The neural basis of trajectory computations in rodent posterior parietal cortex and hippocampus

Persistent Link:
http://hdl.handle.net/10150/289869
Title:
The neural basis of trajectory computations in rodent posterior parietal cortex and hippocampus
Author:
Bower, Mark R.
Issue Date:
2003
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Space is a fundamental property of nature, so it is not surprising that the processing of spatial information involves many brain structures, including the posterior parietal cortex (PPC) and hippocampus. The PPC represents body position in multiple frames of reference, aligning the reference frames of different parts of the body to cooperate in the performance of a task. Hippocampal "place cells" increase their firing rates in specific locations, and place cell responses can be based on information encoded in multiple reference frames, including external, sensory-based reference frames or internal, memory-based frames. The computation of whole-body trajectories is common to all navigation tasks, but little is known about how this computation is performed. Rats were trained to run to distant targets that were presented either randomly or as segments of sequences. When rats were trained to make direct trajectories to distant targets that were presented in random order, no evidence was found that hippocampal place cells encoded distant goals. When rats learned a sequence of goals that contained a repeated segment, hippocampal place cell activity along the repeated segment remained the same. This showed that differential hippocampal codes were not required for rats to differentiate overlapping sequential contexts. Differential hippocampal codes could be formed, however, if rats learned sequences of goals under specific conditions, reflecting differential activity from neural structures outside the hippocampus. At the initiation of trajectories, the phase of hippocampal theta was reset at the peak acceleration of the rat. The activity of some parietal neurons was modulated by hippocampal theta, though the magnitude of modulation was not as great as that for hippocampal units, and the preferred firing phase of parietal units differed from that of theta-modulated place cells. Two classes of units in PPC responded differentially during the early and late stages of trajectories: one class with an increased firing rate during the early stages of trajectories, and the other with an increased firing rate during the late stages. These results provide a foundation for future studies of parieto-hippocampal interactions during trajectory planning.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Neuroscience.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Neuroscience
Degree Grantor:
University of Arizona
Advisor:
McNaughton, Bruce L.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleThe neural basis of trajectory computations in rodent posterior parietal cortex and hippocampusen_US
dc.creatorBower, Mark R.en_US
dc.contributor.authorBower, Mark R.en_US
dc.date.issued2003en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractSpace is a fundamental property of nature, so it is not surprising that the processing of spatial information involves many brain structures, including the posterior parietal cortex (PPC) and hippocampus. The PPC represents body position in multiple frames of reference, aligning the reference frames of different parts of the body to cooperate in the performance of a task. Hippocampal "place cells" increase their firing rates in specific locations, and place cell responses can be based on information encoded in multiple reference frames, including external, sensory-based reference frames or internal, memory-based frames. The computation of whole-body trajectories is common to all navigation tasks, but little is known about how this computation is performed. Rats were trained to run to distant targets that were presented either randomly or as segments of sequences. When rats were trained to make direct trajectories to distant targets that were presented in random order, no evidence was found that hippocampal place cells encoded distant goals. When rats learned a sequence of goals that contained a repeated segment, hippocampal place cell activity along the repeated segment remained the same. This showed that differential hippocampal codes were not required for rats to differentiate overlapping sequential contexts. Differential hippocampal codes could be formed, however, if rats learned sequences of goals under specific conditions, reflecting differential activity from neural structures outside the hippocampus. At the initiation of trajectories, the phase of hippocampal theta was reset at the peak acceleration of the rat. The activity of some parietal neurons was modulated by hippocampal theta, though the magnitude of modulation was not as great as that for hippocampal units, and the preferred firing phase of parietal units differed from that of theta-modulated place cells. Two classes of units in PPC responded differentially during the early and late stages of trajectories: one class with an increased firing rate during the early stages of trajectories, and the other with an increased firing rate during the late stages. These results provide a foundation for future studies of parieto-hippocampal interactions during trajectory planning.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Neuroscience.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineNeuroscienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMcNaughton, Bruce L.en_US
dc.identifier.proquest3089924en_US
dc.identifier.bibrecord.b44418085en_US
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