摘要:

This study was concerned with the effects of left- or right-thalamic stimulation on a simple verbal memory task, involving immediate free recall of lists of common words presented dichotically. The subjects were patients with Parkinson's disease undergoing stereotaxic thalamotomy. As a clinical routine, the patients also underwent a brief period of thalamic electrical stimulations before the lesion was made. The memory tests were performed during the stimulation phase of the operation and were accomplished inside the operating room. The main finding was a general deterioration of performance during thalamic stimulation compared with preoperative and postoperative testing. However, this general effect was modulated by stimulation intensity and side of stimulation. High-intensity stimulation of the left thalamus resulted in significantly fewer words being recalled compared with right thalamus stimulation and low-intensity stimulation. Finally, words presented in the first list were recalled better than words from the second and third lists, particularly during stimulation and at follow-up. The findings are discussed in relation to the thalamic activating-gating model originally proposed by Ojemann.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

In a [99mTc]-hexamethylpropyleneamine oxime single photon emission computed tomography study of cerebral blood flow (CBF) in a visual activation paradigm (awake, eyes closed versus eyes open viewing a reversing checkerboard pattern), the authors systematically measured previously observed qualitative alterations in frontal blood flow associated with visual stimulation (experiment 1). They confirmed a trend toward reductions in CBF throughout precentral cortex that approached significance in areas 9 and 46, in conjunction with significant increases in CBF in postcentral cortices, including visual association area PO, and areas 3–1-2, 22, and 23. The authors posited that these changes may be related to differences in attentional and intentional state in the eyes-closed and eyes-open conditions. Such differences should be associated with alterations in motor preparedness, leading to changes in response times and to alterations in thalamocortical gating of somatosensory information, which in turn lead to changes in somatosensory-evoked potential amplitudes. In experiment 2, the authors measured simple motor response times to a 1500-Hz tone stimulus and early components of somatosensory-evoked potentials under the same experimental conditions. In the visual stimulation condition, there was a significant increase in the evoked potential amplitude (t= 2.686,p= 0.021), and a significant decrease in response time (t= −2.464,p= 0.031). These observations provided tentative support for their hypothesis. The authors also demonstrated the major effect of normalization assumptions on regional blood flow measurements.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

It has long been known that carbon monoxide (CO) poisoning has a spectrum of effects on cognitive functioning, including memory, perception, and attention. The current study reports the investigation of the effects of CO poisoning on short-term verbal memory, both rote and context aided. Impairment was measured before and after hyperbaric oxygen (HBO) treatment. Twenty-six patients who had been admitted for emergency treatment after exposure to significant CO poisoning were tested using a measure of short-term recall for word lists with no or varying degrees of internal context-aided structure. Impairment of context-aided memory (but not rote memory) has been previously reported to be associated with low relative frontal volume in psychiatric patients. Carbon monoxide poisoning was significantly associated with impairment of context-aided memory, with the degree of pretreatment impairment predicting the number of HBO treatments judged to be necessary on the basis of clinical monitoring of the patient. In patients with poisoning of moderate severity, pretreatment performance in context-aided memory improved after the first HBO treatment. The implications of these findings for the effects of CO poisoning on frontal area function are discussed. The memory measure used in this study appears to have considerable potential usefulness in the clinical assessment of the severity of CO poisoning in patients treated in an emergency setting.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

This study sought to produce a cognitive profile of herpes simplex encephalitis (HSE) survivors from a large group of definitively diagnosed, acyclovir-treated participants. Results from 22 adults who underwent a battery of neuropsychological tests indicated anterograde memory dysfunction to be the most severe and common deficit (although the variation was great), with less severe and less frequent impairments in the areas of retrograde memory, executive functions, and language functioning. Overall, neuropsychological outcome was unimpaired in six participants, mildly impaired in thirteen, moderately impaired in one, and severely impaired in two. Older participants and those with a lower level of consciousness before the start of treatment produced poorer scores on certain aspects of cognitive outcome (p< 0.05). A significantly better cognitive outcome was found in participants for whom there was a short delay (fewer than 5 days) between symptom onset and acyclovir treatment compared with those participants for whom there was a longer delay. The two children in the study had disparate results on most tests, the exception being those assessing memory functioning on which both children had scores at population norms. On a naming task designed to explore category-specific knowledge deficits, the adults as a group made more errors on pictures of living things than nonliving things (matched pair-wise for word frequency and visual familiarity), although this difference disappeared on a smaller subset of pictures also matched for visual complexity.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Reduplicative paramnesia (RP) has drawn attention as a distinct behavioral syndrome caused by focal brain damage. To elucidate the pathogenesis of RP, we assessed its prevalence among patients with focal brain damage and followed those patients with typical RP. Seventy-seven patients with focal brain damage (47 with left hemispheric, 21 with right hemispheric, and 9 with bilateral damage) were assessed for the presence of RP using a questionnaire intended to elucidate this condition. Two patients showed typical RP for place, and four patients showed atypical RP (three for place and one for person); altogether, these six patients constituted 7.8% of the sample. In three patients, the lesions were situated in the right hemisphere; in two, the lesions were bilateral (right dominant); and in one, the lesions were in the left hemisphere, indicating the relative importance of right hemispheric damage and a possible contributory role of additional left hemispheric damage in RP. The case studies of patients with typical RP suggest the heterogeneity of the underlying cognitive factors in RP.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Longitudinal progression of impaired deficit awareness across varied functional domains was evaluated in 28 patients diagnosed with probable Alzheimer's disease (AD). Unawareness, as measured by patient-caregiver rating discordance, was first assessed in reference to patient memory, health status, self-care skills, anxiety, depression, and irritability. The identical protocol was then repeated an average of 16.4 months later. Results indicated that, compared with caregiver ratings, patients tended to underestimate their deficits across functional domains. Patient-caregiver rating discrepancies were most pronounced in judgment of memory and self-care decline, indicating domain-specific differences in degree of unawareness. However, patient-caregiver rating discrepancies increased on most measures from time 1 to time 2 with no differences in the magnitude of these increases, suggesting a nonspecific longitudinal progression of unawareness. Although unawareness of deficits increased with time, longitudinal change in unawareness was not related to other disease and demographic variables such as age, education, age at onset, or duration of illness.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Abnormal visual attention may underlie certain visuospatial difficulties in patients with Alzheimer's disease (AD). These patients have hypometabolism and neuropathology in parietal cortex. Given the role of parietal function for visuospatial attention, patients with AD may have relative hemispatial neglect masked by other cognitive disturbances. Fifteen patients with mild-to-moderate AD and 15 healthy elderly controls matched for age, sex, and education were compared on four measures of neglect: the visual search of a complex picture, a letter cancellation task, the Schenkenberg line bisection test, and a computerized line bisection task. Compared with controls, the group with AD was significantly impaired overall in attending to left hemispace on both picture search (F[ 1,56] = 11.27,p< 0.05) and cancellation tasks (F [1,112] = 12.68,p< 0.01); however, a subgroup of patients with AD had disproportionate difficulty in attending to right hemispace. The performance of the groups did not differ on either of the line bisection tasks regardless of the hand used. In AD, hemispatial neglect on visual search tasks may relate to difficulty in disengaging attention or in visual exploration, as well as to the severity of the disease. Future investigations may implicate neglect in visually related deficits in AD, for example, the prominent difficulty with left turns on driving a car.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Serotonin syndrome usually occurs after treatment with monoamine oxydase inhibitors and drugs that enhance serotoninergic transmission. Serotonin agents, such as Prozac, are commonly prescribed drugs; therefore, the serotonin syndrome appears more frequently than before. Clinicians must be able to prevent, recognize, and treat this syndrome in their practice. This review summarizes the literature of case reports of patients who developed the serotonin syndrome.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

A 71-year-old, right-handed woman experienced onset of a slowly progressive, nonfluent language disorder. She maintained normal cognitive abilities until age 80 and developed a mild spastic right hemiparesis the following year. By age 82, she had become severely demented, mute, and akinetic. Postmortem brain examination showed moderate asymmetric atrophy (wt = 1000 g), which was most prominent in the left perisylvian and posterior frontal regions, with disproportionate enlargement of the left lateral ventricle. Microscopically, a high density of neurofibrillary tangles was present in the hippocampal pyramidal cell layer and entorhinal cortex (up to 45/400 % field, R > L). Gliosis and patchy neuronal loss were symmetrically present in the frontal and parietal lobes including speech areas, but neurofibrillary tangles and neuritic plaques were present in only small numbers (0–1/400 % field). In this case of primary progressive aphasia, pathologic changes associated with Alzheimer's disease occurred in allocortex but not in neocortex. These clinical and neuropathologic findings expand on those previously reported in primary progressive aphasia and suggest a need for further study of this syndrome.

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0894-878X    

出版商:OVID    

年代:1997

数据来源: OVID