The neural network sustaining the crossmodal processing of human gender from faces and voices: an fMRI study.

The aim of this fMRI study was to investigate the cerebral crossmodal interactions between human faces and voices during a gender categorization task. Twelve healthy male participants took part to the study. They were scanned in 4 runs that contained 3 conditions consisting in the presentation of faces, voices or congruent face-voice pairs. The task consisted in categorizing each trial (visual, auditory or associations) according to its gender (male or female). The subtraction between the bimodal condition and the sum of the unimodal ones showed that categorizing face/voice associations according to their gender produced unimodal activations of the visual (right calcarine sulcus) and auditory regions (bilateral superior temporal gyri), and specific supramodal activations of the left superior parietal gyrus and the right inferior frontal gyrus. Moreover, psychophysiological interaction analyses (PPI) revealed that both unimodal regions were inter-connected and connected to the prefrontal gyrus and the putamen, and that the left parietal gyrus had an enhanced connectivity with a parieto-premotor circuit involved in the crossmodal control of attention. This fMRI study showed that the crossmodal auditory-visual categorization of human gender is sustained by a network of cerebral regions highly similar to those observed in our previous studies examining the crossmodal interactions involved in face/voice recognition (Joassin et al., 2010). This suggests that the crossmodal processing of human stimuli requires the activation of a network of cortical regions, including both unimodal visual and auditory regions and supramodal parietal and frontal regions involved in the integration of both faces and voices and in the crossmodal attentional processes, and activated independently from the task to perform or the cognitive level of processing.