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At least 955 records · Page 53Linked to original sources
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↗
PubMed2006

Egocentric and nonegocentric coding in memory for spatial layout: evidence from scene recognition.

Much contemporary research has suggested that memories for spatial layout are stored with a preferred orientation. The present research examined whether spatial memories are also stored with a preferred viewpoint position. Participants viewed images of an arrangement of objects taken from a single viewpoint and subsequently were tested on their ability to recognize the arrangement from novel viewpoints that had been translated in either the lateral or the depth dimension. Lateral and forward displacements of the viewpoint resulted in increasing response latencies and errors. Backward displacement showed no such effect, nor did lateral translation that resulted in a centered "canonical" view of the arrangement. These results further constrain the specificity of spatial memory, while also providing some evidence that nonegocentric spatial information is coded in memory.

Adult↗
PubMed1999

Storage and processing in visuo-spatial working memory.

Visuo-spatial working memory has been used to account for performance in a wide range of visuo-spatial tasks, including perceptuo-motor tracking and immediate recall of visually presented patterns. However a developing body of evidence points to a fractionation of the concept into visuo-spatial processing that calls on general purpose executive resources, and a visual 'cache' memory for temporary storage in on-line cognition. Two related experiments are described which address whether processing and temporary memory draw on overlapping or on distinct resources in working memory. Experiment 1 demonstrates that participants can accurately respond to a series of targets appearing in random locations whether or not they have the additional load of retaining and subsequently recalling the appearance of each target. Memory for target appearance likewise is largely unaffected by the additional load of requiring a response to each target. Experiment 2 demonstrates similar findings when verbal labeling of the patterns is inhibited through the use of articulatory suppression. Results are interpreted as consistent with a multiple component working memory system.

Adult↗
PubMed2003

Oculomotor control and the maintenance of spatially and temporally distributed events in visuo-spatial working memory.

Previous studies have demonstrated that working memory for spatial location can be significantly disrupted by concurrent eye or limb movement (Baddeley, 1986; Smyth, Pearson, & Pendleton, 1988). Shifts in attention alone can also interfere with spatial span (Smyth & Scholey, 1994), even with no corresponding movement of the eyes or limbs (Smyth, 1996). What is not clear from these studies is how comparable is the magnitude of effect caused by different forms of spatial disrupter. Recently, it has been demonstrated that limb movements produce as much interference with spatial span as do reflexive saccades (Lawrence, Myerson, Oonk, & Abrams, 2001). In turn this has led to the hypothesis that all spatially directed movement can produce similar effects in visuo-spatial working memory. This paper reports the results of five experiments that have contrasted the effect of concurrent eye movement, limb movement, and covert attention shifts on participants' working memory for sequences of locations. All conditions involving concurrent eye movement produced significantly greater reduction in span than equivalent limb movement or covert attention shifts with eyes fixated. It is argued that these results demonstrate a crucial role for oculomotor control processes during the rehearsal of location-specific representations in working memory.

Adult↗
PubMedDate not supplied

Behavioral studies of the effects of moderate oligemic hypoxia caused by bilateral clamping of carotid arteries in mice. Impairment of spatial working memory.

The experiments carried out on Albino Swiss mice indicated that bilateral clamping of carotid arteries (BCCA) for 30 min caused no neuronal damage but produced an increase in GABA content in the hippocampus, striatum and frontal cortex. The behavioral studies have shown that BCCA did not influence the motor coordination, the spontaneous locomotor activity, the reactivity to pain and the cataleptic response to haloperidol of the mice. However, a significant increase in amphetamine-induced hyperactivity was observed after BCCA. In mice, BCCA did not impair long-term memory and spatial working memory, reflected by alternation behavior in the Y-maze. The same dose of scopolamine impaired the working memory in mice which underwent BCCA much more than sham-operated controls. Naftidrofuryl improved the working memory in mice subjected to BCCA as measured 48 h after the surgery. Pretreatment with naftidrofuryl protected the animals against the impairment of alternation behavior caused by scopolamine administration.

Anesthesia↗
PubMed2005

[Cognitive functions in prepsychotic and negative-symptom schizophrenic patients].

BACKGROUND: Relationship between schizophrenia and cognitive functions has been reported by several studies. Our work group examined the changes of cognitive functions in prepsychotic patients without any relevant psychiatric disorder in their anamnesis, and also in schizophrenic patients with predominantly negative symptoms. METHODS: Measures were carried out by Cambridge Neuropsychological Test Automated Battery (CANTAB), a complex computer-based test battery of 13 tests covering a wide range of cognitive functions. 11 prepsychotic (9 male, 2 female) and 14 negative-symptom schizophrenic patients (all male) took part in the study. RESULTS: Prepsychotic patients showed significant (p < 0.05) impairment in the tests of visual memory, spatial recognition memory, spatial working memory and sustained attention. In patients with negative-symptoms significant deficits were also found (p < 0.05) in the delayed matching to sample, the working memory test, and in the intra-extradimensional shift--an analogue of Wisconsin Card Sorting Test. CONCLUSION: The present results show CANTAB may be a useful tool to detect the emergence of psychosis in an early phase, and also it has been found that in schizophrenic patients with predominantly negative symptoms further areas of cognition are also affected. The results may provide a better understanding about the background of the disorder, and the early recognition of the cognitive deficits may help to initiate a specific therapy in proper time. This could result in the slowing of the progression and an improved chance of recovery.

Adult↗
PubMed2005

Organization of visuo-spatial serial memory: interaction of temporal order with spatial and temporal grouping.

This study investigates whether memory for sequences of spatial locations can be represented hierarchically, that is, as successive groups containing the order of constituent locations. Two grouping manipulations are used: Temporal grouping, based on the verbal serial memory literature, and spatial grouping, based on recent empirical work on visuo-spatial serial memory. In Experiment 1, we examine the relationship between spatial grouping and temporal order and showed that recall performance increases when both temporal and spatial organization correlate, but decreases when they clash. Experiments 2 and 3 show that the latter result is confounded by differences in path length (length of spatial path defined by the locations) between conditions, and that no effect of the spatial organization is observed when path length is controlled for. In Experiment 4, an alternative method to spatial grouping, temporal grouping, is used to induce hierarchical organization. A recall advantage is found in the temporal grouping condition. The results suggest that hierarchical representations can be imposed on order information for visuo-spatial sequences, either when participants have pre-existing knowledge about the form of the path formed by the sequence or when temporal boundaries delimit chunks; that increased path length is the cause of the performance decrement observed when dots from separate spatial groups are presented successively; and that path length and more generally sequence characteristics should be taken into account in designing future research on visuo-spatial serial memory.

Humans↗
PubMed2006

The influence of tobacco smoke and nicotine on antidepressant and memory-improving effects of venlafaxine.

In experimental and clinical studies, central nicotinic systems have been shown to play an important role in cognitive function. Nicotinic acetylcholine receptors also mediate the reinforcing properties of nicotine (NIC) in tobacco products. A variety of studies have shown that acute treatment with NIC or nicotinic agonists can improve working memory function. Moreover, it is known that the monoaminergic system plays an important role in memory function. And there is evidence suggesting that prolonged use of NIC may exert antidepressant action via nicotinic receptors. The purpose of this study was to investigate the interactions between a novel antidepressant, venlafaxine (VEN), a blocker of noradrenaline and 5-hydroxytryptamine reuptake sites, and pure NIC in the context of antidepressant and memory function in tobacco smoke exposed and nonexposed rats. The animals were subjected to Porsolt's test for testing antidepressant activity and their memory function (spatial memory) was evaluated in the Morris Water Maze Test. In tobacco smoke non-exposed and exposed rats both single and chronic administration of VEN (20 mg/kg po) shortened immobility time. NIC (0.2 mg/kg sc) significantly reduced immobility time on the 1st, 7th and 14th test days in both non-exposed and exposed rats. Combined VEN+NIC treatment in tobacco smoke non-exposed rats reduced immobility too. This effect of the combination of drugs was significantly stronger as compared to the effects obtained after individual administration of VEN or NIC. In the group exposed to tobacco smoke, joint administration of VEN+ NIC induced a significant reduction of immobility as compared to the control and NIC groups. In the Morris Water Maze Test single and chronic administration of VEN, lower values of escape latencies and lower numbers of crossed quadrants were noted in both exposed and non-exposed rats, which indicates improved performance. After administering NIC we could observe improvement of spatial memory in both the exposed and non-exposed group. A similar effect of improvement of spatial memory was observed after joint administration of VEN and NIC. The study results support the involvement of nicotinic systems in memory processes in rats. Memory improvement and antidepressant effects following joint administration of VEN and NIC may depend on nicotinic interactions with monoaminergic systems and VEN may represent a new therapeutic approach to smoking cessation.

Animals↗
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↗
PubMed2005

Dissociable brain activations during the retrieval of different kinds of spatial context memory.

Although memory for spatial information has often been regarded as unitary, it may be divided into two distinct types: memory for the place where an individual experienced an event and memory for the location of an experienced event within a specific reference object. We used functional magnetic resonance imaging (fMRI) to elucidate the distinctions between the retrieval of these two types of spatial context memory. During scanning, subjects judged the room (Place task) in which a photograph had been presented or the location of the photograph on the computer display (R-L task) during the encoding phase. In a control task, subjects were asked to judge whether the photograph had been presented or not. The left middle frontal gyrus, lateral parietal and occipital regions, and bilateral precunei were found to be active during both the Place task and the R-L task compared with the control task. Critically, the place task, compared with the R-L task, was associated with activations in the right lateral prefrontal gyri, the posterior part of the left parahippocampal gyrus, bilateral retrosplenial and lateral parieto-occipital areas, whereas the R-L task, relative to the place task, with activation only in the right lateral parietal cortex. These findings indicate that the retrieval processes of spatial context memory are not associated with a single network, but may vary and recruit different neural networks depending on the type of spatial information to be retrieved.

Adult↗
PubMed2004

The effect of memory load on cortical activity in the spatial working memory circuit.

Accumulating evidence from electrophysiology and neuroimaging studies suggests that spatial working memory is subserved by a network of frontal and parietal regions. In the present study, we parametrically varied the memory set size (one to four spatial locations) of a delayed-response task and applied time-resolved fMRI to study the influence of memory load upon the spatial working memory circuit. Our behavioral results showed that performance deteriorates (lower accuracy and longer reaction time) as memory load increases. Memory load influenced cortical activity during the cue, delay, and response phases of the delayed-response task. Although delay-related activity in many regions increased with increasing memory load, it also was significantly reduced in the middle frontal gyrus and frontal eye fields and leveled off in the parietal areas when memory load increased further. Delay-related activity in the left posterior parietal cortex was also lower during the error trials, in comparison with the correct trials. Our findings indicate that the delay period activity in the spatial working memory circuit is load sensitive and that the attenuation of this signal is the neural manifestation of performance limitation in the face of excessive memory load.

Adolescent↗
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↗
PubMed1999

Hemispheric asymmetry of spatial working memory deficit in schizophrenia.

Spatial working memory function was assessed in schizophrenia patients, hypothetically 'psychosis-prone' individuals who report unusual perceptual experiences and normal control subjects with an oculomotor delayed response task. Past studies point to the important role of dorsolateral prefrontal system in spatial working memory deficits of schizophrenia patients. In order to better understand the processes precipitating in working memory deficit, two types of working memory errors were examined: never-corrected vs. immediately-corrected errors. In schizophrenia patients, the loss of spatial representation in working memory, as captured by the presence of never-corrected errors, was much more severe when the target was presented in the right visual hemifield than when the target was presented in the left visual field. The same pattern was observed in healthy, psychometrically ascertained 'psychosis-prone' subjects. Therefore, the observed asymmetry of spatial working memory deficit seems unlikely to be a mere side-effect of medication or hospitalization. Normal control subjects did not show hemispheric asymmetry in error patterns. These results suggest that the loss of spatial representation during a delay period may be more severe in the left hemisphere in patients with schizophrenia and in 'psychosis-prone' individuals.

Adult↗
PubMed2000

Memory for drawings in locations: spatial source memory and event-related potentials.

Event-related potentials (ERPs) were recorded during recognition tasks for line drawings (items) or for both drawings and their spatial locations (sources). Recognized drawings elicited more positive ERPs than new drawings. Independent of accuracy in the spatial judgment, the old/new effect in the source recognition task was larger over the prefrontal scalp, and of longer temporal duration than in the item recognition task, suggesting that the source memory task engaged a qualitatively distinct memory process. More posterior scalp sites were sensitive to the accuracy of the source judgment, but this effect was delayed relative to the difference between studied and unstudied drawings, suggesting that source memory processes are completed after item recognition. Similarities and differences between spatial source memory and memory for conjunctions of other stimulus attributes are discussed, together with the role of prefrontal cortex in memory.

Adult↗
PubMed2005

Evidence for hippocampal role in place avoidance other than merely memory storage.

Spatial navigation is used as a popular animal model of higher cognitive functions in people. The data suggest that the hippocampus is important for both storing spatial memories and for performing spatial computations necessary for navigation. Animals use multiple behavioral strategies to solve spatial tasks often using multiple memory systems. We investigated how inactivation of the rat hippocampus affects performance in a place avoidance task to determine if the role of the hippocampus in this task could be attributed to memory storage/retrieval or to the computations needed for navigation. Injecting tetrodotoxin (TTX) into both hippocampi impaired conditioned place avoidance, but after injecting only one hippocampus, the rats learned the place avoidance as well as without any injections. Retention of the place avoidance learned with one hippocampus was not impaired when the injection was switched to the hippocampus that had not been injected during learning. The result suggests that during learning, the hippocampus did not store the place avoidance memory.

Anesthetics, Local↗
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↗
PubMed2006

Serum- and glucocorticoid-inducible kinase (SGK) is a target of the MAPK/ERK signaling pathway that mediates memory formation in rats.

We have previously demonstrated that serum- and glucocorticoid-inducible kinase (SGK) plays a causal role in facilitating memory formation of spatial learning in rats, but the SGK signaling pathway involved in spatial memory formation is not known. The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) also plays an important role in memory formation. We therefore examined whether SGK is a downstream target of the MAPK/ERK signaling cascade and whether ERK signaling to SGK mediates spatial memory formation in rats. Results from an in vitro kinase assay revealed that ERK directly phosphorylates SGK at Ser78, but not at Thr256 and Ser422, whereas inhibition of ERK by PD98059 significantly decreased SGK phosphorylation at Ser78, Thr256 and Ser422 following spatial training. Prior administration of PD98059 also antagonized the enhancing effect of 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C activator that also causes ERK activation, on SGK phosphorylation and cAMP response element binding protein (CREB) phosphorylation. Moreover, TPA-induced SGK phosphorylation and CREB phosphorylation was abolished by prior SGKS78A mutant DNA transfection. By contrast, SGKS78A mutant DNA transfection to hippocampal area CA1 did not affect spatial memory formation, whereas SGKT256A mutant DNA transfection to area CA1 significantly impaired spatial memory formation. ERK was known to regulate sgk mRNA expression, but in the present study we have demonstrated that SGK is also a downstream target of the ERK signaling cascade; ERK directly phosphorylates SGK at Ser78 and indirectly activates SGK at Thr256 and Ser422 through unknown intermediate molecules. Furthermore, ERK activation of SGK is involved in spatial memory formation in rats.

Animals↗
PubMed2005

Supramammillary and adjacent nuclei lesions impair spatial working memory and induce anxiolitic-like behavior.

The present study assesses the involvement of the supramammillary and adjacent nuclei in spatial memory and anxiety-like behaviors. Rats with electrolytic lesions in the supramammillary nucleus were pre- and post-operatively trained in two spatial memory tasks and two anxiety tasks. Spatial memory tasks were performed in an open field with seven different goal positions containing the reward. Anxiety-like behaviors were tested in the elevated T-maze. In the spatial reference memory task, neither lesioned nor sham-lesioned groups were impaired. In the working memory task, lesioned animals were permanently impaired in their ability to solve the delayed-matching-to-position task. This working memory deficit is not related to increased proactive interference. It could be related to impairment of the rats ability to reorganize spatial stimuli. Consequently, rats were not able to achieve an optimal performance level to solve spatial tasks with continuous changes in the place location. In the elevated T-maze, lesioned rats reduced passive avoidance response but no changes in the escape response were observed. These results suggest a clear involvement of the supramammillary nucleus in working memory and behavioral inhibition but not in either spatial reference memory or in escape responses.

Analysis of Variance↗