TitleThe functional anatomy of hippocampal theta and gamma oscillations
NameMontgomery, Sean M. (author), Tepper, James (chair), Pare, Denis (internal member), Harris, Kenneth (internal member), Buzsaki, Gyorgy (internal member), Kahana, Michael (outside member), Rutgers University, Graduate School - Newark,
DescriptionThis dissertation investigated how theta (4-10Hz) and gamma (40-100Hz) oscillations are coordinated across different hippocampal subnetworks during different behaviors. Using 96-site silicon probes to simultaneously record local field potentials (LFPs) and unit activity from dendritic and somatic layers of the dentate gyrus, CA3 and CA1 regions, I examined how local field potentials (LFPs) and unit activity changed the theta and gamma synchronization of hippocampal networks as a function of behavior. Specifically, I compared hippocampal activity of rats during performance of a hippocampus-dependent delayed spatial alternation task on a modified T-maze versus performance of non-mnemonic control tasks. I also compared hippocampal network activity during active waking behavior versus rapid eye movement (REM) sleep.
The first study examined how theta oscillations throughout the hippocampal subnetworks change during behavioral task performance. Although theta oscillations were generally highly coherent throughout the system, I found that the power, coherence and phase of theta oscillations fluctuated in a layer-specific manner, suggesting the presence of multiple interdependent dipoles. I also found layer-specific changes in theta power and coherence during different portions of both alternation and control tasks, as well as a decreased phase lag between CA3 and CA1 theta oscillations on the center arm of the T-maze compared to other segments of the alternation and control tasks.
The second study examined changes in hippocampal gamma oscillations during performance of the alternation and control tasks. This study found that on the center arm of the T-maze, the power and coherence of gamma oscillations at the CA3-CA1 interface increased compared to other segments in the alternation task or compared to control task segments.
The third study examined changes in theta and gamma coordination of hippocampal networks during active waking versus REM sleep. I found increased dentate/CA3 theta and gamma synchrony, but decreased CA3-CA1 gamma coordination during REM sleep. I also detected phasic bursts of LFP power in the dentate molecular layer that divided REM sleep into phasic and tonic periods. Although tonic periods characterized the majority of REM sleep epochs (~95%), phasic periods exhibited transient increases in theta and gamma coordination among all of the hippocampal subregions.
NoteIncludes bibliographical references (p. 124-148)
Noteby Sean M. Montgomery
CollectionGraduate School - Newark Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.