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PubMedDate not supplied

[Short-term spatial memory in mice].

White mice were presented with two visually identical small cups, one containing a sugar solution, and the other a salt solution. After having once rejected in the course of search for sugar the cup with salt, the mice did not as a rule inspect it the second time, as is usually done by melliferous bees. With three of four cups, of which one contained a sugar solution, and the rest of salt solution, the number of repeated examinations sharply increased, still it did not attain that made by melliferous bees with the same number of objects. Hence, for the given class of problems, the behaviour of mice is superior to that of bees.

Animals↗
PubMed2003

A within-subjects, within-task demonstration of intact spatial reference memory and impaired spatial working memory in glutamate receptor-A-deficient mice.

Gene-targeted mice lacking the AMPA receptor subunit glutamate receptor-A (GluRA) (GluR1) and wild-type controls were compared on a radial-maze task in which the same three of six arms were always baited, but in which the rewards of milk were not replaced within a trial. This procedure allowed not only a within-subjects but also a within-trials assessment of both spatial working memory (WM) and reference memory (RM) in GluRA-/- mice, using identical spatial cues. In experiment 1, the GluRA-/- mice made more WM and RM errors during task acquisition. However, separate groups of GluRA-/- and wild-type mice (experiment 2) acquired a purely RM version of the task at a similar rate, using a paradigm with which it was not possible to make WM errors (doors prevented mice from re-entering an arm that they had already visited on that trial). In contrast, mice with hippocampal lesions were dramatically impaired. These results are consistent with the possibility that the WM impairment in the GluRA-/- mice during experiment 1 produced interference that disrupted RM acquisition. A WM component was therefore introduced after RM acquisition in experiment 2 (i.e., the mice were no longer prevented from re-entering a previously visited arm). The GluRA-/- mice now made considerably more WM errors than did wild-type mice, but simultaneously, RM was only mildly and transiently impaired. These experiments provide additional evidence of a selective spatial WM deficit coexisting with intact spatial RM acquisition in GluRA-/- mice, suggesting that different neuronal mechanisms within the hippocampus may support these different kinds of information processing.

Animals↗
PubMed2000

Nicotine impairs spatial working memory while leaving spatial attention intact.

We investigated the effects of nicotine on spatial working memory and spatial selective attention in young, healthy smokers. Spatial working memory was assessed by a delayed response task. Delayed response performance is associated with the integrity of the dorsolateral prefrontal cortex. Spatial interference and negative priming tasks were used to assess spatial selective attention. Nicotine impaired spatial working memory in smokers but it did not affect spatial selective attention. This result suggests that nicotine may impair dorsolateral prefrontal function, as assessed by the spatial working memory task in young smokers and that this deficit does not stem from impairments in spatial selective attention. However, the effects of nicotine on working memory and selective attention in nonsmokers or in psychiatric population with suspected nicotinic receptor abnormalities (e.g., schizophrenia patients) cannot be deduced from the present study.

Adult↗
PubMed1998

Is impaired memory for spatial location in Parkinson's disease domain specific or dependent on 'strategic' processes?

Spatial memory has been found to be impaired in Parkinson's disease (PD). To determine the nature of the deficit, we compared the performance of'standard' levodopa-treated patients with PD to that of matched control subjects in different situations: (i) spatial versus verbal conditional associative learning; (ii) 'global' versus 'local' contextual encoding; (iii) pattern span and related supraspan learning. The relationship between dopaminergic depletion, which characterizes the disease, and the impaired memory processes was investigated by comparing the performance of 'de novo' not yet treated PD patients to that of matched control subjects. Both groups of PD patients were impaired in all situations requiring strategic processes, shared a decreased pattern span and had a normal visuospatial learning once the pattern span was taken into account. All these results suggest that the memory deficit for spatial location observed in PD results mainly from a disturbance of strategic processes and from decreased attentional resources, which may be due, at least in part, to the dopaminergic depletion and related striatofrontal dysfunction.

Aged↗
PubMed1996

Basolateral amygdala lesions block glucocorticoid-induced modulation of memory for spatial learning.

This study examined the role of the amygdala in mediating the effects of glucocorticoids on spatial memory in rats. Adrenalectomy (ADX) induced 4-5 days prior to training impaired memory in a water-maze spatial task. This effect was reversed by a posttraining injection of dexamethasone (0.3 mg/kg sc) but not by corticosterone (0.3 mg/kg). Lesions of the basolateral (BLA), but not the central (CEA) or the medial (MEA), amygdala blocked the effects of ADX and dexamethasone. ADX also impaired acquisition. CEA, MEA, and BLA lesions blocked the ADX effect on acquisition. In adrenally intact rats, intracerebroventricular posttraining injections of a specific glucocorticoid receptor (GR or Type-II) antagonist impaired retention, and BLA lesions blocked the effect of the GR antagonist. These findings provide evidence that the BLA is involved in mediating glucocorticoid influences on learning and memory.

Adrenalectomy↗
PubMed2002

Cognitive enhancing effects of modafinil in healthy volunteers.

RATIONALE: Modafinil, a novel wake-promoting agent, has been shown to have a similar clinical profile to that of conventional stimulants such as methylphenidate. We were therefore interested in assessing whether modafinil, with its unique pharmacological mode of action, might offer similar potential as a cognitive enhancer, without the side effects commonly experienced with amphetamine-like drugs. OBJECTIVES: The main aim of this study was to evaluate the cognitive enhancing potential of this novel agent using a comprehensive battery of neuropsychological tests. METHODS: Sixty healthy young adult male volunteers received either a single oral dose of placebo, or 100 mg or 200 mg modafinil prior to performing a variety of tasks designed to test memory and attention. A randomised double-blind, between-subjects design was used. RESULTS: Modafinil significantly enhanced performance on tests of digit span, visual pattern recognition memory, spatial planning and stop-signal reaction time. These performance improvements were complemented by a slowing in latency on three tests: delayed matching to sample, a decision-making task and the spatial planning task. Subjects reported feeling more alert, attentive and energetic on drug. The effects were not clearly dose dependent, except for those seen with the stop-signal paradigm. In contrast to previous findings with methylphenidate, there were no significant effects of drug on spatial memory span, spatial working memory, rapid visual information processing or attentional set-shifting. Additionally, no effects on paired associates learning were identified. CONCLUSIONS: These data indicate that modafinil selectively improves neuropsychological task performance. This improvement may be attributable to an enhanced ability to inhibit pre-potent responses. This effect appears to reduce impulsive responding, suggesting that modafinil may be of benefit in the treatment of attention deficit hyperactivity disorder.

Adult↗
PubMed2002

The effects of a confectionery snack on attention in young boys.

The relationship between consumption of a confectionery snack after an overnight fast and cognitive function was examined using a variety of cognitive tasks, including spatial memory, verbal memory, attention, visual perception and short-term memory, in a sample of 21 boys, ages 9-12 years. Performance on the vigilance attention task was significantly improved when the participants consumed a confectionery snack compared to consumption of a noncalorie snack. Participants had significantly higher hit rates and significantly lower miss rates after the confectionery snack. In addition, false alarm rates increased as a function of time for the placebo condition and decreased for the confectionery condition. Thus, the confectionery snack enhanced ability to stay on task for an extended period of time, enabling the children to more accurately identify target information, as well as correctly reject nontarget information. Analysis of the types of errors made also revealed that when the children were in the confectionery condition they were less likely to make more glaring errors. No significant differences were found in tests of digit span, verbal memory, spatial memory or visual perception.

Attention↗
PubMed2002

Mental retardation and memory for spatial locations.

Although memory for spatial location has been frequently investigated with mentally retarded populations, it is not clear that these individuals possess the same spatial memory skills as do their peers without mental retardation. We compared 30 persons with and 30 persons without mental retardation. Following either intentional or incidental learning, participants recalled and then relocated 16 objects on a matrix. The control group recalled more intentionally learned than incidentally learned material. The experimental group performed both tasks better after incidental learning than after intentional learning and scored as highly as the controls on incidental spatial memory. Results suggest that memory for spatial location is an automatic process and, to some extent at least, is not directly affected by the individual's level of intelligence.

Humans↗
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↗
PubMedDate not supplied

The development of visuo-spatial working memory.

Children's performance on tests of visuo-spatial working memory improves with age, although relatively little is known about why this happens. One explanation concerns the development of the ability to recode visually presented information into phonological form. This process appears to be used from around 8 years of age and is a major contributor to tasks in which stimuli can be verbally labelled. However, evidence suggests that phonological recoding cannot account for all of the age-related change in performance on visuo-spatial working memory tasks. In this review, four other mechanisms (knowledge, processing strategies, processing speed, and attentional capacity) are considered in terms of their contribution to children's visuo-spatial working memory development.

Child↗
PubMed2001

Children's spatial behavior is differentially affected after traumatic brain injury.

Spatial behavior in 20 children with severe traumatic brain injury (TBI) and 20 healthy controls was investigated using the Kiel Locomotor Maze. Children had to remember defined locations in an experimental chamber with completely controlled intra- and extra-maze cues until learning criterion was reached. In a second experiment, spatial orientation strategies were assessed. Children with TBI were shown to be impaired in spatial learning and spatial memory. Spatial orientation was found to be deficient even in cases where spatial learning and memory proved to be unimpaired, especially in tasks that demanded the use of relational place strategies. Children who suffered a TBI at an early age proved to be more severely impaired in spatial learning and orientation than older children.

Brain Injuries↗
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↗
PubMed2002

Endogenous estradiol and testosterone levels are associated with cognitive performance in older women and men.

Relatively few studies have investigated the relationship between endogenous sex steroid levels and cognition in older people and the reported results have been inconsistent. A number of experimental hormone replacement studies have suggested that estrogen replacement in older women enhances cognition, especially verbal memory. In contrast, little research has been done focusing on men. In the current study the association between endogenous sex steroids (estradiol and testosterone) and cognition was investigated in 38 healthy older women (mean age 68 years) and 30 healthy older men (mean age 69 years). Five cognitive tests measuring verbal memory, spatial memory, verbal fluency, mental rotation, and susceptibility to interference were administered. Results revealed that in women higher estradiol levels as well as testosterone levels were associated with better verbal memory (paired associates and estradiol; r =.38, P < 0.05; paired associates and testosterone; r =.33, P < 0.05;). Moreover estradiol, but not testosterone was associated with less susceptibility to interference (Stroop color word test; r = -0.34, P < 0.05). In men the only significant association was a negative correlation between testosterone and verbal fluency (r = -0.38, P < 0.05). The associations observed in this small study support the notion that estradiol is protecting verbal memory and possibly also frontal lobe mediated functions in older women. In contrast to the positive findings in women endogenous sex steroids do not appear to be closely linked to better cognition in older men.

Affect↗
PubMed2001

Performance more than working memory disrupted by acute systemic inflammation in rats in appetitive tasks.

Evidence from molecular biology, epidemiology, behavioral pharmacology, and clinical science support the conclusion that brain inflammation contributes to the pathogenesis of cognitive symptoms in Alzheimer's disease (AD) and other neuropsychological disorders. Three different tests were conducted to determine whether the acute inflammatory response induced by systemic lipopolysaccharide (LPS) treatment is accompanied by a selective disruption of working memory functioning in rats. Doses of LPS sufficient to induce a thermoregulatory response were administered intraperitoneally and their effects on behavioral measures of symbolic working memory, spatial learning, and spatial memory consolidation, were assessed. LPS-induced immune activation was found not to significantly affect memory processes in any of the behavioral tests used. However, LPS-induced immune activation caused performance deficits consistent with a disruptive effect of LPS on motivation and arousal. These results suggest that sickness behavior induced by immune stimulation is not necessarily accompanied by selective impairment in memory processes. The importance of distinguishing cognitive disruption from performance impairment in interpreting the behavioral effects of inflammatory mediators is discussed.

Animals↗
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↗
PubMed2002

Effect of atropine and the oxime HI-6 on low-level sarin-induced alteration of performance of rats in a T-maze.

1. To study the influence of antidotes on low-level sarin-induced alteration of cognitive functions, male albino Wistar rats were exposed to three various low concentrations of sarin for 60 minutes in the inhalation chamber. One minute following sarin exposure, the rats were i.m. treated with the oxime HI-6 in combination with atropine. Control rats were treated with antidotes as experimental rats but exposed to the pure air instead of sarin. Cognitive functions of the rats were tested using a T-maze where spatial memory and spatial orientation were evaluated. The performance of sarin-exposed and treated rats in the T-maze was tested several times within six weeks (single exposure) or five weeks (repeated exposure) following inhalation exposure to evaluate cognitive impairments. 2. In the case of single exposure to sarin, no statistically significant differencies between the performances of the control and the experimental groups in the alteration of spatial memory and spatial orientation were observed. The repeated exposure of treated rats to clinically asymptomatic dose of sarin (LEVEL 2) did not change the effect of low-level sarin exposure on spatial memory of the experimental rats compared to the single exposure to the same dose of sarin. 3. The decrease in the T-maze performance of the control rats was caused by the impairments of rat's mobility due to the features of a solution of antidotes.

Animals↗