STIMULATION-EVOKED SACCADES FROM THE DORSOMEDIAL FRONTAL-CORTEX OF THE RHESUS-MONKEY FOLLOWING LESIONS OF THE FRONTAL EYE FIELDS AND SUPERIOR COLLICULUS
Ej. Tehovnik et al., STIMULATION-EVOKED SACCADES FROM THE DORSOMEDIAL FRONTAL-CORTEX OF THE RHESUS-MONKEY FOLLOWING LESIONS OF THE FRONTAL EYE FIELDS AND SUPERIOR COLLICULUS, Experimental Brain Research, 98(2), 1994, pp. 179-190
This study examined whether signals for the generation of eye movement
s from the dorsomedial frontal cortex (DMFC) reach brainstem oculomoto
r centers either through the frontal eye fields (FEF) or through the s
uperior colliculi (SC). The DMFC was stimulated when the monkeys studi
ed were intact and after either one FEF or one SC was ablated. Followi
ng lesions of either the FEF or SC, the topographic order of the DMFC
was largely preserved. After either lesion, stimulation of anterior DM
FC sites still evoked saccades that terminated in contralateral space,
and stimulation of posterior DMFC sites still evoked saccades that te
rminated in central space. The probability of evoking saccades decreas
ed and the latency to evoke saccades increased as fixation neared the
termination zone (a restricted region within craniotopic space) both b
efore and after either lesion. Ablation of the SC. but not of the FEF,
eliminated the saccadic inhibition to visual targets which resulted w
hen the DMFC was stimulated in the intact animal. The findings suggest
that additional channels besides those coursing through the FEF and S
C are utilized by the DMFC to access the saccade generator in the brai
nstem.