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At least 847 records · Page 47Linked to original sources
PubMed2000

Vitamin E supplementation prevents spatial learning deficits and dendritic alterations in aged apolipoprotein E-deficient mice.

Recent studies have suggested that altered function of apolipoprotein E might lead to Alzheimer's disease via oxidative stress. In this context, the objective of this study was to determine if antioxidative treatment with vitamin E was neuroprotective in apolipoprotein E-deficient mice. For this purpose, 1-month-old control and apolipoprotein E-deficient mice received dietary vitamin E for 12 months. We showed that, compared to apolipoprotein E-deficient mice who received a regular diet, mice treated with vitamin E displayed a significantly improved behavioural performance in the Morris water maze. This improved performance was associated with preservation of the dendritic structure in vitamin E-treated apolipoprotein E-deficient mice. In addition, whilst untreated apolipoprotein E-deficient mice displayed increased levels of lipid peroxidation and glutathione, vitamin E-treated mice showed near normal levels of both lipid peroxidation and glutathione. These results support the contention that vitamin E prevents the age-related neurodegenerative alterations in apolipoprotein E-deficient mice.

Animals↗
PubMed1993

[The effects of lesions in the medial septal area to spatial learning in rats].

The effects of a disruption of the septo-hippocampal cholinergic system on learning behavior in rats were investigated. Learning was evaluated using an eight-arm radial maze task before and after electrolytic lesions in the medial septal area (MSA). The normal control rats gradually improved the task performance with an increase of trials and also developed a response strategy to select the arm adjacent to the one currently visited. The rats without any preoperative learning before the operation of MSA showed a persistent disturbance of task performance and the generation and development of the response strategy. On the other hand, rats which had performed learning trials before the operation of MSA only showed a transient disturbance of task performance which then rapidly recovered to the control level. The response strategy was also altered but immediately returned to the control pattern in this rat group. Acetylcholine esterase (AChE) activity was persistently depleted in the hippocampus by the MSA lesion. These results indicate that preoperative learning has a significant contribution to the task performance and the generation and development of the response strategy in rats with MSA lesions and that the septo-hippocampal cholinergic system plays an important role in this generation and development of the response strategy.

Acetylcholine↗
PubMed1995

Spatial and non-spatial learning in the rat following lesions to the nucleus locus coeruleus.

The present experiment examined the effects of unilateral or bilateral locus coeruleus lesions on general activity, acquisition of a non-monotonic serial pattern (14-0-3-7 food pellets, respectively), and response learning acquisition in a Greek cross version of the Morris water maze. Sham-operated control rats were capable of tracking the elements of the serial pattern while rats with a unilateral locus coeruleus lesion were moderately impaired, and those with bilateral locus coeruleus lesions were severely impaired. A similar pattern of working memory deficits emerged in an analysis of the response-learning data in the Greek cross. The results are discussed in terms of the current understanding of norepinephrine and the locus coeruleus in learning and memory processes.

Analysis of Variance↗
PubMed1995

The effects of D-cycloserine and MK-801 on the performance of rats in two spatial learning and memory tasks.

The present study was undertaken to investigate the effects of modulation of the N-methyl-D-aspartate (NMDA) receptor on learning and memory. Thus, the performance of rats treated with D-cycloserine, a partial agonist at the glycine recognition site of the NMDA receptor complex, and MK-801, a noncompetitive NMDA receptor antagonist, either alone or concurrently were assessed in radial arm maze and water maze tasks. Administration of MK-801 (0.1 mg/kg, i.p.) impaired acquisition in the water maze (increased escape latency and distance) and working memory in the radial arm maze (increased re-entries) in rats. Moreover, in the radial arm maze, MK-801 disrupted locomotion (increased latencies and decreased arm entries per minute) and impaired the acquisition of reference memory (increased number of errors) performance of rats. D-Cycloserine (0.03, 0.3, 1.0, 3.0, 10 mg/kg, i.p.) had no effects on acquisition or memory performance of control or MK-801-treated rats in either of these tasks. However, D-cycloserine (0.03, 0.3, 3.0 mg/kg) reversed the MK-801-induced disruption in locomotion. Furthermore, 3.0 mg/kg D-cycloserine increased behavioral activity and also decreased the time needed to complete the task in control animals. To conclude, our results suggest that the consequences of NMDA receptor modulation on learning and memory processes and sensorimotor functions may be functionally different or have distinct anatomical locations.

Adaptation, Psychological↗
PubMed2004

Corticohippocampal contributions to spatial and contextual learning.

Spatial and contextual learning are considered to be dependent on the hippocampus, but the extent to which other structures in the medial temporal lobe memory system support these functions is not well understood. This study examined the effects of individual and combined lesions of the perirhinal, postrhinal, and entorhinal cortices on spatial and contextual learning. Lesioned subjects were consistently impaired on measures of contextual fear learning and consistently unimpaired on spatial learning in the Morris water maze. Neurotoxic lesions of perirhinal or postrhinal cortex that were previously shown to impair contextual fear conditioning (Bucci et al., 2000) or contextual discrimination (Bucci et al., 2002) caused little or no impairment in place learning and incidental learning in the water maze. Combined lesions of perirhinal plus lateral entorhinal or postrhinal plus medial entorhinal cortices resulted in deficits in acquisition of contextual discrimination but had no effect on place learning in the water maze. Finally, a parahippocampal lesion comprising combined neurotoxic damage to perirhinal, postrhinal, and entorhinal cortices resulted in profound impairment in acquisition of a standard passive avoidance task but failed to impair place learning. In the same experiment, rats with hippocampal lesions were impaired in spatial navigation. These results indicate that tasks requiring the association between context and an aversive stimulus depend on corticohippocampal circuitry, whereas place learning in the water maze can be accomplished without the full complement of highly processed information from the cortical regions surrounding the hippocampus. The evidence that different brain systems underlie spatial navigation and contextual learning has implications for research on memory when parahippocampal regions are involved.

Animals↗
PubMed1997

Age-related differences in an ecologically based study of route learning.

Spatial learning abilities in younger adults and in healthy elderly adults were examined in 2 tasks. In the first task, participants were tested for their ability to recall relevant route information as well as to recognize and to order temporally landmark information observed along the route. Older participants had relatively greater difficulty retracing the route and temporospatially ordering landmarks but were equally good at recognition of landmarks occurring on the route. In the second task, participants memorized a 2-dimensional representation of a route and subsequently navigated the route from memory. Older participants had greater difficulty memorizing the route and navigating it. Errors of omission, commission, wrong, and forced choice were analyzed. Group differences in the pattern of errors differed by task.

Adolescent↗
PubMedDate not supplied

Emergence of a cue strategy preference on the water maze task in aged C57B6 x SJL F1 hybrid mice.

The effects of age on cue learning, spatial reference memory, and strategy preference were assessed in B6 x SJL F1 mice by using the Morris water maze. This mouse strain is of particular interest because it is the background strain for a common transgenic model of Alzheimer's disease, the Tg2576 mouse, which develops plaques and other neurobiological markers of pathology beginning at 8 mo and increasing in severity with advanced age. In the current study, 12- and 23-mo-old C57B6 x SJL F1 mice were serially trained in cue and place versions of the Morris water maze task. At the completion of training, mice received a strategy probe test in which place (hidden) and cue (visible) strategies were in competition. Cue and spatial learning ability was maintained between 12 and 23 mo of age; however, on the strategy preference probe test, the 23-mo-old mice exhibited a significant bias toward the selection of a cue strategy. There was no relationship between strategy preference in the probe test and spatial learning ability, but the 23-mo-old mice did exhibit a strong trend toward shorter latencies during visible platform training, possibly reflecting the enhanced function of striatal-based neural systems in aging. These data demonstrate that 23-mo-old C57B6 x SJL F1 mice are capable of effective place learning, but if a place strategy is pitted against the use of a cue strategy, the use of a cue strategy predominates in the aged mice. The strategy preference observed here may reflect an emergence of differential processing in underlying brain circuitry with age in the B6 x SJL F1 mouse strain.

Aging↗
PubMed1997

Spatial training in a complex environment and isolation alter the spine distribution differently in rat CA1 pyramidal cells.

The hippocampus is critically involved in spatial learning. Spatial training in adult rats, which improved their spatial learning ability, increased the number of excitatory hippocampal CA1 spine synapses on basal dendrites as compared with either isolated or standardly housed animals (Moser et al. [1994] Proc. Natl. Acad. Sci. USA 91:12673-12675). In this article, we report that spine synapses on oblique apical dendritic branches do not increase in density or number after the same type of training. When examining the variability of the spine density on basal CA1 dendrites by using variance component analysis, the variance associated with the cells was twice as large in all three groups as that coupled to the rats. Analysis of the spine density plots shows that the enhanced spine density after spatial training is found in most cells recorded from the trained group but that a small subset of CA1 neurones are particularly well supplied with spines. The trained group had a significant right-skewed tail of the spine distribution, i.e., training caused high spine density to occur in a small subset of dendritic segments. Conversely, the isolated group had a significant left-skewed spine distribution, indicating that some of the dendritic segments were undersupplied with spines, whereas the paired group displayed no asymmetry.

Animals↗
PubMed2026

DPAS-Graph: adaptive spatial-feature relation learning for spatial RNA-to-protein prediction and virtual protein profiling.

Paired spatial multi-omics provides a supervised basis for learning RNA-protein correspondence in situ, but predicting protein abundance from spatial transcriptomic data alone remains challenging across tissue contexts and protein panels. Here, we present DPAS-Graph, an adaptive relation-learning framework for spatial RNA-to-protein prediction. Rather than directly merging spatial proximity and transcriptomic similarity as fixed graph priors, DPAS-Graph represents them as two relation channels on a shared edge support and updates their contributions during representation learning for protein prediction. Its Niche-Coupled Field Encoder combines layer-wise edge-relation modeling, intra-branch relation refinement, and cross-branch residual correction to learn spot representations for protein abundance prediction. In a leave-one-dataset-out benchmark across seven paired spatial multi-omics datasets, DPAS-Graph achieved lower aggregate prediction errors and improved spot-level agreement of protein expression profiles, with gains mainly reflected in error-based metrics and PCC-Spot. Spatial autocorrelation and protein-derived domain agreement analyses were further used to characterize the spatial behavior of the predicted protein maps. When applied to external RNA-only spatial sections, DPAS-Graph generated qualitatively interpretable marker-level virtual protein maps, illustrating its use as a complementary tool for protein-level interpretation of transcriptomics-only spatial data.

RNA↗
PubMed2006

From movement to transitivity: the role of hippocampal parallel maps in configural learning.

Whether spatial learning is a special case of configural or relational learning, or whether abstract principles evolved from the concrete need to navigate in space, is a question of long-standing debate. The parallel map theory of hippocampal function offers a resolution of the debate by redefining 'spatial learning' as two parallel, geometric processes, Euclidean metric and topological. Moreover, these processes are subserved by independent hippocampal subfields that underlie two ways of representing space, the bearing and the sketch map. It is possible that configural and relational learning, like spatial learning, should also be distinguished in this way. Transitive inference, requiring the construction of a value gradient, could be analyzed as a Euclidean metric problem. In contrast, transverse patterning could be seen as a topological analysis of the relationships among discrete objects. If this interpretation is correct, lesions to the primary bearing map structure (dentate gyrus) should impair transitivity while lesions to the primary sketch map structure (CA1) should impair transverse patterning and similar topological tasks. Recent results from diverse species and tasks lend support to these predictions, suggesting that the hippocampus not only creates parallel maps but uses these maps to solve more abstract configural or relational problems.

Animals↗
PubMed2003

Consolidation during sleep of perceptual learning of spoken language.

Memory consolidation resulting from sleep has been seen broadly: in verbal list learning, spatial learning, and skill acquisition in visual and motor tasks. These tasks do not generalize across spatial locations or motor sequences, or to different stimuli in the same location. Although episodic rote learning constitutes a large part of any organism's learning, generalization is a hallmark of adaptive behaviour. In speech, the same phoneme often has different acoustic patterns depending on context. Training on a small set of words improves performance on novel words using the same phonemes but with different acoustic patterns, demonstrating perceptual generalization. Here we show a role of sleep in the consolidation of a naturalistic spoken-language learning task that produces generalization of phonological categories across different acoustic patterns. Recognition performance immediately after training showed a significant improvement that subsequently degraded over the span of a day's retention interval, but completely recovered following sleep. Thus, sleep facilitates the recovery and subsequent retention of material learned opportunistically at any time throughout the day. Performance recovery indicates that representations and mappings associated with generalization are refined and stabilized during sleep.

Humans↗
PubMed2002

Frontal cortex atrophy predicts cognitive impairment in multiple sclerosis.

The association between regional measures of cortical atrophy and neuropsychological (NP) dysfunction was studied in 35 multiple sclerosis (MS) patients. Patients underwent neurological examination, MRI, and NP testing. Blind quantitative MRI analysis yielded total T(2) lesion area (TLA) and third ventricle width (3VW). Cortical atrophy, rated by blind visual inspection, was more extensive in superior frontal and parietal cortices than in other regions. No MRI measures were correlated with depression scores. TLA and 3VW were significantly correlated with each NP test. Cortical atrophy measures for bilateral superior frontal cortex were retained in regression models predicting impairments in verbal learning, spatial learning, attention, and conceptual reasoning. The authors conclude that cerebral atrophy predicts NP impairment while accounting for the influence of TLA or 3VW. Regions of cortex most susceptible to atrophic and cognitive changes in MS are the right and left superior frontal lobes.

Adult↗
PubMed1997

Measures of spatial memory and routes of learning.

Spatial memory was investigated in two experiments by direct methods. Methods included scaling of distances, estimation of bearings, and positioning of objects. Participants learned small-scale configurations under different orders of presentation. In Exp. 1, routes included a shortest path, i.e., a traveling salesman solution, a random sequence, and a path that maximized distances. In Exp. 2, spatial and temporal distances varied independently. It was analyzed whether the different methods yielded the same information. For bearing estimates a new scaling procedure was developed. Computations resulted in two-dimensional Euclidean solutions in close correspondence with the stimulus configuration. In addition, solutions showed an effect of temporal conditions of learning.

Attention↗