Rhythmic fluctuations in mnemonic signatures during associative recall

Kerrén, Casper (2020). Rhythmic fluctuations in mnemonic signatures during associative recall. University of Birmingham. Ph.D.

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Abstract

The intricate linking of information processing and neural representations to the underlying hippocampal neural rhythms during episodic memory retrieval are yet to be fully explored in human subjects. In this doctoral thesis, the temporal order of these relationships was investigated, with emphasis on how the processes evolve and take place over time. Empirical evidence and neural network models suggest that hippocampus and the hippocampal theta rhythm play a central role in episodic memory. In the first two studies, different oscillatory dynamics in the hippocampal circuit thought to provide optimal states for encoding and retrieval were investigated. The third study investigated the role of the hippocampal theta oscillation as an adaptive mechanism in regulating competition between similar memories. And lastly, the fourth study investigated sharp-wave ripples in promoting successful episodic memory retrieval. Throughout the four chapters, memory content was decoded using multivariate pattern classification, and the timing of memory reactivation was linked to two prominent oscillatory brain signatures: the hippocampal theta rhythm on the one hand, and hippocampal sharp-wave ripples on the other. In sum, this doctoral thesis provides support for the powerful computations along the hippocampal theta oscillation, and the close interplay between hippocampus and neocortical areas, foremost at time of retrieval

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):