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Biomedical subjects

J Grafman

Publications and source records attributed to J Grafman.

At least 109 records · Page 6Linked to original sources
PubMed1995

Brain activation during the generation of non-emotional and emotional plans.

We studied 12 normal volunteers who were asked to imagine and plan their behavior in emotional and nonemotional situations while their regional cerebral blood flow was measured with positron emission tomography. The dorsolateral prefrontal and posterior temporal cortex were more activated during the nonemotional situation whereas the medial prefrontal cortex and anterior temporal cortex were more activated during the emotional situation. These results demonstrate that distinctive regions of the prefrontal and temporal cortex used to imagine and plan behavior are activated during the expression of emotional and non-emotional plans.

Adult↗
PubMed1995

Neuropsychological features of progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) is the epitome of a subcortical dementia process. Due to its relative rarity, there is only a small literature on the neuropsychological consequences of PSP. The findings to date demonstrate that PSP patients have dramatically slowed information processing and motor execution, rapid forgetting, problems in orienting attentional resources, and difficulty in planning and shifting conceptual sets. The pattern and severity of these deficits are unique to PSP and suggest that the study of PSP patients can provide a special insight into brain-behavior relations.

Brain↗
PubMed1995

The role of prefrontal regions in the Stroop task.

The Stroop is a classical paradigm that presumably involves the inhibition of automatic responses and is frequently used to assess the frontal lobe functions. We investigated the effect of discrete prefrontal lesions in a Stroop task. A sample of 32 patients with frontal lesions were matched with normal controls by sex, age and years of education. Significant differences between patients and controls were found for errors but not for reaction time. Regression analysis showed that the region most related to errors was the right prefrontal lateral cortex. Left lobectomies did not impair the Stroop performance. Our results favour the role of the right prefrontal cortex in sustained attention, and disagree with the conception of the left prefrontal cortex having a role in the inhibition of verbal automatic responses.

Adult↗
PubMed1995

Are the frontal lobes implicated in "planning" functions? Interpreting data from the Tower of Hanoi.

Twenty adult patients with lesions in the prefrontal cortex were tested on the Tower of Hanoi puzzle. The performance of patients was significantly worse than that of controls. This difference could not be accounted for in terms of a general decline in intelligence or memory, or by the size of the lesion. The results further suggest that both patients and controls used the same general strategy to solve the problem and that patients' difficulties with the task have little to do with planning or "look ahead" deficits (as is generally assumed in the neuropsychology literature). Patient performance is best explained in terms of an inability to see or resolve a goal-subgoal conflict. This interpretation is compatible with several existing accounts of frontal lobe dysfunction that postulate a failure of inhibition of a prepotent response to explain poor performance on the Wisconsin Card Sorting task, the Stroop task, the Antisaccade task, the A-Not-B task, and the Delayed Alternation task.

Adult↗
PubMed1995

Selective impairments in managerial knowledge following pre-frontal cortex damage.

Script generation was investigated in patients with lesions in the prefrontal (n = 9) and posterior (n = 8) cortical regions and in normal subjects (n = 16). Three different activities ranging in degree of familiarity were studied. Frontal patients did not differ from patients with posterior lesion and Normal subjects in the number of actions evoked, mean evocation time, or centrality. Impairments in script information processing were observed only in patients with prefrontal lesions, and for the three types of scripts. Specifically these patients made errors in ordering actions in the correct temporal sequence, failed to close scripts and to remain within the stated boundaries, and made deviant estimates of action importance. The results suggest that pre-frontal cortical lesions provoke a selective impairment in managerial knowledge (Grafman, 1989) that may contribute to difficulties in the formulation and execution of plans.

Adult↗
PubMed1995

The relationship between seizure subtype and interictal personality. Results from the Vietnam Head Injury Study.

A wide variety of interictal personality traits has been associated with complex partial (CP) epilepsy. However, the specificity of these behavioural changes to CP epilepsy has been questioned in several controlled studies. To address this issue, we examined personality and behavioural characteristics in 467 Vietnam veterans 15 years post penetrating head injury. Of this sample, 238 (51%) had developed seizure disorders which were classified as follows: 39 simple partial (SP), 59 CP, 76 partial with secondary generalization (PG), and 64 generalized (G). Seizure patients were compared with two demographically matched control groups: 229 penetrating head-injured Veterans without seizures (PHI-C) and 84 uninjured veterans (UC). Dependent measures included self-report and examiner rating scales, and history of psychiatric treatment. Pre-injury intelligence, brain volume loss (CT scan), seizure frequency and duration of epilepsy served as covariates. We found statistically significant increases in interictal psychopathology in the CP, PG and G groups when compared with the two control groups (PHI-C and UC). No group differences were observed across seizure subtypes. These results suggest that interictal personality and behavioural abnormalities are not specific to individuals with CP seizures. Furthermore, the increased psychopathology in seizure groups when compared with the PHI-C group suggests that personality changes cannot be accounted for by structural brain damage alone.

Adult↗
PubMed1995

What can preservation of autobiographic memory after muscarinic blockade tell us about the scopolamine model of dementia?

Autobiographic memory is reported to be impaired in patients with Alzheimer's disease (AD). To determine if cholinergic blockade fully reproduces the amnestic disorder found in dementia, we evaluated aspects of autobiographic and episodic memory in six healthy elderly controls after both scopolamine and placebo administration compared with untreated age- and education-matched patients with AD. The performance of patients with AD was significantly worse than that of controls after both treatment conditions. Scopolamine impaired episodic but not autobiographic memory. Thus, even though the cholinergic system is severely affected in patients with AD, muscarinic blockade alone does not seem to be a good model of this disorder.

Aged↗
PubMed1994

Induction of a recall deficit by rapid-rate transcranial magnetic stimulation.

We used rapid-rate, repetitive transcranial magnetic stimulation (rTMS) for the noninvasive study of verbal recall. Five right-handed normal subjects were studied. Recall followed immediately after presentation of a 12-word list. Focal rTMS was applied with a figure eight coil in trains of 500 ms duration to F7, F8, T5, T6, P3, P4, or O1, O2 at latencies of 0, 250, 500, or 1000 ms during word list presentation. Recall was consistently significantly diminished only after left mid-temporal and bilateral dorsofrontal rTMS at both 0 and 250 ms latencies. We conclude that rTMS may be useful as a non-invasive tool for the study of verbal memory processes.

Adolescent↗
PubMed1994

Modulation of cortical motor output maps during development of implicit and explicit knowledge.

The excitability of the human motor cortex during the development of implicit and declarative knowledge of a motor task was examined. During a serial reaction time test, subjects developed implicit knowledge of the test sequence, which was reflected by diminishing response times. Motor cortical mapping with transcranial magnetic stimulation revealed that the cortical output maps to the muscles involved in the task became progressively larger until explicit knowledge was achieved, after which they returned to their baseline topography. These results illustrate the rapid functional plasticity of cortical outputs associated with learning and with the transfer of knowledge from an implicit to explicit state.

Brain Mapping↗
PubMed1994

Implicit and explicit memory in patients with Parkinson's disease with and without dementia.

OBJECTIVE: To study explicit and implicit memory processes in patients with Parkinson's disease. DESIGN: Case-control design. All subjects were given a neuropsychological test battery, and the test scores were compared among the groups. SETTING: Government-funded research facility. All subjects were examined as outpatients. PATIENTS: We tested nondemented (n = 13) and demented (n = 5) patients with Parkinson's disease and normal controls (n = 12) matched for age, gender, and educational level. MAIN OUTCOME MEASURES: Memory for verbal and pictorial stimuli under both explicit and implicit retrieval conditions. RESULTS: Both nondemented and demented patients with Parkinson's disease exhibited impairment on tests of explicit memory. Their impairment could be graded based on the level of effort required by the task: impaired free recall in nondemented patients and impaired free recall, cued recall, and recognition in demented patients. By contrast, neither group showed evidence of impairment on automatic (modality monitoring and word frequency estimation) or implicit (word and picture fragment identification) memory tasks. Correlation analyses did not support any association between the effortful memory deficits and neurologic variables, mood, or performance on executive function tests. CONCLUSIONS: Memory deficits in patients with Parkinson's disease primarily involve the conscious, effortful strategic aspects of searching long-term memory.

Aged↗
PubMed1994

Pharmacological evaluation of the cholinergic system in progressive supranuclear palsy.

Severe cholinergic loss occurs in the brains of patients with progressive supranuclear palsy. To evaluate the functional implications of this neuronal deficit, dose-response curves were obtained in patients with progressive supranuclear palsy and normal control subjects undergoing intravenous cholinergic blockade (scopolamine) and stimulation (physostigmine). Physostigmine had no significant neurobehavioral effects at any dose in patients with progressive supranuclear palsy. Scopolamine, at low and medium doses, significantly impaired memory performance of both groups, but worsened the gait of only the patients. High-dose scopolamine, which could not be tolerated by the patients, resulted in gait deterioration among control subjects. Thus, patients with progressive supranuclear palsy have increased sensitivity to cholinergic blockade compared to control subjects. Since loss of cholinergic neurons appears to contribute to the pathogenesis of certain cognitive and motor deficits found in progressive supranuclear palsy, the use of oral anticholinergics should ordinarily be avoided in this disorder. On the other hand, physostigmine at clinically tolerated dose levels seems to be therapeutically ineffective.

Aged↗
PubMed1994

Event-related brain potential evidence for a verbal working memory deficit in multiple sclerosis.

Memory deficits are frequently identified in patients with multiple sclerosis. Both working (short-term) and long-term memory appear affected, particularly on free-recall tasks. The focus of our study was to examine neurophysiological correlates of working memory processes and to identify the specific components responsible for the working memory deficits reported in multiple sclerosis. Event-related brain potentials (ERPs) were recorded from the scalp of mildly afflicted multiple sclerosis patients and their matched normal controls during the performance of phonological and visuo-spatial working memory tasks. Neuropsychological test, behavioural performance and ERP data all indicated that verbal working memory is especially susceptible to impairment by multiple sclerosis, while visuospatial working memory is less susceptible. The pattern of results further indicated that the verbal working memory dysfunction in multiple sclerosis is at least partially due to impairment in the phonological loop, a rehearsal mechanism for retaining verbal information in working memory.

Adult↗
PubMed1994

Magnetic resonance imaging functional activation of left frontal cortex during covert word production.

Six normal volunteers underwent 4-T functional magnetic resonance imaging while performing a covert letter fluency task. An echo planar imaging sequence was utilized to detect activation based on deoxyhemoglobin contrast. All 6 subjects showed consistent activation in the frontal operculum and premotor and primary motor cortices. Activation was also detected in the supramarginal gyrus and the posterior part of the superior temporal gyrus. These results show that magnetic resonance functional neuroimaging can be used to investigate cerebral activity noninvasively during performance of complex cognitive tasks.

Adult↗
PubMed1994

A personality profile of patients diagnosed with post-polio syndrome.

Post-polio syndrome (PPS) refers to the late development of new neuromuscular symptoms in previously stable poliomyelitis patients. Whether psychological disturbance plays a role in the manifestation of symptoms in these patients is unclear. We examined 22 patients fulfilling the clinical criteria for PPS with the Minnesota Multiphasic Personality Inventory-II (MMPI-II), Beck Depression Inventory, Spielberger State-Trait Anxiety Scales, Chapman and Chapman Psychosis-Proneness Scales, Fatigue Scales, a neurobehavioral rating scale, and Cognitive Symptoms Self-Report Scales. The overwhelming majority of scale scores were within normal limits, and there was no indication that psychopathologic symptoms were associated with the development or severity of new muscle weakness in PPS patients. Women with PPS had significantly more somatic complaints, but were less socially isolated than men with PPS. This study confirms that the development or severity of new muscle weakness in carefully diagnosed PPS patients is not due to, or influenced by, underlying psychopathology.

Adult↗
PubMed1994

Relationship between frontal lobe lesions and Wisconsin Card Sorting Test performance in patients with multiple sclerosis.

Conceptual reasoning deficits are common in patients with multiple sclerosis (MS) and are typically associated with focal lesions involving the frontal lobes. In this study, we predicted that MS patients with frontal white matter lesions (MS-F) would be more impaired on a standard conceptual reasoning task (Wisconsin Card Sorting Test; WCST) than patients with minimal frontal lesions (MS-NF), even if the total cerebral lesion area (TLA), measured from MRI, was equivalent across groups. We subdivided 43 definite MS patients into three groups based on MRI findings: seven in the MS-F group (mean TLA = 41.4 cm2) and seven in the MS-NF group (mean TLA = 50.0 cm2); 29 MS patients served as a low lesion burden control group (MS-C; mean TLA = 6.4 cm2). The groups did not differ with regard to demographic and illness characteristics. Although the three subgroups obtained comparable scores on a measure of global cognitive functioning (verbal intelligence), the MS-F group achieved significantly fewer categories and made more total errors on the WCST than did the MS-NF and MS-C groups. The MS-F group made significantly more perseverative responses than the MS-C group and nonsignificantly more than the MS-NF group. These results suggest that the pattern of cognitive decline in MS is a function of the location of demyelinating lesions within the cerebral hemispheric white matter. Finally, we supplement the group study results with a case report of an MS patient who was studied serially with MRI and cognitive testing.

Adult↗
PubMed1994

Induction of visual extinction by rapid-rate transcranial magnetic stimulation of parietal lobe.

We used repetitive, rapid-rate transcranial magnetic stimulation (rTMS) for the noninvasive study of visual attention in humans. Six right-handed volunteers completed eight blocks of 20 single- and 10 double-visual-stimulus trials. The visual stimulus was a single asterisk on the right or left side of a computer screen or two asterisks presented simultaneously. The subject had to respond to the stimulus by pressing the right or left response key or both keys simultaneously. During six of the blocks, we applied focal rTMS in trains of five pulses at 25 Hz and 115% of the subject's motor threshold intensity to scalp positions O1, O2, P3, P4, T5, or T6. Occipital rTMS led to a large number of misses of the contralateral asterisk regardless of whether a single or double stimulus was presented. Parietal rTMS did not induce misses of single stimuli but led to a large number of misses of the contralateral asterisk in the double-stimulus condition. The effects of temporal rTMS were inconsistent. We conclude that rTMS to the occipital lobe causes a sensory detection block, whereas rTMS to the parietal lobe can induce selective extinction of contralateral visual stimuli during a simultaneous double stimulus.

Adolescent↗