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Spatial Memory (spatial + memory)
Kinds of Spatial Memory Terms modified by Spatial Memory Selected Abstracts043.20 HISTAMINE and SPATIAL MEMORYEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2000S. Rubio No abstract is available for this article. [source] Sensory Systems and Spatial Memory in the Fruit Bat Rousettus aegyptiacusETHOLOGY, Issue 8 2005Richard A. Holland The megachiropteran fruit bat Rousettus aegyptiacus is able to orient and navigate using both vision and echolocation. These two sensory systems have different environmental constraints however, echolocation being relatively short range when compared with vision. Despite this difference, an experiment testing their memory of a perch location demonstrates that once the location of a perch is learned R. aegyptiacus is not influenced by the movement of local landmark cues in the vicinity of the perch under either light or dark conditions. Thus despite the differing constraints of vision and echolocation, this suggests a place is remembered as a location in space and not by associations with landmarks in the vicinity. A decrease in initial performance when the task was repeated in the dark suggested the possibility that a memory of a location learned using vision does not generalize to echolocation. [source] Spatial memory and the monkey hippocampus: Not all space is created equalHIPPOCAMPUS, Issue 1 2009Pamela Banta Lavenex Abstract Studies of the role of the monkey hippocampus in spatial learning and memory, however few, have reliably produced inconsistent results. Whereas the role of the hippocampus in spatial learning and memory has been clearly established in rodents, studies in nonhuman primates have made a variety of claims that range from the involvement of the hippocampus in spatial memory only at relatively longer memory delays, to no role for the hippocampus in spatial memory at all. In contrast, we have shown that selective damage restricted to the hippocampus (CA regions) prevents the learning or use of allocentric, spatial relational representations of the environment in freely behaving adult monkeys tested in an open-field arena. In this commentary, we discuss a unifying framework that explains these apparently discrepant results regarding the role of the monkey hippocampus in spatial learning and memory. We describe clear and strict criteria to interpret the findings from previous studies and guide future investigations of spatial memory in monkeys. Specifically, we affirm that, as in the rodent, the primate hippocampus is critical for spatial relational learning and memory, and in a time-independent manner. We describe how claims to the contrary are the result of experimental designs that fail to recognize, and control for, egocentric (hippocampus-independent) and allocentric (hippocampus-dependent) spatial frames of reference. Finally, we conclude that the available data demonstrate unequivocally that the central role of the hippocampus in allocentric, spatial relational learning and memory is conserved among vertebrates, including nonhuman primates. © 2008 Wiley-Liss, Inc. [source] Environmental impoverishment and aging alter object recognition, spatial learning, and dentate gyrus astrocytesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2010Daniel G. Diniz Abstract Environmental and age-related effects on learning and memory were analysed and compared with changes observed in astrocyte laminar distribution in the dentate gyrus. Aged (20 months) and young (6 months) adult female albino Swiss mice were housed from weaning either in impoverished conditions or in enriched conditions, and tested for episodic-like and water maze spatial memories. After these behavioral tests, brain hippocampal sections were immunolabeled for glial fibrillary acid protein to identify astrocytes. The effects of environmental enrichment on episodic-like memory were not dependent on age, and may protect water maze spatial learning and memory from declines induced by aging or impoverished environment. In the dentate gyrus, the number of astrocytes increased with both aging and enriched environment in the molecular layer, increased only with aging in the polymorphic layer, and was unchanged in the granular layer. We suggest that long-term experience-induced glial plasticity by enriched environment may represent at least part of the circuitry groundwork for improvements in behavioral performance in the aged mice brain. [source] Hippocampal synaptic transmission and LTP in vivo are intact following bilateral vestibular deafferentation in the ratHIPPOCAMPUS, Issue 4 2010Yiwen Zheng Abstract Numerous studies in animals and humans have shown that damage to the vestibular system in the inner ear results in spatial memory deficits, presumably because areas of the brain such as the hippocampus require vestibular input to accurately represent the spatial environment. Consistent with this hypothesis, studies in animals have demonstrated that complete bilateral vestibular deafferentation (BVD) causes a disruption of place cell firing as well as theta activity. The aim of this study was to investigate whether BVD in rats affects baseline field potentials (field excitatory postsynaptic potentials and population spikes) and long-term potentiation (LTP) in CA1 and the dentate gyrus (DG) of awake freely moving rats up to 43 days post-BVD and of anesthetized rats at 7 months post-BVD. Compared to sham controls, BVD had no significant effect on either baseline field potentials or LTP in either condition. These results suggest that although BVD interferes with the encoding, consolidation, and/or retrieval of spatial memories and the function of place cells, these changes are not related to detectable in vivo decrements in basal synaptic transmission or LTP, at least in the investigated pathways. © 2009 Wiley-Liss, Inc. [source] Reversible inactivation of the hippocampal formation in food-storing black-capped chickadees (Poecile atricapillus)HIPPOCAMPUS, Issue 4 2003Michael W. Shiflett Abstract The role of the hippocampal formation (HF) in memory processing was assessed in food-storing black-capped chickadees (Poecile atricapilla) by reversibly inactivating the HF during different memory tests. The memory tests required birds to remember a location based on spatial cues only, or based on a combination of both spatial and distinct visual cues. Inactivation of the HF impaired short-term spatial memory, but not visual-spatial memory. Inactivation of the HF impaired the retrieval of short-term (15 min) spatial memories, but not long-term (3-h) spatial memories. The pattern of deficits produced by inactivation of the HF in chickadees suggests a possible function of the hippocampal specialization of food-storing birds, as well as extends the notion of functional homology between the avian and mammalian HF. Hippocampus 2003;13:437,444. © 2003 Wiley-Liss, Inc. [source] When goals constrain: Eye movements and memory for goal-Oriented map studyAPPLIED COGNITIVE PSYCHOLOGY, Issue 6 2009Tad T. Brunyé Perspective goals, such as studying a map to learn a route through an environment or the overall layout of an environment, produce memory congruent with the goal-directed rather than the studied perspective. One explanation for this finding is that perspective goals guide attention towards actively gathering relevant information during learning. A second explanation is that information is automatically organized into a goal-congruent spatial model that guides retrieval. Both explanations predict goal-congruent memory, but only the former one predicts eye movement differences during study. The present experiment investigated the effect of perspective goals on eye movement during map study and the flexibility of resulting spatial memories. Results demonstrate eye movements towards goal-congruent map elements during learning, and lasting memory effects at test. These findings carry implications for the design of adaptive hand-held and in-vehicle navigation interfaces that accommodate for varied user goals. Copyright © 2008 John Wiley & Sons, Ltd. [source] Hippocampal lesions impair spatial memory performance, but not song,A developmental study of independent memory systems in the zebra finchDEVELOPMENTAL NEUROBIOLOGY, Issue 8 2009David J. Bailey Abstract Songbirds demonstrate song- and spatial-learning, forms of memory that appear distinct in formal characteristics and fitting the descriptions and criteria of procedural and episodic-like memory function, respectively. As in other vertebrates, the neural pathways underlying these forms of memory may also be dissociable, and include the corresponding song circuit and hippocampus (HP). Whether (or not) these two memory systems interact is unknown. Interestingly, the HP distinguishes itself as a site of immediate early gene expression in response to song and as a site of estrogen synthesis, a steroid involved in song learning. Thus, an interaction between these memory systems and their anatomical substrates appears reasonable to hypothesize, particularly during development. To test this idea, juvenile male or female zebra finches received chemical lesions of the HP at various points during song learning, as did adults. Song structure, singing behavior, song preference, and spatial memory were tested in adulthood. Although lesions of the HP severely compromised HP-dependent spatial memory function across all ages and in both sexes, we were unable to detect any effects of HP lesions on song learning, singing, or song structure in males. Interestingly, females lesioned as adults, but not as juveniles, did lose the characteristic preference for their father's song. Since compromise of the neural circuits that subserve episodic-like memory does very little (if anything) to affect procedural-like (song learning) memory, we conclude that these memory systems and their anatomical substrates are well dissociated in the developing male zebra finch. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009 [source] Learning large-scale spatial relationships in a maze and effects of MK-801 on retrieval in the rhesus monkeyDEVELOPMENTAL NEUROBIOLOGY, Issue 13 2007Jian Hong Wang Abstract Monkeys have strong abilities to remember the visual properties of potential food sources for survival in the nature. The present study demonstrated the first observations of rhesus monkeys learning to solve complex spatial mazes in which routes were guided by visual cues. Three monkeys were trained in a maze (6 m × 6 m) included of four different mazes. We recorded the cue and cup errors, latencies, and pathway for each trial. The data showed that monkeys learned the target place after three days in the first maze and spent a shorter time in learning the following mazes. The maze was an efficient method to measure the ability and proceeding of spatial memory in monkeys. Moreover, working memory can also be tested by using the maze. MK-801 at 0.02 mg/kg but not at 0.005 mg/kg impaired monkeys' retrieval of spatial memory after they learned all four mazes. The present maze may provide an efficient method to help bridging the gap in cognition between nonhuman primates and humans, and in particular to gain insight into human cognitive function and dysfunction. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007. [source] Developmental profiles for multiple object tracking and spatial memory: typically developing preschoolers and people with Williams syndromeDEVELOPMENTAL SCIENCE, Issue 3 2010Kirsten O'Hearn The ability to track moving objects, a crucial skill for mature performance on everyday spatial tasks, has been hypothesized to require a specialized mechanism that may be available in infancy (i.e. indexes). Consistent with the idea of specialization, our previous work showed that object tracking was more impaired than a matched spatial memory task in individuals with Williams syndrome (WS), a genetic disorder characterized by severe visuo-spatial impairment. We now ask whether this unusual pattern of performance is a reflection of general immaturity or of true abnormality, possibly reflecting the atypical brain development in WS. To examine these two possibilities, we tested typically developing 3- and 4-year-olds and people with WS on multiple object tracking (MOT) and memory for static spatial location. The maximum number of objects that could be correctly tracked or remembered (estimated from the k -statistic) showed similar developmental profiles in typically developing 3- and 4-year-old children, but the WS profile differed from either age group. People with WS could track more objects than 3-year-olds, and the same number as 4-year-olds, but they could remember the locations of more static objects than both 3- and 4-year-olds. Combining these data with those from our previous studies, we found that typically developing children show increases in the number of objects they can track or remember between the ages of 3 and 6, and these increases grow in parallel across the two tasks. In contrast, object tracking in older children and adults with WS remains at the level of 4-year-olds, whereas the ability to remember multiple locations of static objects develops further. As a whole, the evidence suggests that MOT and memory for static location develop in tandem typically, but not in WS. Atypical development of the parietal lobe in people with WS could play a causal role in the abnormal, uneven pattern of performance in WS. This interpretation is consistent with the idea that multiple object tracking engages different mechanisms from those involved in memory for static object location, and that the former can be particularly disrupted by atypical development. [source] The evolution of hippocampus volume and brain size in relation to food hoarding in birdsECOLOGY LETTERS, Issue 12 2004László Zsolt Garamszegi Abstract Food-hoarding birds frequently use spatial memory to relocate their caches, thus they may evolve a larger hippocampus in their brain than non-hoarder species. However, previous studies testing for such interspecific relationships provided conflicting results. In addition, food hoarding may be a cognitively complex task involving elaboration of a variety of brain regions, even outside of the hippocampus. Hence, specialization to food hoarding may also result in the enlargement of the overall brain. In a phylogenetic analysis of distantly related birds, we studied the interspecific association between food hoarding and the size of different brain regions, each reflecting different resolutions. After adjusting for allometric effects, the relative volume of the hippocampus and the relative size of the entire brain were each positively related to the degree of food-hoarding specialization, even after controlling for migration and brood parasitism. We also found some significant evidence for the relative volume of the telencephalon being associated with food hoarding, but this relationship was dependent on the approach we used. Hence, neural adaptation to food hoarding may favour the evolution of different brain structures. [source] Changes in individual and group spatial and verbal learning characteristics after anterior temporal lobectomyEPILEPSIA, Issue 6 2009Mario F. Dulay Summary Purpose:, To evaluate the effects of anterior temporal lobectomy (ATL) on individual and group spatial and verbal learning and memory abilities as a function of side of surgery and seizure control outcome. Methods:, We evaluated pre- and postsurgical learning and memory abilities of 75 left-hemisphere language dominant individuals who underwent ATL (33 left, 42 right) using the 8-trial Nonverbal Selective Reminding test and the 12-trial Verbal Selective Reminding test. Results:, Reliable change index methods indicated that 40.5% of individuals who underwent right-ATL had a clinically significant decline in spatial memory, and 62.5% of individuals who underwent left-ATL had a significant reduction in verbal memory. Growth curve analyses indicated that both side of surgery and poor seizure outcome independently affected the learning slope in the best fitting models. Left-ATL reduced the slope, but did not affect the overall shape, of verbal learning across trials. On the other hand, poor seizure control outcome affected the slope of spatial learning regardless of the side of surgery. Discussion:, Results demonstrate both individual and group declines in spatial memory and learning after ATL. Results suggest that individuals who undergo right-ATL should be counseled regarding the likelihood of a decline in spatial memory and learning abilities after ATL. Results also suggest that individuals with poor seizure control after ATL should be referred for rehabilitation services given the significant declines in spatial and verbal memory that occurred in our sample regardless of side of surgery. [source] Seizures in the Developing Brain Cause Adverse Long-term Effects on Spatial Learning and AnxietyEPILEPSIA, Issue 12 2004Umit Sayin Summary:,Purpose: Seizures in the developing brain cause less macroscopic structural damage than do seizures in adulthood, but accumulating evidence shows that seizures early in life can be associated with persistent behavioral and cognitive impairments. We previously showed that long-term spatial memory in the eight-arm radial-arm maze was impaired in rats that experienced a single episode of kainic acid (KA)-induced status epilepticus during early development (postnatal days (P) 1,14). Here we extend those findings by using a set of behavioral paradigms that are sensitive to additional aspects of learning and behavior. Methods: On P1, P7, P14, or P24, rats underwent status epilepticus induced by intraperitoneal injections of age-specific doses of KA. In adulthood (P90,P100), the behavioral performance of these rats was compared with that of control rats that did not receive KA. A modified version of the radial-arm maze was used to assess short-term spatial memory; the Morris water maze was used to evaluate long-term spatial memory and retrieval; and the elevated plus maze was used to determine anxiety. Results: Compared with controls, rats with KA seizures at each tested age had impaired short-term spatial memory in the radial-arm maze (longer latency to criterion and more reference errors), deficient long-term spatial learning and retrieval in the water maze (longer escape latencies and memory for platform location), and a greater degree of anxiety in the elevated plus maze (greater time spent in open arms). Conclusions: These findings provide additional support for the concept that seizures early in life may be followed by life-long impairment of certain cognitive and behavioral functions. These results may have clinical implications, favoring early and aggressive control of seizures during development. [source] Pentylenetetrazol-induced Recurrent Seizures in Rat Pups: Time Course on Spatial Learning and Long-term EffectsEPILEPSIA, Issue 6 2002Li-Tung Huang Summary: ,Purpose: Recurrent seizures in infants are associated with a high incidence of neurocognitive deficits. Animal models have suggested that the immature brain is less vulnerable to seizure-induced injury than is that in adult animals. We studied the effects of recurrent neonatal seizures on cognitive tasks performed when the animals were in adolescence and adulthood. Methods: Seizures were induced by intraperitoneal injection of pentylenetetrazol (PTZ) for 5 consecutive days, starting from postnatal day 10 (P10). At P35 and P60, rats were tested for spatial memory by using the Morris water maze task. In adulthood, motor performance was examined by the Rotarod test, and activity level was assessed by the open field test. Seizure threshold was examined by inhalant flurothyl. To assess presence or absence of spontaneous seizures, rats were video recorded for 4 h/day for 10 consecutive days for the detection of spontaneous seizures. Finally, brains were examined for histologic evidence of injury with cresyl violet stain and Timm staining in the supragranular zone and CA3 pyramidal cell layers of the hippocampus. Results: PTZ-treated rats showed significant spatial deficits in the Morris water maze at both P35 and P60. There were no differences in seizure threshold, motor balance, or activity level during the open field test. Spontaneous seizures were not recorded in any rat. The cresyl violet stain showed no cell loss in either the control or experimental rats. PTZ-treated rats exhibited more Timm staining in the CA3 subfield. However, the control and experimental rats showed similar Timm staining within the supragranular zone. Conclusions: Our findings indicate that recurrent PTZ-induced seizures result in long-term cognitive deficits and morphologic changes in the developing brain. Furthermore, these cognitive deficits could be detected during pubescence. [source] PRECLINICAL STUDY: Pentylenetetrazole-induced status epilepticus following training does not impair expression of morphine-induced conditioned place preferenceADDICTION BIOLOGY, Issue 2 2009Jie Zhang ABSTRACT Learning and memory play an important role in morphine addiction. Status epilepticus (SE) can impair the spatial and emotional learning and memory. However, little is known about the effects of SE on morphine-induced conditioned place preference (CPP). The present study was designed to investigate the effects of SE on morphine CPP, with food CPP being used as a control. The effects of SE on spatial memory in the Morris water maze (MWM) and Y-maze were investigated. SE was induced in adult mice using intraperitoneal injection of pentylenetetrazole; control mice received saline. The data indicated that SE had no effects on the formation of morphine CPP; however, the formation of food CPP was blocked by SE. Meanwhile, spatial memory assayed in the MWM and Y-maze was impaired by SE. In addition, the data demonstrated that SE did not cause a lasting disturbance of motor activity nor a change in the mice's appetite. These results suggested that although SE had no effects on morphine CPP, there was impaired food CPP and spatial memory in both the MWM and the Y-maze. The mechanisms underlying memory process of morphine CPP may be different from other types of memory. [source] Functional interaction between the associative parietal cortex and hippocampal place cell firing in the ratEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2005Etienne Save Abstract The hippocampus and associative parietal cortex (APC) both contribute to spatial memory but the nature of their functional interaction remains unknown. To address this issue, we investigated the effects of APC lesions on hippocampal place cell firing in freely moving rats. Place cells were recorded from APC-lesioned and control rats as they performed a pellet-chasing task in a circular arena containing three object cues. During successive recording sessions, cue manipulations including object rotation in the absence of the rat and object removal in the presence of the rat were made to examine the control exerted by the objects or by non-visual intramaze cues on place field location, respectively. Object rotations resulted in equivalent field rotation for all cells in control rats. In contrast, a fraction of place fields in APC-lesioned rats did not rotate but remained stable relative to the room. Object removal produced different effects in APC-lesioned and control rats. In control rats, most place fields remained stable relative to the previous object rotation session, indicating that they were anchored to olfactory and/or idiothetic cues. In APC-lesioned rats, a majority of place fields shifted back to their initial, standard location, thus suggesting that they relied on uncontrolled background cues to maintain place field stability. These results provide strong evidence that the hippocampus and the APC cooperate in the formation of spatial memory and suggest that the APC is involved in elaboration of a hippocampal map based on proximal landmarks. [source] Dissociation of function between the dorsal and the ventral hippocampus in spatial learning abilities of the rat: a within-subject, within-task comparison of reference and working spatial memoryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2004Helen H. J. Pothuizen Abstract Lesions restricted to the dorsal, but not the ventral, hippocampus severely impair the formation of spatial memory. This dissociation was first demonstrated using the water maze task. The present study investigated whether the dorsal and the ventral hippocampus are involved differentially in spatial reference and spatial working memory using a four-baited/four-unbaited version of the eight-arm radial maze task. This test allows the concurrent evaluation of reference and working memory with respect to the same set of spatial cues, and thereby enables a within-subjects within-task comparison between the two forms of memory functions. Rats with N -methyl- d -aspartic acid-induced excitotoxic lesions of the dorsal hippocampus, ventral hippocampus or both were compared with sham and unoperated controls. We showed that dorsal lesions were as effective as complete lesions in severely disrupting both reference and working spatial memory, whereas rats with ventral lesions performed at a level comparable with controls. These results lend further support to the existence of a functional dissociation between the dorsal and the ventral hippocampus, with the former being preferentially involved in spatial learning. [source] Hippocampal long-term depression as an index of spatial working memoryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2002Kazuhito Nakao Abstract Long-term potentiation (LTP), a form of synaptic plasticity in the hippocampus, is a cellular model for the neural basis of learning and memory, but few studies have investigated the contribution of long-term depression (LTD), a counterpart of LTP. To address the possible relationship between hippocampal LTD and spatial performance, the spatial cognitive ability of a rat was assessed in a spontaneous alternation test and, thereafter, LTD in response to low-frequency burst stimulation (LFBS) was monitored in the dentate gyrus of the same rat under anaesthesia. To enhance a divergence in the ability for spatial performance, some of the animals received fimbria,fornix (FF) transection 14 days before the experiments. LTD was reliably induced by application of LFBS to the medial perforant path of intact rats, while no apparent LTD was elicited in rats with FF lesions. The behavioural parameters of spatial memory showed a significant correlation with the magnitude of LTD. We found no evidence that the cognitive ability correlated with other electrophysiological parameters, e.g. basal synaptic responses, stimulus intensity to produce half-maximal responses, paired-pulse facilitation or paired-pulse depression. These results suggest that the magnitude of LTD in the dentate gyrus serves as a reliable index of spatial cognitive ability, providing insights into the functional significance of hippocampal LTD. [source] Genetic loss of D-amino acid oxidase activity reverses schizophrenia-like phenotypes in miceGENES, BRAIN AND BEHAVIOR, Issue 1 2010V. Labrie Reduced function of the N -methyl- d -aspartate receptor (NMDAR) has been implicated in the pathophysiology of schizophrenia. The NMDAR contains a glycine binding site in its NR1 subunit that may be a useful target for the treatment of schizophrenia. In this study, we assessed the therapeutic potential of long-term increases in the brain levels of the endogenous NMDAR glycine site agonist D-serine, through the genetic inactivation of its catabolic enzyme D-amino acid oxidase (DAO) in mice. The effects of eliminating DAO function were investigated in mice that display schizophrenia-related behavioral deficits due to a mutation (Grin 1D481N) in the NR1 subunit that results in a reduction in NMDAR glycine affinity. Grin 1D481N mice show deficits in sociability, prolonged latent inhibition, enhanced startle reactivity and impaired spatial memory. The hypofunctional Dao 1G181R mutation elevated brain levels of D-serine, but alone it did not affect performance in the behavioral measures. Compared to animals with only the Grin 1D481N mutation, mice with both the Dao1G181R and Grin 1D481N mutations displayed an improvement in social approach and spatial memory retention, as well as a reversal of abnormally persistent latent inhibition and a partial normalization of startle responses. Thus, an increased level of D-serine resulting from decreased catalysis corrected the performance of mice with deficient NMDAR glycine site activation in behavioral tasks relevant to the negative and cognitive symptoms of schizophrenia. Diminished DAO activity and elevations in D-serine may serve as an effective therapeutic intervention for the treatment of psychiatric symptoms. [source] 5-HT1A and NMDA receptors interact in the rat medial septum and modulate hippocampal-dependent spatial learningHIPPOCAMPUS, Issue 12 2009Elin Elvander-Tottie Abstract Cholinergic and GABAergic neurons in the medial septum/vertical limb of the diagonal band of Broca (MS/vDB) projecting to the hippocampus, constitute the septohippocampal projection, which is important for hippocampal-dependent learning and memory. There is also evidence for an extrinsic as well as an intrinsic glutamatergic network within the MS/vDB. GABAergic and cholinergic septohippocampal neurons express the serotonergic 5-HT1A receptor and most likely also glutamatergic NMDA receptors. The aim of the present study was to examine whether septal 5-HT1A receptors are important for hippocampal-dependent long-term memory and whether these receptors interact with glutamatergic NMDA receptor transmission in a manner important for hippocampal-dependent spatial memory. Intraseptal infusion of the 5-HT1A receptor agonist (R)-8-OH-DPAT (1 or 4 ,g/rat) did not affect spatial learning in the water maze task but impaired emotional memory in the passive avoidance task at the higher dose tested (4 ,g/rat). While intraseptal administration of (R)-8-OH-DPAT (4 ,g) combined with a subthreshold dose of the NMDA receptor antagonist D-AP5 (1 ,g) only marginally affected spatial acquisition, it produced a profound impairment in spatial memory. In conclusion, septal 5-HT1A receptors appears to play a more prominent role in emotional than in spatial memory. Importantly, septal 5-HT1A and NMDA receptors appear to interact in a manner, which is particularly critical for the expression or retrieval of hippocampal-dependent long-term spatial memory. It is proposed that NMDA receptor hypofunction in the septal area may unmask a negative effect of 5-HT1A receptor activation on memory, which may be clinically relevant. © 2009 Wiley-Liss, Inc. [source] Spatial memory and the monkey hippocampus: Not all space is created equalHIPPOCAMPUS, Issue 1 2009Pamela Banta Lavenex Abstract Studies of the role of the monkey hippocampus in spatial learning and memory, however few, have reliably produced inconsistent results. Whereas the role of the hippocampus in spatial learning and memory has been clearly established in rodents, studies in nonhuman primates have made a variety of claims that range from the involvement of the hippocampus in spatial memory only at relatively longer memory delays, to no role for the hippocampus in spatial memory at all. In contrast, we have shown that selective damage restricted to the hippocampus (CA regions) prevents the learning or use of allocentric, spatial relational representations of the environment in freely behaving adult monkeys tested in an open-field arena. In this commentary, we discuss a unifying framework that explains these apparently discrepant results regarding the role of the monkey hippocampus in spatial learning and memory. We describe clear and strict criteria to interpret the findings from previous studies and guide future investigations of spatial memory in monkeys. Specifically, we affirm that, as in the rodent, the primate hippocampus is critical for spatial relational learning and memory, and in a time-independent manner. We describe how claims to the contrary are the result of experimental designs that fail to recognize, and control for, egocentric (hippocampus-independent) and allocentric (hippocampus-dependent) spatial frames of reference. Finally, we conclude that the available data demonstrate unequivocally that the central role of the hippocampus in allocentric, spatial relational learning and memory is conserved among vertebrates, including nonhuman primates. © 2008 Wiley-Liss, Inc. [source] Effect of tooth loss on spatial memory and trkB-mRNA levels in ratsHIPPOCAMPUS, Issue 6 2008Kaoruko Yamazaki Abstract The mechanism by which tooth loss accelerates spatial memory impairment is unknown. The purpose of this study was to test the hypothesis that tooth loss affects trkB-mRNA levels and leads to an accelerated decrease in the hippocampal cell density in rats. A radial maze was used to evaluate the spatial memory of male Wistar rats that were categorized based on the number of extracted molar teeth. Number of hippocampal pyramidal cells and the trkB-mRNA expressions in the amygdala, perirhinal cortex, thalamus, and the hippocampal CA1, CA3, and CA4 areas, were evaluated using molecular biological techniques. Seven weeks after tooth extraction, maze performance was significantly lower in each tooth loss group than in the control group, and the number of extracted teeth was inversely proportional to the induction of the trkB-mRNA and the hippocampal cell density. The average weight of rats increased by controlled feeding throughout the experiment without showing a significant difference between the control and experimental groups. The results indicated that, in rats, the spatial memory-linked trkB-mRNA was reduced in association with the tooth loss; this supports the hypothesis and suggests that teeth have a role in the prevention of spatial memory impairment. © 2008 Wiley-Liss, Inc. [source] Ventral hippocampal involvement in temporal order, but not recognition, memory for spatial informationHIPPOCAMPUS, Issue 3 2008John G. Howland Abstract The hippocampus is critical for spatial memory. Recently, subregional differences in the function of hippocampus have been described in a number of behavioral tasks. The present experiments assessed the effects of reversibly lesioning either the dorsal (dHip) or ventral hippocampus (vHip) on spontaneous tests of spatial recognition and temporal order memory. We report that although the dHip is necessary for spatial recognition memory (RM) (distinguishing a novel from a familiar spatial location), the vHip is involved in temporal order memory (the capacity to distinguish between two spatial locations visited at different points in time), but not RM. These findings and others are consistent with the hypothesis that temporal order memory is supported by an integrated circuit of limbic areas including the vHip and the medial prefrontal cortex. © 2007 Wiley-Liss, Inc. [source] A single application of MK801 causes symptoms of acute psychosis, deficits in spatial memory, and impairment of synaptic plasticity in ratsHIPPOCAMPUS, Issue 2 2008Denise Manahan-Vaughan Abstract Schizophrenia is mostly a progressive psychiatric illness. Although cognitive changes in chronic schizophrenia have been investigated, little is known about the consequences of a single psychotic episode on memory mechanisms and formation. We investigated changes in hippocampal long-term potentiation (LTP) and spatial memory in a rat model of an acute psychotic episode. Application of NMDA receptor antagonists, such as MK801 (dizolcilpine) in rats, have been shown to give rise to an acute and short-lasting behavioral state, which mirrors many symptoms of schizophrenia. Furthermore, NMDA antagonist-intake in humans elicits symptoms of schizophrenia such as hallucinations, delusions, and affective blunting. We therefore treated animals with a single systemic injection of MK801 (5 mg/kg). Increased stereotypy, locomotion, and ataxia were evident immediately after MK801-treatment, with effects disappearing within 24 h. MK801-treatment caused a disruption of prepulse inhibition of the acoustic startle reflex, 1 day but not 7 or 28 days after treatment. These effects were consistent with the occurrence of an acute psychotic episode. LTP was profoundly impaired in freely moving rats 7 days after MK801 application. Four weeks after treatment, a slight recovery of LTP was seen, however marked deficits in long-term spatial memory were evident. These data suggest that treatment with MK801 to generate an acute psychotic episode in rats, gives rise to grave disturbances in synaptic plasticity and is associated with lasting impairments with the ability to form spatial memory. © 2007 Wiley-Liss, Inc. [source] Influence of predator stress on the consolidation versus retrieval of long-term spatial memory and hippocampal spinogenesisHIPPOCAMPUS, Issue 7 2006David M. Diamond Abstract We have studied the influence of predator stress (30 min of cat exposure) on long-term (24 h) spatial memory and the density of spines in basilar dendrites of CA1 neurons. Predator stress occurred either immediately before water maze training (Stress Pre-Training) or before the 24 h memory test (Stress Pre-Retrieval). The Control (nonstress) group exhibited excellent long-term spatial memory and a robust increase in the density of stubby, but not mushroom, shaped spines. The Stress Pre-Training group had impaired long-term memory and did not exhibit any changes in spine density. The Stress Pre-Retrieval group was also impaired in long-term memory performance, but this group exhibited an increase in the density of stubby, but not mushroom, shaped spines, which was indistinguishable from the control group. These findings indicate that: (1) A single day of water maze training under control conditions produced intact long-term memory and an increase in the density of stubby spines in CA1; (2) Stress before training interfered with the consolidation of information into long-term memory and suppressed the training-induced increase in spine density; and (3) Stress immediately before the 24 h memory test trial impaired the retrieval of the stored memory, but did not reverse the training-induced increase in CA1 spine density. Overall, this work provides evidence of structural plasticity in dendrites of CA1 neurons which may be involved in the consolidation process, and how spinogenesis and memory are modulated by stress. © 2006 Wiley-Liss, Inc. [source] Selective hippocampal damage in rhesus monkeys impairs spatial memory in an open-field test,HIPPOCAMPUS, Issue 7 2004Robert R. Hampton Abstract The hippocampus is critical for remembering locations in a wide variety of species, including humans. However, recent findings from monkeys following selective hippocampal lesions have been equivocal. To approximate more closely the situations in which rodents and birds are tested, we used a spatial memory task in which rhesus monkeys (Macaca mulatta) moved about freely in a large room, on a tether. We used MRI-guided stereotaxic surgery to produce selective hippocampal lesions in five monkeys, and retained five unoperated control monkeys. In the study phase of each trial of the matching-to-location task, monkeys found food in one site in an array of identical foraging sites. During the test, which occurred after a delay, monkeys could return to the site where the food had been found during study to obtain more food. In Experiment 1, normal monkeys showed a small significant tendency to return directly to a site where they had previously found food that day. Operated monkeys showed no such matching tendency. In Experiment 2, further training produced reliable matching-to-location performance in both groups at short delays, but monkeys with selective hippocampal lesions rapidly forgot the location of the food. In Experiment 3, we tested whether monkeys used a "cognitive map" to encode the location of the hidden food, by requiring them to relocate the food from a starting location different from that used during study. As a group, monkeys were more accurate than expected by chance, indicating that they did encode the rewarded location with respect to allocentric landmarks; however, both groups of monkeys were significantly worse at relocating the food when required to approach from a different location. In Experiment 4, probe trials using symmetrical test arrays found no evidence for egocentric coding of the rewarded location. © 2004 Wiley-Liss, Inc. [source] Reversible inactivation of the hippocampal formation in food-storing black-capped chickadees (Poecile atricapillus)HIPPOCAMPUS, Issue 4 2003Michael W. Shiflett Abstract The role of the hippocampal formation (HF) in memory processing was assessed in food-storing black-capped chickadees (Poecile atricapilla) by reversibly inactivating the HF during different memory tests. The memory tests required birds to remember a location based on spatial cues only, or based on a combination of both spatial and distinct visual cues. Inactivation of the HF impaired short-term spatial memory, but not visual-spatial memory. Inactivation of the HF impaired the retrieval of short-term (15 min) spatial memories, but not long-term (3-h) spatial memories. The pattern of deficits produced by inactivation of the HF in chickadees suggests a possible function of the hippocampal specialization of food-storing birds, as well as extends the notion of functional homology between the avian and mammalian HF. Hippocampus 2003;13:437,444. © 2003 Wiley-Liss, Inc. [source] Individual differences in spatial memory among aged rats are related to hippocampal PKC, immunoreactivityHIPPOCAMPUS, Issue 2 2002Paul J. Colombo Abstract We reported previously that the extent of spatial memory impairment among aged rats was correlated positively with levels of protein kinase C, in hippocampal homogenates measured by quantitative Western blotting (Colombo et al., 1997). In the current study, immunocytochemistry was used to test whether the relationship between elevated PKC, and memory impairment among aged rats could be localized further within regions of the hippocampus. Six- and 24-month-old male Long-Evans rats were first trained in the water maze on a standard place-learning task and then trained 2 weeks later on a transfer task designed for rapid acquisition. In comparison with young rats, aged rats with impaired spatial memory had increased PKC,-immunoreactivity (PKC,-ir) in CA1 of the hippocampus, but not the dentate gyrus. In addition, PKC,-ir in CA1 was correlated positively with spatial memory impairment among aged rats on the standard place-learning and the transfer training tasks. The current results are consistent with our previous report of PKC, in hippocampal homogenates, and show further that the relationships between PKC,-ir and memory impairments among aged rats are most evident in area CA1. Thus age-related impairments of spatial memory, as well as deficits in the flexible use of previously acquired information, may result from dysregulation of PKC,. Hippocampus 2002;12:285,289. © 2002 Wiley-Liss, Inc. [source] Sequestration of serum response factor in the hippocampus impairs long-term spatial memoryJOURNAL OF NEUROCHEMISTRY, Issue 2 2005Pramod K. Dash Abstract The formation of long-term memory has been shown to require protein kinase-mediated gene expression. One such kinase, mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK), can lead to the phosphorylation of serum response factor (SRF) and Elk-1, enhancing the expression of target genes. However, a direct involvement of these transcription factors in memory storage has not been demonstrated. We have employed an oligonucleotide decoy technique to interrogate SRF and Elk-1. Previously, it has been shown that intra-amygdalal infusion of small double-stranded decoy oligonucleotides for nuclear factor-kappaB (NFkappaB) can impair long-term memory for fear-potentiated startle. Using this approach, we found that intra-hippocampal infusion of NFkappaB decoy oligonucleotides also impairs long-term spatial memory, consistent with a role for this factor in long-term memory storage. Decoy oligonucleotides containing the binding site for SRF, as confirmed by shift-western, did not influence memory acquisition but impaired long-term spatial memory. Analysis of search behavior during the transfer test revealed deficits consistent with a loss of precise platform location information. In contrast, oligonucleotides with a binding site for either Elk-1 or another target of ERK activity, SMAD3/SMAD4, did not interfere with memory formation or storage. These findings suggest that SRF-mediated gene expression is required for long-term spatial memory. [source] Fast Effects of Glucocorticoids on Memory-Related Network Oscillations in the Mouse HippocampusJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2008E. K. Weiss Transient or lasting increases in glucocorticoids accompany deficits in hippocampus-dependent memory formation. Recent data indicate that the formation and consolidation of declarative and spatial memory are mechanistically related to different patterns of hippocampal network oscillations. These include gamma oscillations during memory acquisition and the faster ripple oscillations (approximately 200 Hz) during subsequent memory consolidation. We therefore analysed the effects of acutely applied glucocorticoids on network activity in mouse hippocampal slices. Evoked field population spikes and paired-pulse responses were largely unaltered by corticosterone or cortisol, respectively, despite a slight increase in maximal population spike amplitude by 10 ,m corticosterone. Several characteristics of sharp waves and superimposed ripple oscillations were affected by glucocorticoids, most prominently the frequency of spontaneously occurring sharp waves. At 0.1 ,m, corticosterone increased this frequency, whereas maximal (10 ,m) concentrations led to a reduction. In addition, gamma oscillations became slightly faster and less regular in the presence of high doses of corticosteroids. The present study describes acute effects of glucocorticoids on sharp wave-ripple complexes and gamma oscillations in mouse hippocampal slices, revealing a potential background for memory deficits in the presence of elevated levels of these hormones. [source] | ||||||||||||||||