Blind people rely more on vocal cues when they recognize a person's identity than sighted people. Indeed, a number of studies have reported better voice recognition skills in blind than in sighted adults. The present functional magnetic resonance imaging study investigated changes in the functional organization of neural systems involved in voice identity processing following congenital blindness. A group of congenitally blind individuals and matched sighted control participants were tested in a priming paradigm, in which two voice stimuli (S1, S2) were subsequently presented. The prime (S1) and the target (S2) were either from the same speaker (person-congruent voices) or from two different speakers (person-incongruent voices). Participants had to classify the S2 as either a old or a young person. Person-incongruent voices (S2) compared with person-congruent voices elicited an increased activation in the right anterior fusiform gyrus in congenitally blind individuals but not in matched sighted control participants. In contrast, only matched sighted controls showed a higher activation in response to person-incongruent compared with person-congruent voices (S2) in the right posterior superior temporal sulcus. These results provide evidence for crossmodal plastic changes of the person identification system in the brain after visual deprivation.

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Blind individuals are trained in identifying other people through voices. In congenitally blind adults the anterior fusiform gyrus has been shown to be active during voice recognition. Such crossmodal changes have been associated with a superiority of blind adults in voice perception. The key question of the present functional magnetic resonance imaging (fMRI) study was whether visual deprivation that occurs in adulthood is followed by similar adaptive changes of the voice identification system. Late blind individuals and matched sighted participants were tested in a priming paradigm, in which two voice stimuli were subsequently presented. The prime (S1) and the target (S2) were either from the same speaker (person-congruent voices) or from two different speakers (person-incongruent voices). Participants had to classify the S2 as either coming from an old or a young person. Only in late blind but not in matched sighted controls, the activation in the anterior fusiform gyrus was modulated by voice identity: late blind volunteers showed an increase of the BOLD signal in response to person-incongruent compared with person-congruent trials. These results suggest that the fusiform gyrus adapts to input of a new modality even in the mature brain and thus demonstrate an adult type of crossmodal plasticity.

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The aim of the present study was to better understand the interaction of face and voice processing when identifying people. In a S1-S2 crossmodal priming fMRI experiment, the target (S2) was a disyllabic voice stimulus, whereas the modality of the prime (S1) was manipulated blockwise and consisted of the silent video of a speaking face in the crossmodal condition or of a voice stimulus in the unimodal condition. Primes and targets were from the same speaker (person-congruent) or from two different speakers (person-incongruent). Participants had to classify the S2 as either an old or a young person. Response times were shorter after a congruent than after an incongruent face prime. The right posterior superior temporal sulcus (pSTS) and the right angular gyrus showed a significant person identity effect (person-incongruent > person-congruent) in the crossmodal condition but not in the unimodal condition. In the unimodal condition, a person identity effect was observed in the bilateral inferior frontal gyrus. Our data suggest that both the priming with a voice and with a face result in a preactivated voice representation of the respective person, which eventually facilitates (person-congruent trials) or hampers (person-incongruent trials) the processing of the identity of a subsequent voice. This process involves activation in the right pSTS and in the right angular gyrus for voices primed by faces, but not for voices primed by voices. Hum Brain Mapp 38:2553-2565, 2017. © 2017 Wiley Periodicals, Inc.