also investigated associations with cognitive reserve, neuroimaging markers, subjective memory complaints, depressive symptomatology, and gender.

Method: Thirty-one 50 ± 2 years old individuals were investigated as target group and deviation was studied in comparison to a reference younger group of 30 individuals 40 ± 2 years old. Comprehensive neuropsychological and structural imaging protocols were collected. Brain regional volumes and cortical thickness were calculated with FreeSurfer, white matter hyperintensities with CASCADE, and mean diffusivity with FSL.

Results: Across-individuals variability showed greater dispersion in lexical access, processing speed, executive functions, and memory. Variability in global cognition correlated with, reduced cortical thickness in the right parietal-temporal-occipital association cortex, and increased mean diffusivity in the cingulum bundle and right inferior fronto-occipital fasciculus. A trend was also observed for the correlation between global cognition and hippocampal volume and female gender. All these associations were influenced by cognitive reserve. No correlations were found with subjective memory complaints, white matter hyperintensities and depressive symptomatology. Across-domains and across-tasks variability was greater in several executive components and cognitive processing speed.

Conclusion: Variability in cognition during middle-age is associated with neurodegeneration in the parietal–temporal–occipital association cortex and white matter tracts connecting this to the prefrontal dorsolateral cortex and the hippocampus. Moreover, this effect is influenced by cognitive reserve. Studying variability offers valuable information showing that differences do not occur in the same magnitude and direction across individuals, cognitive domains and tasks. These findings may have important implications for early detection of subtle cognitive impairment and clinical interpretation of deviation from normality.

Lack of Degradation in Visuospatial Perception of Line Orientation after One Night of Sleep Loss

Sleep deprivation impairs a variety of cognitive abilities including vigilance, attention, and executive function. Although sleep loss has been shown to impair tasks requiring visual attention and spatial perception, it is not clear whether these deficits are exclusively a function of reduced attention and vigilance or if there are also alterations in visuospatial perception. Visuospatial perception and sustained vigilance performance were therefore examined in 54 healthy volunteers at rested baseline and again after one night of sleep deprivation using the Judgment of Line Orientation Test and a computerized test of psychomotor vigilance. Whereas psychomotor vigilance declined significantly from baseline to sleep-deprived testing, scores on the Judgment of Line Orientation did not change significantly. Results suggest that documented performance deficits associated with sleep loss are unlikely to be the result of dysfunction within systems of the brain responsible for simple visuospatial perception and processing of line angles.

ERPs in an oddball task under vection-inducing visual stimulation

The neural mechanisms underlying the vection illusion are not fully understood. A few studies have analyzed visually evoked potentials or event-related potentials (ERPs) when participants were exposed to vection-inducing stimulation. However, none of them tested how such stimulation influences the brain activity during performance of the simultaneous visual task. In the present study, ERPs were recorded while subjects (N = 19) performed a discrimination oddball task. Two stimuli (O or X) were presented on the background of central and peripheral visual fields consisting of altered black and white vertical stripes that were stationary or moving horizontally. Three different combinations of these fields were created: (1) both center and periphery stationary (control condition), (2) both center and periphery moving, (3) center stationary and periphery moving. Mean reaction times to targets were shortest in the control condition. The amplitudes of P1 and N2 at occipital locations, and the amplitude of P3 at frontal, central, and parietal locations, were attenuated, and the P3 exhibited longer peak latency when both central and peripheral visual fields were moving. These potentials reflect initial sensory processing and the degree of attention required for processing visual stimuli and performing the task. Our findings suggest that the integration of central and peripheral moving visual fields enhances the vection illusion and slows down reaction times to targets in the oddball task and disrupts the magnitude of electrophysiological responses to targets.

Neuropsychological Impact of West Nile Virus Infection: An Extensive Neuropsychiatric Assessment of 49 Cases in Canada

BACKGROUND

West Nile virus emerged as an important human pathogen in North America and continues to pose a risk to public health. It can cause a highly variable range of clinical manifestations ranging from asymptomatic to severe illness. Neuroinvasive disease due to West Nile virus can lead to long-term neurological deficits and psychological impairment. However, these deficits have not been well described. The objective of this study was to characterize the neuropsychological manifestations of West Nile virus infection with a focus on neuroinvasive status and time since infection.

METHODS

Patients from Ontario Canada with a diagnosis of neuroinvasive disease (meningitis, encephalitis, or acute flaccid paralysis) and non-neuroinvasive disease who had participated in a cohort study were enrolled. Clinical and laboratory were collected, as well as demographics and medical history. Cognitive functioning was assessed using a comprehensive battery of neuropsychological tests.

RESULTS

Data from 49 individuals (32 with West Nile fever and 17 with West Nile neuroinvasive disease) were included in the present cross-sectional analysis. Patterns of neuropsychological impairment were comparable across participants with both neuroinvasive and non-neuroinvasive West Nile virus infection on all cognitive measures. Neuropsychiatric impairment was also observed more frequently at two to four years post-infection compared to earlier stages of illness.

CONCLUSIONS

Our data provide objective evidence for cognitive difficulties among patients who were infected with West Nile virus; these deficits appear to manifest regardless of severity of West Nile virus infection (West Nile fever vs. West Nile neuroinvasive disease), and are more prevalent with increasing illness duration (2-4 years vs. 1 month). Data from this study will help inform patients and healthcare providers about the expected course of recovery, as well as the need to implement effective treatment strategies that include neuropsychological interventions.

The effect of rotating random dot motion on visuospatial line orientation in patients with right-sided stroke

Spatial deficits are frequent after brain damage, particularly right hemisphere stroke. Visual judgments of line orientation (LINE) are often impaired after right parietal lesions. Perception of line orientation is an important visuoperceptual component of visuoconstructive capacities. Yet, little is known about modulating factors in LINE and effective treatments are rare for this disorder. Studies in patients with spatial neglect show that horizontal random dot motion (RDM) significantly modulates horizontal spatial disorders, both transiently and permanently after treatment. In the current study, we investigated whether rotational RDM modulates judgements in an oblique LINE task in 20 patients with right-hemispheric first ever stroke (10 of them with a disorder in LINE and 10 without such a disorder), and 10 healthy, age-matched subjects. Subjects were tested under three experimental conditions: (1) with a static background of small white dots, (2) with slow clockwise or (3) counterclockwise circular RDM of these background stimuli, while they performed the LINE task. In the baseline condition with static background, the impaired patient group showed a significant counterclockwise tilt. Clockwise rotating RDM normalized this deficit transiently but completely, while counterclockwise rotating RDM slightly aggravated it, though not significantly. Tilts in the LINE task were significantly correlated with left visuospatial neglect. Similar but much smaller effects were obtained in the spatially unimpaired patients and the normal controls. These results show that rotational RDM modulates deficits of line orientation in patients with right-sided stroke, possibly by influencing higher spatial representations devoted to the perception of oblique lines.

Visuospatial and mathematical dysfunction in major depressive disorder and/or panic disorder: A study of parietal functioning

The parietal cortex is critical for several different cognitive functions, including visuospatial processing and mathematical abilities. There is strong evidence indicating parietal dysfunction in depression. However, it is less clear whether anxiety is associated with parietal dysfunction and whether comorbid depression and anxiety are associated with greater impairment. The present study compared participants with major depression (MDD), panic disorder (PD), comorbid MDD/PD and controls on neuropsychological measures of visuospatial processing, Judgement of Line Orientation (JLO), and mathematical abilities, Wide Range Achievement Test (WRAT) Arithmetic. Only comorbid MDD/PD was associated with decreased performance on JLO, whereas all psychopathological groups exhibited comparably decreased performance on WRAT Arithmetic. Furthermore, the results were not accounted for by other comorbid disorders, medication use or psychopathology severity. The present study suggests comorbid depression and anxious arousal are associated with impairment in visuospatial processing and provides novel evidence indicating mathematical deficits across depression and/or anxiety. Implications for understanding parietal dysfunction in internalising psychopathology are discussed.

Holistic neural coding of Chinese character forms in bilateral ventral visual system

How are Chinese characters recognized and represented in the brain of skilled readers? Functional MRI fast adaptation technique was used to address this question. We found that neural adaptation effects were limited to identical characters in bilateral ventral visual system while no activation reduction was observed for partially overlapping characters regardless of the spatial location of the shared sub-character components, suggesting highly selective neuronal tuning to whole characters. The consistent neural profile across the entire ventral visual cortex indicates that Chinese characters are represented as mutually distinctive wholes rather than combinations of sub-character components, which presents a salient contrast to the left-lateralized, simple-to-complex neural representations of alphabetic words. Our findings thus revealed the cultural modulation effect on both local neuronal activity patterns and functional anatomical regions associated with written symbol recognition. Moreover, the cross-language discrepancy in written symbol recognition mechanism might stem from the language-specific early-stage learning experience.

Social cognition in schizophrenia and healthy aging: differences and similarities

Social cognition is impaired in schizophrenia but it is not clear whether this is specific for the illness and whether emotion perception is selectively affected. To study this we examined the perception of emotional and non-emotional clues in facial expressions, a key social cognitive skill, in schizophrenia patients and old healthy individuals using young healthy individuals as reference. Tests of object recognition, visual orientation, psychomotor speed, and working memory were included to allow multivariate analysis taking into account other cognitive functions

RESULTS

Schizophrenia patients showed impairments in recognition of identity and emotional facial clues compared to young and old healthy groups. Severity was similar to that for object recognition and visuospatial processing. Older and younger healthy groups did not differ from each other on these tests. Schizophrenia patients and old healthy individuals were similarly impaired in the ability to automatically learn new faces during the testing procedure (measured by the CSTFAC index) compared to young healthy individuals.

CONCLUSIONS

Social cognition is distinctly impaired in schizophrenia compared to healthy aging. Further study is needed to identify the mechanisms of automatic social cognitive learning impairment in schizophrenia patients and healthy aging individuals and determine whether similar neural systems are affected.

Frontal-executive constructional apraxia: when delayed recall is better than copying

In assessments of visuospatial function and memory, patients are often required to copy a figure and later to reproduce that figure from memory. Whereas most people perform better on a copying task than when drawing from memory, in this study we describe an unusual pattern of performance in which patients are better at drawing from memory than copying. Consecutive patients in a neurocognitive disorders clinic were given a battery of clinical cognitive tests that included copying a figure of intersecting pentagons and then drawing the figure from memory. Patterns of drawing performance at the two time points were compared to the profile of other cognitive deficits.

RESULTS

A subgroup of four patients with frontal dysfunction showed marked improvement in drawings at a delay compared to copying. Prior studies have indicated that most patients have declines in drawing performance at a delay. The unusual pattern of better performance at a delay compared to an initial copy occurred in patients with frontal dysfunction. These patients' visuoconstructive deficit and subsequent improvement could be related to either a failure to disengage when a model is present, to memory consolidation with increased reliance on top-down processing in the delay condition, or to relative preservation of global versus local aspects of a stimulus in memory. The addition of a task to assess drawing after a delay to a standard clinical screening battery such as the Mini-Mental Status Examination (MMSE) provides the opportunity to evaluate this phenomenon that may be indicative of frontal-executive dysfunction.

True functional ability of chronic stroke patients

BACKGROUND

There is a paucity of information regarding visuospatial (VS) and visuomotor (VM) task performance in patients with chronic right fronto-parietal lobe stroke, as the majority of knowledge to date in this realm has been gleaned from acute stroke patients. The goal of this paper is to determine how VS and VM performance in chronic stroke patients compare to the performance of healthy participants.

METHODS

Nine patients with stroke involving the right fronto-parietal region were evaluated against match controls on neuropsychological tests and a computerized visuomotor assessment task.

RESULTS

Initial evaluation indicated that performance between participant groups were relatively similar on all measures. However, an in-depth analysis of variability revealed observable differences between participant groups. In addition, large effect sizes were also observed supporting the theory that using only conventional examination (e.g., p-values) measures may result in miss-identifying crucial stroke-related differences.

CONCLUSION

Through conventional evaluation methods it would appear that the chronic stroke participants had made significant functional gains relatively to a control group many years post-stroke. It was shown that the type of evaluation used is essential to identifying group differences. Thus, supplementary methods of evaluation are required to unmask the true functional ability of individuals many years post-stroke.

Effects of Feedback-Based Visual Line-Orientation Discrimination Training for Visuospatial Disorders After Stroke

Background. Patients with right or more rarely left parietotemporal lesions after stroke may have profound visuospatial disorders that impair activities of daily living (ADL) and long-term outcome. Clinical studies indicate improvements with systematic training of perception. Studies of perceptual learning in healthy persons suggest rapid improvements in perceptual learning of spatial line orientation with partial transfer to nontrained line orientations. Objective. The authors investigated a novel feedback-based perceptual training procedure for the rehabilitation of patients after stroke. Methods. In an uncontrolled trial, 13 participants showing profound deficits in line orientation and related visuospatial tasks within 12 to 28 weeks of onset performed repetitive feedback-based, computerized training of visual line orientation over4 weeks of treatment. Visual line-orientation discrimination and visuospatial and visuoconstructive tasks were assessed before and after training. Results. The authors found ( a) rapid improvements in trained but also in nontrained spatial orientation tests in all 13 participants, partially up to a normal level; ( b) stability of the obtained improvements at 2-month follow-up; ( c) interocular transfer of training effects to the nontrained eye in 2 participants suggesting a central, postchiasmatic locus for this perceptual improvement; and ( d) graded transfer of improvements to related spatial tasks, such as horizontal writing, analog clock reading, and visuoconstructive capacities but no transfer to unrelated measures of visual performance. Conclusions. These results suggest the potential for treatment-induced improvements in visuospatial deficits by feedback-based, perceptual orientation training as a component of rehabilitation after stroke.

Assessing language and visuospatial functions with one task: a "dual use" approach to performing fMRI in children

In order to increase the rate of successful functional MR studies in children it is helpful to shorten the time spent in the scanner. To this effect, assessing two cognitive functions with one task seems to be a promising approach. The hypothesis of this study was that the control condition of an established language task (vowel identification task, VIT) requires visuospatial processing and that the control condition (VIT(CC)) therefore may also be applicable to localize visuospatial functions. As a reference task, a visual search task (VST, previously established for use in children) was employed. To test this hypothesis, 43 children (19 f, 24 m; 12.0±2.6, range 7.9 to 17.8 years) were recruited and scanned using both tasks. Second-level random effects group analyses showed activation of left inferior-frontal cortex in the active condition of the VIT, as in previous studies. Additionally, analysis of the VIT(CC) demonstrated activation in right-dominant superior parietal and high-frontal brain regions, classically associated with visuospatial functions; activation seen in the VST was similar with a substantial overlap. However, lateralization in the parietal lobe was significantly more bilateral in the VST than in the VIT(CC). This suggests that the VIT can not only be applied to assess language functions (using the active>control contrast), but also that the control>active condition is useful for assessing visuospatial functions. Future task design may benefit from such a "dual use" approach to performing fMRI not only, but also particularly in children.

The need for a revised version of the Benton judgment of line orientation test

The Judgment of Line Orientation Test (JLOT) is considered a valid task for the assessment of visuospatial perception, and, for this reason, it is also considered to be a sensitive tool able to discriminate between right-hemisphere-damaged (RHD) patients and left-hemisphere-damaged (LHD) patients. In contrast with this view, we report evidence that the greater impairment in JLOT usually shown by RHD patients is unrelated to the supposed JLOT effectiveness in measuring visuospatial judgment ability and to the putative dominant role of the right hemisphere in visuospatial processing. JLOT is characterized by a left-right structural asymmetry (i.e., left-side lines are easier to judge) that seriously undermines the test validity: This asymmetry interacts with ipsilesional attentional biases of brain-damaged patients and affects their performance. Results obtained with a JLOT version composed of both the original items and their mirror-reversed versions clearly indicate that the cognitive functions tested by the JLOT are distributed across the two hemispheres: LHD and RHD patients did not differ from each other or from their matched controls when their performances were compared on this balanced JLOT version. Impaired performances of either RHD or LHD patients were found only when performances in original and mirror-reversed items were considered separately. This suggests that the original JLOT cannot assess visuospatial perception independently from attentional biases. The test can be a powerful clinical tool, as long as both original and mirror-reversed items are used, and the standard scoring method is replaced by the evaluation of the individual lines of stimulus pairs.

Relationships between Constructional and Visuospatial Abilities in Normal Subjects and in Focal Brain-damaged Patients

We tested 125 normal subjects and 24 right and 22 left focal brain-damaged patients (RBD and LBD) on the Rey figure copying test and on a battery of perceptual and representational visuospatial tasks, in search of relationships between constructional and visuospatial abilities. Selected RBD and LBD were not affected by severe aphasia, unilateral spatial neglect or general intellectual defects. Both RBD and LBD showed defective performances on the constructional task with respect to normal subjects. As regards visuospatial tasks, both patient groups scored lower than normal subjects in judging angle width and mentally assembling geometrical figures; moreover, RBD, but not LBD, achieved scores significantly lower than healthy controls in judging line orientation and analyzing geometrical figures. Post-hoc comparisons did not reveal any significant differences between RBD and LBD. Multiple regression analysis showed that visuospatial abilities correlate with accuracy in copying geometrical drawings in normal subjects and in RBD, but not in LBD. From a theoretical perspective, these findings support the idea that visual perceptual and representational abilities do play a role in constructional skills.

Altered parietal brain oxygenation in Alzheimer's disease as assessed with near-infrared spectroscopy

OBJECTIVE

Visuospatial deficits are among the first symptoms of Alzheimer disease (AD) and linked to lower activation in the superior parietal cortex as assessed with functional imaging. Near-infrared spectroscopy (NIRS) is an optical method to measure changes in the concentration of oxygenated hemoglobin and deoxygenated hemoglobin in the microvascular system of the cortex. Because of its advantages in measurement situation, NIRS has proven to be especially suited for investigating psychiatric patients. The aim of this study was to probe the activation of parietal regions in patients with AD, performing a visuospatial task by means of functional NIRS (fNIRS).

METHODS

Thirteen patients with suspected mild AD and 13 healthy subjects comparable in age and gender were investigated while working on a modified version of the Benton Line Orientation Task.

RESULTS

During the spatial task, healthy subjects showed explicit parietal activation, whereas patients displayed only activation during the control task. Interestingly, there was no difference in visuospatial performance between the two groups.

CONCLUSION

The results indicate that fNIRS is able to measure parietal activation deficits in patients with AD, which could be developed into an early detection method in the future.

Activation of the limbic system under 30% oxygen during a visuospatial task: an fMRI study

The purpose of this study was to observe activation of the limbic system during the performance of visuospatial tasks under 21% O(2) or 30% O(2). Eight right-handed male college students were selected as subjects for this study. A visuospatial task was presented while brain images were scanned by a 3T fMRI system. The experiment consisted of the following two runs: a visuospatial task under normal air (21% O(2)) and a visuospatial task under hyperoxia (30% O(2)). The accuracy rate on the visuospatial task was enhanced during 30% O(2) compared to 21% O(2). The neural activation areas of the limbic system were similar in the cingulate gyrus, thalamus, limbic lobe and parahippocampal gyrus. Increased neural activation was observed in the cingulate gyrus and thalamus under 30% O(2) compared to 21% O(2). Under 30% O(2), the improvement in visuospatial task performance was related to an increase in neural activation of subcortical structures, such as the thalamus and cingulate gyrus, as well as the cerebral cortex.

Developmental shifts in fMRI activations during visuospatial relational reasoning

To investigate maturational plasticity of fluid cognition systems, functional brain imaging was undertaken in healthy 8-19 year old participants while completing visuospatial relational reasoning problems similar to Raven's matrices and current elementary grade math textbooks. Analyses revealed that visuospatial relational reasoning across this developmental age range recruited activations in the superior parietal cortices most prominently, the dorsolateral prefrontal, occipital-temporal, and premotor/supplementary cortices, the basal ganglia, and insula. There were comparable activity volumes in left and right hemispheres for nearly all of these regions. Regression analyses indicated increasing activity predominantly in the superior parietal lobes with developmental age. In contrast, multiple anterior neural systems showed significantly less activity with age, including dorsolateral and ventrolateral prefrontal, paracentral, and insula cortices bilaterally, basal ganglia, and particularly large clusters in the midline anterior cingulate/medial frontal cortex, left middle cingulate/supplementary motor cortex, left insula-putamen, and left caudate. Findings suggest that neuromaturational changes associated with visuospatial relational reasoning shift from a more widespread fronto-cingulate-striatal pattern in childhood to predominant parieto-frontal activation pattern in late adolescence.

Judgment of line orientation in children with congenital unilateral lesions

The Judgment of Line Orientation test (JLO) is widely used to assess visuospatial processing. To investigate whether JLO is impaired compared to the normal population, whether it is worse if the lesion affects right-hemisphere or cerebral structures involved in JLO processing in adults, and how JLO correlates with the extent of the lesion, Wechsler Intelligence Scale for Children (WISC) IQs and WISC subtests, we assessed 20 children with congenital unilateral lesion (12 left and 8 right). Only 50% of our children had a borderline or significantly impaired performance in the JLO test, with a prevalence of females and left-hemisphere-impaired participants. The brain areas affected do not generally coincide with the network identified by functional magnetic resonance imaging (fMRI) on healthy adults, suggesting that the neural correlates are distributed differently in children depending on their age and on functional reorganization. Further research, including functional studies on larger samples of children of different age groups, are needed to elucidate the network subserving this ability in developmental age.

Regional cerebral blood flow correlates of visuospatial tasks in Alzheimer's disease

This study investigated the role of visuospatial tasks in identifying cognitive decline in patients with Alzheimer's disease (AD), by correlating neuropsychological performance with cerebral perfusion measures. There were 157 participants: 29 neurologically healthy controls (age: 70.3 +/- 6.6, MMSE > or = 27), 86 patients with mild AD (age: 69.18 +/- 8.28, MMSE > or = 21) and 42 patients moderate/severe AD (age: 68.86 +/- 10.69, MMSE 8-20). Single Photon Emission Computerized Tomography (SPECT) was used to derive regional perfusion ratios, and correlated using partial least squares (PLS) with neuropsychological test scores from the Benton Line Orientation (BLO) and the Rey-Osterrieth Complex Figure (RO). Cross-sectional analysis demonstrated that mean scores differed in accordance with disease status: control group (BLO 25.5, RO 33.3); mild AD (BLO 20.1, RO 25.5); moderate/severe AD (BLO 10.7, RO 16). Correlations were observed between BLO/RO and right parietal SPECT regions in the AD groups. Visuospatial performance, often undersampled in cognitive batteries for AD, is clearly impaired even in mild AD and correlates with functional deficits as indexed by cerebral perfusion ratios on SPECT implicating right hemisphere circuits. Furthermore, PLS reveals that usual spatial tasks probe a distributed brain network in both hemispheres including many areas targeted by early AD pathology.

Verbal as well as spatial working memory predicts visuospatial processing in male schizophrenia patients

BACKGROUND

Visuospatial processing (VSP) is impaired in schizophrenia. Recent studies showed significant associations between the Judgment of Line Orientation (JLO) test, a common test of VSP and Verbal (VWM) as well as Spatial (SWM) working memory. VWM and SWM show different associations with various genes so subgroups of patients with similar VSP but different WM impairment profiles may vary in genetic associations. In this study we investigated the relationship among VSP, VWM and SWM.

METHODS

Sixty seven men with schizophrenia and 51 healthy men completed computerized JLO and tests of VWM (digit span), and SWM (Dot test). Tests of attention (CPT) and psychomotor processing speed (Finger Tap) were also included.

RESULTS

Patients' performance was impaired on all tests. Multivariate regression with JLO as the outcome variable and VWM, SWM, attention, psychomotor processing speed and interactions between group and these variables, as predictors showed significant contribution of VWM and SWM. The model explained 34.4% of the variance (R(2)=0.344).

CONCLUSION

VSP, as measured by JLO, receives independent contributions from VWM and SWM. Patient subgroups matched for VSP may differ in the relative contributions and impairments of VWM and SWM. Such heterogeneity may limit the usefulness of VSP in genetic studies. The possibility that WM may be more useful than VSP in this regard deserves further study.

Visuospatial performance on an internet line judgment task and potential hormonal markers: sex, sexual orientation, and 2D:4D

We investigated whether performance on a visuospatial line judgment task, the Judgment of Line Angle and Position-15 test (JLAP-15), showed evidence of sensitivity to early sex steroid exposure by examining how it related to sex, as well as to sexual orientation and 2D:4D digit ratios. Participants were drawn from a large Internet study with over 250,000 participants. In the main sample (ages 12-58 years), males outperformed females on the JLAP-15, showing a moderate effect size for sex. In agreement with a prenatal sex hormone hypothesis, line judgment accuracy in adults related to 2D:4D and sexual orientation, both of which are postulated to be influenced by early steroids. In both sexes, better visuospatial performance was associated with lower (more male-typical) digit ratios. For men, heterosexual participants outperformed homosexual/bisexual participants on the JLAP-15 and, for women, homosexual/bisexual participants outperformed heterosexual participants. In children aged 8-10 years, presumed to be a largely prepubertal group, boys also outperformed girls. These findings are consistent with the hypothesis that visuospatial ability is influenced by early sex steroids, although they do not rule out alternative explanations or additional influences. More broadly, such results support a prenatal sex hormone hypothesis that degree of androgen exposure may influence the neural circuitry underlying cognition (visuospatial ability) and sexual orientation as well as aspects of somatic (digit ratio) development.

Processing Abilities Associated with Math Skills in Adult Learning Disability

This study evaluated college adults (N = 138) referred for learning problems using a Cattell-Horn-Carroll based intelligence measure (Woodcock Johnson-Revised: WJ-R) and spatial and executive function neuropsychological measures to determine processing abilities underlying math skills. Auditory and visual perceptual (WJ-R Ga and Gv), long- and short-memory (WJ-R Glr and Gsm), crystallized and fluid intellectual (WJ-R Gc and Gf), and spatial and executive function (Judgment of Line Orientation [JLO] and Category Test) measures differentiated those with and without math deficits. Multiple regression revealed selective processing abilities (Gf, JLO, and Category) predicting about 16% of the variance in math skills after variance associated with general intelligence (also about 16%) was removed. Cluster analysis found evidence for a selective spatial deficit group, a selective executive function deficit group and a double deficit (spatial and executive function) group. Results were discussed in relation to a double deficit hypothesis associated with developmental dyscalculia.

Sex differences in cerebral laterality of language and visuospatial processing

Sex differences on language and visuospatial tasks are of great interest, with differences in hemispheric laterality hypothesized to exist between males and females. Some functional imaging studies examining sex differences have shown that males are more left lateralized on language tasks and females are more right lateralized on visuospatial tasks; however, findings are inconsistent. Here we used functional magnetic resonance imaging to study thirty participants, matched on task performance, during phonological and visuospatial tasks. For each task, region-of-interest analyses were used to test differences in cerebral laterality. Results indicate that lateralization differences exist, with males more left lateralized during the phonological task and showing greater bilateral activity during the visuospatial task, whereas females showed greater bilateral activity during the phonological task and were more right lateralized during the visuospatial task. Our data provide clear evidence for differences in laterality between males and females when processing language versus visuospatial information.

The effect of oxygen administration on visuospatial cognitive performance: time course data analysis of fMRI

This study investigated the effects of 30% oxygen administration on visuospatial cognitive ability using time course data analysis of fMRI. A visuospatial task was presented while brain images were scanned by a 3T MRI system. The results showed that there was an improvement in performance and also increased BOLD intensity in the parietal lobe in the higher oxygen condition. There was positive relation between behavior performance and BOLD intensity in the right parietal lobe. This result supports the conclusion that the increase in the cognitive processing ability due to highly concentrated oxygen can be explained by the increase in the BOLD intensity.

Cognitive impairment but preservation of sexual dimorphism in cognitive abilities in chronic schizophrenia

Neurocognitive impairment in schizophrenia is well established, though sex differences on cognitive tasks have produced equivocal findings. The present study was designed to examine performance of schizophrenia patients on a sexually dimorphic cognitive battery. The cognitive battery comprising tests of spatial (mental rotation, computerized version of the Benton Judgment of Line Orientation) and verbal abilities (phonological and semantic fluency) was administered to men (n = 22) and women (n = 21) with schizophrenia and healthy controls (n = 21 men and 21 women). A series of multivariate analyses showed that the patient group performed worse than controls on all the cognitive tasks. Cognitive sexual dimorphism on all spatial tasks favoring men and verbal tasks favoring women remained. Within the patient sample, correlational data demonstrated that earlier age at onset of illness related to poorer spatial performance. It is concluded that normal sexual dimorphism is undisturbed on both spatial and verbal tasks by the schizophrenia disease process.

The cerebellum's involvement in the judgment of spatial orientation: a functional magnetic resonance imaging study

A functional magnetic resonance imaging (fMRI) study was conducted to integrate the clinical observations of the impaired judgment of spatial orientation of cerebellar patients with recent theoretical discoveries about the role of the cerebellum in cognitive functions. Ten normal healthy male right-handed Chinese postgraduates consented to participate in this study. The experimental task employed was a modified version of Benton's Judgment of Line Orientation Test, administered in a blocked fMRI study. The findings indicated activation of the cerebellar regions, the Hemisphere Lobules IV, VI and Crus I, while the subjects were performing the experimental task of the judgment of the orientation of lines. Furthermore, cortical regions were activated, including the bilateral precuneus (BA 7), the extrastriate regions (BA 19), and the bilateral prefrontal regions (BA 9, 10, 44, 46). The imaging data confirmed that the activity of the cerebellum is associated with judging spatial orientation. The theoretical and clinical implications of the findings are discussed.

Near-infrared optical topography to assess activation of the parietal cortex during a visuo-spatial task

Multi-channel near-infrared spectroscopy (NIRS) is a relatively new method to investigate the brain activation, based on changes in oxygenated haemoglobin (O2Hb) and deoxygenated haemoglobin (HHb). Recently, it has been shown that NIRS seems to be able to detect even small changes in O2Hb and HHb concentration due to cognitive demands. This study aimed at investigating the changes in O2Hb and HHb concentrations of the parietal cortex during a spatial task, a modified version of the Benton Line Orientation Task [Gur, R. C., Alsop, D., Glahn, D., Petty, R., Swanson, C. L., Maldjian, J. A., et al. (2000). An fMRI study of sex differences in regional activation to a verbal and a spatial task. Brain & Language, 74(2), 157-170.]. Twenty-four subjects were measured with NIRS while they had to estimate the orientation of a given line or to name the colour of the line in the control condition. Both conditions consisted of three activation phases each lasting 30 s, with a 10 s baseline and a 20 s post resting period. For assessing the changes in O2Hb and HHb concentrations, we measured with 24 NIRS channels over the parietal cortex using the NIRS apparatus ETG-100 (Hitachi Medical Ltd.). O2Hb concentration significantly increased during the active phase compared to the baseline for both conditions, but was significantly higher in the active phase for the line orientation condition compared to the colour naming condition bilaterally parieto-occipital. For the HHb concentrations, we only found significant decreases for both conditions but no differences between the conditions. The results of our study underscore the value of multi-channel NIRS for assessing cortical activation during cognitive tasks.

Attention to simultaneous unrelated auditory and visual events: behavioral and neural correlates

The cognitive and neural bases of the ability to focus attention on information in one sensory modality while ignoring information in another remain poorly understood. We hypothesized that bimodal selective attention results from increased activity in corresponding sensory cortices with a suppression of activity in non-corresponding sensory cortices. In a functional magnetic resonance imaging (fMRI) study, we presented melodies and shapes alone (unimodal) or simultaneously (bimodal). Subjects monitored for changes in an attended modality while ignoring the other. Subsequently, memory for both attended and unattended stimuli was tested. Subjects remembered attended stimuli equally well in unimodal and bimodal conditions, and significantly better than ignored stimuli in bimodal conditions. When a subject focused on a stimulus, the blood-oxygen-level-dependent (BOLD) response increased in sensory cortices corresponding to that modality in both unimodal and bimodal conditions. Additionally, the BOLD response decreased in sensory cortices corresponding to the non-presented modality in unimodal conditions and the unattended modality in bimodal conditions. We conclude that top-down attentional effects modulate the interaction of sensory cortical areas by gating sensory input. This interaction between sensory cortices enhances processing of one modality at the expense of the other during selective attention, and subsequently affects memory encoding.

Dementia as a window to the neurology of art

Art is an expression of neurological function and how it organizes and interprets perception. Recent reports of changes in art performance among patients with frontotemporal dementia have provided an unexpected window to the neurology of art. They confirm that visual art is predominantly in the right hemisphere and suggest a neuroanatomical schema for artistic creativity. The right parietal region is critical for the visuospatial prerequisites of art, and the right temporal lobe integrates and interprets these percepts. The right temporal lobe appears necessary for extracting and exaggerating the essential features of an artistic composition. In contrast, the left parietal region and the left temporal lobe have inhibitory effects on artistic expression through attention to visuospatial detail and semantic labeling, respectively. Frontal-executive functions are also required for artistic expression, particularly right dorsolateral frontal initiation of a network for novelty-seeking behavior. Further study of art in dementia can profitably evaluate this proposed schema for the mechanisms of art in the brain.

Is judgement of line orientation selectively impaired in right brain damaged patients?

The judgement of line orientation test (JLOT) is widely used to assess visuo-spatial processing. Most neuropsychological studies have shown that on this task right hemisphere damaged (RHD) patients are significantly more impaired than left hemisphere damaged (LHD) patients, suggesting a dominant role of the right hemisphere in discriminating line orientation. To investigate whether other factors can affect performance on JLOT, a modified version of the test, consisting of the 30 original test items and their mirror images, was employed. In Experiment 1 normal participants were more accurate in discriminating the left lines of the original items, and the right lines of the mirror-reversed items, thus indicating that in original JLOT the stimulus arrays comprise lines on the left side that are easier to judge than lines on the right. In Experiment 2, RHD patients with visual neglect were significantly more impaired than patients without neglect, who performed similarly independently from the side of the lesion. Among patients without neglect, however, LHD patients were more accurate than RHD patients without neglect with the original items, but produced more errors than RHD patients without neglect when faced with the mirror-reversed items. Overall, the results of the present study suggest that the greater impairment on standard JLOT shown by RHD patients has to be interpreted as the by-product of the presence of visual neglect, which is more frequent following right hemisphere damage, and of the uneven distribution of the stimulus lines, which are easier to discriminate in the left space. The clinical and theoretical implications of the results are discussed.

30% Oxygen Inhalation Enhances Cognitive Performance through Robust Activation in the Brain

This study aimed to investigate whether inhalation of the air with 30% oxygen compared with normal air enhances cognitive functioning through increased activation in the brain. The verbal and visuospatial tasks were performed while brain images were scanned. The results showed that there were improvements in performance and also increased activation in several brain areas under the condition of 30% oxygen. These results suggest that a higher concentration of the inhaled oxygen increases the saturation of the blood oxygen in the brain, and facilitates cognitive performance.

Dissociating Processes Supporting Causal Perception and Causal Inference in the Brain

An understanding of relations between causes and effects is essential for making sense of the dynamic physical world. It has been argued that this understanding of causality depends on both perceptual and inferential components. To investigate whether causal perception and causal inference rely on common or on distinct processes, the authors tested 2 callosotomy (split-brain) patients and a group of neurologically intact participants. The authors show that the direct perception of causality and the ability to infer causality depend on different hemispheres of the divided brain. This finding implies that understanding causality is not a unitary process and that causal perception and causal inference can proceed independently.