Gamma-band EEGs predict autonomic responses during mental arithmetic.

Relationship between gamma-band (20-80 Hz) EEGs and autonomic functions (heart rate, blood pressure, instantaneous lung flow) in a mental arithmetic task (MAT) were investigated. Subjects were instructed to add 2 integers after presentation of audio voices indicating the integers in the MAT, and to listen to the same voices without mental arithmetic in the control task. The gamma-EEGs and autonomic functions coherently changed in response to the voices before mental arithmetic in the MAT. Furthermore, an increase in gamma-EEGs went ahead of the autonomic fluctuation. The results suggest that the gamma-band activity modulates and adjusts peripheral autonomic functions in advance before actual mental activity. This is the first demonstration that cortical gamma-band activity triggers peripheral autonomic responses during mental activity.