Biomedical subjects

Eli Vakil

Publications and source records attributed to Eli Vakil.

16 recordsLinked to original sources

PubMed2006

Basal forebrain amnesia: a case study.

OBJECTIVE: To provide new evidence of the existence of basal forebrain amnesia, as a different entity from hippocampal or diencephalic amnesia. BACKGROUND: Some authors consider that the characteristics of amnesia do not depend on lesion site, although others claim there are neuropsychologic differences between amnesias due to hippocampal, diencephalic, and basal forebrain lesions. As to the latter, literature is scarce and controversial. The opportunity to thoroughly study J.S., a man with a high IQ and amnesia, enabled us to reinforce the second hypothesis. METHODS: J.S. is a 47-year-old man who underwent surgery for a pituitary adenoma, the resulting lesion involving only the basal forebrain. We gave him a complete neuropsychologic battery for amnesia and executive functions. RESULTS: J.S. showed severe amnesia with a flat learning curve, a rapid forgetting rate and good recognition, a temporal gradient of several years for remote memory, preserved semantic and procedural memory. Most of the tests for executive functions were normal, although he did have a significant personality change after surgery. CONCLUSIONS: This patient is different from patients with hippocampal or diencephalic lesions, and is similar to other patients reported with basal forebrain lesions. The main difference is the relation between his flat learning curve and preserved recognition, both for visual and verbal material.

Adenoma↗

PubMed2005

Presymptomatic signs in healthy CJD mutation carriers.

Creutzfeldt-Jacob disease (CJD) is a rapidly progressing dementia with neurological, psychiatric and cognitive symptoms. We focused our study on the familial CJD form among Libyan Jews (the E200K mutation), trying to identify preclinical neuropsychological signs in mutation carriers to facilitate early diagnosis of the disease. A wide range of neuropsychological tests was administered to 27 healthy volunteers, all first-degree relatives of genetic CJD patients. Thirteen of our participants were gene mutation carriers (E200K) and 14 controls. The healthy mutation carriers reported significantly lower Trait and higher State anxiety scores. Repeated Measure analysis showed statistical significance. The Anxiety Index (State-Trait Anxiety Score) progressed with age in the carriers' group but not in the controls. Since this was more pronounced in the older subjects, we suggest that abnormal stress mechanisms precede the clinical onset of CJD. Cognitive differences have also been found between carriers and controls, especially in visual recognition of pictured objects. Both kinds of differences (anxiety levels and cognitive deficits) were most pronounced in elderly subjects. This study is the first to show any dysfunction in healthy CJD mutation carriers.

Aged↗

PubMed2005

The effect of moderate to severe traumatic brain injury (TBI) on different aspects of memory: a selective review.

Deficient learning and memory are frequently reported as a consequence of traumatic brain injury (TBI). Because of the diffuse nature of the injury, patients with TBI are not the ideal group for studying brain-behavior relations. Nevertheless, characterization of the memory breakdown following TBI could contribute to the assessment and rehabilitation of this patient population. It is well documented that memory is not a unitary system. Accordingly, in this article I review studies that have investigated the long-term effect of moderate to severe TBI on different memory aspects, including explicit and implicit tests of memory. This review demonstrates that TBI affects a large range of memory aspects. One of the conclusions is that the memory impairment observed in TBI patients could be viewed, at least to some degree, as a consequence of a more general cognitive deficit. Thus, unlike patients suffering from global amnesia, memory in patients with TBI is not selectively impaired. Nevertheless, it is possible to detect a subgroup of patients that do meet the criteria of amnesia. However, the most common vulnerable memory processes following TBI very much resemble the memory deficits reported in patients following frontal lobe damage, e.g., difficulties in applying active or effortful strategy in the learning or retrieval process. The suggested similarity between patients with TBI and those suffering from frontal lobe injury should be viewed cautiously; considering the nature of TBI, patients suffering from such injuries are not a homogeneous group. In view of this limitation, the future challenge in this field will be to identify subgroups of patients, either a priori according to a range of factors such as severity of injury, or a posteriori based on their specific memory deficit characteristics. Such a research approach has the potential of explaining much of the variability in findings reported in the literature on the effect of TBI on memory.

Amnesia↗

PubMed2005

Symptom checklist-90 revised scores in persons with traumatic brain injury: affective reactions or neurobehavioral outcomes of the injury?

The goal of this study was to examine the concurrent validity of the Symptom Checklist-90 Revised (SCL-90-R) as a measure of emotional distress among persons with traumatic brain injuries (TBI). Following previous studies, the scale was divided into a "Brain Injury Subscale" (BIS), composed of items that are confounded with the neurobehavioral outcomes of TBI, and a "Non Brain Injury Subscale" (NBIS), composed of items unrelated to the neurobehavioral outcomes. The scores of 94 persons with TBI were analyzed on the two subscales. Although more frequently endorsed, the BIS items were equally related to the cognitive and behavioral outcomes of the injury and to the respondents' affective dispositions. The same pattern of correlations was evident with the NBIS items. In addition, both scales were predicted by measures of emotional reactions to the injury. These results were interpreted as supporting the validity of the SCL-90-R as a measure of emotional distress among persons with brain injuries.

Adolescent↗

PubMed2005

Motor and non-motor sequence learning in children and adolescents with cerebellar damage.

Cerebellar involvement in motor and non-motor sequence learning was examined with serial reaction time tasks (SRT). Our sample consisted of 8 children and adolescents who had undergone surgical removal of a benign posterior fossa tumor (PFT) during childhood. None of them had undergone chemotherapy or cranial radiation therapy (CRT). Ages ranged from 1-11 years at surgery and 9-17 years at testing. The children were tested not earlier than 2.5 years after surgery (M = 5.9 years), enabling brain plasticity and recovery of functions. Their performance was compared with a matched control sample. The PFT group was not impaired in the implicit learning of sequences, as reflected in their performance in blocks with a repeated sequence, both before and after a random block. However, in the perceptual task, their performance deteriorated more than that of the control group when a random block was introduced, suggesting that it was more difficult for the patients to respond flexibly or change their response set when encountering changing task demands. These results are in line with another study by our group on task switching with the same patients.

Adolescent↗

PubMed2004

Unawareness of cognitive deficits and daily functioning among persons with traumatic brain injuries.

This study examines levels of unawareness of cognitive deficits and their relationship to functional outcome among persons with traumatic brain injury (TBI). Data from 61 persons with TBI and 34 family members consisting of various measures were used. The results suggest that awareness of cognitive deficits is not differentially distributed along a concrete-abstract continuum of cognitive domains. Awareness in this sample was significantly related to psychiatric symptomatology and partially associated with behavior disturbances and daily functioning, but not with vocational outcomes. Persons with TBI who over-estimated their cognitive abilities were found to function worse on most outcome measures, except vocation, than persons who did not overestimate their abilities.

Activities of Daily Living↗

PubMed2004

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.

Acoustic Stimulation↗

PubMed2004

The role of the cerebral hemispheres in specific versus abstract priming.

The present study examined specific and abstract priming for pictures in unilateral brain-damaged patients using a picture fragment identification task. Participants were 10 posterior right hemisphere (RH) damaged patients, 11 posterior left hemisphere (LH) damaged patients, and 30 healthy normal controls. Results reveal that RH patients perform specific priming tasks significantly worse than healthy participants (p < .005). There was a trend (p < .1) towards worse abstract priming in LH patients when compared to healthy participants. These results are additional evidence that specific priming depends on normal functioning of the posterior right cerebral hemisphere, while abstract priming depends on normal functioning of the posterior left cerebral hemisphere, and extend this finding from verbal to non-verbal stimuli.

Aged↗

PubMed2004

Dissociation between two types of skill learning tasks: the differential effect of divided attention.

The proposed distinction between perceptual and conceptual skill-learning tasks was tested. Eighty participants were administered a cued recall task and two priming tasks, one perceptual (partial word identification) and one conceptual (category production). Two skill-learning task were administered as well, one putative perceptual (mirror reading) and the other putative conceptual (Tower of Hanoi puzzle). Each task was performed by half of the participants under a full attention condition, and by the other half under a divided attention condition. Consistent with previous reports in the literature, divided attention did not interfere with the perceptual priming task, but did interfere with the conceptual priming and cued recall tasks. Dissociation was also observed for the skill-learning tasks. Divided attention did not affect either baseline performance or learning rate on the mirror reading task. However, on the Tower of Hanoi puzzle, divided attention did interfere with baseline performance, but contrary to prediction it did not interfere with learning rate. The differential effect of divided attention on the baseline performance in these two tasks was interpreted as supporting the distinction between conceptual and perceptual skill-learning tasks.

Adolescent↗

PubMed2004

Differential effect of right and left basal ganglionic infarctions on procedural learning.

OBJECTIVE: To assess the effect of ischemic infarctions affecting the basal ganglia (BG) region on a series of procedural learning tasks. BACKGROUND: The basal ganglia hypothesis of procedural learning is a matter of debate. As most of the relevant research so far is based on examination of patients suffering from Parkinson disease, this inconsistency might reflect either lesion heterogeneity existing in this pathologic group or the heterogeneity of the procedural learning tasks. METHOD: Twelve patients with lesions confined to the right (BGr), 10 to the left (BGI) BG region, and 15 matched controls participated in the study. Three procedural learning tasks were used: Tower of Hanoi Puzzle, Mirror Reading, and Porteus Mazes. Declarative memory and general intelligence were also tested. RESULTS: Verbal declarative memory was impaired in the BG1 group. For each procedural learning task, baseline performance and learning rate were analyzed. Tower of Hanoi Puzzle: Baseline performance of the BG1 group was impaired compared with the other groups. The BGr group was the only group that did not improve over learning trials. MR: Baseline performance of the BGr group was impaired compared with the other groups. The groups' learning rate did not differ significantly. Porteus Mazes: Baseline performance of both patient groups was impaired compared with that of the control group. Learning rate over repetitive trials of the same maze was impaired in the BGr group. However, the transfer of procedural learning to a newly exposed maze was impaired in the BG1 group. CONCLUSIONS: First, right and left basal ganglia play different roles in different procedural learning tasks. Second, procedural learning is not a unitary capacity subserved by any single neural mechanism.

Aged↗

PubMed2003

Comparison between three memory tests: cued recall, priming and saving closed-head injured patients and controls.

Twenty closed-head injured (CHI) patients and 20 matched controls were tested with three different memory tasks: cued recall, word stem completion (WSC), and saving. Saving is defined as the advantage of relearning of a list of word pairs, in terms of the number of learning trials to the criterion of one errorless trial, over the original learning of the same list. It was predicted that CHI patients' explicit memory (i.e., cued recall), but not implicit memory (i.e., WSC), would be impaired. The question addressed in this study is whether the memory of CHI patients will be impaired when memory is tested with a saving task, with 2 weeks delay between original learning and relearning. The findings confirm impairment of CHI patients in explicit memory, although the learning rate is preserved. Implicit memory is preserved in CHI patients only when based on reactivation of preexisting knowledge, but not when dependent on forming new associations. Finally, the CHI patients, even after 2 weeks delay, demonstrated a significant saving in relearning old, as compared to new, pairs of words. The clinical contribution of this study is the delineation of those aspects of memory that are impaired and those that are preserved in CHI patients. The theoretical implications of the finding that memory could be preserved in CHI patients when measured by saving, are discussed in terms of the relationship between implicit memory and saving.

Adult↗

PubMed2003

Script memory for typical and atypical actions: controls versus patients with severe closed-head injury.

OBJECTIVE: When typical and atypical information about a situation is presented, the latter is usually better recognized. This phenomenon is referred to as the 'typicality effect'. It is claimed by most theories that typical and atypical information are mediated by automatic and effortful processes, respectively. Previous studies reported that patients with closed-head injury (CHI) are impaired only on memory tasks that required effortful but not automatic processes. Accordingly, it was hypothesized that these patients would not show the typicality effect when presented with scripts composed of typical and atypical actions. METHOD: Twenty-two patients with CHI and 23 matched controls listened to two scripts which consisted of typical and atypical activities. RESULTS: As predicted, the findings of the present study revealed impaired typicality effect for patients with CHI as compared with controls. The advantage of the control group over the CHI group was more pronounced in the recognition of atypical than typical actions. CONCLUSIONS: The results are discussed in terms of the limited attentional capacity or passive learning strategy, characteristic of memory impairment in patients with CHI.

Adolescent↗

PubMed2003

The effect of aging on script memory for typical and atypical actions.

When typical and atypical information about a situation are presented, the atypical is found to be better recognized. This phenomenon is referred to as the "typicality effect." To test whether the typicality effect is age related, 41 younger and 36 older participants listened to two scripts that consisted of typical and atypical activities. The recognition was scored in two ways-with and without taking confidence rating into account. The two scoring systems yielded a similar pattern of results. Nevertheless, the weighted scores analyses were more sensitive to group differences than the unweighted scores. The older adults demonstrated typicality effect with the false alarm and hit rates corrected for false alarms scores but not with the hit rate score. A key factor in understanding the effect of age on the typicality effect is taking into consideration the conservative response bias found in the older group. The clinical contribution of these findings, in terms of assessment and remediation of age-related memory impairment, is discussed.

Adolescent↗

PubMed2002

Impaired skill learning in patients with severe closed-head injury as demonstrated by the serial reaction time (SRT) task.

A group of 20 patients who sustained closed-head injury (CHI) and a matched control group of 20 individuals were tested on the serial reaction time (SRT) task. Three different sequence-learning measures were generated from the task: two implicit and one explicit. The two implicit sequence-learning measures include: (1) the learning rate on the first five blocks of the repeated sequence, assumed to reflect primarily general reaction time learning, and (2) the difference between the fifth block of the repeated sequence and the sixth block, a random sequence that reflects implicit sequence-specific learning. In addition, an explicit measure of sequence learning was generated. The results indicate that the CHI group was impaired on the explicit measure of sequence learning. The groups did not differ on general reaction time learning, one of the implicit measures of sequence learning. However, the control group was superior to the CHI group in learning the specific sequence repeated in the SRT task. This pattern of results is unique to the CHI group, corresponding with neither that of amnesic patients nor with that of patients with dysfunction of the basal ganglia (i.e., Parkinson's diseases).

Adolescent↗

PubMed2002

Comparison of the predictive power of socio-economic variables, severity of injury and age on long-term outcome of traumatic brain injury: sample-specific variables versus factors as predictors.

The primary objective of this study was to measure the predictive power of pre-injury socio-economic status (SES), severity of injury and age variables on the very long-term outcomes of traumatic brain injury (TBI). By applying a within-subjects retroactive follow-up design and a factor analysis, the study also compared the relative power of sample-specific predictors to that of more commonly used variables and conceptually based factors. Seventy-six participants with severe TBI were evaluated at an average of 14 years post-injury with an extensive neuropsychological battery. The results show that pre-injury SES variables predict long-term cognitive, psychiatric, vocational, and social/familial functioning. Measures of severity of injury predict daily functioning, while age at injury fails to predict any of these variables. Sample-specific predictors were more powerful than more commonly used predictors. Implications regarding long-term clinically based and conceptually based prediction, and those regarding comparisons of predictors across samples are further discussed.

Activities of Daily Living↗

PubMedDate not supplied

Plasma homocysteine levels and Parkinson disease: disease progression, carotid intima-media thickness and neuropsychiatric complications.

OBJECTIVE: To determine whether plasma homocysteine (Hcy) levels are associated with clinical characteristics, neuropsychological and psychiatric manifestations and cardiovascular comorbidity in patients with Parkinson disease (PD). BACKGROUND: Elevated Hcy levels are linked to atherosclerosis, vascular disease, depression, and dementia. Patients with PD treated with L-dopa have been shown to have elevated Hcy levels. DESIGN/METHODS: Idiopathic PD patients were evaluated using the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr stage, Parkinson Psychosis Rating Scale, Beck Depression Inventory, Frontal Assessment Battery, Mini-Mental Status Examination, and several tests for frontal type cognitive functions. Fasting blood samples were collected for the measurement of Hcy, and carotid B-mode ultrasound was performed to measure intima-media thickness of the common carotid arteries. RESULTS: Seventy-two consecutive PD patients (46 men; average age, 68.7 +/- 11.6 years; average disease duration, 7.0 +/- 4.7 years) were recruited. All but 10 patients were treated with L-dopa. The average level of Hcy was 16.4 +/- 7.8 micromol/L, and 38.9% of the patients had Hcy level above the reference range (>15.0 micromol/L). The Hcy levels were associated with PD duration as they were with L-dopa treatment duration but were not associated with the parameters of disease severity or with L-dopa dose. The Hcy levels were associated neither with the common carotid intima-media thickness nor with cardiovascular morbidity. No association was found between Hcy and the neuropsychiatric features of PD such as depression, cognitive performance, or psychosis. CONCLUSIONS: Hyperhomocystinemia is common in L-dopa-treatedPD patients but was not associated with neuropsychological complications (depression, dementia, and cognitive decline associated with frontal lobe functioning or psychosis), enhanced disease severity, or vascular comorbidity.

Adult↗