Spatial Memory Demands Research Articles

Spatial memory demands modulate shape representations

Spatial memory demands modulate shape representations

Distraction of Counting by the Meaning of Background Speech: Are Spatial Memory Demands a Prerequisite?

SummaryThis paper reexamines the effects of background speech on counting. Previous studies have shown that background sound disrupts counting in comparison with silence, but the magnitude of disruption is no larger for spoken numbers compared with that for non‐number speech (there is no effect of the meaning of background speech). The typical task used previously has been to count the number of sequentially presented visual events. We replicated the general finding in Experiment 1—that there is no effect of the meaning of background speech—in the context of the classic sequence counting task. In Experiment 2, the task was changed by having to‐be‐counted dots presented simultaneously and randomly across the visual field. Here, an effect attributable to the meaning of background speech emerged. Background speech that is similar in meaning to the focal task process contributes to the magnitude of disruption, but apparently only when spatial memory processes are a task prerequisite. Copyright © 2015 John Wiley & Sons, Ltd.

When 2 is Better Than 1 + 1

Little is known about older spousal dyads’ collaborative problem solving. Although typically collaborating dyads perform worse than nominal dyads in other dyadic cognition tasks, we assumed that older couples might profit from collaboration in a highly demanding problem-solving task requiring the sequential and complementary use of spatial memory and reasoning abilities. In this paper, we examine whether older couples profit from the dyadic situation on a computer-based problem-solving task that can most likely be optimally solved when dyads manage to distribute responsibilities between the spatial memory demands and the reasoning demands of the task. In 50 married couples consisting of N = 100 older individuals (M = 67.3 years, SD = 4.9), we tested the hypothesis that compared to their own individual performance, compared to repeated individual performance of a control group (N = 41, M = 66.0 years, SD = 3.8), and compared to nominal pairs (same 100 participants as in the experimental group), older couples would show the best performance on the task. The comparison of individual versus dyadic problem-solving performance demonstrates that dyads consisting of old spouses outperform old individuals as well as nominal pairs on the problem-solving task. Our results suggest that older familiar dyads are expert collaborators whose collaborative expertise might be able to overcome individual deficits in problem-solving skills through dyadic cognition.

Brain tissue oxygen amperometry in behaving rats demonstrates functional dissociation of dorsal and ventral hippocampus during spatial processing and anxiety

Traditionally, the function of the hippocampus (HPC) has been viewed in unitary terms, but there is growing evidence that the HPC is functionally differentiated along its septotemporal axis. Lesion studies in rodents and functional brain imaging in humans suggest a preferential role for the septal HPC in spatial learning and a preferential role for the temporal HPC in anxiety. To better enable cross-species comparison, we present an in vivo amperometric technique that measures changes in brain tissue oxygen at high temporal resolution in freely-moving rats. We recorded simultaneously from the dorsal (septal; dHPC) and ventral (temporal; vHPC) HPC during two anxiety tasks and two spatial tasks on the radial maze. We found a double-dissociation of function in the HPC, with increased vHPC signals during anxiety and increased dHPC signals during spatial processing. In addition, dHPC signals were modulated by spatial memory demands. These results add a new dimension to the growing consensus for a differentiation of HPC function, and highlight tissue oxygen amperometry as a valuable tool to aid translation between animal and human research.

Evaluation of spatial memory of C57BL/6J and CD1 mice in the Barnes maze, the Multiple T-maze and in the Morris water maze

Evaluation of spatial learning and memory is mainly carried out using the Morris water maze as a single paradigm. We intended to test whether mice in the Barnes maze and Multiple T-maze would lead to comparable results and to test two individual mouse strains with different anxiety levels. C57BL/6J and CD1 male mice were used in the experiments. During the acquisition phase, learning was measured using parameters latency, path length, errors in the BM and correct decisions in MTM. Mice were trained for 4 days and probe trials were performed on days 5 and 12. Latencies reduction over the training period indicated that both strains learned all tasks. During retention phase at days 5 and 12 C57BL/6J performed the Barnes maze and Multiple T-maze task better than CD1 mice while CD1 performed better than C57BL/6J in the Morris water maze. In the BM at day 12, C57BL/6J kept the level of visits to target observed at day 5 whereas CD1 performed worse. Strain- and task-dependent differences were observed using the three mazes. Therefore, fair evaluation of spatial memory demands application of (at least) two different test systems, a water- and a land maze. Different anxiety-related behaviour as well as stress-responses in the strains used may help to interpret the findings reported and again may propose the use of at least two mouse strains when robust evaluation of spatial memory is considered.

Sex differences in the effects of captivity on hippocampus size in brown-headed cowbirds (Molothrus ater obscurus).

In brood parasitic cowbirds, hippocampus (Hp) size is correlated with environmental spatial memory demands. Searching for host nests is the presumed causal factor influencing cowbird Hp size, because Hp volumes vary across species, sexes, and seasons according to nest-searching participation. Brown-headed cowbirds have female-only nest searching and, at least in the eastern subspecies, a larger Hp in females than in males, suggesting that nest searching influences cowbird Hp size. We predicted that female brown-headed cowbirds housed in aviaries lacking host nests would have a smaller Hp than wild-caught females whereas males would be unaffected. We found that the Hp was smaller in captive females, but not males, compared to their wild-caught counterparts. This did not appear to be due to general effects of an impoverished environment on all brain regions. Our results imply that interruption of nest searching in cowbirds prevents seasonal increase in Hp size in females. Future studies should isolate which behavioral differences between wild and captive birds contributed to captivity-induced changes in Hp volume in females while not affecting males.

Seasonal changes of hippocampus volume in parasitic cowbirds

Avian brain plasticity has been demonstrated by seasonal variations in neuroanatomy correlated with changes in singing and hoarding behaviour. We report a new instance of plasticity. Brood parasitism in South American cowbirds involves memory for location of hosts' nests, and is associated with an enlarged hippocampus relative to telencephalon size. This effect holds between sexes and species during the breeding season. We report that for two parasitic species, relative hippocampal volume is smaller during the non-breeding than the breeding season, and that sexual dimorphism present in summer in one of the species is not found in winter. These results support the hypothesis that the avian hippocampal formation shows neuroanatomical plasticity associated with seasonal changes in spatial memory demands.