Intracranial electrophysiological recordings of human orbitofrontal responses to emotional stimuli

The orbitofrontal cortex involvement in processing facial expressions as its role in affective processing has been reported in numerous electrophysiological and functional neuroimaging studies. However, the literature does not provide precise data on the temporal course of emotional facial expressions processing. Intracranial event-related potentials were recorded in epileptic patients implanted with depth electrodes during a presurgical evaluation. Patients had to perform a gender judgement task while viewing fearful, happy and neutral high-spatial-frequency (HSF), low-spatial-frequency (LSF) and broadband face stimuli. Orbitofrontal responses were observed to all emotions and to all spatial frequency contents with latencies between 100 and 200 ms post-stimulus. This study shed light on the temporal course of the facial emotions information processing and on the involvement of the orbitofrontal cortex in the neural network recruited to process emotional information