41 © Springer Nature Switzerland AG 2021 E. Mandonnet, G. Herbet (eds.), Intraoperative Mapping of Cognitive Networks, https://doi.org/10.1007/978-3-030-75071-8_3 G. Herbet (*) Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier & Institute of Functional Genomics, University of Montpellier, INSERM, CNRS, Montpellier, France e-mail: guillaume.herbet@igf.cnrs.fr 3 Frontal Eye Fields Guillaume Herbet 3.1 Anatomy and Connectivity of FEFs 3.1.1 Physiological Definition and Brief Historical Background The frontal eye feld is defned physiologically as a restrict area of the primate’s posterior prefrontal cortex whose low-intensity electrostimulation is associated with involuntary ocular movements [1, 2]. Such observation go back far into the past; indeed, David Ferrier [3] was the frst to report that, in some animals (includ- ing monkeys), stimulating an area situated in the posterior half of the superior and middle frontal cortex caused head and eye movements to the opposite side as well as dilatation of pupils in some cases. Since that time, the fnding of a frontal ocular area has been widely replicated, frst in lower and higher primates (e.g., [4, 5]) and then in humans in the context of neurosurgery. On the latter point, Foerster [6, 7] found conjugate horizontal deviation of the eyes to the opposite side, and sometimes upward deviation, in response to stimulation of the posteriormost portion of the middle frontal gyrus. Likewise, Penfeld and collaborators [8, 9] not only confrmed that applying stimulation on the posterior part of the dorsolateral prefrontal cortex (caudal part of the mid-lateral area according to the authors) caused “adversive movements” of the eyes toward and upward the hemisphere contralateral to the stimulation, but also reported that epileptic discharges in areas situated in or in the vicinity of the ocular frontal areas replicated some of the clinical observations evoked during stimulation, including eye movements [10]. Penfeld and associates also identifed eye-related areas in other frontal structures, including the precentral gyrus [9].