Wai-Ling Bickerton

Separating neural correlates of allocentric and egocentric neglect: Distinct cortical sites and common white matter disconnections

Insights into the functional nature and neuroanatomy of spatial attention have come from research in neglect patients but to date many conflicting results have been reported. The novelty of the current study is that we used voxel-wise analyses based on information from segmented grey and white matter tissue combined with diffusion tensor imaging to decompose neural substrates of different neglect symptoms. Allocentric neglect was associated with damage to posterior cortical regions (posterior superior temporal sulcus, angular, middle temporal and middle occipital gyri). In contrast, egocentric neglect was associated with more anterior cortical damage (middle frontal, postcentral, supramarginal, and superior temporal gyri) and damage within subcortical structures. Damage to intraparietal sulcus (IPS) and the temporo-parietal junction (TPJ) was associated with both forms of neglect. Importantly, we showed that both disorders were associated with white matter lesions suggesting damage within long association and projection pathways such as the superior longitudinal, superior fronto-occipital, inferior longitudinal, and inferior fronto-occipital fascicule, thalamic radiation, and corona radiata. We conclude that distinct cortical regions control attention (a) across space (using an egocentric frame of reference) and (b) within objects (using an allocentric frame of reference), while common cortical regions (TPJ, IPS) and common white matter pathways support interactions across the different cortical regions.

Treatment for Children and Adolescents with Depression: Lessons from a Controlled Trial

Cognitive-behavioural treatment (CBT) appears to have considerable value in the treatment of childhood depression. Its key components are self-monitoring, social problem-solving and cognitive restructuring. Such a treatment programme was compared with a non-focused control intervention (NFI) in 57 outpatient children and adolescents with depression. Both groups improved significantly on depressive and anxiety symptoms, self-esteem and social functioning, with the majority of children (87 percent of CBT subjects and 75 percent of controls) no longer being clinically depressed. Non-specific psychotherapeutic elements such as empathy, sympathetic listening, reassurance, reinforcement and indirect ways of achieving self-understanding and problem-solving may be involved in the recovery. In out-patient settings, we recommend that social problem-solving and cognitive restructuring be introduced during the first two to three sessions, which may help the young person gain self-control relatively early and engage more with the treatment.

Systematic assessment of apraxia and functional predictions from the Birmingham Cognitive Screen

Objective The validity and functional predictive values of the apraxia tests in the Birmingham Cognitive Screen (BCoS) were evaluated. BCoS was developed to identify patients with different forms of praxic deficit using procedures designed to be inclusive for patients with aphasia and/or spatial neglect. Method Observational studies were conducted from a university neuropsychological assessment centre and from acute and rehabilitation stroke care hospitals throughout an English region. Volunteers from referred patients with chronic acquired brain injuries, a consecutive hospital sample of patients within 3 months of stroke (n=635) and a population based healthy control sample (n=100) were recruited. The main outcome measures used were the Barthel Index, the Nottingham Extended Activities of Daily Living Scale as well as recovery from apraxia. Results There were high inter-rater reliabilities and correlations between the BCoS apraxia tasks and counterpart tests from the literature. The vast majority (88.3%) of the stroke survivors were able to complete the screen. Pantomime and gesture recognition tasks were more sensitive in differentiating between individuals with left hemisphere damage and right hemisphere damage whereas the Multistep Object Use test and the imitation task had higher functional correlates over and above effects of hemiplegia. Together, the initial scores of the four tasks enabled predictions with 75% accuracy, the recovery of apraxia and independence level at 9 months. Conclusions As a model based assessment, BCoS offers a quick and valid way to detect apraxia and predict functional recovery. It enables early and informative assessment of most stroke patients for rehabilitation planning.

The Oxford Cognitive Screen (OCS): Validation of a stroke-specific short cognitive screening tool

There is currently no existing freely available short screen for cognitive problems that targets stroke survivors specifically. We have developed a short cognitive screen, the Oxford Cognitive Screen (OCS), to be completed in 15-20 min, designed for use with stroke patients. To maximize inclusion, the test is aphasia- and neglect friendly and covers domains of cognition where deficits frequently occur after stroke, including apraxia and unilateral neglect as well as memory, language, executive function, and number abilities. Domain-specific scores are returned to help direct rehabilitation. This article presents the normative data in a large sample of 140 neurologically healthy participants, a report on incidences of impairments in a sample of 208 acute stroke patients (within 3 weeks of stroke onset), measures of test-retest reliability on an alternate form and convergent and divergent validity. In addition, the full test materials are made freely available for clinical use.

The prognosis of allocentric and egocentric neglect: evidence from clinical scans.

We contrasted the neuroanatomical substrates of sub-acute and chronic visuospatial deficits associated with different aspects of unilateral neglect using computed tomography scans acquired as part of routine clinical diagnosis. Voxel-wise statistical analyses were conducted on a group of 160 stroke patients scanned at a sub-acute stage. Lesion-deficit relationships were assessed across the whole brain, separately for grey and white matter. We assessed lesions that were associated with behavioural performance (i) at a sub-acute stage (within 3 months of the stroke) and (ii) at a chronic stage (after 9 months post stroke). Allocentric and egocentric neglect symptoms at the sub-acute stage were associated with lesions to dissociated regions within the frontal lobe, amongst other regions. However the frontal lesions were not associated with neglect at the chronic stage. On the other hand, lesions in the angular gyrus were associated with persistent allocentric neglect. In contrast, lesions within the superior temporal gyrus extending into the supramarginal gyrus, as well as lesions within the basal ganglia and insula, were associated with persistent egocentric neglect. Damage within the temporo-parietal junction was associated with both types of neglect at the sub-acute stage and 9 months later. Furthermore, white matter disconnections resulting from damage along the superior longitudinal fasciculus were associated with both types of neglect and critically related to both sub-acute and chronic deficits. Finally, there was a significant difference in the lesion volume between patients who recovered from neglect and patients with chronic deficits. The findings presented provide evidence that (i) the lesion location and lesion size can be used to successfully predict the outcome of neglect based on clinical CT scans, (ii) lesion location alone can serve as a critical predictor for persistent neglect symptoms, (iii) wide spread lesions are associated with neglect symptoms at the sub-acute stage but only some of these are critical for predicting whether neglect will become a chronic disorder and (iv) the severity of behavioural symptoms can be a useful predictor of recovery in the absence of neuroimaging findings on clinical scans. We discuss the implications for understanding the symptoms of the neglect syndrome, the recovery of function and the use of clinical scans to predict outcome.

The neural substrates of drawing: A voxel-based morphometry analysis of constructional, hierarchical, and spatial representation deficits

Deficits in the ability to draw objects, despite apparently intact perception and motor abilities, are defined as constructional apraxia. Constructional deficits, often diagnosed based on performance on copying complex figures, have been reported in a range of pathologies, perhaps reflecting the contribution of several underlying factors to poor figure drawing. The current study provides a comprehensive analysis of brain–behavior relationships in drawing disorders based on data from a large cohort of subacute stroke patients (n = 358) using whole-brain voxel-wise statistical analyses linked to behavioral measures from a complex figure copy task. We found that (i) overall poor performance on figure copying was associated with subcortical lesions (BG and thalamus), (ii) lateralized deficits with respect to the midline of the viewer were associated with lesions within the posterior parietal lobule, and (iii) spatial positioning errors across the entire figure were associated with lesions within visual processing areas (lingual gyrus and calcarine) and the insula. Furthermore, deficits in reproducing global aspects of form were associated with damage to the right middle temporal gyrus, whereas deficits in representing local features were linked to the left hemisphere lesions within calcarine cortex (extending into the cuneus and precuneus), the insula, and the TPJ. The current study provides strong evidence that impairments in separate cognitive mechanisms (e.g., spatial coding, attention, motor execution, and planning) linked to different brain lesions contribute to poor performance on complex figure copying tasks. The data support the argument that drawing depends on several cognitive processes operating via discrete neuronal networks and that constructional problems as well as hierarchical and spatial representation deficits contribute to poor figure copying.

The frequency and severity of extinction after stroke affecting different vascular territories.

We examined the frequency and severity of visual versus tactile extinction based on data from a large group of sub-acute patients (n=454) with strokes affecting different vascular territories. After right hemisphere damage visual and tactile extinction were equally common. However, after left hemisphere damage tactile extinction was more common than visual. The frequency of extinction was significantly higher in patients with right compared to left hemisphere damage in both visual and tactile modalities but this held only for strokes affecting the MCA and PCA territories and not for strokes affecting other vascular territories. Furthermore, the severity of extinction did not differ as a function of either the stimulus modality (visual versus tactile), the affected hemisphere (left versus right) or the stroke territory (MCA, PCA or other vascular territories). We conclude that the frequency but not severity of extinction in both modalities relates to the side of damage (i.e. left versus right hemisphere) and the vascular territories affected by the stroke, and that left hemisphere dominance for motor control may link to the greater incidence of tactile than visual extinction after left hemisphere stroke. We discuss the implications of our findings for understanding hemispheric lateralization within visuospatial attention networks.

The case of the unfamiliar implement: schema-based over-riding of semantic knowledge from objects in everyday action.

We examined the role of schema knowledge in everyday action by assessing the use of unfamiliar implements by patients with subcortical and frontal lobe damage. Although the patients were relatively good at naming or showing how the unfamiliar implements could be used outside of the task context, the patients omitted using the objects in everyday life tasks more often than control participants--either omitting the action step involving the objects or performing the action using a familiar object that was not normally used for this purpose. The data suggest that knowledge about objects in the context of a task can play a determining role in how objects are used in everyday action. In patients with reduced attentional resources, the task schema can over-ride weak bottom-up cueing of action from the objects, with the result that unfamiliar implements are not used.

Common and distinct neural mechanisms of visual and tactile extinction: A large scale VBM study in sub-acute stroke.

Extinction is diagnosed when patients respond to a single contralesional item but fail to detect this item when an ipsilesional item is present concurrently. Extinction has been studied mainly in the visual modality but it occurs also in other sensory modalities (touch, audition) and hence can be considered a multisensory phenomenon. The functional and neuroanatomical relations between extinction in different modalities are poorly understood. Here, we used voxel-based mophometry (VBM) to examine the neuronal substrates of visual versus tactile extinction in a large group of sub-acute patients (n = 454) with strokes affecting different vascular territories. We found that extinction deficits in tactile and visual modalities were significantly correlated (r = 0.341; p < 0.01). Several lesions within the right hemisphere were linked to extinction including the inferior parietal lobule, the superior parietal lobule, the middle frontal and occipital gyri, while lesions involving the superior temporal gyrus, inferior temporal gyrus and putamen were associated with tactile extinction. Damage within the middle temporal gyrus and superior temporal sulcus was linked to both deficits. We conclude that extinction in different modalities emerges after damage to both common (supra-modal) and distinct (modality specific) brain regions, and that contrasting sites emerge after damage to different vascular territories. We discuss the implications for understanding extinction as a multisensory disorder.

Mother and teacher ratings of maladaptive behaviour in children with special needs

ABSTRACT Parents and teachers of 109 children selected from the Special Needs Register and living in a multiethnic urban health district participated in the study. Their perceptions of childrens behaviour at home and at school were measured by the Aberrant Behavior Checklist(ABC). About two‐thirds of the subjects presented with at least one type of maladaptive behaviour of at least moderate severity within their family, and 50 per cent had similar difficulties at school. The dimensions of hyperactivity and irritability were the main causes for concern by both sources. Contrary to previous studies, high rates of parent‐teacher agreement were found. This significant association was not affected by factors such as age, ethnicity or type of school. The implications for the provision of services for children in special education are discussed.