Hippocampal theta oscillations support successful associative memory formation

Kota, Srinivas, Rugg, Michael D. and Lega, Bradley C. (2020) Hippocampal theta oscillations support successful associative memory formation. The Journal of Neuroscience, 40 (49). pp. 9507-9518. ISSN 0270-6474

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Models of memory formation posit that episodic memory formation depends critically on the hippocampus, which binds features of an event to its context. For this reason, the contrast between study items that are later recollected with their associative pair versus those for which no association is made should reveal electrophysiological patterns in the hippocampus selectively involved in associative memory encoding. Extensive data from studies in rodents support a model in which theta oscillations fulfill this role, but results in humans have not been as clear. Here, we used an associative recognition memory procedure to identify hippocampal correlates of successful associative memory encoding and retrieval in patients (10 females and 9 males) undergoing intracranial EEG monitoring. We identified a dissociation between 2–5 Hz and 5–9 Hz theta oscillations, by which power increases in 2–5 Hz oscillations were uniquely linked with successful associative memory in both the anterior and posterior hippocampus. These oscillations exhibited a significant phase reset that also predicted successful associative encoding and distinguished recollected from nonrecollected items at retrieval, as well as contributing to relatively greater reinstatement of encoding-related patterns for recollected versus nonrecollected items. Our results provide direct electrophysiological evidence that 2–5 Hz hippocampal theta oscillations preferentially support the formation of associative memories, although we also observed memory-related effects in the 5–9 Hz frequency range using measures such as phase reset and reinstatement of oscillatory activity.

Item Type: Article
Uncontrolled Keywords: associative recognition,episodic memory,hippocampus,intracranial electroencephalography,neuroscience(all) ,/dk/atira/pure/subjectarea/asjc/2800
Faculty \ School: Faculty of Social Sciences > School of Psychology
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Depositing User: LivePure Connector
Date Deposited: 21 Jan 2021 00:55
Last Modified: 22 Oct 2022 07:40
URI: https://ueaeprints.uea.ac.uk/id/eprint/78244
DOI: 10.1523/JNEUROSCI.0767-20.2020

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