The effects of ventromedial hypothalamic (VMH) lesions were studied in female rats made diabetic with streptozotocin that were given twice daily injections of protamine zinc insulin (0.75 mu/100g/day) and in non-diabetic animals of the same sex. Hyperphagia resulted from VMH lesions in both diabetic animals whose insulin levels were controlled and in non-diabetic animals. All animals with lesions exhibited persistent increases in feeding during the light protion of the light-dark cycle. Significant increases in body weight gain were observed in both diabetic and non-diabetic lesioned animals, but the magnitude of wegith gain was greater after VMH lesions in non-diabetic rats. VMH lesions also reduced wood-gnawing and increased emotionality, aversion to quinine and reactivity to electric shock. None of the behavioral changes were dependent on hyperinsulinemia, although hyperinsulinemia may contribute to the magnitude of certain of these effects.

Animals↗

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Effects of ovariectomy and estradiol injections on food intake and body weight in rats with ventromedial hypothalamic lesions.

Female rats with lesions of the ventromedial hypothalamus (VMH) were ovariectomized during the static obese stage after body weight levels had stabilized. Following ovariectomy, rats with VMH lesions showed smaller increases in food intake and less body weight gain than non-lesioned controls ovariectomized at the same time. Subsequently, the effects of peripheral injections of estradiol benzoate (EB) on feeding and body weight were examined. Ovariectomized rats with VHM lesions were also less responsive to exogenous EB treatment; they lost significantly less weight in response to estrogen than controls. EB caused a somewhat smaller reduction in food intake by the VMH group but this difference was not significant. Considered together the available data on changes in responsiveness to endogenous and exogenous estrogen following VMH lesions suggest a role for VMH estrogen receptors in the regulation of body weight, but these estrogen receptors may not modulate weight by directly altering food intake as previously suggested.

Animals↗

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Effects of long-term restricted feeding on radial maze performance by aged rats.

Rats were fed every other day (EOD) from 3-21 months of age prior to training in an 8-arm radial maze with retention intervals of 0, 1 or 5 hr imposed between the fourth and fifth choices. Their performance was compared to that of another aged group fed ad lib throughout life prior to radial maze training and to 3 month old controls. Rats fed ad lib until training adapted to the maze more slowly than young controls and were impaired in acquiring accurate spatial memory. EOD feeding eliminated age-related differences in the initial rate of adaptation to the radial maze but had no effect on the development of accurate spatial memory at any of the retention intervals. These results indicate that differences in deprivation history are probably not responsible for previous findings that radial maze training early in life prevents the appearance of age-related deficits in accurate spatial memory.

Aging↗

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Comparative effects of long-term ethanol consumption and forebrain lesions on maze learning and active avoidance behavior in rats.

Male rats consumed a liquid diet containing 10.7% ethanol as their only source of food and fluid for 6.5 months, beginning at 2 months of age. During withdrawal, there were no differences between the alcohol group and their pair-fed or free-fed controls on EEG, body temperature, irritability and tremor measures. In behavioral tests begun 4-5 weeks after withdrawal, the rats that had consumed alcohol acquired accurate spatial behavior in a cross maze task more slowly than controls, but were unimpaired in shuttle-avoidance learning. In concurrent studies with groups of rats that had sustained lesions of the dorsal hippocampus, the mamillary bodies (MMB), or the mediodorsal thalamus, the pattern of behavioral deficits after MMB lesions was found to be qualitatively similar to that observed after the cessation of long-term alcohol consumption. These findings provide renewed hope that a useful rodent model for studying the neuropsychology of cognitive deficits associated with human alcoholism can be developed.

Alcoholism↗

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Retrograde amnesia in patients with Alzheimer's disease or Huntington's disease.

Retrograde amnesia (RA) was studied in patients with Huntington's disease (HD) or Alzheimer's disease (AD) using an updated version of the remote memory battery originally developed by Albert, Butters and Levin. Regardless of whether remote memory was measured by unaided recall or cued recall, HD patients exhibited deficits that were equally severe across decades. RA was more severe in AD than in HD patients and the AD patients recalled significantly more items from the 1940s and 50s than from the 60s, 70s or 80s. The AD patients also displayed dysnomia, while the HD patients did not. Naming difficulties appeared to contribute to the poor overall performance of the AD patients, but did not account for the temporal gradient of their RA. These findings, like recent reports focusing on these patients' ability to learn new information and to search semantic memory, indicate that the processes underlying AD and HD patients' memory failures are distinct.

Adult↗

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Preservation and loss of spatial memory in aged rats and humans: implications for the analysis of memory dysfunction in dementia.

Research with laboratory rats and humans demonstrating that the usual age-related deficits in spatial working memory can be attenuated or eliminated by prior training earlier in adult life is reviewed and possible mechanisms for this phenomenon are considered. A new technique for measuring remote memory for spatial information in humans is described and preliminary results with demented patients are discussed.

Aging↗

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Attention in multiple sclerosis: correlates of impairment on the WAIS-R Digit Span Test.

To re-examine the status of attention in multiple sclerosis (MS) 109 patients with clinically definite MS were administered the WAIS-R Digit Span (DS) and a battery of other neuropsychological (NP) tests of problem solving, abstraction, short-term memory (STM), long-term memory and verbal fluency. Compared to a group of controls of equivalent age and education, the MS patients were impaired on DS and all of the other NP tests. Although the magnitude of the patients' overall DS deficits was comparable for forward and backward spans, the patterns of correlations of NP tests with performance on the forward and backward DS tests were distinctly different. These results can be accounted for by postulating that MS patients suffer from a mild generalized difficulty in maintaining concentration and a more specific impairment in regulatory systems that allocate limited attentional resources among multiple stimulus inputs or tasks.

Journal Article↗

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Cognitive disturbances in Parkinson's disease.

To test the hypothesis that the cognitive impairments that accompany Parkinson's disease (PD) arise from frontal lobe dysfunction, patients with idiopathic PD and controls were tested on a neuropsychological battery that included measures of anterograde memory, visuospatial perception, and naming, as well as several tests that are known to be sensitive to lesions of the frontal lobes. PD patients of normal mental status as measured by the Mini-Mental State Examination performed normally on the naming, line orientation, and verbal recognition memory tests but exhibited deficits on verbal recall. On tests of frontal lobe function, these patients showed mild deficits on a category fluency task and on the Wisconsin Card Sorting Test. However, their errors on the latter were not typical of patients with frontal lesions, and they performed normally on a letter fluency task and exhibited normal release from proactive interference. Patients of lower than normal mental status performed poorly on nearly all of the cognitive tasks including confrontational naming, line orientation, and recognition memory, suggesting that their cerebral dysfunction extended beyond subcortical-frontal circuits. The present study supports the usefulness of the Mini-Mental State Examination for cognitive screening of PD patients, but does not support the hypothesis that the cognitive impairments in PD arise principally from disruption of frontal lobe functioning.

Aged↗

PubMedDate not supplied

Geographical knowledge in patients with Alzheimer's disease.

Geographical knowledge, a measure of remote memory for visuospatial information, was studied in mildly and moderately demented patients who met NINCDS-Alzheimer's Disease and Related Disorders Association criteria for Alzheimer's disease. Alzheimer's disease patients were moderately impaired on a test that emphasizes locating gross features of US geography and profoundly impaired in locating cities on a map of the region of the United States in which they resided. The possibility that performance on tests of geographical knowledge can be used to predict impending difficulties of demented patients in wayfinding is discussed.

Aged↗

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Lexical processing in Parkinson's disease and multiple sclerosis.

Patients with Parkinson's disease (PD) or multiple sclerosis (MS) were categorized as normal in naming (NN) or impaired in naming (IN) based on their performance on the Boston Naming Test. All patients scored at least 23 on the Mini-Mental State Examination. Both PDIN and MSIN patient groups exhibited poor naming performance when target words were elicited with semantic, visual or rhyming cues. They also performed poorly on the vocabulary subtest of the Wechsler Adult Intelligence Scale-Revised and had difficulty repeating sentences. PDNN and MSNN patients showed more selective deficits. These findings add to a growing literature demonstrating that language in general, and naming in particular, can be compromised in subcortical diseases even when global mental status is only mildly affected. The clinical implications of these observations are, however, unclear.

Adult↗

PubMedDate not supplied

Access to semantic memory in Parkinson's disease and multiple sclerosis.

The capacity to access semantic memory and the efficiency of the memory search were studied in patients with Parkinson's disease (PD) or multiple sclerosis (MS) using a modified version of the "Supermarket Test." PD and MS patients who performed normally on the Boston Naming Test generated as many specific exemplars and category labels as did controls, and these patients also searched their semantic memories as efficiently as controls. In contrast, PD and MS patients with impaired confrontational naming generated fewer specific exemplars, but a normal number of generic category labels. These naming-impaired patients searched their semantic memories less efficiently than controls. For both MS and PD patients, the efficiency of semantic memory search was significantly correlated with measures that reflect access to semantic memory (eg, performance on letter or category fluency tasks), but was not significantly related to measures of problem-solving ability derived from the Wisconsin Card Sorting Test. Inefficient search of semantic memory in MS and PD appears to arise from an inability to retrieve knowledge from semantic memory quickly or from the loss of information from semantic memory stores, rather than from impairment in the ability to formulate and deploy appropriate strategies for task solution.

Aged↗

PubMedDate not supplied

Problem solving in Parkinson's disease: comparison of performance on the Wisconsin and California Card Sorting Tests.

Previous demonstrations that problem solving deficits may occur early in the course of Parkinson's disease (PD) have been taken to support the view that disturbances in the functioning of the frontal lobes are responsible for the initial cognitive deficits in this disease. However, no specific pattern of responding associated with poor problem solving by PD patients has been observed consistently. In an effort to clarify the nature of the problem solving deficits in PD we administered the Wisconsin Card Sorting Test (WCST) and the California Card Sorting Test (CCST), a new test which provides separate measures of concept generation, concept identification, and concept execution as well as several different measures of perseveration. On both tests PD patients of lower than normal mental status performed poorly and their patterns of performance resembled those previously described for patients with focal frontal lobe lesions, but PD patients of normal mental status performed normally. Because poor problem solving in association with increased perseverative responding was only observed for patients with global cognitive deficits these findings do not necessarily support the idea that frontal dysfunction is the principal cause of impaired cognition in PD. Although the overall pattern of results was similar for the WCST and the CCST, the CCST was more sensitive for detecting deficits than was the WCST.

Aged↗

PubMedDate not supplied

Picture and motor sequencing in Parkinson's disease.

A recent report found that the discrepancy between scaled scores on the Vocabulary and Picture Arrangement subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was much larger for patients with Parkinson's disease than for healthy controls or patients with Alzheimer's disease. On this basis, it was argued that Parkinson's disease causes a specific deficit in cognitive sequencing that occurs even when the memory and speed requirements of the task are minimal. However, other work indicated that Parkinson's disease patients are almost as severely impaired on other Performance subtests from the WAIS-R that do not require sequencing. In the present study, an extremely simple, untimed test of picture sequencing and a version of the Luria three-step test of motor sequencing were employed. Parkinson's disease patients were impaired on both tasks. The extent of their impairments on picture and motor sequencing were positively correlated, and the severity of deficits on both sequencing tests was related to global mental status and to performance on the Wisconsin Card Sorting Test, but not to neurologic measures of disease severity. However, the patients' performance on the picture sequencing test but not on the motor sequencing test was related to performance on Benton's Facial Recognition Test. These results demonstrate the existence of a generalized sequencing deficit in Parkinson's disease that appears dissociable from impairment in performing simple motor acts.

Aged↗

PubMedDate not supplied

Remote memory for visuospatial information in patients with Alzheimer's disease.

Remote memory for visuospatial information was studied in patients with dementia of the Alzheimer type (DAT) using a test of geographic knowledge previously employed in a study of patients with Huntington's disease. When asked to locate places on a map of the region of the United States in which they were born and raised or on a map of California where they currently resided, the DAT patients performed less accurately than controls. However, unlike controls, the performance of DAT patients in locating places was relatively more accurate using the map of the region in which they were born and raised than using the map of California. Thus, the DAT patients exhibited temporally graded retrograde amnesia for visuospatial knowledge, which parallels the pattern of retrograde amnesia reported for DAT patients when remote memory was assessed with tests requiring identification of famous persons or recall of past public events.

Aged↗