Changes in contingent-negative variation and reaction time related to precueing of direction and force of a forearm...

Scalp-recorded contingent-negative variation was analyzed in a reaction time paradigm with full, partial, or no prior information regarding two dimensions of a forearm response: direction (flexion/extension) and force level (weak/strong). Visual cues (light-emitting diodes) were used for the warning and response signals. The reaction time was shorter when direction, rather than force, was known in advance. Source derivation techniques revealed that the somatosensory arm area was more 'activated' by direction than force information, whereas the precentral cortex seemed to be more strongly influenced by force information. Partial advance information was sufficient to trigger preparatory activities specific for the revealed dimension of the ensuing movement.