Theta phase synchronization is the glue that binds human associative memory

Clouter, A., Shapiro, K. L. and Hanslmayr, S. (2017) Theta phase synchronization is the glue that binds human associative memory. Current Biology, 27(20), 3143-3148.e6. (doi: 10.1016/j.cub.2017.09.001) (PMID:28988860)

Abstract

Episodic memories are information-rich, often multisensory events that rely on binding different elements [1]. The elements that will constitute a memory episode are processed in specialized but distinct brain modules. The binding of these elements is most likely mediated by fast-acting long-term potentiation (LTP), which relies on the precise timing of neural activity [2]. Theta oscillations in the hippocampus orchestrate such timing as demonstrated by animal studies in vitro [3, 4] and in vivo [5, 6], suggesting a causal role of theta activity for the formation of complex memory episodes, but direct evidence from humans is missing. Here, we show that human episodic memory formation depends on phase synchrony between different sensory cortices at the theta frequency. By modulating the luminance of visual stimuli and the amplitude of auditory stimuli, we directly manipulated the degree of phase synchrony between visual and auditory cortices. Memory for sound-movie associations was significantly better when the stimuli were presented in phase compared to out of phase. This effect was specific to theta (4 Hz) and did not occur in slower (1.7 Hz) or faster (10.5 Hz) frequencies. These findings provide the first direct evidence that episodic memory formation in humans relies on a theta-specific synchronization mechanism.

• Item Type: Articles
• Additional Information: This work was supported by a grant from the European Research Council (Consolidator Grant Agreement 647954) awarded to S.H., who is further supported by the Wolfson Society and the Royal Society.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hanslmayr, Professor Simon
• Authors: Clouter, A., Shapiro, K. L., and Hanslmayr, S.
• College/School: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Journal Name: Current Biology
• Publisher: Elsevier (Cell Press)
• ISSN: 0960-9822
• ISSN (Online): 1879-0445
• Published Online: 05 October 2017