PHASE-TRANSITIONS IN SPATIOTEMPORAL PATTERNS OF BRAIN ACTIVITY AND BEHAVIOR

Spatial patterns of brain electrical activity from 61 electrodes were recorded during a sensorimotor coordination task. Subjects were required to syncopate finger movement with a series of auditory stimuli whose rate of presentation was systematically increased as a control parameter. Spontaneous transitions from syncopated to synchronized behavior were accompanied by transitions in electroencephalographic (EEG) signals as calculated from relative phase measures. The transition was most prominent at left central and antero-central scalp sites. Fluctuations in relative phase in both the behavior and brain activity increased systematically before the transition, indicating the presence of dynamic pattern forming instabilities on both levels of observation.