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Title: The plasticity potential of structured neural activity in the hippocampus
Author: Sadowski, Josef H. L. P.
ISNI:       0000 0004 5917 1680
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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Spatial information coding and synaptic plasticity are two well characterised features of hippocampal physiology, but relatively little is understood about how the two interact. Recently active place cell firing sequences are replayed during rest and sleep. In quiet rest, replay events coincide with transient, high-frequency network oscillations known as sharp-wave ripples (SWRs). SWR-associated place cell firing sequences occur over faster timescales than those observed during behaviour. It is hypothesised that these time compressed spiking events could enable synaptically coupled place cells to enhance their connectivity by engaging spike-timing-dependant plasticity (STOP) mechanisms. In this thesis I present data I obtained using a combination of in vivo and in vitro electrophysiological recordings in the rodent hippocampus which aimed to directly test this hypothesis. I recorded place cell firing patterns during rest epochs following behaviour, and used them to stimulate synapses in acute hippocampal slices. My data demonstrate a potentially crucial role for SWRs not only in triggering place cell reactivation but also in facilitating STOP at mature Schaffer collateral synapses. The process relies on the additional high-frequency synaptic input that CA 1 pyramidal cells are known to receive during SWRs. This input produces a transient depolarisation of the cell membrane. Reproducing this depolarisation by somatic current injection has no effect, suggesting that the integration of excitatory inputs in the apical dendritic tree is a vital factor mediating this form of synaptic plasticity. These data provided tangible evidence to support the theory that SWR-associated replay could play an important role in the consolidation of hippocampal-dependent memory.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available