Localization of human frontal eye fields: anatomical and functional findings of functional magnetic resonance imaging and intracerebral electrical stimulation

Object. The goal of this study was to investigate the anatomical localizati on and functional role of human frontal eye fields (FEFs) by comparing find ings from two independently conducted studies. Methods. In the first study, 3-tesla functional magnetic resonance (fMR) im aging was performed in 14 healthy volunteers divided into two groups: the f irst group executed self-paced voluntary saccades in complete darkness and the second group repeated newly learned or familiar sequences of saccades. In the second study, intracerebral electrical stimulation (IES) was perform ed in 38 patients with epilepsy prior to surgery, and frontal regions where stimulation induced versive eye movements were identified. These studies s howed that two distinct oculomotor areas (OMAs) could be individualized in the region classically corresponding to the FEFs. One OMA was consistently located at the intersection of the superior frontal sulcus with the fundus of the superior portion of the precentral sulcus, and was the OMA in which saccadic eve movements could be the most easily elicited by electrical stim ulation. The second OMA was located more laterally, close to the surface of the precentral gyrus. The fMR imaging study and the DES study demonstrated anatomical ana stereotactic agreement in the identification of these corti cal areas. Conclusions. These findings indicate that infracentimetric localization of cortical areas can be achieved by measuring the vascular signal with the ai d of 3-tesla fMR imaging and that neuroimaging and electrophysiological rec ording can be used together to obtain a better understanding of the human c ortical functional anatomy.