Standing still: Is there a role for the cortex?

In humans, standing still appears so automatic that high-level cortical processes seem unnecessary. However, by measuring cortical activity time-locked to reactive control events arising from naturally occurring instability while standing still, we detected cortical involvement in the form of an evoked N1 potential prior to the onset of balance reactions. Peak amplitude and spectral power of this event-related activity increased as postural challenges and demand for reactive control increased.