SEARCH · Search PubMed

Results for “Spatial Learning”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources

PubMed2003

Internal connectivity of the homing pigeon (Columba livia) hippocampal formation: an anterograde and retrograde tracer study.

The avian hippocampal formation (HF) is a structure necessary for learning and remembering aspects of environmental space. Therefore, understanding the connections between different HF regions is important for determining how spatial learning processes are organized within the avian brain. The prevailing feed-forward, trisynaptic internal connectivity of the mammalian hippocampus and its importance for cognition have been well described, but the internal connectivity of the avian HF has only recently been investigated. To examine further the connectivity within the avian HF, small amounts of cholera toxin subunit B, primarily a retrograde tracer (n = 15), or biotinylated dextran amine, primarily an anterograde tracer (n = 10), were injected into localized regions of the HF. Examination of the immunohistochemically labeled tissue showed projections from extrinsic sensory processing areas into dorsolateral HF and the dorsal portion of the dorsomedial HF (DMd). DMd in turn projected into the medial (VM) and lateral (VL) ventral cell layers. A projection from VM into VL was found, and together these areas and DM provided input into the contralateral ventral cell layers. Ipsilaterally, a ventral portion of dorsomedial HF (DMv) received input from VL and VM. From DMv, projections exited HF laterally. The highlighted projections formed a discernible feed-forward processing network through the avian HF that resembled the trisynaptic circuit of the mammalian HF.

Animals↗

PubMed1992

Long-Evans and Sprague-Dawley rats differ in their spatial navigation performance during ontogeny and at maturity.

The Morris maze has become a popular method for the assessment of spatial navigation. However, its use to study the development of spatial abilities has been limited to pigmented rats. Thus, the aim of the present study was to compare albino Sprague-Dawley and pigmented Long-Evans rats using this test during postnatal Days 20 through 27, and Day 90. It was found that Long-Evans rats showed significantly shorter escape latencies and swim distances than the Sprague-Dawley rats on Days 20-25 but not on Days 26-27. However, when tested at Day 90, the Long-Evans rats again showed more rapid location of the escape platform and shorter swim distances than the Sprague-Dawley rats. Probe trial analysis (platform removed) indicated that Long-Evans rats were generally more accurate in their localization of the former platform location than Sprague-Dawley rats. In a second experiment in which 21-day-old rats of both strains were tested in a proximal-cue version of the maze, the question of whether this performance difference might have related to visuo-perceptual differences was considered. Since no dissimilarity in performance was observed, a spatial-learning difference between the two strains would seem best able to explain the preceding data.

Animals↗

PubMed2006

Contribution of a single CA3 neuron to network synchrony.

Oscillations at theta (3-8 Hz) and gamma (30-80 Hz) frequencies co-occur during arousal, exploration, and rapid eye movement sleep and relate to information processing underlying learning and memory within neuronal networks. In hippocampus, gamma and theta frequency oscillations are associated with modification of synaptic weights, spatial learning, and short-term memory. These oscillations are referred to as network phenomena and, thereby, the role of single neuron oscillations in the generation of neuronal networks remains unclear. We report that an individual CA3 pyramidal cell can activate the CA1 neuronal network in vivo in rat hippocampus using electrical stimulations with simultaneous intracellular gamma and extracellular theta and slow (0.5-1 Hz) frequencies. These results suggest that an individual pyramidal cell can contribute to self-organization of a neuronal small-scale network.

Animals↗

PubMed1997

Effects of maternal oral administration of monosodium glutamate at a late stage of pregnancy on developing mouse fetal brain.

Monosodium glutamate (MSG) was shown to penetrate placental barrier and to distribute to embryonic tissues using [3H]glutamic acid ([3H]Glu) as a tracer. However, the distribution is not even; the uptake of MSG in the fetal brain was twice as great as that in the maternal brain in Kunming mice. Other maternal mice were given per os MSG (2.5 mg/g or 4.0 mg/g body weight) at 17-21 days of pregnancy, and their offspring behaviors studied. The results showed that maternal oral administration of MSG at a late stage of pregnancy decreased the threshold of convulsion in the litters at 10 days of age. Y-maze discrimination learning was significantly impaired in the 60-day-old filial mice. On the other hand, no significant difference in spatial learning or tail flick latency was measured between the experimental animals and the controls. The filial mice of MSG-treated mothers could either not grasp a rope tightly, or grasped the rope tightly but could not crawl along the rope at the beginning of the training. However, such mice, after training, could grasp and crawl along the rope as well as controls. Obvious neuronal damage was not detected in the periventricular organs or the hypothalamus under a light microscope. The rate of weight gain for experimental animals was greater than for controls throughout the period from 20 to 90 days. Mating of treated males with treated females resulted in pregnancies and normal offspring, indicating that oral administration of MSG at a late stage of pregnancy did not affected the reproductive capacity of the offspring. The possible differences and relationship between MSG-induced damage to developing human and rodent brain are discussed.

Administration, Oral↗

PubMed1997

The functional outcome of shunting H-Tx rat pups at different ages.

"Normal", untreated hydrocephalic and CSF shunted hydrocephalic Texas (H-Tx) rat pups at different ages and Sprague-Dawley controls were tested for spatial learning and memory acquisition in an 8-arm radial maze. Shunting 5 day old hydrocephalic pups improved their performance to the level of that of "normal" litter-mates, whereas shunting at 10 days produced no improvement, and the performance of these animals was comparable to that of the untreated hydrocephalics. None of the H-Tx rats, whether treated, untreated or "normal", performed as well as the Sprague-Dawley controls. These findings suggest that shunting prior to skull plate fusion, which occurs at approximately the tenth post-natal day, is capable of protecting brain function involved in memory and learning. The poor functional scores achieved by the "normal" as well as the treated and untreated H-Tx animals compared to the control Sprague-Dawleys, raises the possibility that the H-Tx rat has brain deficits in addition to those caused by hydrocephalus.

Aging↗

PubMed2003

Absence of overshadowing and blocking between landmarks and the geometric cues provided by the shape of a test arena.

In three experiments rats were required to escape from a pool of water by swimming to a submerged platform. The position of the platform was determined by the shape of the pool, which was either rectangular or triangular. A landmark that was located on the surface of the pool near the platform failed to overshadow (Experiment 1) or block (Experiment 2) learning about the position of the platform with reference to the shape of the pool. Experiment 3 revealed a similar outcome with cues outside the pool, which could be used, in addition to the shape of the pool, to identify the location of the platform. These findings imply that theories of learning that assume that stimuli must compete with each other for the control that they acquire may not apply to spatial learning based on the shape of the environment.

Association Learning↗

PubMed2005

Vestibular loss causes hippocampal atrophy and impaired spatial memory in humans.

The human hippocampal formation plays a crucial role in various aspects of memory processing. Most literature on the human hippocampus stresses its non-spatial memory functions, but older work in rodents and some other species emphasized the role of the hippocampus in spatial learning and memory as well. A few human studies also point to a direct relation between hippocampal size, navigation and spatial memory. Conversely, the importance of the vestibular system for navigation and spatial memory was until now convincingly demonstrated only in animals. Using magnetic resonance imaging volumetry, we found that patients (n = 10) with acquired chronic bilateral vestibular loss (BVL) develop a significant selective atrophy of the hippocampus (16.9% decrease relative to controls). When tested with a virtual variant (on a PC) of the Morris water task these patients exhibited significant spatial memory and navigation deficits that closely matched the pattern of hippocampal atrophy. These spatial memory deficits were not associated with general memory deficits. The current data on BVL patients and bilateral hippocampal atrophy revive the idea that a major--and probably phylogenetically ancient--function of the archicortical hippocampal tissue is still evident in spatial aspects of memory processing for navigation. Furthermore, these data demonstrate for the first time in humans that spatial navigation critically depends on preserved vestibular function, even when the subjects are stationary, e.g. without any actual vestibular or somatosensory stimulation.

Adult↗

PubMed1992

Noradrenaline depletion blocks behavioral sparing and alters cortical morphogenesis after neonatal frontal cortex damage in rats.

The possibility that cortical noradrenaline (NA) is necessary for sparing of function that occurs after neonatal frontal cortex damage was examined. Spatial localization by rats with frontal cortex damage on postnatal day 7 (P7) was better than that by rats with similar damage sustained as adults. The sparing was abolished in rats depleted of cortical NA by means of neonatal 6-hydroxydopamine (6HDA) administration. The blockade of sparing in the P7 frontal operates was associated with a smaller brain, thinner cortex, and reduced cortical dendritic branching relative to saline-treated P7 frontal operates. NA depletion alone in unoperated rats did not affect spatial learning but did reduce brain size and dendritic branching. Rats with frontal lesions on P4 did not show sparing of spatial localization, and 6HDA administration had no additional behavioral effect. Overall, these data are consistent with the notion that NA has some general function in maintaining some forms of plasticity in posterior cortex.

Animals↗

PubMed2004

The geometric module in the rat: independence of shape and feature learning in a food finding task.

Rats found food in a rectangular enclosure in three experiments testing how learning about a distinctive feature near a goal interacts with learning based on the geometry of an enclosure. Rats trained to follow a feature in square and triangular enclosures and to use geometry in the rectangle followed the feature when it was in the rectangle (Experiment 1). Rats trained with the feature in a geometrically consistent corner of the rectangle learned about both geometry and the feature (Experiment 2). Training with the feature in the square did not block learning of geometry when both predicted the location of food in the rectangle (Experiment 3). The "geometric module" (Cheng, 1986) may have a special status in spatial learning.

Animals↗

PubMed1994

Bilateral destruction of the ventrolateral orbital cortex produces allocentric but not egocentric spatial deficits in rats.

Previous studies have implicated the ventrolateral orbital cortex (VLO) in spatial attention and orientation. Unilateral destruction of the VLO has been found to produce severe multimodal neglect to unilateral stimulation which is qualitatively quite similar to that found following unilateral destruction of either the medial agranular or posterior parietal cortices. A series of anatomical studies have shown that the VLO is reciprocally interconnected with both the medial agranular cortex and the posterior parietal cortex, which are involved in egocentric and allocentric spatial processing respectively. However, the role of the VLO in either egocentric or allocentric spatial processing has never been directly examined. The present study directly examined the role of the VLO in spatial learning by examining the effects of bilateral VLO destruction on performance in both egocentric (adjacent-arm maze task) and allocentric (cheeseboard task) spatial tasks. Subjects in either the cheese board task or the adjacent arm maze were given presurgical maze training and then were assigned to one of three surgical groups: a bilateral VLO group, a lesion control group which received bilateral destruction of the laterally adjacent lateral orbital cortex which has a quite different pattern of connectivity than the VLO, or a sham operated control group. The results indicated that the VLO operates were significantly impaired in the cheeseboard task (allocentric task) relative to controls, but displayed no deficits in the adjacent-arm maze (egocentric task), a pattern of results similar to those found for the posterior parietal cortex. The results of the present study strongly support the contention that the VLO is a component of the cortical circuitry for spatial processing in rodents.

Animals↗

PubMed1999

Global ischemia and behavioural deficits.

Global cerebral ischemia in rodents is an established model in experimental research on cerebral ischemia which is characterized morphologically by a selective neuronal damage in the hippocampus, striatum and cortex. Using this model many studies have been performed to examine the pathophysiology of ischemic neuronal damage. Based upon these results it has been analysed whether substances which interact with the pathophysiological processes reduce the ischemic neuronal damage. Besides the morphological changes global ischemia leads to functional changes which can be assessed by behavioural studies. The Morris water maze examines the animals' abilities to learn, remember and go to a place in space only defined by its position relative to distal extramaze cues. In this test ischemic animals display a deficit in spatial learning as revealed by an increase in latency and in swim distance in the escape trials and a deficit in spatial memory as shown by reduced quadrant time and crossings over the former platform position during the probe trial. In several studies it could be demonstrated that neuroprotective strategies which reduce ischemic neuronal damage also attenuate or even completely prevent the ischemia-induced behavioural deficits in the water maze. Transplantation of fetal tissue which can also be used to achieve morphological recovery following global ischemia results in an amelioration of the ischemia-induced deficit. Thus, the water maze can clearly show that transplanted tissue can be functionally relevant. Data from the water maze seem to be a valuable completion to morphology which is especially important with respect to the relevance of experimental studies for clinical trials.

Animals↗

PubMed2001

Hyperactivity, neuromotor defects, and impaired learning and memory in a mouse model for metachromatic leukodystrophy.

Deficiency of arylsulfatase A (ASA) causes the autosomal recessive lipidosis, metachromatic leukodystrophy (MLD). Performance on tests of activity, motor ability and learning/memory was assessed in ASA-deficient mice and normal controls at 3, 6 and 12 months-of-age. ASA-deficient mice showed consistently increased cage activity in all age groups, whereas open field activity was increased only in the 3-month-old group. Motor coordination and equilibrium, as tested in the rotarod test, was impaired in 12-month-old ASA-deficient mice. Passive avoidance learning was tested in the step-through box. Performance on this test was impaired in the 12-month-old group only. Spatial learning and memory abilities were tested in the Morris water maze. Six-month-old ASA-deficient mice displayed slightly impaired hidden-platform acquisition performance. Three-month-old animals, on the other hand, did not show any acquisition or retention defect on this task, notwithstanding significantly reduced swimming velocity. Acquisition training, both in the hidden- and visible-platform conditions of the Morris water maze, and retention performance during the probe trials were impaired in 12-month-old ASA-deficient mice. The hyperactivity, motor incoordination and slowing, and the age-related learning/memory defects, reported here in ASA-deficient mice, may relate to the decline of neuromotor and cognitive functions in MLD patients, and could be used as correlative or outcome measures in the study of MLD pathophysiology and treatment.

Age Factors↗

PubMed2005

Persisting behavioral consequences of prenatal domoic acid exposure in rats.

To investigate the behavioral effects of prenatal exposure to the marine toxin domoic acid, pregnant female rats were injected subcutaneously with 0, 0.3, 0.6, or 1.2 mg/kg of domoic acid on gestational day 13. The offspring were then run through a behavioral testing battery to determine the developmental effects of the toxin on spontaneous alternation in the T-maze, on locomotor activity in the Figure-8 maze, and on working memory in the 8-arm radial maze. In the T-maze, no significant domoic acid induced differences were seen on spontaneous alternation, but there were significant domoic acid effects on latency. Prenatal domoic acid exposure caused a dose-related increase in response latency in the second spontaneous alternation test. There was also a significant domoic acid effect seen in the 1-h long Figure-8 maze test. Locomotor activity measured in the Figure-8 maze detected a persisting effect of the 1.2 mg/kg domoic acid dose, which significantly increased the rate of habituation over the activity test session. This was characterized by higher initial activity followed by greater decline in activity. In the radial-arm maze the control vehicle treated rats showed the normal sex-related difference in spatial learning and memory with males outperforming females. Developmental domoic acid exposure decreased this effect such that the normal sex difference in spatial memory was not seen with the 1.2 mg/kg domoic acid dose. The rats of both sexes with a history of prenatal domoic acid exposure showed increased susceptibility to the amnestic effects of the muscarinic acetylcholine scopolamine, suggesting that they had less functional reserve with which to solve the radial-arm maze memory task. This study demonstrates persisting neurobehavioral effects of acute prenatal exposure to domoic acid at doses that do not cause overt clinical signs of toxicity.

Animals↗

PubMed1997

Place cells and place navigation.

The assumption that hippocampal place cells (PCs) form the neural substrate of cognitive maps can be experimentally tested by comparing the effect of experimental interventions on PC activity and place navigation. Conditions that interfere with place navigation (darkness, cholinergic blockade) but leave PC activity unaffected obviously disrupt spatial memory at a post-PC level. Situations creating a conflict between egocentric and allocentric orientation (place navigation in the Morris water maze filled with slowly rotating water) slow down spatial learning. PC recording in rats searching food pellets in a rotating arena makes it possible to determine which firing fields are stable relative to the room (allocentrically dependent on sighted extramaze landmarks), to the surface of the arena (dependent on egocentric path integration mechanisms and intra-arena cues), or disappear during rotation. Such comparison is made possible by the computerized tracking system simultaneously displaying a rat's locomotion and the respective firing rate maps both in the room reference and arena reference frames. More severe conflict between allocentric and egocentric inputs is produced in the field clamp situation when the rat searching food in a ring-shaped arena is always returned by rotation of the arena to the same allocentric position. Ten-minute exposure to this condition caused subsequent disintegration or remapping of 70% PCs (n = 100). Simultaneous examination of PC activity and navigation is possible in the place avoidance task. A rat searching food in a stationary or rotating arena learns to avoid an allocentrically or egocentrically defined location where it receives mild electric footshock. In the place preference task the rat releases pellet delivery by entering an unmarked goal area and staying in it for a criterion time. Both tasks allow direct comparison of the spatial reference frames used by the PCs and by the behaving animal.

Animals↗

PubMed1993

The interaction of L-deprenyl and scopolamine on spatial learning/memory in rats.

L-Deprenyl, a specific MAO-B inhibitor, has been reported to improve learning/memory in some cognitive tests in aged rats. The present study investigated whether L-deprenyl could alleviate the spatial learning deficit induced by muscarinic blockade and aging in OFA rats. Scopolamine (0.25 mg/kg) impaired the acquisition of a water maze task in adult rats and increased their swimming speeds. L-Deprenyl (0.25 mg/kg, 14 days) had no effect on water maze performance in saline treated adult rats, but markedly alleviated the learning deficit induced by scopolamine and increased the time and distance of swimming in the training quadrant when the platform was removed (spatial probe trial). L-Deprenyl partly reduced the effect of scopolamine on speed of swimming. Nevertheless, administration of l-deprenyl (0.25 mg/kg, 14 days) had no effect on spatial learning/memory in aged rats. We suggest that the l-deprenyl-scopolamine interaction in the water maze test may be considered as a premise for further investigations of l-deprenyl as cognition enhancer.

Aging↗

PubMed2001

Ontogeny of spatial navigation in rats: a role for response requirements?

Three experiments investigated the role of response requirements in the Morris water maze for pre- and postweanling rats. Fischer-344N pups were required to locate a hidden platform using extramaze cues in a tank modified for the pups' immature response repertoire. Weanlings (20-22 days) displayed spatial learning in a pool 1/2 the size of the adults' (Experiment 1); by 26-28 days of age, probe performance was comparable to adults' on quadrant preference and platform-crossing measures. Preweanlings (17 days), in a pool 1/3 the original size, significantly reduced escape latencies and displayed quadrant preference and platform-crossing scores indicative of spatial navigation. These results suggest that despite its protracted postnatal development, the preweanling hippocampus allows neural integration of visual-spatial information; however, the capacity to demonstrate such learning is dependent on task parameters and the pup's response repertoire.

Age Factors↗

PubMed2006

Sex- and APOE isoform-dependent effects of radiation on cognitive function.

Clinical irradiation of the brain induces hippocampus-dependent cognitive impairments in some but not all individuals, suggesting the involvement of genetic risk factors. Deficiency of apolipoprotein E (APOE), which is important for the metabolism and redistribution of lipoproteins and cholesterol, increases behavioral impairments after irradiation, supporting a protective role for APOE against radiation-induced cognitive injury. Compared to APOE3, APOE4 increases while APOE2 decreases the risk of developing age-related cognitive decline and Alzheimer's disease, particularly in women. To determine the potential effects of APOE isoform and sex on radiation-induced cognitive impairments, we irradiated 2-month-old male and female APOE2, APOE3 and APOE4 mice and assessed their cognitive performance 3 months later. When hippocampus-dependent spatial learning and memory were assessed in the water maze, sham-irradiated female APOE2, APOE3 and APOE4 and irradiated female APOE2 mice showed spatial memory retention, but irradiated female APOE3 and APOE4 mice did not. Compared to sham-irradiated female APOE4 mice, irradiated female APOE4 mice also required more trials to reach criterion in the hippocampus-dependent passive avoidance test. Radiation had no effects on water maze or passive avoidance learning and memory of male APOE2, APOE3 or APOE4 mice, indicating that the effects of radiation on cognitive performance are dependent on sex- and APOE isoform.

Animals↗

PubMed2002

Regulated transcription of the immediate-early gene Zif268: mechanisms and gene dosage-dependent function in synaptic plasticity and memory formation.

The immediate-early gene Zif268 is a member of the Egr family of inducible transcription factors. Data from gene expression studies have suggested that this gene may play a critical role in initial triggering of the genetic machinery that has long been considered a necessary mechanism for maintenance of the later phases of LTP and also for the consolidation or stabilization of long-lasting memories. Until recently, however, the data supporting this assumption have been based primarily on circumstantial evidence, with no direct evidence to suggest that Zif268 is required for long-lasting synaptic plasticity and memory. In this report, we review our own data using Zif268 mutant mice; we show that although the early phase of dentate gyrus LTP is normal in these mice, the later phases are not present, and the ability of the mice to maintain learned information over a 24-h period is deficient. In addition, we present new information showing a task-dependent gene dosage effect in Zif268 heterozygous mice. We show that spatial learning is particularly sensitive to reduced levels of Zif268, as one-half of the complement of Zif268 in heterozygous mice is insufficient to maintain spatial long-term memories.

Animals↗