Saccades are phase-locked to alpha oscillations in the occipital and medial temporal lobe during successful memory encoding.

Tobias Staudigl,Ole Jensen,Elisabeth Hartl,Christian F Doeller,Soheyl Noachtar,Frank Tong

doi:10.1371/journal.pbio.2003404

Abstract

Efficient sampling of visual information requires a coordination of eye movements and ongoing brain oscillations. Using intracranial and magnetoencephalography (MEG) recordings, we show that saccades are locked to the phase of visual alpha oscillations and that this coordination is related to successful mnemonic encoding of visual scenes. Furthermore, parahippocampal and retrosplenial cortex involvement in this coordination reflects effective vision-to-memory mapping, highlighting the importance of neural oscillations for the interaction between visual and memory domains.

Highlights

Sampling of visual information has been shown to be rhythmic rather than continuous [1,2,3]
The present study provides novel evidence for how this coordination is achieved at the neuronal level, from 2 independent data sets: direct brain recordings in epileptic patients and noninvasive magnetoencephalography recordings in healthy participants
Both studies showed that eye movements are locked to the phase of alpha oscillations—synchronous and coherent neuronal electrical activity at 7–14 Hz—just prior to a saccade, i.e., a rapid eye movement that abruptly changes the point of fixation

Summary

Introduction

Sampling of visual information has been shown to be rhythmic rather than continuous [1,2,3]. We ask how brain oscillations and saccades are coordinated in order to allow visual information to be encoded in memory areas. We addressed this question by tracking eye movements in separate memory experiments involving MEG in healthy adults and intracranial recordings in epileptic patients (Fig 1). Building on prior evidence on the cortical origins of alpha activity underlying visual information sampling [8,9], we hypothesized that higher phase locking in occipital lobe would be related to successful memory performance. MEG and intracranial data both showed that eye movements are locked to the phase of alpha oscillations prior to a saccade This coordination was related to successful memory encoding

Methods

Results

Discussion

Conclusion