SACCADES INDUCED ELECTRICALLY FROM THE DORSOMEDIAL FRONTAL-CORTEX - EVIDENCE FOR A HEAD-CENTERED REPRESENTATION

The amplitude and direction of saccadic eye movements evoked electrica lly from the dorsomedial frontal cortex (DMFC) of monkeys vary with st arting eye position. This observation has been used to argue that the DMFC codes saccadic eye movements in head-centered coordinates. Whethe r the amplitude and direction of the evoked saccades are also affected by changes in head position has never been demonstrated. Such a resul t would argue against a head-centered representation, and instead woul d suggest a representation anchored to another body part. Tests were c onducted on rhesus monkeys to determine whether changing the position of the head with respect to the trunk or changing the position of the head with respect to the gravitational axis alters saccadic parameters . The amplitude and direction of saccadic eye movements remained invar iant to such manipulations. These findings confirm the claim that the DMFC encodes saccadic eye movements in head-centered coordinates. (C) 1998 Elsevier Science B.V. All rights reserved.