Traveling waves appear and disappear in unison with produced speech

TL;DR

This study reveals that traveling waves in brain activity are synchronized with speech production, appearing before and disappearing after consonant-vowel syllables, and reversing during silence, indicating a close link between neural waves and speech behavior.

Contribution

First demonstration of traveling waves related to speech production and their behavioral correlates in humans, showing precise timing with speech syllables.

Findings

TWs appear before CVS initiation

TWs disappear before CVS termination

TWs reverse during silence periods

Abstract

In Rapela (2016) we reported traveling waves (TWs) on electrocorticographic (ECoG) recordings from an epileptic subject over speech processing brain regions, while the subject rhythmically produced consonant-vowel syllables (CVSs). In Rapela (2017) we showed that TWs are precisely synchronized, in dynamical systems terms, to these productions. Here we show that TWs do not occur continuously, but tend to appear before the initiation of CVSs and tend to disappear before their termination. During moments of silence, between productions of CVSs, TWs tend to reverse direction. To our knowledge, this is the first study showing TWs related to the production of speech and, more generally, the first report of behavioral correlates of mesoscale TWs in behaving humans.