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PubMed1991

Determinants of spatial priming in environmental memory.

Spatial priming in recognizing objects in experimentally learned environments has been proposed as strong evidence for spatial organization of environmental memory. However, in all studies showing recognition priming effects, encoding and rehearsal contiguity may have coincided with spatial proximity, and thus priming may have been due to temporal associations formed during rehearsal, not encoded spatial relations per se. We investigated this question in four experiments, using a trip trial learning method in which temporal contiguity and spatial relations were independent. In Experiment 1, no spatial priming in recognition was found, even though indirect evidence suggested that subjects had encoded spatial relations. In Experiment 2, the trip trial method was compared with the free study procedure commonly used in previous priming studies. Spatial priming occurred only for free study subjects, even though the two groups were equivalent on direct measures of encoding accuracy. In Experiment 3, spatial priming in recognition was obtained with a modification of the trip trial method in which temporal and spatial contiguity were deliberately confounded. In Experiment 4, the unmodified trip trial method produced spatial priming in a location-decision task. Taken together, our results suggest that environmental memory may be spatially organized, but retrieval of object identities does not necessarily activate encoded spatial relations.

Adult↗
PubMed1990

Hippocampal mossy fibers and radial-maze learning in the mouse: a correlation with spatial working memory but not with non-spatial reference memory.

One hundred and eight male mice from nine different inbred strains were tested for two aspects of learning in an eight-arm radial maze. In the first experimental arrangement of the maze, measuring spatial working memory, clear strain differences were found on the fifth day of training. Furthermore, this type of learning showed a high positive correlation with the size of the intra- and infrapyramidal hippocampal mossy fiber terminal field as revealed with Timm's staining. In the second experiment, in which non-spatial reference memory was tested, significant strain differences were found for the learning variables, but there were no significant covariations with the sizes of the intra- and infrapyramidal mossy fiber terminal fields. These results, combined with previous data, suggest that heritable variations of the hippocampal intra- and infrapyramidal mossy fiber projection influence processes determining spatial learning capabilities in mice.

Animals↗
PubMed1992

A new one-trial test for neurobiological studies of memory in rats. III. Spatial vs. non-spatial working memory.

Rats were submitted to object and spatial recognition tests (both based on the same paradigm) and to the radial-arm maze. The results are as follows: (1) rats could discriminate between a new and a familiar object when the retention delay was 1 min, 15 min or 60 min but not 24 h. The relationship between the level of discrimination and intertrial delays is quadratic with a maximum for 15 min. (2) Exposure to distractive stimuli during the retention delay may impair object recognition. (3) Rats discriminated between a new and a familiar space. (4) There is no correlation between the three tests which argues for a multiple form of working memory, especially a spatial and a non-spatial one. (5) Medial septal lesion did not impair object and spatial recognition memory, but the level of discrimination in the spatial recognition test was significantly reduced compared to that of control.

Aging↗
PubMed1992

Neuropsychological functioning of first-episode schizophreniform patients.

OBJECTIVE AND METHOD: This study compared 32 consecutively admitted first-episode schizophreniform patients, 26 patients with chronic schizophrenia according to the DSM-III-R criteria, and 25 normal comparison subjects on a comprehensive battery of neuropsychological tests to determine the degree of cognitive impairment existing at the onset of schizophrenic illness. Patients were tested within 2 weeks of admission to the hospital, after their medication had been stabilized. RESULTS: With age and education controlled, the first-episode and chronic patients performed significantly worse than the normal subjects on neuropsychological summary measures of executive function, verbal memory, spatial memory, concentration/speed, and global cognitive function and on left and right hemisphere function scales. The first-episode patients were as cognitively impaired as the chronic patients on all summary scales and many of the individual tests. Both groups showed relatively greater left than right hemisphere dysfunction. CONCLUSIONS: These findings suggest that substantial cognitive deficits, comparable to those of chronic patients, are present early in the course of psychotic illness.

Adult↗
PubMed1996

Sex differences in neuropsychological functioning among schizophrenic patients.

OBJECTIVE: The view of schizophrenic men as having poorer premorbid development, earlier age at onset, and worse outcome than schizophrenic women predicts greater neuropsychological impairment in the former than the latter. The authors examined in detail neuropsychological functioning in a large group of schizophrenic patients and a healthy comparison group. METHOD: Neuropsychological functioning in 132 male and 63 female patients with schizophrenia or schizoaffective disorder was extensively studied and compared with that of 99 (40 male, 59 female) healthy individuals. RESULTS: As expected, the schizophrenic patients as a group were pervasively and significantly more impaired than the comparison group. Within schizophrenia, in contrast to the prediction, women performed significantly more poorly than men in verbal memory, spatial memory, and visual processing. Female schizophrenic patients also had significantly poorer right than left hemisphere performance, whereas male schizophrenic patients had identical scores for right and left hemisphere impairment. CONCLUSIONS: The findings are consistent with the hypothesis that schizophrenia among women may be partially understood as a right hemisphere dysfunction. Sampling, diagnostic, and epidemiologic factors may have affected the results.

Adult↗
PubMed1996

The bailiwick of visuo-spatial working memory: evidence from unilateral spatial neglect.

An accurate representation of the visual environment is crucial for successful interaction with objects in that environment. The means by which that representation is formed in working memory is a major focus of the issues and research discussed in this paper. The discussion draws on experimental studies of healthy adults and of patients with impairments of visual perceptual processing or of visuo-spatial mental representation. These disorders are most commonly linked with the disorder referred to clinically as unilateral spatial neglect. We discuss the observed dissociation between perceptual neglect and representational neglect, and the phenomenon of implicit processing of information in the neglected hemifield. In so doing we explore the implications of the findings from this literature for the development of theories of visuo-spatial working memory.

Attention↗
PubMed1993

Memory impairments following lesions to the mammillary region of the rat.

The contribution of the mammillary region to learning and memory was investigated. It was demonstrated that lesions of this region impair performance on tasks that require memory for spatial information but that the deficit depends both on the amount of damage within the region and the difficulty of the task. A dissociation in the effect of such lesions on performance of comparable spatial and non-spatial memory tasks was shown. In contrast to the deficits observed on spatial memory tasks, the acquisition and retention of a complex non-spatial memory task was not impaired after extensive damage to the mammillary region. Such lesions also did not impair performance in a conditioned taste aversion task. These experiments suggest that the mammillary region may be selectively involved in spatial learning and memory.

Animals↗
PubMed1995

Visuo-spatial working memory limitations in low visuo-spatial high verbal intelligence children.

Visuo-spatial working memory was investigated in a group of 37 children aged between 10 and 14 years with low visuo-spatial intelligence. Their performance was poorer than that of a matched control group on a series of tests devised to ascertain visuo-spatial working memory yet was broadly similar in a language test and in school achievement tests. It is argued that low visuo-spatial intelligence children typically present limitations in the storage capacity of a passive system of the visuo-spatial working memory (with a raw measure of four-five stored elements) and especially in the operations required to process that information.

Adolescent↗
PubMed1996

Executive and mnemonic functions in early Huntington's disease.

Eighteen patients with early Huntington's disease were compared with age- and IQ-matched control volunteers on tests of executive and mnemonic function taken from the Cambridge Neuropsychological Test Automated Battery. Tests of pattern and spatial recognition memory, spatial span, spatial working memory, spatial planning and visual discrimination learning/attentional set shifting were employed. These tests have previously been found to be sensitive to the later stages of Huntington's disease. Patients with early Huntington's disease were found to have a wide range of cognitive impairments encompassing both visuospatial memory and executive functions, a pattern distinct from those seen in other basal ganglia disorders. In contrast to patients with more advanced Huntington's disease, early Huntington's disease patients were not impaired at simple reversal learning, but were impaired at performing an extradimensional shift (EDS). The results will be discussed in relation to the hypothesized neuropathological staging of Huntington's disease and to the anatomical connectivity of the striatum.

Adult↗
PubMedDate not supplied

A spatial arrangement memory testing unit.

The Spatial Arrangement Memory Testing Unit is a new apparatus which has been designed to provide a low-cost, portable instrument for assessing visuo-spatial memory performance. It is particularly useful for aiding diagnosis and planning rehabilitation programmes for patients that have suffered brain damage. The application of microprocessor technology has allowed a flexible programmable approach to the operation of the equipment. The system uses a dedicated Zilog Z80 microprocessor with associated software held in EPROM. An integral printer is used to provide a permanent record of patient performance.

Biomedical Engineering↗
PubMed1980

Memory for verbal and spatial information as a function of age.

The present study investigated whether there is a differential decline with age in verbal and spatial memory, by measuring the ability of 24 young (mean age = 18.8) and 24 elderly (mean age = 69.5) subjects to remember verbal and spatial information under identical task conditions. Subjects recalled either the identities or spatial locations of seven letters arranged randomly within a 5 x 5 grid. To determine whether subjects actually encoded the verbal and spatial characteristics of the array differently, verbal and spatial interference tasks were administered during the retention interval. Results showed that the memory decrement in the elderly was not greater for the spatial aspects of the stimulus array than for its verbal aspects. Thus, there was no evidence for a greater decline with age in spatial memory than in verbal memory. Limited support was found for the utility of the selective interference paradigm to demonstrate separate and independent verbal and spatial memory codes.

Adolescent↗
PubMed1996

Oxotremorine infusions into the medial septal area of middle-aged rats affect spatial reference memory and ChAT activity.

Age-related spatial memory deficits are correlated with septohippocampal cholinergic system degeneration. The present study examined the effect of intraseptal infusions of the cholinergic agonist, oxotremorine, on spatial reference memory in middle-aged rats using place discrimination in the water maze, and on cholinergic activity using choline acetyltransferase (ChAT) activity. Oxotremorine mildly improved the rate of place discrimination acquisition of middle-aged rats during initial sessions only, but did not affect asymptotic levels of performance achieved. Of the brain regions assayed, ChAT activity increased with age in the temporal cortex and dorsal CA2/3 region of the hippocampus. Oxotremorine significantly decreased ChAT activity in the dorsal hippocampus. In contrast to our previous results in aged rats indicating a more robust effect of oxotremorine on spatial working memory, the present results suggest a modest effect of intraseptal oxotremorine on the acquisition of a spatial reference memory task.

Aging↗
PubMedDate not supplied

Dissociating verbal and spatial working memory using PET.

Three experiments used position emission tomography (PET) to study the neural basis of human working memory. These studies ask whether different neural circuits underly verbal and spatial memory. In Experiment 1, subjects had to retain for 3 sec. either the names of four letters (verbal memory) or the positions of three dots (spatial memory). The PET results manifested a clear cut double dissociation, as the verbal task activated primarily left-hemisphere regions whereas the spatial task activated only right-hemisphere regions. In Experiment 2, the identical sequence of letters was presented in all conditions, and what varied was whether subjects had to remember the names of the letters (verbal memory) or their positions in the display (spatial memory). In the verbal task, activation was concentrated more in the left than the right hemisphere; in the spatial task, there was substantial activation in both hemispheres, though in key regions, there was more activation in the right than the left hemisphere. Experiment 3 studied only verbal memory, and showed that a continuous memory task activated the same regions as the discrete verbal task used in Experiment 1. Taken together, these results indicate that verbal and spatial working memory are implemented by different neural structures.

Humans↗
PubMed1996

Serial order in spatial immediate memory.

Serial order effects in spatial memory are investigated in three experiments. In the first an analysis of errors in recall data suggested that immediate transpositions were the most common error and that order errors over 2 or 3 adjacent items accounted for the majority of errors in recall. The first and last serial positions are less error-prone than is the middle position in sets of six and seven items. A second experiment investigated recognition of transpositions and found that immediate transpositions were hardest to recognize but that a traditional serial position effect was not found. This may be due to the difficulty of maintaining one set of spatial items when another set is presented for comparison. A probe experiment, in which subjects were asked to recognize whether a single item came from a memory set and then to assign it to its position in the set indicated that the first and last positions were remembered more accurately than were central positions. The combination of serial order data in recall and position data suggests that there are similarities between serial order and position effects in the verbal and spatial domains and that serial order in spatial sequences is position-based.

Adult↗
PubMed1990

The effects of aging in rats on working and reference memory performance in a spatial holeboard discrimination task.

The effects of aging on spatial memory performance of rats was studied in a holeboard task in which 4 of 16 holes were baited with food. Brown-Norway rats of five ages (4, 13, 19, 25, and 30 months) received a total of 80 acquisition trials. A clear age-related decline of spatial working and reference memory performance was found. The decline was most profound between 19 and 25 months of age. The speed of visiting holes and the development of a preferred pattern of hole-visits did not influence spatial discrimination performance. Correlational analysis supported the view that the working and reference memory measures represent distinct aspects of spatial memory.

Aging↗
PubMed1994

Evidence for spatial working memory in honeybees (Apis mellifera).

Spatial working memory (the ability to represent multiple locations in a flexible, dynamic manner) has been studied in a range of vertebrate species. The results of 3 experiments indicate that this ability also exists in at least one invertebrate (honeybees; Apis mellifera). Individual honeybees collected sugar solution from a matrix of 6 locations. They avoided revisits to locations previously depleted of solution more accurately than expected by chance. The results rule out several nonmemorial explanations for this ability, and it is therefore best explained by a spatial working memory system that allows discrimination of previously visited locations from those not yet visited. These results substantially expand the range of species in which spatial working memory has been demonstrated.

Animals↗
PubMed1993

Complex figure recall in the elderly: a deficit in memory or constructional strategy?

Spatial memory declines with age. This study investigated the hypothesis that the decline in spatial memory in the elderly is due to a dysfunction in frontal lobe-mediated planning and organization. The copy and recall ability of 49 elderly subjects and 20 younger subjects was assessed using the Rey-Osterrieth Figure. In addition, the manner of construction, (e.g., the order that each line was produced) was compared between groups. Despite comparable performance with the younger subjects when copying the figure, older subjects performed significantly worse than younger subjects when asked to reproduce the figure from memory. However, this was not due to the organizational strategies they used while copying the figure. They constructed the figure in the same manner as the younger subjects. Therefore, the spatial memory deficits in the elderly are not due to an abnormal organizational strategy. These results are discussed in relation to those of patients with frontal lobe damage and preliminary data from subjects with mild dementia.

Adult↗
PubMed1996

Spatial working memory and strategy formation in patients with frontal lobe excisions.

Spatial working memory was investigated in 20 patients with unilateral neurosurgical excisions of the frontal cortex (UFL), nine with right (RFL) and eleven with left lesions (LFL), comparing their performance to a matched control group. Spatial memory was tested using the Executive Golf Task, a test that also measures spatial strategy formation. Overall the UFL were significantly impaired, the greatest impairment being found in the RFL group. The difference between the RFL and LFL groups was abolished when a measure of strategy formation was used as a covariate in the analysis. A further test of spatial working memory, the Owl Spatial Working Memory Task, which prevents the use of a spatial strategy, showed a significant and equivalent impairment in both the RFL and LFL patients. The data are consistent with neuropsychological and functional neuroimaging investigations supporting the role of the pre-frontal cortex in spatial working memory.

Adult↗