The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Rebecca D Burwell - One of the best experts on this subject based on the ideXlab platform.
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Instantaneous amplitude and shape of Postrhinal theta oscillations differentially encode running speed
2020Co-Authors: Megha Ghosh, Rebecca D Burwell, Sharon C. Furtak, Benjamin E. Shanahan, George A. Mashour, Omar J. AhmedAbstract:Hippocampal theta oscillations have a temporally asymmetric waveform shape, but it is not known if this theta asymmetry extends to all other cortical regions involved in spatial navigation and memory. Here, using both established and improved cycle-by-cycle analysis methods, we show that theta waveforms in the Postrhinal Cortex are also temporally asymmetric. On average, the falling phase of Postrhinal theta cycles lasts longer than the subsequent rising phase. There are, however, rapid changes in both the instantaneous amplitude and instantaneous temporal asymmetry of Postrhinal theta cycles. These rapid changes in amplitude and asymmetry are very poorly correlated, indicative of a mechanistic disconnect between these theta cycle features. We show that the instantaneous amplitude and asymmetry of Postrhinal theta cycles differentially encode running speed. Although theta amplitude continues to increase at the fastest running speeds, temporal asymmetry of the theta waveform shape plateaus after medium speeds. Our results suggest that the amplitude and waveform shape of individual Postrhinal theta cycles may be governed by partially independent mechanisms and emphasize the importance of employing a single cycle approach to understanding the genesis and behavioral correlates of cortical theta rhythms.
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Instantaneous amplitude and shape of Postrhinal theta oscillations differentially encode running speed.
Behavioral neuroscience, 2020Co-Authors: Megha Ghosh, Rebecca D Burwell, Sharon C. Furtak, Benjamin E. Shanahan, George A. Mashour, Omar J. AhmedAbstract:Hippocampal theta oscillations have a temporally asymmetric waveform shape, but it is not known if this theta asymmetry extends to all other cortical regions involved in spatial navigation and memory. Here, using both established and improved cycle-by-cycle analysis methods, we show that theta waveforms in the Postrhinal Cortex are also temporally asymmetric. On average, the falling phase of Postrhinal theta cycles lasts longer than the subsequent rising phase. There are, however, rapid changes in both the instantaneous amplitude and instantaneous temporal asymmetry of Postrhinal theta cycles. These rapid changes in amplitude and asymmetry are very poorly correlated, indicative of a mechanistic disconnect between these theta cycle features. We show that the instantaneous amplitude and asymmetry of Postrhinal theta cycles differentially encode running speed. Although theta amplitude continues to increase at the fastest running speeds, temporal asymmetry of the theta waveform shape plateaus after medium speeds. Our results suggest that the amplitude and waveform shape of individual Postrhinal theta cycles may be governed by partially independent mechanisms and emphasize the importance of employing a single cycle approach to understanding the genesis and behavioral correlates of cortical theta rhythms. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
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disconnection of the perirhinal and Postrhinal cortices impairs recognition of objects in context but not contextual fear conditioning
The Journal of Neuroscience, 2017Co-Authors: Victoria R Heimermcginn, Devon L Poeta, Krishan Aghi, Methma Udawatta, Rebecca D BurwellAbstract:The perirhinal Cortex (PER) is known to process object information, whereas the rodent Postrhinal Cortex (POR), homolog to the parahippocampal Cortex in primates, is thought to process spatial information. A number of studies, however, provide evidence that both areas are involved in processing contextual information. In this study, we tested the hypothesis that the rat POR relies on object information received from the PER to form complex representations of context. Using three fear-conditioning (FC) paradigms (signaled, unsignaled, and renewal) and two context-guided object recognition tasks (with 3D and 2D objects), we examined the effects of crossed excitotoxic lesions to the POR and the contralateral PER. Performance of rats with crossed lesions was compared with that of rats with ipsilateral POR plus PER lesions and sham-operated rats. We found that rats with contralateral PER-POR lesions were impaired in object-context recognition but not in contextual FC. Therefore, interaction between the POR and PER is necessary for context-guided exploratory behavior but not for associating fear with context. Our results provide evidence for the hypothesis that the POR relies on object and pattern information from the PER to encode representations of context. The association of fear with a context, however, may be supported by alternate cortical and/or subcortical pathways when PER-POR interaction is not available. Our results suggest that contextual FC may represent a special case of context-guided behavior.SIGNIFICANCE STATEMENT Representations of context are important for perception, memory, decision making, and other cognitive processes. Moreover, there is extensive evidence that the use of contextual representations to guide appropriate behavior is disrupted in neuropsychiatric and neurological disorders including developmental disorders, schizophrenia, affective disorders, and Alzheimer's disease. Many of these disorders are accompanied by changes in parahippocampal and hippocampal structures. Understanding how context is represented in the brain and how parahippocampal structures are involved will enhance our understanding and treatment of the cognitive and behavioral symptoms associated with neurological disorders and neuropsychiatric disease.
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Behavioral/Systems/Cognitive Corticohippocampal Contributions to Spatial and Contextual Learning
2013Co-Authors: Rebecca D Burwell, David J Bucci, Michael P. Saddoris, Kjesten A. WiigAbstract: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
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borders and comparative cytoarchitecture of the perirhinal and Postrhinal cortices in an f1 hybrid mouse
Cerebral Cortex, 2013Co-Authors: Stephane A Beaudin, Teghpal Singh, Kara L Agster, Rebecca D BurwellAbstract:We examined the cytoarchitectonic and chemoarchitectonic organization of the cortical regions associated with the posterior rhinal fissure in the mouse brain, within the framework of what is known about these regions in the rat. Primary observations were in a first-generation hybrid mouse line, B6129PF/J1. The F1 hybrid was chosen because of the many advantages afforded in the study of the molecular and cellular bases of learning and memory. Comparisons with the parent strains, the C57BL6/J and 129P3/J are also reported. Mouse brain tissue was processed for visualization of Nissl material, myelin, acetyl cholinesterase, parvalbumin, and heavy metals. Tissue stained for heavy metals by the Timm’s method was particularly useful in the assignment of borders and in the comparative analyses because the patterns of staining were similar across species and strains. As in the rat, the areas examined were parcellated into 2 regions, the perirhinal and the Postrhinal cortices. The perirhinal Cortex was divided into areas 35 and 36, and the Postrhinal Cortex was divided into dorsal (PORd) and ventral (PORv) subregions. In addition to identifying the borders of the perirhinal Cortex, we were able to identify a region in the mouse brain that shares signature features with the rat Postrhinal Cortex.
John Patrick Aggleton - One of the best experts on this subject based on the ideXlab platform.
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Medial temporal pathways for contextual learning: Network c-fos mapping in rats with or without perirhinal Cortex lesions.
Brain and Neuroscience Advances, 2017Co-Authors: Lisa Kinnavane, Eman Amin, C.m. Olarte-sánchez, John Patrick AggletonAbstract:In the rat brain, context information is thought to engage network interactions between the Postrhinal Cortex, medial entorhinal Cortex, and the hippocampus. In contrast, object information is thought to be more reliant on perirhinal Cortex and lateral entorhinal Cortex interactions with the hippocampus. The ‘context network’ was explored by mapping expression of the immediate-early gene, c-fos, after exposure to a new spatial environment. Structural equation modelling of Fos counts produced networks of good fit that closely matched prior predictions based on anatomically-grounded functional models. These same models did not, however, fit the Fos data from home-cage controls nor did they fit the corresponding data from a previous study exploring object recognition. These additional analyses highlight the specificity of the context network. The home-cage controls, meanwhile, showed raised levels of inter-area Fos correlations between the many sites examined, i.e., their changes in Fos levels lacked anatomical specificity. Two additional groups of rats received perirhinal Cortex lesions. While the loss of perirhinal Cortex reduced lateral entorhinal c-fos activity, it did not affect mean levels of hippocampal c-fos expression. Likewise, overall c-fos expression in the prelimbic Cortex, retrosplenial Cortex and nucleus reuniens of the thalamus appeared unaffected by the perirhinal Cortex lesions. Nevertheless, the perirhinal Cortex lesions disrupted network interactions involving the medial entorhinal Cortex and the hippocampus, highlighting ways in which perirhinal Cortex might affect specific aspects of context learning.
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Anterior thalamic lesions stop immediate early gene activation in selective laminae of the retrosplenial Cortex: evidence of covert pathology in rats?
The European journal of neuroscience, 2004Co-Authors: Trisha A. Jenkins, Seralynne Denise Vann, Eman Amin, John Patrick AggletonAbstract:Lesions involving the anterior thalamic nuclei stopped immediate early gene (IEG) activity in specific regions of the rat retrosplenial Cortex, even though there were no apparent cytoarchitectonic changes. Discrete anterior thalamic lesions were made either by excitotoxin (Experiment 1) or radiofrequency (Experiment 2) and, following recovery, the rats foraged in a radial-arm maze in a novel room. Measurements made 6-12 weeks postsurgery showed that, in comparison with surgical controls, the thalamic lesions produced the same, selective patterns of Fos changes irrespective of method. Granular (caudal granular Cortex and rostral granular Cortex), but not dysgranular (dysgranular Cortex), retrosplenial Cortex showed a striking loss of Fos-positive cells. While a loss of between 79 and 89% of Fos-positive cells was found in the superficial laminae, the deeper layers appeared normal. In Experiments 3 and 4, rats 9-10 months postsurgery were placed in an activity box for 30 min. Anterior thalamic lesions (Experiment 3) led to a pronounced IEG decrease of both Fos and zif268 throughout the retrosplenial Cortex that now included the dysgranular area. These IEG losses were found even though the same regions appeared normal using standard histological techniques. Lesions of the Postrhinal Cortex (Experiment 4) did not bring about a loss of retrosplenial IEG activity even though this region is also reciprocally connected with the retrosplenial Cortex. This selective effect of anterior thalamic damage upon retrosplenial activity may both amplify the disruptive effects of anterior thalamic lesions and help to explain the posterior cingulate hypoactivity found in Alzheimer's disease.
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Novel spatial arrangements of familiar visual stimuli promote activity in the rat hippocampal formation but not the parahippocampal cortices: a c-fos expression study
Neuroscience, 2004Co-Authors: Trisha A. Jenkins, Eman Amin, John M. Pearce, Malcolm W. Brown, John Patrick AggletonAbstract:The novelty of a cue may arise from the presence of an element that has not previously been experienced or from familiar elements that have been rearranged. The present study mapped the anatomical basis of responding to this second form of novelty. For this, rats were trained on a working memory spatial task in a radial-arm maze in a cue-controlled environment. On the final test day the positions of the familiar, extra-maze cues were rearranged for half of the rats (group Novel). The spatial configuration of the cues now matched that of the control rats (group Familiar). Neuronal activation, as measured by the immediate early gene, c-fos, was then compared between the two groups. Rearrangement of visual stimuli led to significant increases in Fos-positive cells in various hippocampal subfields (rostral CA1, rostral CA3 and rostral dentate gyrus) as well as the parietal Cortex and the postsubiculum. In contrast, no changes were observed in other sites including the perirhinal Cortex, Postrhinal Cortex, lateral and medial entorhinal cortices, retrosplenial cortices, or anterior thalamic nuclei. These results highlight the selective involvement of the hippocampus for processing novel rearrangements of visual stimuli and suggest that this involvement is intrinsic as it is independent of the parahippocampal cortices. This pattern of Fos changes is the mirror image of that repeatedly found for novel individual stimuli (perirhinal increase, no hippocampal change), demonstrating that these two forms of novelty have qualitatively different neural attributes.
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Fos imaging reveals differential neuronal activation of areas of rat temporal Cortex by novel and familiar sounds
The European journal of neuroscience, 2001Co-Authors: H Wan, John Patrick Aggleton, E. C. Warburton, Paweł Kuśmierek, D M Kowalska, M. W. BrownAbstract:To provide information about the possible regions involved in auditory recognition memory, this study employed an imaging technique that has proved valuable in the study of visual recognition memory. The technique was used to image populations of neurons that are differentially activated by novel and familiar auditory stimuli, thereby paralleling previous studies of visual familiarity discrimination. Differences evoked by novel and familiar sounds in the activation of neurons were measured in different parts of the rat auditory pathway by immunohistochemistry for the protein product (Fos) of the immediate early gene c-fos. Significantly higher counts of stained neuronal nuclei (266 ± 21/mm2) were evoked by novel than by familiar sounds (192 ± 17/mm2) in the auditory association Cortex (area Te3; AudA). No such significant differences were found for the inferior colliculus, primary auditory Cortex, Postrhinal Cortex, perirhinal Cortex (PRH), entorhinal Cortex, amygdala or hippocampus. These findings are discussed in relation to the results of lesion studies and what is known of areas involved in familiarity discrimination for visual stimuli. Differential activation is produced by novel and familiar individual stimuli in sensory association Cortex for both auditory and visual stimuli, whereas the PRH is differentially activated by visual but not auditory stimuli. It is suggested that this latter difference is related to the nature of the particular auditory and visual stimuli used.
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Intact negative patterning in rats with fornix or combined perirhinal and Postrhinal Cortex lesions.
Experimental brain research, 2000Co-Authors: Timothy J Bussey, Rebecca Dias, Edward S. Redhead, John M. Pearce, Janice L. Muir, John Patrick AggletonAbstract:It has been proposed that the hippocampal formation is necessary for the acquisition of tasks that require the use of configural representations for their solution, including spatial learning and negative patterning. Tests of this influential view have, however, yielded conflicting results. For example fornix or hippocampal lesions, which reliably impair spatial learning, do not reliably impair negative patterning. A problem in interpreting these results has been the lack of controls for factors such as over-responding, excitatory effects of reward, and the possibility of non-configural solutions. At the same time, other studies have pointed to a role in configural learning for parahippocampal regions such as the perirhinal Cortex. The present experiments controlled for the above factors and revealed that neither lesions of the fornix nor of the perirhinal/Postrhinal Cortex in the rat had any effect on negative patterning, although subsequent tests of object and spatial memory demonstrated the functional efficacy of the lesions.
Alfred I Geller - One of the best experts on this subject based on the ideXlab platform.
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Genetic labeling of both the axons of transduced, glutamatergic neurons in rat Postrhinal Cortex and their postsynaptic neurons in other neocortical areas by Herpes Simplex Virus vectors that coexpress an axon-targeted β-galactosidase and wheat germ agglutinin from a vesicular glutamate transporter-1 promoter
Brain Research, 2010Co-Authors: Guorong Zhang, Hua Zhao, Xu Li, Alfred I GellerAbstract:Neuronal circuits comprise the foundation for neuronal physiology and synaptic plasticity, and thus for consequent behaviors and learning, but our knowledge of neocortical circuits is incomplete. Mapping neocortical circuits is a challenging problem because these circuits contain large numbers of neurons, a high density of synapses, and numerous classes and subclasses of neurons that form many different types of synapses. Expression of specific genetic tracers in small numbers of specific subclasses of neocortical neurons has the potential to map neocortical circuits. Suitable genetic tracers have been established in neurons in subcortical areas, but application to neocortical circuits has been limited. Enabling this approach, Herpes Simplex Virus (HSV-1) plasmid (amplicon) vectors can transduce small numbers of neurons in a specific neocortical area. Further, expression of a particular genetic tracer can be restricted to specific subclasses of neurons; in particular, the vesicular glutamate transporter-1 (VGLUT1) promoter supports expression in VGLUT1-containing glutamatergic neurons in rat Postrhinal (POR) Cortex. Here, we show that expression of an axon-targeted β-galactosidase (β-gal) from such vectors supports mapping specific commissural and associative projections of the transduced neurons in POR Cortex. Further, coexpression of wheat germ agglutinin (WGA) and an axon-targeted β-gal supports mapping both specific projections of the transduced neurons and identifying specific postsynaptic neurons for the transduced neurons. The neocortical circuit mapping capabilities developed here may support mapping specific neocortical circuits that have critical roles in cognitive learning.
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glutamatergic or gabaergic neuron specific long term expression in neocortical neurons from helper virus free hsv 1 vectors containing the phosphate activated glutaminase vesicular glutamate transporter 1 or glutamic acid decarboxylase promoter
Brain Research, 2007Co-Authors: Morten Arendt Rasmussen, Xiaodan Wang, Lingxin Kong, Guorong Zhang, Meng Liu, Gabor Szabo, Norman P Curthoys, Alfred I GellerAbstract:Many potential uses of direct gene transfer into neurons require restricting expression to one of the two major types of forebrain neurons, glutamatergic or GABAergic neurons. Thus, it is desirable to develop virus vectors that contain either a glutamatergic or GABAergic neuron-specific promoter. The brain/kidney phosphate-activated glutaminase (PAG), the product of the GLS1 gene, produces the majority of the glutamate for release as neurotransmitter, and is a marker for glutamatergic neurons. A PAG promoter was partially characterized using a cultured kidney cell line. The three vesicular glutamate transporters (VGLUTs) are expressed in distinct populations of neurons, and VGLUT1 is the predominant VGLUT in the neoCortex, hippocampus, and cerebellar Cortex. Glutamic acid decarboxylase (GAD) produces GABA; the two molecular forms of the enzyme, GAD65 and GAD67, are expressed in distinct, but largely overlapping, groups of neurons, and GAD67 is the predominant form in the neoCortex. In transgenic mice, an approximately 9 kb fragment of the GAD67 promoter supports expression in most classes of GABAergic neurons. Here, we constructed plasmid (amplicon) Herpes Simplex Virus (HSV-1) vectors that placed the Lac Z gene under the regulation of putative PAG, VGLUT1, or GAD67 promoters. Helper virus-free vector stocks were delivered into Postrhinal Cortex, and the rats were sacrificed 4 days or 2 months later. The PAG or VGLUT1 promoters supported approximately 90% glutamatergic neuron-specific expression. The GAD67 promoter supported approximately 90% GABAergic neuron-specific expression. Long-term expression was observed using each promoter. Principles for obtaining long-term expression from HSV-1 vectors, based on these and other results, are discussed. Long-term glutamatergic or GABAergic neuron-specific expression may benefit specific experiments on learning or specific gene therapy approaches. Of note, promoter analyses might identify regulatory elements that determine a glutamatergic or GABAergic neuron.
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A tyrosine hydroxylase-neurofilament chimeric promoter enhances long-term expression in rat forebrain neurons from helper virus-free HSV-1 vectors.
Molecular Brain Research, 2000Co-Authors: Guorong Zhang, Xiaodan Wang, T Yang, M Sun, W Zhang, Y Wang, Alfred I GellerAbstract:Helper virus-free herpes simplex virus (HSV-1) plasmid vectors are attractive for neural gene transfer, but a promoter that supports neuronal-specific, long-term expression is required. Although expression from many promoters is unstable, a 6.8-kb, but not a 766-bp, fragment of the tyrosine hydroxylase (TH) promoter supports long-term expression. Thus, 5′ upstream sequences in this promoter may enhance expression. In this study, we evaluated expression from vectors that contain 5′ upstream sequences from this promoter (−0.5 to −6.8 kb) inserted at the 5′ end of either a neurofilament heavy subunit (NF-H) promoter or the cytomegalovirus (CMV) immediate early promoter. The TH-NFH promoter supported expression for 6 months in the striatum, 2 months in the hippocampus, and for 1 month in both perirhinal and Postrhinal Cortex (the longest time points examined). Expression was targeted to neurons. The enhanced expression may require specific sequences in the TH promoter fragment because replacing this fragment with a similar sized fragment of bacteriophage λ DNA did not enhance expression. The reverse orientation of the TH promoter fragment also enhanced expression. Insertion of insulators from the chicken β-globin locus between the TH-NFHlac transcription unit and the vector backbone may support a modest additional enhancement in expression. Other eucaryotic sequences may also enhance expression; a S. cerevisiae (40-kb fragment)-NFH promoter enhanced expression. In contrast, the TH-CMV promoter did not enhance expression. Thus, the TH-NFH promoter may support some physiological studies that require long-term expression in forebrain neurons.
Timothy J Bussey - One of the best experts on this subject based on the ideXlab platform.
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Cortex and Hippocampal Lesions on Tests of Object Recognition and Spatial Memory: Heterogeneity of Function within the Temporal Lobe
2013Co-Authors: Boyer D Winters, Suzanna E Forwood, Rosemary A Cowell, Lisa M Saksida, Timothy J BusseyAbstract:It is widely believed that declarative memory is mediated by a medial temporal lobe memory system consisting of several distinct structures, including the hippocampus and perirhinal Cortex. The strong version of this view assumes a high degree of functional homogeneity and serial organization within the medial temporal lobe, such that double dissociations between individual structures should not be possible. In the present study, we tested for a functional double dissociation between the hippocampus and peri-Postrhinal Cortex in a single experiment. Rats with bilateral excitotoxic lesions of either the hippocampus or peri-Postrhinal Cortex were assessed in tests of spatial memory (radial maze) and object recognition memory. For the latter, the spontaneous object recognition task was conducted in a modified apparatus designed to minimize the potentially confounding influence of spatial and contextual factors. A clear functional double dissociation was observed: rats with hippocampal lesions were impaired relative to controls and those with periPostrhinal Cortex lesions on the spatial memory task, whereas rats with peri-Postrhinal lesions were impaired relative to the hippocampal and control groups in object recognition. These results provide strong evidence in favor of heterogeneity and independence of function within the temporal lobe. Key words: hippocampus; medial temporal lobe; object recognition memory; perirhinal Cortex; radial maze; rat; memor
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double dissociation between the effects of peri Postrhinal Cortex and hippocampal lesions on tests of object recognition and spatial memory heterogeneity of function within the temporal lobe
The Journal of Neuroscience, 2004Co-Authors: Boyer D Winters, Suzanna E Forwood, Rosemary A Cowell, Lisa M Saksida, Timothy J BusseyAbstract:It is widely believed that declarative memory is mediated by a medial temporal lobe memory system consisting of several distinct structures, including the hippocampus and perirhinal Cortex. The strong version of this view assumes a high degree of functional homogeneity and serial organization within the medial temporal lobe, such that double dissociations between individual structures should not be possible. In the present study, we tested for a functional double dissociation between the hippocampus and peri-Postrhinal Cortex in a single experiment. Rats with bilateral excitotoxic lesions of either the hippocampus or peri-Postrhinal Cortex were assessed in tests of spatial memory (radial maze) and object recognition memory. For the latter, the spontaneous object recognition task was conducted in a modified apparatus designed to minimize the potentially confounding influence of spatial and contextual factors. A clear functional double dissociation was observed: rats with hippocampal lesions were impaired relative to controls and those with periPostrhinal Cortex lesions on the spatial memory task, whereas rats with peri-Postrhinal lesions were impaired relative to the hippocampal and control groups in object recognition. These results provide strong evidence in favor of heterogeneity and independence of function within the temporal lobe.
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Intact negative patterning in rats with fornix or combined perirhinal and Postrhinal Cortex lesions.
Experimental brain research, 2000Co-Authors: Timothy J Bussey, Rebecca Dias, Edward S. Redhead, John M. Pearce, Janice L. Muir, John Patrick AggletonAbstract:It has been proposed that the hippocampal formation is necessary for the acquisition of tasks that require the use of configural representations for their solution, including spatial learning and negative patterning. Tests of this influential view have, however, yielded conflicting results. For example fornix or hippocampal lesions, which reliably impair spatial learning, do not reliably impair negative patterning. A problem in interpreting these results has been the lack of controls for factors such as over-responding, excitatory effects of reward, and the possibility of non-configural solutions. At the same time, other studies have pointed to a role in configural learning for parahippocampal regions such as the perirhinal Cortex. The present experiments controlled for the above factors and revealed that neither lesions of the fornix nor of the perirhinal/Postrhinal Cortex in the rat had any effect on negative patterning, although subsequent tests of object and spatial memory demonstrated the functional efficacy of the lesions.
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functionally dissociating aspects of event memory the effects of combined perirhinal and Postrhinal Cortex lesions on object and place memory in the rat
The Journal of Neuroscience, 1999Co-Authors: Timothy J Bussey, Janice L. Muir, John Patrick AggletonAbstract:Reciprocal interactions between the hippocampus and the perirhinal and parahippocampal cortices form core components of a proposed temporal lobe memory system. For this reason, the involvement of the hippocampus in event memory is thought to depend on its connections with these cortical areas. Contrary to these predictions, we found that NMDA-induced lesions of the putative rat homologs of these cortical areas (perirhinal plus Postrhinal cortices) did not impair performance on two allocentric spatial tasks highly sensitive to hippocampal dysfunction. Remarkably, for one of the tasks there was evidence of a facilitation of performance. The same cortical lesions did, however, disrupt spontaneous object recognition and object discrimination reversal learning but spared initial acquisition of the discrimination. This pattern of results reveals important dissociations between different aspects of memory within the temporal lobe. Furthermore, it shows that the perirhinal–Postrhinal Cortex is not a necessary route for spatial information reaching the hippocampus and that object familiarity–novelty detection depends on different neural substrates than do other aspects of event memory.
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Functionally dissociating aspects of event memory: The effects of combined perirhinal and Postrhinal Cortex lesions on object and place memory in the rat
1999Co-Authors: Timothy J Bussey, John Patrick Aggleton, Janice L. Muir, Alison Baird, Angie MorganAbstract:Reciprocal interactions between the hippocampus and the perirhinal and parahippocampal cortices form core components of a proposed temporal lobe memory system. For this reason, the involvement of the hippocampus in event memory is thought to depend on its connections with these cortical areas. Contrary to these predictions, we found that NMDAinduced lesions of the putative rat homologs of these cortical areas (perirhinal plus Postrhinal cortices) did not impair performance on two allocentric spatial tasks highly sensitive to hippocampal dysfunction. Remarkably, for one of the tasks there was evidence of a facilitation of performance. The same cortical lesions did, however, disrupt spontaneous object recognition and object discrimination reversal learning but spared initial acquisition of the discrimination. This pattern of results reveals important dissociations between different aspects of memory within the temporal lobe. Furthermore, it shows that the perirhinal-Postrhinal Cortex is not a necessary route for spatial information reaching the hippocampus and that object familiaritynovelty detection depends on different neural substrates than do other aspects of event memory. Processing of a complex event memory likely involves the association of information from multiple brain regions. One such contributing region may be the perirhinal -parahippocampal Cortex Contrary to these predictions, some studies have revealed dissociations between fornix and perirhinal Cortex lesions MATERIALS AND METHODS Surgical and histological methods Fifteen adult male rats (DA strain; Bantin-K ingman, Hull, UK) received bilateral injections of NMDA in five sites in the PPRH Cortex. This PPRH group was compared with 13 control (C ON T) rats that received sham surgeries. All animals were deeply anesthetized by intraperitoneal injection (60 mg / kg) of pentobarbitone sodium (Sagatal, Rhône Mérieux) and then placed in a stereotaxic head holder (David Kopf Instruments, T ujunga, CA) with the nose bar at ϩ5.0. The scalp was then cut and retracted to expose the skull. For the PPRH lesion, injections of 0.2 l of 0.09 M NMDA (Sigma, Poole, UK) dissolved in phosphate buffer, pH 7.2, were made through a 1 l Hamilton syringe into five sites in each hemisphere. Each injection was made gradually over a 5 min period, and the needle was left in situ for an additional 4 min before being withdrawn. The stereotaxic coordinates relative to ear-bar zero were a
David J Bucci - One of the best experts on this subject based on the ideXlab platform.
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Toward a conceptualization of retrohippocampal contributions to learning and memory.
Neurobiology of learning and memory, 2014Co-Authors: David J Bucci, Siobhan RobinsonAbstract:A wealth of data supports the notion that the hippocampus binds objects and events together in place and time. In support of this function, a cortical circuit that includes the retrosplenial Cortex (RSC) and various structures in the parahippocampal region is thought to provide the hippocampus with essential information regarding the physical and temporal context in which the object/event occurs. However, it remains unclear if and how individual components of this so-called ‘where’ circuit make unique contributions to processing context-related information. Here we focus on the RSC and the Postrhinal Cortex (POR; homologous with parahippocampal Cortex (PHC) in primates), two of the most strongly interconnected components of the where pathway and the foci of an increasing amount of recent research. Much of the behavioral evidence to date suggests that RSC and POR/PHC work closely together as a functional unit. We begin by briefly reviewing studies that have investigated the involvement of RSC and POR/PHC in contextual and spatial learning, both of which involve learning associations and relationships between the individual stimuli that compose an environment (i.e., where information). However, we propose that potential differences have been overlooked because most studies to date have relied on behavioral paradigms and experimental approaches that are not well suited for distinguishing between different aspects of information processing. We then consider the anatomical differences between RSC and POR/PHC and emerging behavioral evidence that gives rise to a working model of how these regions may differentially contribute to hippocampal-dependent learning and memory. We then discuss experimental designs and behavioral methods that may be useful in testing the model. Finally, approaches are described that may be valuable in probing the nature of information processing and neuroplasticity in the myriad of local circuits that are nested within the where pathway.
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Behavioral/Systems/Cognitive Corticohippocampal Contributions to Spatial and Contextual Learning
2013Co-Authors: Rebecca D Burwell, David J Bucci, Michael P. Saddoris, Kjesten A. WiigAbstract: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
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contributions of the retrosplenial and posterior parietal cortices to cue specific and contextual fear conditioning
Behavioral Neuroscience, 2008Co-Authors: Christopher S Keene, David J BucciAbstract:The retrosplenial Cortex (RSP) and the posterior parietal Cortex (PPC) are the primary sources of cortical sensory input to the Postrhinal Cortex (POR) in rodents. Together, these areas compose a major corticohippocampal circuit that is involved in processing visuospatial information. The POR has been implicated in contextual learning and memory, consistent with the type of information presumably being processed by this region. By comparison, little is known about the role of the RSP or the PPC in contextual learning. In the present study, rats were trained either before or after surgery in a standard signaled fear conditioning task in which an auditory cue was paired with foot shock. Contextual fear and tone-specific fear were assessed in subsequent test sessions. In Experiment 1, electrolytic damage to the RSP either before or immediately after training impaired the expression of contextual fear but not tone-specific fear. In contrast, electrolytic damage to the PPC had no effect on conditional fear to the context or the tone in Experiment 2. These findings indicate that the RSP, but not the PPC, contributes to the processing of contextual information by the POR corticohippocampal processing stream.
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contributions of Postrhinal and perirhinal Cortex to contextual information processing
Behavioral Neuroscience, 2000Co-Authors: David J Bucci, Russell G Phillips, Rebecca D BurwellAbstract:The role of the Postrhinal Cortex (POR) and the perirhinal Cortex (PER) in processing relational or contextual information was examined with Pavlovian fear conditioning. Rats with electrolytic or neurotoxic lesions of the POR or PER were tested in 2 contextual fear conditioning paradigms. In Experiment 1, electrolytic lesions of the POR or PER produced impairments in contextual fear conditioning but not in conditioning to a phasic auditory conditioned stimulus. Neurotoxic lesions of the POR or PER likewise resulted in anterograde (Experiment 2) and retrograde (Experiment 3) deficits in fear conditioning to the training context in an unsignaled shock paradigm. The results suggest that operations performed on sensory information by the POR and PER are necessary to support contextual learning.
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contributions of Postrhinal and perirhinal Cortex to contextual information processing
Behavioral Neuroscience, 2000Co-Authors: David J Bucci, Russell G Phillips, Rebecca D BurwellAbstract:The role of the Postrhinal Cortex (POR) and the perirhinal Cortex (PER) in processing relational or contextual information was examined with Pavlovian fear conditioning. Rats with electrolytic or neurotoxic lesions of the POR or PER were tested in 2 contextual fear conditioning paradigms. In Experiment 1, electrolytic lesions of the POR or PER produced impairments in contextual fear conditioning but not in conditioning to a phasic auditory conditioned stimulus. Neurotoxic lesions of the POR or PER likewise resulted in anterograde (Experiment 2) and retrograde (Experiment 3) deficits in fear conditioning to the training context in an unsignaled shock paradigm. The results suggest that operations performed on sensory information by the POR and PER are necessary to support contextual learning. (PsycInfo Database Record (c) 2021 APA, all rights reserved).