Sleep and spatial memory consolidation: a role for replay in hippocampal place cell assemblies?

Bezema, S.M.C. (2013) Sleep and spatial memory consolidation: a role for replay in hippocampal place cell assemblies? Bachelor's Thesis, Biology.

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Abstract

In this thesis, the role of sleep in spatial memory consolidation is investigated. The two stage model of memory consolidation predicts that memories acquired during the waking period are rapidly encoded by the hippocampus, and consolidated (i.e. strengthened and integrated) throughout the sleeping period. The consolidation process is thought to involve the reactivation of recently encoded memory traces in the hippocampus during slow-wave sleep (SWS), a sleep stage in which highly synchronous activity patterns termed sharp-wave ripples (SWRs) are most prominently observed. These SWR events might provide the optimal conditions for neuronal plasticity and communication between the hippocampus and other brain areas to take place, thereby facilitating the consolidation process. SWR-related reactivation has been observed in place cell assemblies in the CA3 and CA1 areas of the rodent hippocampus. Throughout SWS, the firing patterns observed during spatial navigation and exploration in place cell assemblies are sequentially reactivated in a temporally conserved manner during SWRs. This reactivation is thought to reflect the “replay” of recently encoded memories, and occurs in a compressed timescale, which puts the synaptic activity during replay within the timeframe of long-term potentiation. Thus, replay provides a possible neural mechanism for memory consolidation during sleep. However, SWR-associated replay is also observed during extended periods of inactivity during waking (i.e. “quiet wakefulness”), and it is accordingly thought that these instances of replay reflect consolidation as well. This suggests that consolidation of spatial memories is an opportunistic process that takes place whenever the brain is not primarily preoccupied with encoding new memories. While this opportunistic account of consolidation is not directly at odds with the two-stage model of memory consolidation, it does provide an important addition to the current theoretical framework, and deepens our understanding of the consolidation process and the role for sleep in spatial memory consolidation.

Item Type:	Thesis (Bachelor's Thesis)
Degree programme:	Biology
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	15 Feb 2018 07:54
Last Modified:	15 Feb 2018 07:54
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/11243

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