Rehabilitation of visuospatial neglect by prism adaptation: effects of a mild treatment regime. A randomised controlled trial.

Closely examining the effects, optimal regime and time window of prism adaptation (PA) promotes guidelines for effective rehabilitation practice. The effects of short-term repetitive PA on spatial neglect manifestations were evaluated in patients with heterogeneous post-stroke delays, using a digital Visuospatial Neglect Test Battery. Subsequently, potential differences in PA effects between acute, subacute or chronic neglect were explored. A multicentre randomised controlled trial was conducted in 43 right-hemisphere neglect patients. They were treated with a mild PA regime: seven sessions of experimental or placebo prism training over 7-12 days. The outcome measures were diverse neglect variables related to peripersonal navigation, visual extinction, visuospatial memory, bisection, cancellation, drawing and visual search. The treatment effects were assessed after a short and a long time interval. Two to 24 hours after PA, conventional effects were found for drawing and centred bisection, and novel effects for peripersonal visuospatial navigation, visual extinction, and non-motor memory (with caution). No effects were found for visual search times and cancellation. The assessments after three months were still indicative of PA benefits for navigational, drawing and memory functions. PA did not prove to be more effective in acute, subacute or chronic patients. The extension of effects is theoretically framed within the debate about the levels of cognitive processing that are impacted by PA. Clinical suggestions are formulated regarding PA implementation in neglect treatment.

Capturing peripersonal spatial neglect: an electronic method to quantify visuospatial processes.

Computerized as well as paper-and-pencil tasks are applied in mapping visuospatial neglect in experimental research and clinical practice. This article presents a new kind of computer-based assessment method, using an electronic pen display and user-friendly software. The approach is tailored to specific spatial processes and highlights the usefulness of a pen display in neglect patients. The advantages of the introduced method are illustrated by a recently designed battery of classic, as well as new, types of tests. The development of the appropriate stimuli and the assorted scoring systems is addressed, as well as the resulting types of task implementation and data generation. The diagnostic value of the different visuospatial neglect tests is demonstrated by comparative analyses between a neglect group and a control group. Among the benefits of the proposed assessment method are (1) the opportunity to perform standardized repeated measurements to quantify recovery, (2) online performance monitoring, (3) flexible employment, (4) the collection of exact data over a short period, and (5) the easy availability of more refined quantitative as well as interesting qualitative information, especially as compared to classic or paper-and-pencil tasks. To indicate that this method also lends itself well to measures for treatment procedures, an illustration is given with respect to specific measurements during prism adaptation. The tasks of the Visuospatial Neglect Test Battery and the prism adaptation measures are illustrated by a case study. The outlined applications are discussed with respect to experimental as well as clinical purposes.

Exploration of the Raven APM-National Adult Reading Test discrepancy as a measure of intellectual decline in older persons.

Previous studies have shown that the discrepancy between performance on "fluid" and "crystallized" intelligence measures may serve as an indicator for intellectual decline. The validity of this procedure in older persons is unknown. The present study developed a multiple regression equation, to predict the Raven Advanced Progressive Matrices (APM) score from the National Adult Reading Test (NART) score and demographic variables in a large sample of healthy older persons (n = 270). The discrepancy between the predicted and observed Raven APM scores was transformed into a percentile distribution as an indicator of intellectual decline, which can be used in clinical practice. The validity of the procedure was further examined by comparing the proportion of persons with a significant decline (at the -1 and -1.65 SD level) between two older patient samples (87 patients with cerebral stroke and 387 patients with diabetes mellitus) by means of χ(2) tests. There was a significantly higher rate of intellectual decline at the -1 SD ("below average") and -1.65 SD ("impaired") cutoff levels for patients with stroke compared with patients with diabetes (stroke, 34% and 14%; diabetes, 16% and 5%, p < .05). These findings suggest that the Raven APM-NART discrepancy may be a useful measure of intellectual decline in older persons.

Cognitive differences between patients with left-sided and right-sided Parkinson's disease. A review.

At disease onset, patients with Parkinson's disease (PD) typically report one side of the body to be more affected than the other. Previous studies have reported that this motor symptom asymmetry is associated with asymmetric dopaminergic degeneration in the brain. Research on the cognitive repercussions of this asymmetric degeneration has yielded inconsistent results. Here, we review studies that reported on the cognitive performance of patients with left-sided (LPD) or right-sided (RPD) motor symptom predominance. We present evidence that patients with RPD typically experience problems with language-related tasks and verbal memory, whereas patients with LPD more often perform worse on tasks of spatial attention, visuospatial orienting and memory and mental imagery. In general, no differences were found between both groups on tasks measuring attention and executive function. The association between motor asymmetry and cognitive performance indicates that PD does not lead to one typical cognitive profile. The effect of symptom laterality on the cognitive complaints should be considered in the assessment and treatment of each individual patient.

Delirium in acute stroke: a predictor of subsequent cognitive impairment? A two-year follow-up study.

OBJECTIVE: Delirium is an independent risk factor for cognitive impairment and development of dementia in medical patients. It has never been thoroughly studied whether this association is also present in the stroke population. Our aim was to evaluate the effects of delirium in the acute phase after stroke on cognitive functioning two years later. METHODS: Two years after stroke, 50 patients (22 with and 28 without delirium in the acute phase) were assessed on two screening instruments for dementia and a neuropsychological test battery. RESULTS: Delirium was an independent predictor for development of dementia as assessed by the Clinical Dementia Rating Scale (odds ratio (OR) 4.7; 95% confidence interval (CI) 1.08 to 20.42) and by the Rotterdam-CAMCOG (OR 7.2, 95% CI 1.88 to 27.89). Cognitive domains most affected in patients with previous delirium were memory, language, visual construction and executive functioning. CONCLUSIONS: Delirium in the acute phase after stroke is an independent predictor for severe cognitive impairment two years after stroke. These findings emphasize the importance of both rapid detection and treatment of delirium after stroke. Furthermore, periodic monitoring and evaluation of cognitive functioning in these vulnerable patients in the years after stroke is strongly recommended.

Repetitive long-term prism adaptation permanently improves the detection of contralesional visual stimuli in a patient with chronic neglect.

The aim of the current study was to investigate long-term effects in spatial awareness after daily exposure to prism adaptation during three months in a patient with hemispatial neglect. Results showed improvement in the detection of stimuli in the contralesional visual field, as measured with perimetry, in the contralesional visual field up to 24 months after ending prism adaptation. These perimetrical results suggest that compensatory eye movements are an unlikely candidate for an underlying mechanism.

Horizontal and vertical attentional orienting in Parkinson's disease.

Patients with Parkinson's disease (PD) typically suffer from an asymmetric degeneration of dopaminergic cells in the substantia nigra, resulting in right-sided (RPD) or left-sided (LPD) predominance of motor symptomatology. As the dopaminergic system is also involved in attention, we examined horizontal and vertical orienting of attention in LPD (N=10), RPD (N=9) and controls (N=10). Four LPD patients demonstrated left neglect and three LPD patients demonstrated neglect for the upper visual field. LPD patients demonstrated a slower performance in detecting targets in the left hemifield and did not demonstrate a validity effect, unlike RPD patients and controls. RPD patients performed similar to controls, with the exception of one patient showing left and another showing right neglect, and two RPD patients demonstrated lower neglect. In sum, horizontal and vertical orienting of attention can be affected in Parkinson's disease - particularly in LPD - from very subtle slowing to clinically detectable horizontal and/or vertical neglect.

Repetitive exploration towards locations that no longer carry a target in patients with neglect.

About 50% of neglect patients show ipsilesional target re-exploration on neglect tasks and in daily life. The present study examines whether omissions and revisitings are due to disengagement failure from visible stimuli on the ipsilesional side. Thirteen patients with neglect and nine healthy controls were tested with three versions of the Bells test on touch screen, i.e. a standard cancellation in which targets have to be marked, an erase cancellation in which targets have to be erased, and a condition in which all items (including distracters) have to be erased. Whereas omissions decreased in the full-erase condition, revisitings were the most prominent in this condition. Our study shows that neglect patients also return to previously visited locations which no longer carry a target.

The Brixton Spatial Anticipation Test as a test for executive function: validity in patient groups and norms for older adults.

Impairments in executive functioning frequently occur after acquired brain damage, in psychiatric disorders, and in relation to aging. The Brixton Spatial Anticipation Test is a relatively new measure for assessing the ability to detect and follow a rule, an important aspect of executive functioning. To date, normative data on this task are limited, particularly concerning the elderly. This study presents age- and education-adjusted regression-based norms obtained in a group of healthy older participants (n = 283; mean age 67.4 +/- 8.5 years). The applicability and validity of these norms were further examined in different groups of patients with stroke (n = 106), diabetes mellitus (n = 376), MCI/early dementia (n = 70), psychiatric disorders (n = 63), and Korsakoff's syndrome (n = 41). The results showed that patients with Korsakoff's syndrome, stroke, and psychiatric disorders performed significantly worse than healthy controls. Test-retest correlation (n = 83), learning effects, and correlations with other neuropsychological tests were also explored. Based on the present study, the Brixton test appears a useful addition to existing measures of executive functioning. Moreover, the test can be reliably applied in different groups of clinical patients.

A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level sensory impairments. The patient was not able to indicate the darker or the lighter of two grey squares, even though she was able to see that they differed. In addition, she could not indicate whether the lights in a room were switched on or off, nor was she able to differentiate between normal greyscale images and inverted greyscale images. As the patient recognised objects, colours, and shapes correctly, the impairment is specific for brightness. As low-level, sensory processing is normal, this specific deficit in the recognition and appreciation of brightness appears to be of a higher, cognitive level, the level of semantic knowledge. This appears to be the first report of 'brightness agnosia'.

Prism adaptation moves neglect-related perseveration to contralesional space.

BACKGROUND: Hemi-neglect is a disorder characterized by a disregard of contralesional stimuli. Some neglect patients also show an "exaggerated attention" for the ipsilesional field, reflected in perseverative responses, such as repetitive fixations in the ipsilesional field, ipsilesional revisitings on standard cancellation, or exaggerations in drawings on the ipsilesional side. OBJECTIVE AND METHOD: It is still unclear whether neglect and perseveration are due to a single underlying mechanism. In the present study, we will examine the effect of 4-day-in-a-row prism adaptation on neglect and perseveration severity in a patient with severe perseverations. Additionally, we will examine whether the position of omissions and perseverations on the Star Cancellation will change during the intervention. RESULTS: Our patient showed a decrease in neglect severity and an increase in perseveration severity, suggesting that perseveration and neglect are dissociated phenomena. Interestingly, 4-day-in-a-row prism adaptation gradually moved the predominant position of perseverative responses from right to left as neglect decreased with treatment. CONCLUSIONS: Perseverative responses do not necessarily occur in the ipsilesional sector of space as is generally assumed. Instead, the position of the revisits may be determined by the severity of the neglect, and may shift when the focus of attention moves more contralesionally with recovery.

Confabulation behavior and false memories in Korsakoff's syndrome: role of source memory and executive functioning.

AIMS: Confabulation behavior is common in patients with Korsakoff's syndrome. A distinction can be made between spontaneous and provoked confabulations, which may have different underlying cognitive mechanisms. Provoked confabulations may be related to intrusions on memory tests, whereas spontaneous confabulations may be due to executive dysfunction or a source memory deficit. METHODS: In 19 chronic Korsakoff patients, spontaneous confabulations were quantified by third-party rating (Likert scale). Provoked confabulations were assessed using the Dalla Barba Confabulation Battery. Furthermore, assessment of executive function was performed using an extensive neuropsychological battery. False memories (i.e. intrusions) and source memory were measured using twoparallelversions of a word-list learning paradigm (a modification of the Rey Auditory Verbal Learning Test). RESULTS: There were deficits in source memory, in which patients incorrectly assigned previously learned words to an incorrect word list. Also, Korsakoff patients had extensive executive deficits, but no relationship between the severity of these deficits and the severity of confabulation or intrusions on a memory task was found. CONCLUSION: The present findings provide evidence for a dissociation between spontaneous confabulation, provoked confabulation and false memories.

Prism adaptation improves voluntary but not automatic orienting in neglect.

Prism adaptation has been shown to temporarily ameliorate the symptoms of unilateral neglect. The underlying mechanisms of change are not yet fully understood. In this study, we investigate the influence of this treatment on attentional orienting under conditions of exogenous (peripheral onset) and endogenous (central symbolic) cueing. In one patient with left visual extinction and recovered neglect, and another patient with left visual neglect, visuo-motor adaptation to a rightward prismatic shift of 10 degrees improved leftward orienting of attention following an endogenous but not an exogenous cue; leftward re-orienting of attention was also improved in the endogenous task for the second patient. We suggest that prism adaptation may ameliorate neglect by improving compensatory processes of leftward voluntary orienting, rather than by a fundamental change in attentional bias.

The physiological basis of visual hallucinations after damage to the primary visual cortex.

We used functional magnetic resonance imaging to examine the neuroanatomical correlates of visual hallucinations in a patient with a left visual field defect who had suffered bilateral occipital infarction. By cross-correlating the functional magnetic resonance imaging data with the hallucination events, we were able to identify the cerebral activity underlying the hallucinations. Bilateral activation was observed during visual stimulation in the calcarine fissure and the same activation was found medially in the left and right occipital cortex adjacent to the infarcted areas. This pattern of perilesional visual cortex activation is consistent with the suggestion that primary sensory areas may be involved in visual hallucinations after stroke.

The perception of emotional facial expressions in stroke patients with and without depression.

BACKGROUND: Emotion perception may be impaired after stroke. No study on emotion perception after stroke has taken the influence of post-stroke depressive symptoms into account, although depressive symptoms themselves may hamper emotion perception. OBJECTIVE: To compare the perception of emotional facial expressions in stroke patients with and without depressive symptoms. METHODS: Twenty-two stroke patients participated whose depressive symptoms were classified using the Montgomery-Åsberg Depression Rating Scale (cutoff = 10) and who were compared with healthy controls. Emotion recognition was measured using morphed images of facial expressions. RESULTS: Patients with depressive symptoms performed worse than controls on all emotions; patients without depressive symptoms performed at control level. Patients with depressive symptoms were less sensitive to the emotions anger, happiness and sadness compared with patients without depressive symptoms. CONCLUSIONS: Post-stroke depressive symptoms impair emotion perception. This extends findings in bipolar disorder indicating that emotion perception deficits are strongly related to the level of depression.

Cognitive function following stroke and vascular cognitive impairment.

PURPOSE OF REVIEW: This review of the cognitive status following stroke and vascular cognitive impairment starts by questioning the concept of vascular dementia and related concepts. Our position is that in many cases these labels promote a superficial conceptualization of an inherently complex and heterogeneous phenomenon hampering a more detailed understanding. RECENT FINDINGS: After stroke or disease of the cerebral vasculature, the cognitive and emotional outcome is dependent on a combination of three factors with the relative importance differing between causes. First, focal damage may lead to selective impairments that are dependent on the localization of the (grey matter) lesion. Second, diffuse neuronal dysfunction produces a more uniform profile of a decrease in mental speed, memory problems, and reduced executive functioning. Third, cognitive outcome is further modulated - notably in terms of severity - by patient variables such as age, sex, premorbid level of functioning, and comorbidity (e.g. hypertension). SUMMARY: The complex character of the cognitive repercussions of stroke can be better harnessed by employing modern neuropsychological assessment procedures. This allows both a detailed categorization of the patients for the selection and effectiveness of therapeutic intervention, as well as the construction of reliable prognostic models.

The modified Location Learning Test: norms for the assessment of spatial memory function in neuropsychological patients.

This study examines the applicability of the modified Location Learning Test (mLLT) as a test of spatial memory in neuropsychological patients. Three groups of participants were examined: stroke patients, patients with diabetes mellitus and healthy participants (N=411). Three error measures were computed, the Total Score (index of overall performance), the Learning Index (the learning curve over subsequent trials) and the Delayed Recall Score, measuring decay over time. The Learning Index was the most sensitive measure, showing differences between the three groups as well as lateralization effects within the stroke group. Also, the mLLT correlated significantly with the Rey Auditory Verbal Learning Test, as well as with age and education level. Regression-based normative data were computed based on the healthy participants. In all, the mLLT appears to be a sensitive and valid test for the detection of object-location memory impairments in clinical groups.

The role of executive functioning in spontaneous confabulation.

OBJECTIVE: To follow the recovery course of a patient who exhibited an amnesic-confabulatory syndrome in conjunction with severe executive dysfunction in the first week following bithalamic infarction. BACKGROUND: Previous studies have shown that spontaneous confabulation originates from the combination of amnesia and executive dysfunction and that the degree of confabulation is determined by the degree of executive dysfunction. However, a few studies have also reported a dissociation between spontaneous confabulation and executive dysfunction. Therefore, the role of executive functioning in spontaneous confabulation is presently unclear. METHOD: Clinical examinations, magnetic resonance imaging (MRI), and cognitive and behavioral assessments with a focus on executive functions were conducted within the first week poststroke and after 6 months. RESULTS: MRI showed a bithalamic infarction involving the territory of the paramedian arteries predominantly affecting the dorsomedial and intralaminar nuclei of the thalami. Disappearance of spontaneous confabulation paralleled a specific recovery in mental flexibility, whereas all other executive components and long-term memory remained severely impaired at 6 months poststroke. CONCLUSIONS: Our case study provides additional evidence that mental flexibility, but not executive functioning in general, is a prerequisite for spontaneous confabulation. Direct or indirect functional deactivation of dorsolateral prefrontal cortex may be necessary for the development of spontaneous confabulation.

Transient binding by time: Neuropsychological evidence from anti-extinction.

Anti-extinction occurs when there is poor report of a single stimulus presented on the contralesional side of space, but better report of the same item when it occurs concurrently with a stimulus on the ipsilesional side (Goodrich & Ward, 1997). We report a series of experiments that examine the factors that lead to anti-extinction in a patient GK, who has bilateral parietal lesions but more impaired identification of left-side stimuli. We show a pattern of anti-extinction when stimuli are briefly presented, which is followed by an extinction effect when stimuli are left for longer in the visual field. In Experiments 1 and 2 we present evidence that the anti-extinction effects are determined by stimuli onsetting together, and it is not apparent when stimuli are defined by offsets. In Experiments 3 and 4 we report that performance is not strongly affected by whether the same or different tasks are performed on the ipsi- and contralesional stimuli, and the anti-extinction effect also survives trials where eye movements are made to right-side stimuli. Experiment 5 provides evidence that anti-extinction is due to temporal grouping between stimuli, rather than to increased arousal or cueing attention to the contralesional side. Experiment 6 demonstrates that anti-extinction dissociates from GK's conscious perception of when contra- and ipsilesional stimuli occur together. We interpret the data as indicating that there is unconscious and transient temporal binding in vision.