摘要:

SummaryVisual cortex in the nonhuman primate (NHP) consists of a hierarchy of interconnected representations of the visual field arranged in parallel pathways. Knowledge of human visual cortex has been inferred from lesion and electrophysiological studies of the NHP and accidental pathology in human subjects. Recently, the functional imaging techniques of positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have for the first time provided a direct demonstration of functional specialization within human visual cortex. This article reviews NHP research and lesion studies in humans, which have suggested a segregation of visual information in the cortex for perception (areas V1, V2, V3) and the interpretation of form (areas V3, V4), color (area V4), and motion (area V5). The applications of functional imaging to support these data and, in some cases, verify the respective deficits associated with damage to these visual areas, such as visual field defects, akinetopsia (failure to appreciate motion), achromatopsia (failure to appreciate colors), and prosopagnosia (inability to recognize familiar faces), are detailed. In particular, several clinical settings in which PET and SPECT may be employed to evaluate visual cortex are discussed.

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

SummaryOne form of failure on Digit Span (DSp) occurs when performance on Digits Forward (DF) is exceeded by that on Digits Backward (DB). Such performance has been described both as rare and as indicative of a lack of motivation on a simple task. However, it does not appear that there have been any empirical efforts to verify these assertions. The current study was undertaken to investigate the frequency and correlates of such performance on DSp in a cohort of community-dwelling older adults. Seventy-three older adults (age: 62.2 ± 5.2 mean ± SD, range 55–75 years) were categorized on DSp performance as typical (TR), relatively aberrant (RA), or absolutely aberrant (AA) responders and compared on a variety of dimensions (i.e., sex; age; WAIS-R Information, Vocabulary, & Digit Symbol; Selective Reminding Memory Test; Geriatric Depression Scale; Epp-worth Sleepiness Scale; Finger Oscillation; Trail-Making Test; PASAT-R; Airplane Test; COWA; and Steer Clear). The current findings fail to support either assertion regarding DB exceeding DF; that is, in this sample of community-dwelling older adults, DB exceeding DF was not rare (occurring in 14% or 6% of the sample, depending on the stringency of the categorization criteria employed) and did not appear to be associated with other neuropsychological measures in a manner suggestive of a motivational deficit.

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

SummaryDespite the frequency of visuospatial complaints in patients with dementia of the Alzheimer type, little is understood about the mechanisms underlying those symptoms. Letter-cancellation tasks were obtained from 50 patients with a clinical diagnosis of Alzheimer's disease (AD). Twenty-two of the 50 subjects (44%) made a total of 36 errors in which they failed to cancel a target letter. There were no differences in mean age, education, gender, or Mini-Mental State Examination score between error-makers and those making no errors. The distribution of errors on the page was not random. When compared to previously reported results of healthy subjects on the same task, the proportion of AD subjects making errors was higher (44% vs. 26%), but the number of errors per error-maker did not differ. AD subjects demonstrated a high proportion of errors in the central region of the page, but did not show the normally expected performance bias to the left or distant half of the page. The pattern of errors reinforces past findings that deficits in the allocation and movement of visual attention across space occur in AD and that disorganization in visual search may contribute to AD patients' visuospatial dysfunction.

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

SummaryDelusions are common in Alzheimer's disease (AD), but their pathophysiological basis is poorly understood. Fifteen patients meeting NINCDS-ADRDA criteria for probable AD were studied with psychometric assessment and brain-dedicated SPECT (xenon-133 and HMPAO). None of the subjects had delusions at the start of the study. One year later, psychometric testing and SPECT were repeated. Three patients had developed Capgras syndrome, and three others had developed non-Capgras delusional disorders in the interval. Psychometric and rCBF measures at baseline and at one year were compared. At baseline rCBF was significantly higher in the right temporal regions in the patients who developed delusions (P< 0.05). One year later, rCBF in the right temporal regions had declined in the psychotic patients. AD patients who developed delusions showed deterioration in right anterior temporal rCBF compared to AD without delusions. In the setting of AD, right temporal function deterioration may contribute to the development of delusions.

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

SummaryThe influence of depressed mood on the cerebral hemispheric motor functioning of 38 right-handed women, half of whom had been classified as depressed and the other half as nondepressed, was examined. The women with depressed mood were also characterized by elevated state and trait anxiety, suggestive of an anxious-depressive state with heightened arousal. A hand dynamometer was used as a standardized measure of hemispheric motor functioning, such as hand-grip strength and fatigue. Primary findings indicated that the women with depressed mood displayed significantly less hand-grip fatigue of the left hand than did nondepressed women. These results suggest possible arousal of the right cerebral hemisphere in this sample of anxious-depressed women; we discuss these findings in terms of arousal theory.

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

SummaryWhile frontal lobe dysfunction has been hypothesized to account for the cognitive and behavioral symptoms characteristic of Attention Deficit Disorder (ADD), inconsistent neuropsychological findings have been reported in adults with residual ADD. Twenty-five ADD adults were compared to 30 gender-, age-, and education-matched healthy controls on measures of sustained attention, psychomotor speed and integration, executive functioning, and verbal learning. There were no group differences in accuracy on the Continuous Performance Task; however. ADD patients exhibited slower reaction time to targets. In addition, patients exhibited slowed psychomotor speed relative to controls. No group differences were observed in executive functioning. For memory, patients acquired less information and displayed inconsistent application of a semantic clustering strategy. Cuing memory with semantic prompts improved memory performance to a greater degree for patients than for controls. Patients were susceptible to retroactive interference and item recall inconsistency. The results indicate a selective pattern of deficits, revealing slowed cognitive processing and a significant list-learning deficit. Neurobehavioral deficits are discussed in relation to hypotheses of frontal lobe dysfunction in ADD.

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

SummaryThe neural mechanism underlying the interrelation between weeping and depression was explored. Weeping might be more characteristic of nonendogenous depression, which women are more prone to show. Investigations of blood flow changes demonstrated that the right and left hemispheres have the same activity levels in females, either during rest or during work on a psychological task, while they often have strikingly different levels in males. The neural mechanism for weeping that operates when female patients are depressed may be inhibited by a lateralized neural inhibition commonly operating in males.

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

SummaryNeuropsychiatry, neuropsychology, and behavioral neurology share similar interests in brain-behavior disturbances. Recent advances in neuroscience have encouraged an increasing convergence of the three disciplines. These fields have differences in theoretical basis, professional and developmental background, most common brain-behavior focus, and principle clinical methods and therapies. This article compares neuropsychiatry, neuropsychology and behavioral neurology and suggests how improved interdisciplinary knowledge and interactions can lead to greater understanding of the neurobiologic basis of behavior.

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0894-878X    

出版商:OVID    

年代:1995

数据来源: OVID