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.     

Decision-making impairments in patients with Parkinson's disease

A high percentage of Parkinson's disease (PD) patients show cognitive impairments in addition to the cardinal motor symptoms. These deficits primarily concern executive functions most probably linked to dysfunctions in prefrontal regions due to decreased dopaminergic transmission in fronto-striatal loops. To investigate possible associations between decision-making and executive functions in PD, we examined 20 non-demented PD patients and 20 healthy control subjects with a neuropsychological test battery and the Game of Dice Task. In this computerised decision-making task, the rules for gains and losses and the winning probabilities are obvious and stable. Thus, strategic components besides feedback processing might influence decision-making in this task. We found that PD patients were impaired in the Game of Dice task performance and that the frequency of disadvantageous choices correlated with both executive functions and feedback processing. We suggest that decision-making deficits of PD patients in explicit gambling situations might be associated with dysfunctions in two different fronto-striatal loops: the limbic-orbitofrontal-striatal loop, involved in feedback processing, and the dorsolateral prefrontal-striatal loop, involved in executive functions.     

A comparison of paper-and-pencil and computerized forms of Line Orientation and Enhanced Cued Recall Tests

The purpose of this study was to assess whether a computerized battery of neuropsychological tests could produce similar results as the conventional forms. Comparisons on 77 volunteer undergraduates were carried out with two neuropsychological tests: Line Orientation Test and Enhanced Cued Recall Test. Firstly, students were assigned randomly across the test medium (paper-and-pencil versus computerized). Secondly, the groups were given the same test in the other medium after a 30-day interval between tests. Results showed that the Enhanced Cued Recall Test-Computer-based did not correlate with the Enhanced Cued Recall Test-Paper-and-pencil results. Line Orientation Test-Computer-based scores, on the other hand, did correlate significantly with the Line Orientation Test-Paper-and-pencil version. In both tests, scores were higher on paper-and-pencil tests compared to computer-based tests. Total score difference between modalities was statistically significant for both Enhanced Cued Recall Tests and for the Line Orientation Test. In both computer-based tests, it took less time for participants to complete the tests.     

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.     

Sentence processing in Lewy body spectrum disorder: the role of working memory

Prior work has related sentence processing to executive deficits in non-demented patients with Parkinson's disease (PD). We extended this investigation to patients with dementia with Lewy bodies (DLB) and PD dementia (PDD) by examining grammatical and working memory components of sentence processing in the full range of patients with Lewy body spectrum disorder (LBSD). Thirty-three patients with LBSD were given a two-alternative, forced-choice sentence-picture matching task. Sentence type, working memory, and grammatical structure were systematically manipulated in the sentences. We found that patients with PDD and DLB were significantly impaired relative to non-demented PD patients and healthy controls. The deficit in PDD/DLB was most pronounced for sentences lengthened by the strategic placement of an additional prepositional phrase and for sentences with an additional proposition due to a center-embedded clause. However, there was no effect for subject-relative versus object-relative grammatical structure. An MRI voxel-based morphometry analysis in a subset of patients showed significant gray matter thinning in the frontal lobe bilaterally, and this extended to temporal, parietal and occipital regions. A regression analysis related sentence processing difficulty in LBSD to frontal neocortex, including inferior prefrontal, premotor, and dorsolateral prefrontal regions, as well as right superior temporal cortex. These findings are consistent with the hypothesis that patients with PDD and DLB have difficulty processing sentences with increased working memory demands and that this deficit is related in part to their frontal disease.     

Virtual action planning in Parkinson's disease: a control study.

Cognitive planning deficits affect patients with Parkinson's disease (PD) and traditional psychometric tests meet difficulties to evaluate their impact on daily life activities. Virtual reality (VR) may provide a new means of assessment. The objective of this study was firstly to develop a virtual environment (VE) useful to explore planning and secondly to examine the effectiveness of using VR in the assessment of cognitive planning for patients with PD. A virtual supermarket (VS) was designed in which participants carried out a task close to daily activities: a test of shopping list. There were two preliminary sessions to familiarize the participants with the software and the supermarket's layout. Then, during the assessment session, participants completed the task, without any time limitation. Global intellectual efficiency was assessed in order to exclude patients with dementia. Data related to the performance in the VS were recorded. Five patients with PD and five age-matched healthy volunteers, meeting inclusion criteria, constituted our convenience sample. The patients did not perform as well as the control group. In particular, the session's duration and the distance covered were longer. The patients' path is specific with numerous stops, turning around, and hesitancies. Finally, their motivation for further training sessions is aroused. The results underline the potential of using VR in the assessment of cognitive planning in PD. A larger analysis is currently being carried out to confirm and to explore all the outcome measures.     

Sequence learning in Parkinson's disease: the effect of spatial stimulus-response compatibility

Patients with Parkinson's disease (PD) have repeatedly demonstrated reduced sequence-specific learning effects in serial reaction time tasks (SRTs). Previous research with PD patients has mainly employed the 'classical' SRT task, involving a spatially compatible assignment of stimuli and responses. From cognitive research, it is known that spatial compatibility triggers rapid, automatic responses in the direction of the stimulus. Automatic responding has shown to be disinhibited in PD patients and may therefore interfere with stimulus anticipation during the learning process. The aim of the present study was to test this hypothesis by investigating if reduced sequence-specific learning depends on spatial stimulus-response compatibility. PD patients and age-matched controls were examined either with an SRT variant involving central stimulus presentation, thereby preventing automatic linking of stimulus and response locations, or with a spatially compatible SRT task. Patients showed reduced sequence-specific learning effects only when the stimulus-response assignment was spatially compatible. This pattern of results confirms the hypothesis that sequence learning deficits in PD may result from a predominance of automatic response activation over learning-based stimulus anticipations during the learning phase.     

Impairments of speech fluency in Lewy body spectrum disorder

Few studies have examined connected speech in demented and non-demented patients with Parkinson’s disease (PD). We assessed the speech production of 35 patients with Lewy body spectrum disorder (LBSD), including non-demented PD patients, patients with PD dementia (PDD), and patients with dementia with Lewy bodies (DLB), in a semi-structured narrative speech sample in order to characterize impairments of speech fluency and to determine the factors contributing to reduced speech fluency in these patients. Both demented and non-demented PD patients exhibited reduced speech fluency, characterized by reduced overall speech rate and long pauses between sentences. Reduced speech rate in LBSD correlated with measures of between-utterance pauses, executive functioning, and grammatical comprehension. Regression analyses related non-fluent speech, grammatical difficulty, and executive difficulty to atrophy in frontal brain regions. These findings indicate that multiple factors contribute to slowed speech in LBSD, and this is mediated in part by disease in frontal brain regions.     

Computational models inform clinical science and assessment: An application to category learning in striatal-damaged patients

In this article we develop a new model of classification that is intermediate between the static, single strategy decision-bound models and the dynamic trial by trial multiple systems model, dCOVIS. The new model, referred to as the sCOVIS model, assumes hypothesis-testing and procedural-based subsystems are active on each trial, but that the parameters that govern behavior of the system are fixed (static) within a block of trials. To determine the clinical utility of the model, it was applied to nonlinear information-integration classification data from patients with Parkinson’s (PD) and Huntington’s disease (HD). In one application, the models suggest that the locus of HD patients’ nonlinear information-integration deficits is in their increased reliance on hypothesis-testing strategies, whereas the locus of PD patients’ deficit is in the application of sub-optimal procedural-based strategies. In a second application, the weight associated with the hypothesis-testing subsystem is shown to account for a significant amount of the variance in longitudinal cognitive decline in non-demented PD patients above and beyond that predicted by accuracy alone. Together, the accuracy rate and this model index account for 72% of the total variance associated with cognitive decline in this sample of PD patients. Interestingly, the Wisconsin Card Sort task added no additional predictive power above and beyond that predicted by nonlinear accuracy alone.     

Dysexecutive syndrome in Parkinson’s disease: the GREFEX study

The objectives of this study were to characterize the frequencies and profiles of behavioral and cognitive dysexecutive syndromes in PD (based on validated battery and diagnostic criteria) and to develop a shortened diagnostic battery. Eighty-eight non-demented patients with a diagnosis of PD were examined with an executive validated battery. Using a validated framework, the patients’ test results were interpreted with respect to normative data from 780 controls. A dysexecutive syndrome was observed in 80.6% of the patients [95% confidence interval: 71.1–90.1]. The dysexecutive profile was characterized by prominent impairments in deduction, flexibility, inhibition and initiation in the cognitive domain, and by global hypoactivity with apathy and hyperactivity in the behavioral domain. This finding implies that patients with PD should be assessed with cognitive tests and a validated inventory for behavioral dysexecutive syndromes. A shortened battery (based on three cognitive tests and three behavioral domains) provided high diagnostic accuracy.     

Motor deficits in Parkinsonian reaching: dopa-sensitivity influenced by real-world task constraint

Parkinson's disease (PD) patients can perform many daily activities, but movement deficits are evident. Those deficits may be increased when the required movement is constrained in accuracy. Variable improvements in performance with PD medication have been demonstrated, and sensitivity to task constraint has been evident in some studies. The authors quantified both specific movement deficits and improvements for PD patients in a reaching task. PD patients (N=8) both on and off medication showed a need for greater ongoing control in movements with higher task-accuracy constraints. Increased task-accuracy constraints further compromised movement timing and structure among PD patients who were off medication, suggesting that unmedicated PD patients may typically compensate by using more conscious control of movement, resulting in increased slowing and segmentation of components when higher task accuracy is required.     

The validity of the hospital anxiety and depression scale and the geriatric depression scale in Parkinson's disease

We assessed the concurrent validity of the Hospital Anxiety and Depression Scale (HADS) and the Geriatric Depression Scale (GDS) against the Hamilton Rating Scale for Depression (Ham-D) in patients with Parkinson's disease (PD). Forty-six non-demented PD patients were assessed by a neurologist on the Ham-D. Patients also completed four mood rating scales: the HADS, the GDS, the VAS and the Face Scale. For the HADS and the GDS, Receiver Operating Characteristics (ROC) curves were obtained and the positive and negative predictive values (PPV, NPV) were calculated for different cut-off scores. Maximum discrimination between depressed and non-depressed PD patients was reached at a cut-off score of 10/11 for both the HADS and the GDS. At the same cut-off score of 10/11 for both the HADS and the GDS, the high sensitivity and NPV make these scales appropriate screening instruments for depression in PD. A high specificity and PPV, which is necessary for a diagnostic test, was reached at a cut-off score of 12/13 for the GDS and at a cut-off score of 11/12 for the HADS. The results indicate the validity of using the HADS and the GDS to screen for depressive symptoms and to diagnose depressive illness in PD.     

The line copy task for kinesthesia and internal movement representation: application in children

In the present study a new test is proposed and tested, which requires ability to use information both from kinesthesia and from mental rotation of previously produced cyclic movements over a distinct trajectory. This Line Copy Test (LICT) was performed by 58 children aged 7-11 years. For the S-part, the participants first had to make movements till they reached a barrier and then they were required to reproduce the same (S) movements without the barrier. For the O-part of the test the participants had to rely on an internal representation of a felt trajectory length, and reproduce the movement orthogonal (O) to the ones felt. Trajectory Length Error (TLE) and variable error (VE) were measured. Furthermore, results of the LICT were correlated to the Kinesthetic Acuity Test and a pegboard task. The general finding was that the TLE, capturing the spatial calibration of the movement, and the VE, used as a measure of noise or inconsistency in the 10 reproductions, was largest for the youngest children, but this developmental effect was not significant in the O-part of the test. Although participants of all age groups made much larger TLE in the rotated task (O-part) than in the LICT_S-part, the VE was much smaller. This can be explained by assuming that different underlying control mechanisms underlie each task. Also differences in correlations of the two parts of the test with the other measures infer that they measure dissimilar underlying entities. It is likely that at least some portion of the increased movement variability in the S-part seen during development in young children can be attributed to partly unstable kinesthetic representations for hand movements. The finding that no significant development was found on the O-part indicates that changes in the use of internal models must occur outside the age window studied.     

Orbital and ventromedial prefrontal cortex functioning in Parkinson's disease: neuropsychological evidence

A recent paper (Zald & Andreotti, 2010) reviewed neuropsychological tasks that assess the function of the orbital and ventromedial portions of the prefrontal cortex (OMPFC). Neuropathological studies have shown that the function of the OMPFC should be preserved in the early stages of Parkinson's disease (PD) but becomes affected in the advanced stages of PD. This pattern has also been suggested by studies that have shown that dopaminergic drugs impair the performance of early PD patients in OMPFC tasks that involve reinforcement learning but enhance the performance of advanced PD patients. Based on these empirical findings, we reviewed the neuropsychological evidence of OMPFC functions in PD patients to test two hypotheses regarding the following: (1) OMPFC functions at different stages of PD; (2) different effects of dopaminergic drugs on OMPFC functions based on PD stage and task demand. We focused our review only on the neuropsychological tasks that were specific and sensitive to the functions of the OMPFC and that were adopted at different stages of PD, such as reversal learning tasks, the Iowa Gambling Task and the affective Theory of Mind task. We found robust empirical evidence that in early PD, OMPFC functions are preserved and dopaminergic drugs result in a detrimental effect when the task involves reinforcement learning. Further studies are needed to verify the status of OMPFC functions in non-demented, advanced PD and to describe the longitudinal course of OMPFC functions in this clinical population.     

The visuospatial functions in children after cerebellar low‐grade astrocytoma surgery: A contribution to the pediatric neuropsychology of the cerebellum

The aim of this study was to specify whether cerebellar lesions cause visuospatial impairments in children. The study sample consisted of 40 children with low‐grade cerebellar astrocytoma, who underwent surgical treatment and 40 healthy controls matched with regard to age and sex. Visuospatial abilities were tested using the spatial WISC‐R subtests (Block Design and Object Assembly), Rey–Osterrieth Complex Figure, Benton Judgment of Line Orientation Test, PEBL Mental Rotation Task, and Benton Visual Retention Test. To exclude general diffuse intellectual dysfunction, the WISC‐R Verbal Intelligence IQ, Performance IQ, and Full‐Scale IQ scores were analysed. Post‐surgical medical consequences were measured with the International Cooperative Ataxia Rating Scale. Compared to controls, the cerebellar group manifested problems with mental rotation of objects, visuospatial organization, planning, and spatial construction processes which could not be explained by medical complications or general intellectual retardation. The intensity of visuospatial syndrome highly depends on cerebellar lesion side. Patients with left‐sided cerebellar lesions display more severe spatial problems than those with right‐sided cerebellar lesions. In conclusion, focal cerebellar lesions in children affect their visuospatial ability. The impairments profile is characterized by deficits in complex spatial processes such as visuospatial organization and mental rotation, requiring reconstruction of visual stimuli using the imagination, while elementary sensory analysis and perception as well as spatial processes requiring direct manipulation of objects are relatively better preserved. This pattern is analogous to the one previously observed in adult population and appears to be typical for cerebellar pathology in general, regardless of age.     

Strategic sequence planning and prospective memory impairments in frontally lesioned head trauma patients performing activities of daily living

The aim of this research was to study strategic sequence planning and prospective memory in activities of daily living (ADL) in 10 patients with frontal lobe lesions after a mild to moderate closed head injury (CHI). The lesions were documented radiologically. The CHI patients were compared to 12 normal controls with a neuropsychological test battery and a realistic simulation of complex multitask ADL (planning and preparing a meal). Though the CHI patients were significantly slow on one test and subject to interference on an attention test, they manifested no basic executive or memory deficit on the paper-pencil tests. However, the CHI patients manifested marked anomalies in the organization of behavior in the meal preparation task. While small sequences of actions were easily produced, large action sets could not be correctly executed. An outstanding difficulty in strategic planning and prospective memory, particularly time-based more than event-based, appears to be an important underpinning of the impairment of ADL observed in the CHI patients with frontal lobe lesions.     

Characterization of memory impairment following closed-head injury in children using the Rey Auditory Verbal Learning Test (AVLT).

Memory impairment following closed-head injury (CHI) in children is well documented. Characterization of the memory deficits of children with CHI could contribute to the prediction of academic performance and rehabilitation of these children. Twenty-five children who sustained closed-head injury and 25 matched controls were administered the Rey Auditory Verbal Learning Test (AVLT). The advantage of this memory test is that a number of memory components are measured simultaneously, thus enabling us to study the relations between different aspects of memory within the same patient sample. The findings indicate that the Rey AVLT is a good test for characterization of impaired verbal memory in children following CHI. Transformation of scores derived from the Rey AVLT to Z-scores enables us to determine the relative effect of CHI in children on different memory scores. Raw scores were more vulnerable than relational ones, derived as the difference between two raw scores (e.g., learning, Trial 5 - 1), to closed-head injury in children, and scores reflecting word span were the least vulnerable. The results are discussed in terms of the possible contribution of the frontal lobes, which are frequently affected in closed-head injuries, to memory performance.     

Sex Differences in Vulnerability to Developmental Spatial Learning Deficits Induced by Limited Binge Alcohol Exposure in Neonatal Rats

The two main objectives of this study were (1) to replicate previous findings that 6 days of binge-like exposure to alcohol during the neonatal brain growth spurt induces significant place learning deficits in juvenile rats and (2) to determine whether more limited (3-day) binge-like exposure during the neonatal period induces place learning deficits and whether the effects depend on the developmental timing of the exposure. Using artificial rearing methods and a split-litter experimental design, groups of male and female neonatal rats were given binge-like exposure to 4.5 g/kg/day of ethanol in milk formula either on Postnatal Days (PD) 4–6, PD 7–9, or PD 4–9, which yielded mean peak blood alcohol concentrations of 230–260 mg/dl. Controls included an artificially reared gastro- stomy control group (GC) given an isocaloric milk formula diet on PD 4–9 and a suckle control group reared normally by lactating dams. Acquisition of place learning in the Morris spatial navigation task was trained for 6 consecutive days beginning on PD 26; a probe trial was given at the end of the sixth day. As expected, both males and females given alcohol on PD 4–9 had significant deficits in acquisition and probe trial performance relative to SC and GC groups. Males given the PD 7–9 exposure had significant place learning deficits which were as severe as with the full 6-day exposure. The PD 4–6 exposure in males produced only a nonsignificant trend toward slower acquisition. Females were not significantly affected by either 3-day exposure. The latter phase of the neonatal brain growth spurt appears to constitute a sex-specific period of enhanced vulnerability to alcohol-induced developmental spatial learning deficits.     

Characterization of Memory Impairment Following Closed-Head Injury in Children Using the Rey Auditory Verbal Learning Test (AVLT)

Memory impairment following closed-head injury (CHI) in children is well documented. Characterization of the memory deficits of children with CHI could contribute to the prediction of academic performance and rehabilitation of these children. Twenty-five children who sustained closed-head injury and 25 matched controls were administered the Rey Auditory Verbal Learning Test (AVLT). The advantage of this memory test is that a number of memory components are measured simultaneously, thus enabling us to study the relations between different aspects of memory within the same patient sample. The findings indicate that the Rey AVLT is a good test for characterization of impaired verbal memory in children following CHI. Transformation of scores derived from the Rey AVLT to Z-scores enables us to determine the relative effect of CHI in children on different memory scores. Raw scores were more vulnerable than relational ones, derived as the difference between two raw scores (e.g., learning, Trial 5?1), to closed-head injury in children, and scores reflecting word span were the least vulnerable. The results are discussed in terms of the possible contribution of the frontal lobes, which are frequently affected in closed-head injuries, to memory performance.     

Mechanisms underlying corruption of working memory in Parkinson's disease

Working memory (WM) impairments are reported to occur in patients with Parkinson's disease (PD). However, the mechanisms are unclear. Here, we investigate several putative factors that might drive poor performance, by examining the precision of recall, the order in which items are recalled and whether memories are corrupted by random guessing (attentional lapses). We used two separate tasks that examined the quality of WM recall under different loads and retention periods, as well as a traditional digit span test. Firstly, on a simple measure of WM recall, where patients were asked to reproduce the orientation of a centrally presented arrow, overall recall was not significantly impaired. However, there was some evidence for increased guessing (attentional lapses). On a new analogue version of the Corsi-span task, where participants had to reproduce on a touchscreen the exact spatial pattern of presented stimuli in the order and locations in which they appeared, there was a reduction in the precision of spatial WM at higher loads. This deficit was due to misremembering item order. At the highest load, there was reduced recall precision, whereas increased guessing was only observed at intermediate set sizes. Finally, PD patients had impaired backward, but not forward, digit spans. Overall, these results reveal the task- and load-dependent nature of WM deficits in PD. On simple low-load tasks, attentional lapses predominate, whereas at higher loads, in the spatial domain, the corruption of mnemonic information—both order item and precision—emerge as the main driver of impairment.