Extended and Distant Cortical Areas Coordinate Their Oscillations Approaching the Instant of Decision Making During Recognition of Words

By measuring magnetic signals of the brain during recognition of spoken words, we have found that several large neural populations in the cortex start to oscillate in concert before the subject makes a decision about which word was heard. This coordination takes place for several cycles of basic oscillatory activity and the events differ in the number, relative amplitude and shape of the cycles and their duration. We observe nine functional groups which are active during 40 words long recognition task. However, only some of them produce high amplitude signals when a single word is recognized. For every new word, a new combination of neural clusters is formed. Such measurements imply that nearly the whole rear part of the brain cortex is involved in the word recognition process.