All talk? Challenging the use of left-temporal EEG alpha oscillations as valid measures of verbal processing and conscious motor control

This study tested the validity of EEG left-temporal alpha power and upper-alpha T7-Fz connectivity as indices of verbal activity and conscious motor control. Participants (n = 20) reached for, and transported, a jar under three conditions: a control condition and two self-talk conditions aimed at eliciting either task-unrelated verbal processing or task-related conscious control, while EEG and hand kinematics were recorded. Compared to the control condition, both self-talk conditions increased self-reported verbal processing, but only the task-related self-talk condition increased left-temporal activity (i.e., alpha power decreased). However, as cortical activity increased across the entire scalp topography, conscious control likely elicits a multitude of processes that may not be explained by left-temporal activity or verbal processing alone, but by a widespread decrease in neural efficiency. No significant effects for T7-Fz connectivity were detected. Results suggest that left-temporal EEG alpha oscillations are unlikely to uniquely reflect verbal processing during conscious motor control.