Artikel
Early thalamocortical phase synchronization entrains gamma oscillations during human long-term memory retrieval
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Veröffentlicht: | 4. Juni 2012 |
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Gliederung
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Objective: The thalamus is believed to be a key node in human memory networks, however, very little is known about its real-time functional role. Here we examined the real-time dynamics of thalamocortical communication during human long-term episodic memory retrieval.
Methods: We recorded intrathalamic and surface EEG during a recognition memory test from an epileptic patient implanted with depth electrodes for brain stimulation therapy.
Results: Early (300–500 ms) stimulus-linked oscillatory synchrony between dorsomedial thalamic and frontal surface electrodes at beta frequency (20 Hz) was enhanced for remembered old compared to new recognition test items. Measures of directionality (Granger causality) and cross-frequency coupling indicated that the thalamus was the sender, and the neocortex the receiver, of this beta signal, which also modulated the power of neocortical gamma (55–80 Hz) oscillations.
Conclusions: Together with anatomical data on thalamic connectivity with frontal neocortex, these results suggest that the thalamus sends an early memory signal to frontal regions, triggering further memory search processes. Characterizing the functional role of the thalamus in memory may be of importance for understanding possible cognitive effects of deep brain stimulation therapy at thalamic sites.