PEEF: Premotor Ear-Eye Field. A New Vista of Area 8B

In macaque monkeys, area 8B may be considered cytoarchitectonically as atransitional area between the granular area 9, rostrally, and the rostral part of the dorsalagranular area 6 (FC or F7), caudally. This area is anatomically connected with auditorycortical areas, cerebellum and superior colliculus. Microstimulation of area 8B evokesear movements or eye movements in some sites; in other sites, it evokes both ear and eyemovements by varying the intensity of electric stimulation. Unit activity recording showsthat neurons in area 8B have a role in encoding different auditory environmental stimuliand movements of the ear and eye. In addition, fixation of a visual stimulus, whenattention is engaged, modulates the discharge of auditory environmental neurons, andsensory-motor neurons.Current functional and anatomical evidences strongly support the proposal that area8B is a specific Premotor Ear-Eye Field (PEEF) involved in the recognition of auditorystimuli and in orienting processes. Moreover, activation by specific environmentalauditory stimuli, suggests that PEEF is an important node in the hierarchical organisationof the auditory network. The inhibitory effects on neural discharge of auditory andauditory-motor cells might be a consequence of the engagement of attention duringvisual fixation. This phenomenon may be the expression of a combination of a covertorienting of attention relative to eye effectors, and an overt orienting of attention relativeto ear effectors. It seems that attention may affect more than one channel at the same timeduring a conditioned task or during natural behaviour. Then the PEEF, based on itsconnections and functional characteristics may be involved in three circuits: 1) anauditory circuit, 2) an oculomotor circuit, 3) and a fronto-cerebellar circuit