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At least 1,063 records · Page 59Linked to original sources
PubMed2004

The role of gestures in spatial working memory and speech.

Co-speech gestures traditionally have been considered communicative, but they may also serve other functions. For example, hand-arm movements seem to facilitate both spatial working memory and speech production. It has been proposed that gestures facilitate speech indirectly by sustaining spatial representations in working memory. Alternatively, gestures may affect speech production directly by activating embodied semantic representations involved in lexical search. Consistent with the first hypothesis, we found participants gestured more when describing visual objects from memory and when describing objects that were difficult to remember and encode verbally. However, they also gestured when describing a visually accessible object, and gesture restriction produced dysfluent speech even when spatial memory was untaxed, suggesting that gestures can directly affect both spatial memory and lexical retrieval.

Adult↗
PubMed1994

Functional magnetic resonance imaging of human prefrontal cortex activation during a spatial working memory task.

High-speed magnetic resonance (MR) imaging was used to detect activation in the human prefrontal cortex induced by a spatial working memory task modeled on those used to elucidate neuronal circuits in nonhuman primates. Subjects were required to judge whether the location occupied by the current stimulus had been occupied previously over a sequence of 14 or 15 stimuli presented in various locations. Control tasks were similar in all essential respects, except that the subject's task was to detect when one of the stimuli presented was colored red (color detection) or when a dot briefly appeared within the stimulus (dot detection). In all tasks, two to three target events occurred randomly. The MR signal increased in an area of the middle frontal gyrus corresponding to Brodmann's area 46 in all eight subjects performing the spatial working memory task. Right hemisphere activation was greater and more consistent than left. The MR signal change occurred within 6-9 sec of task onset and declined within a similar period after task completion. An increase in MR signal was also noted in the control tasks, but the magnitude of change was less than that recorded in the working memory task. These differences were replicated when testing was repeated in five of the original subjects. The localization of spatial working memory function in humans to a circumscribed area of the middle frontal gyrus supports the compartmentalization of working memory functions in the human prefrontal cortex and the localization of spatial memory processes to comparable areas in humans and nonhuman primates.

Color Perception↗
PubMed1990

Effects of distinctive context on memory for objects and their locations in young and elderly adults.

Sharps and Gollin (1987, 1988) reported that older adults' memory for both objects and their spatial location is more facilitated than that of young adults when items are studied in a distinctive visual context. They also reported that age differences in spatial memory and item memory can be ameliorated if the items are studied in a distinctive context. The goal of this study was to verify and extend these findings by examining memory for everyday objects when the objects were studied on a (a) plain surface, (b) black-and-white schematic map, or (c) colored model. In Experiment 1, item memory was examined, and in Experiment 2, spatial memory was studied. The results indicated that spatial memory improved with the addition of distinctive context but item memory did not. Moreover, there was no evidence that elderly adults were more facilitated by the distinctive context than were the young.

Age Factors↗
PubMedDate not supplied

Dopamine controls fundamental cognitive operations of multi-target spatial working memory.

This study addresses computationally how the prefrontal cortical circuit performs operations of multiple items in spatial working memory. The basic idea is that dopamine controls the circuit dynamics for the operations by changing the ratio of the NMDA-channel transmission to the AMPA-channel transmission. There is evidence that this ratio is a function of dopamine D1 receptor activation. The simulation shows that the model circuit performs several different operations of multi-target spatial working memory depending on this ratio. When the ratio is low, 'replacement' occurs from the previously loaded target to a new one. In intermediate levels of the ratio, a new target is 'added' to the previously loaded target, resulting in the coexistence of more than one target. For higher ratios, the circuit 'rejects' other succeedingly received target stimuli. This study suggests four important issues: First, the cortical circuit can perform operations of multi-target spatial working memory. Second, the circuit can switch the modes of the operations by changing the NMDA-to-AMPA ratio. Third, dopamine would have major roles in the operations of multi-target spatial working memory. Fourth, the intracortical inhibition (especially of the cross-directional) plays an important role in regulating the competition between targets.

Animals↗
PubMed2002

Verbal and spatial working memory performance among HIV-infected adults.

Subtypes of working memory performance were examined in a cohort of 50 HIV-infected adults and 23 uninfected controls using an n-back paradigm (2-back) in which alphabetic stimuli were quasi-randomly presented to a quadrant of a computer monitor. In the verbal working memory condition, participants determined whether each successive letter matched the letter that appeared two previously in the series, regardless of spatial location. In the spatial working memory condition, participants determined whether each letter matched the spatial location of the letter that had appeared two previously, regardless of letter identity. The dependent variable was percent accuracy in each condition. Results of mixed model ANOVA revealed that the HIV-infected participants performed significantly worse than controls on both the verbal and spatial working memory tasks. A significant main effect for working memory condition was also present with both participant groups performing better on the spatial working memory task. These results, the first study of HIV-infected adults to directly compare verbal versus spatial working memory performance using the identical test stimuli across task conditions, suggests that HIV infection is associated with a decrement in working memory efficiency that is equally apparent for both verbal and spatial processing. These findings implicate central executive dysfunction as a likely substrate and provide the basis for hypothesizing that decline in working memory may contribute to other HIV-associated neuropsychological deficits.

Adult↗
PubMed1997

Effect of prior receptor antagonism on behavioral morbidity produced by combined fluid percussion injury and entorhinal cortical lesion.

We have used an animal model of traumatic brain injury (TBI) that incorporates both the neurotransmitter toxicity of fluid percussion TBI and deafferentation of bilateral entorhinal cortical (BEC) lesion to explore whether administration of muscarinic cholinergic or N-methyl-D-aspartate glutamatergic antagonists prior to injury ameliorates cognitive morbidity. Fifteen minutes prior to moderate central fluid percussion TBI, rats were given intraperitoneal injections of either scopolamine (1.0 mg/kg) or MK-801 (0.3 mg/kg) and 24 hr later underwent BEC lesion. Body weight was followed for 5 days postinjury, as was beam balance and beam walk performance to assure motor recovery prior to spatial memory testing. Each group was assessed for spatial memory deficits with the Morris water maze at short term (days 11-15) and long-term (60-64 days) postinjury intervals and then compared with untreated combined insult and sham-injured controls. Results showed that each drug significantly elevated body weight relative to untreated injured cases. Both scopolamine and MK-801 reduced beam balance deficits, whereas neither drug had a significant effect on beam walk deficits. Interestingly, short-term cognitive deficits assessed on days 11-15 were differentially affected by the two drugs: MK-801 pretreatment enhanced the recovery of spatial memory performance, whereas scopolamine pretreatment did not. Long-term (days 60-64) deficits in spatial memory were not altered by pretreatment with either drug. Our results suggest that, unlike fluid percussion TBI alone, behavioral impairment may require more select intervention when deafferentation is part of the head trauma pathology.

Animals↗
PubMed2000

Spatial working memory is independent of hippocampal CA1 long-term potentiation in rats.

This study investigated the relationship between spatial working memory and hippocampal long-term potentiation (LTP) using the allocentric place discrimination task (APDT) in rats, in which the selection accuracy is a good index for spatial working memory. Either the selective M1 muscarinic receptor antagonist pirenzepine (50 microg) or the choline uptake inhibitor hemicholinium-3 (5 microg) impaired APDT selection accuracy, but neither affected the induction of LTP in the hippocampal CA1 region in anesthetized rats. In contrast, the selective N-methyl-D-aspartate receptor antagonist D-amino-5-phosphonopentanoate (200 nmol) did not impair APDT selection accuracy but completely blocked hippocampal CA1 LTP. These results suggest that spatial working memory is independent of hippocampal CA1 LTP and that the central cholinergic system is involved in spatial working memory, but not through the modulation of hippocampal CAI LTP.

Animals↗
PubMed2001

Spatial reference memory and neocortical neurochemistry vary with the estrous cycle in C57BL/6 mice.

Estrous cycle-related variations of spatial reference memory and neurochemistry in intact female mice were examined. Spatial reference memory was tested in cycling females, ovariectomized (OVX) females, and males by using a 1-day water maze protocol. Choline acetyltransferase (ChAT) and glutamic acid decarboxylase (GAD) activities were measured in the hippocampus and neocortex. Estrus females exhibited worse spatial acquisition and 30-min retention than did proestrus and metestrus females, higher neocortical ChAT activity than proestrus females, and higher neocortical GAD activity than OVX females and males. Neocortical, rather than hippocampal, neurochemistry was more sensitive to hormonal modulation, suggesting that hormonal mediation of neocortical function may play a critical role in regulating spatial reference memory in female mice.

Animals↗
PubMed2000

LP-BM5 infection impairs spatial working memory in C57BL/6 mice in the Morris water maze.

Previous studies show that the LP-BM5 murine leukemia virus causes an acquired immunodeficiency syndrome in C57BL/6 mice (MAIDS) and impairs learning and memory without gross motor impairment. To assess spatial working memory impairment after LP-BM5 infection and the time course of this impairment, we tested mice in a modified working-memory version of the Morris water maze. Twenty mice were inoculated with LP-BM5; controls received medium (Minimum Essential Medium). In the test procedure, animals had two 1-min training sessions to learn the position of a randomly placed hidden platform. Thirty seconds after the second training session, animals were placed in the maze without the platform, and time and pathlength spent in each quadrant of the maze were measured. For 9 weeks after LP-BM5 infection, both groups showed preference for the target quadrant compared to the opposite quadrant. At 10 and 11 weeks after infection, the LP-BM5 virus infected mice lost this target quadrant preference. We conclude that LP-BM5 infection impaired spatial working memory in a modified working-memory version of the Morris water maze test in C57BL/6 mice at 10 and 11 weeks after virus infection.

Animals↗
PubMed2004

Sex differences and correlations in a virtual Morris water task, a virtual radial arm maze, and mental rotation.

Different tasks are often used to assess spatial memory in humans compared to nonhumans. In order to bridge this paradigmatic gap, we used a within-subject design to test 61 undergraduates on three spatial memory tasks. One of these tasks, the Vanderberg 3D mental rotation task, is classically used to assess spatial memory in humans. The other two tests are virtual analogues of two tasks used classically to assess spatial memory in rodents: the Morris water task and an eight-arm radial maze. We find that males perform significantly better than females on the mental rotation task and in finding a hidden platform in the virtual Morris water task. Moreover, during a probe trial, males spend significantly more distance of their swim in the training quadrant, but males and females do not differ in navigating to a visible platform. However, for the virtual eight-arm radial maze, there is no sex difference in working memory errors, reference memory errors, or distance to find the rewards. Surprisingly, an examination of the correlations among the three tasks indicates that only mental rotation ability and Morris water task probe trial performance correlate significantly among the three tasks (i.e. there are no significant correlations with traditional measures the tasks, e.g. time or distance to completion). Hence, the Morris water task and the eight-arm radial maze do not assess spatial memory in the same manner, and even after equating factors such as motivation, stress, and motor demands, there still are procedural demands of the tasks that reinforce differential strategy selection during spatial memory. This suggests that caution should be taken when utilizing these two tasks interchangeable as tests of spatial memory.

Adolescent↗
PubMed2007

Aging and the intrusion superiority effect in visuo-spatial working memory.

This study investigated the active component of visuo-spatial working memory (VSWM) in younger and older adults testing the hypotheses that elderly individuals have a poorer performance than younger ones and that errors in active VSWM tasks depend, at least partially, on difficulties in avoiding intrusions (i.e., avoiding already activated information). In two experiments, participants were presented with sequences of matrices on which three positions were pointed out sequentially: their task was to process all the positions but indicate only the final position of each sequence. Results showed a poorer performance in the elderly compared to the younger group and a higher number of intrusion (errors due to activated but irrelevant positions) rather than invention (errors consisting of pointing out a position never indicated by the experiementer) errors. The number of errors increased when a concurrent task was introduced (Experiment 1) and it was affected by different patterns of matrices (Experiment 2). In general, results show that elderly people have an impaired VSWM and produce a large number of errors due to inhibition failures. However, both the younger and the older adults' visuo-spatial working memory was affected by the presence of activated irrelevant information, the reduction of the available resources, and task constraints.

Adolescent↗
PubMed2004

Microarray analysis of gene expression on herbal glycoside recipes improving deficient ability of spatial learning memory in ischemic mice.

In order to reveal the mechanism of herbal glycoside recipes retrieving deficient ability of spatial learning memory in mice suffering from cerebral ischemia/reperfusion, a microarray system was used to analyze gene expression in those groups with increasing ability of spatial learning memory who were different from ischemic mice. In this work, we reported a comprehensive characterization of gene expression profiles of mouse hippocampus by the use of cDNA microarray system containing 1176 known genes in middle cerebral artery occlusion (MCAO) ischemic mice after treating with different dosage recipes of glycoside herbs (30, 90, and 270 mg/kg). The ability of spatial learning memory in ischemic mice was found to be decreased. The pathological process in ischemic mouse brain showed that a complex related to 100 genes' expression yielded 1.8-fold. Dose-dependent effects showed an improvement in the deficient ability and reduction in infarct volume when treated with glycoside recipes. Many genes (38-46) in expression were found greater than 1.8-fold in those effective recipes groups, including genes in cell cycle regulation, signal transduction, nerve system transcription factors, DNA binding protein, etc. Nine genes related to retrieving deficient ability of spatial learning memory treated with glycoside recipes were also found in this study. These results suggest that microarray analysis of gene expression might be useful for elucidating the mechanisms of pharmacological function of recipes.

14-3-3 Proteins↗
PubMed1993

Cholinergic modulation of spatial working memory of mice in radial maze performance: retention curve analysis.

Cholinergic modulation of the spatial working memory of mice was investigated in an eight-arm radial maze. The mice were trained to achieve a stable baseline level of performance, and the retention of spatial working memory was then examined by means of imposition of retention intervals of 45, 90, 180, and 360 min between choices four and five. The animals were removed from the apparatus during these intervals. The effects of oxotremorine (0.025-0.1 mg/kg, ip), physostigmine (0.025-0.1 mg/kg, ip), and scopolamine (0.1-0.4 mg/kg, ip) on the number of the correct responses after the various time intervals (5-8 choices) were studied. Mice received drug injections 30 min prior to the first four arm-choices before delay intervals (1-4 choices). The number of correct responses after the intervals decreased with the increased length of the retention interval. Oxotremorine and physostigmine exhibited dose-dependent stimulating effects of resistance to decreases in the number of correct responses, but scopolamine potentiated the decline in a dose-dependent manner. Significant interactions between the effects of cholinergic drugs and the length of retention over time were also observed. These observations indicate a cholinergic modulation of spatial working memory in mice engaged in radial maze performance, as assessed by means of retention curve analysis.

Animals↗
PubMed1995

Visuo-spatial working memory: structures and variables affecting a capacity measure.

The present paper examines the issue of the capacity of visuo-spatial working memory. A series of experiments test the hypothesis that two different components are critical in visuo-spatial working memory (passive store and active imagery operations), and, thereafter, attempt to specify the variables that affect the capacity of the passive store component. In the experiments, congenitally blind and sighted participants were asked to remember the spatial positions of target objects in two-dimensional matrices, with or without simultaneously performing a sequence of spatially-based imagery operations. We considered both the positions recall performance (the passive storage component) and the sequential imagery processing performance (the active processing component). We suggest that the two components of visuo-spatial working memory are independent. We also propose that both the number of relevant matrices and the number of target objects within each matrix affect the capacity of visuo-spatial working memory, with the latter factor possibly playing a greater role than the former one.

Adult↗
PubMed1996

Consequences of selective blockade of septal noradrenergic afferents on anxiety and spatial working memory performance in mice.

This experiment was designed to investigate the role of septal noradrenergic (NA) afferents in the control of anxiety and spatial working memory. To this end, C57Bl/6 mice were infused bilaterally into the lateral septal nuclei with 500 ng/0.2 microliter of BE 2254, a selective alpha 1 postsynaptic adrenoceptor antagonist. The consequences of this reversible treatment were evaluated 20 min later on the anxiety level measured in an elevated plus-maze and on spatial working memory, evaluated under four different conditions via the learning of a delayed nonmatching to place (DNMTP) rule achieved in an eight-arm radial maze. In these conditions, the BE 2254, as well as the saline-injected control group, showed an elevation of the anxiety level that may be the indirect expression of a nonspecific septal dysfunction induced by the vehicle injection rather than the normal behavioral response produced by the decrease of septal NA activity. This septal dysfunction also impaired spatial working memory but only when mnesic difficulty of the task is increased, suggesting that this impairment expresses a general memory deficit rather than a working memory deficit per se. A lack of spatial working memory deficits in BE 2254 or saline-injected animals was also observed in two other conditions of the behavioral protocol. However, when treatments were applied before the first exposure of animals to the radial maze (exploration session), only the group which received BE 2254 was impaired during the acquisition session for the rule performed 24 h later. This delayed perturbation seems to be linked, at this stage of the learning procedure, to the lack of NA-dependent processes taking place during the exploration session. Taken together, these data suggest that septal NA mechanisms are more essential at initial stage of this learning, when animals process new features of the situation, than during the expression of spatial working memory per se.

Adrenergic Fibers↗
PubMed2002

Spatial working memory in human extrastriate cortex.

The performance of spatial working memory tasks is known to evoke activity in a set of higher-order association areas, including the prefrontal cortex, posterior parietal cortex and the frontal and supplementary eye fields. Recent physiological studies in monkey have shown that memory-related activity also is found in extrastriate cortex [J. Neurophysiol. 84 (2000) 677]. We conducted functional magnetic resonance imaging studies to determine whether human extrastriate cortex contributes to the on-line maintenance of spatial information in an eye movement task. We found that performance of memory-guided saccades, as compared to visually guided saccades, elicited significant activation in two areas of extrastriate cortex: the posterior superior temporal sulcus (PST) and lateral occipitotemporal cortex (LOT). Both areas also were activated during the basic sensorimotor task of visually guided saccades as compared to fixation. We further determined that area LOT is close to but distinct from motion-sensitive area MT+. These findings demonstrate that areas PST and LOT, along with higher-level association cortex, help to encode and maintain spatial representations.

Adult↗
PubMed1996

Interference with rehearsal in spatial working memory in the absence of eye movements.

We have previously argued that rehearsal in spatial working memory is interfered with by spatial attention shifts rather than simply by movements to locations in space (Smyth & Scholey, 1994). It is possible, however, that the stimuli intended to induce attention shifts in our experiments also induced eye movements and interfered either with an overt eye movement rehearsal strategy or with a covert one. In the first experiment reported here, subjects fixated while they maintained a sequence of spatial items in memory before recalling them in order. Fixation did not affect recall, but auditory spatial stimuli presented during the interval did decrease performance, and it was further decreased if the stimuli were categorized as corning from the right or the left. A second experiment investigated the effects of auditory spatial stimuli to which no response was ever required and found that these did not interfere with performance, indicating that it is the spatial salience of targets that leads to interference. This interference from spatial input in the absence of any overt movement of the eyes or limbs is interpreted in terms of shifts of spatial attention or spatial monitoring, which Morris (1989) has suggested affects spatial encoding and which our findings suggest also affects reactivation in rehearsal.

Adult↗
PubMed2002

Excitotoxic lesions of the rhinal cortex in the baboon differentially affect visual recognition memory, habit memory and spatial executive functions.

To specify the functional role of the rhinal cortex, baboons with bilateral excitotoxic lesions of the rhinal cortex (RH group) were tested on a series of computerized memory and learning tasks. Preoperatively, they were trained to and then tested on a delayed nonmatching-to-sample (DNMS) task with trial-unique stimuli. Postoperatively, this visual recognition memory task was given twice. As compared to a sham-operated group, the RH group showed good retention of rule learning and were unimpaired on the Delay memory subtest. Performance on the List Length memory subtest was, however, severely impaired at both postoperative evaluations, with a significant negative correlation between cognitive performance and neuronal loss in rhinal areas. Visual habit memory and spatial working memory were assessed postoperatively only, using a concurrent discrimination learning task and both a delayed-response task (with a two- and four-location choice) and a delayed alternation task, respectively. The RH group was unimpaired on the first two tasks and was even faster than the controls in learning the delayed-response task with four locations. Finally, most RH baboons failed to learn the delayed alternation task within the limits of testing. These results indicate that neuronal loss in the rhinal cortex is sufficient to impair visual recognition memory, and extend the implication of this area to spatial executive functions. Furthermore, the observation of impaired recognition memory and executive processes with preserved procedural memory and retrograde memory suggests that damage to the rhinal cortex probably participates in the cognitive deficits typical of the early stages of Alzheimer's disease.

Animals↗