Neurophysiological evidence for crossmodal (face-name) person-identity representation in the human left ventral temporal cortex.

Angélique Volfart,Louis Maillard,Bruno Rossion,Jacques Jonas,Sophie Colnat-Coulbois

doi:10.1371/journal.pbio.3000659

Abstract

Putting a name to a face is a highly common activity in our daily life that greatly enriches social interactions. Although this specific person-identity association becomes automatic with learning, it remains difficult and can easily be disrupted in normal circumstances or neurological conditions. To shed light on the neural basis of this important and yet poorly understood association between different input modalities in the human brain, we designed a crossmodal frequency-tagging paradigm coupled to brain activity recording via scalp and intracerebral electroencephalography. In Experiment 1, 12 participants were presented with variable pictures of faces and written names of a single famous identity at a 4-Hz frequency rate while performing an orthogonal task. Every 7 items, another famous identity appeared, either as a face or a name. Robust electrophysiological responses were found exactly at the frequency of identity change (i.e., 4 Hz / 7 = 0.571 Hz), suggesting a crossmodal neural response to person identity. In Experiment 2 with twenty participants, two control conditions with periodic changes of identity for faces or names only were added to estimate the contribution of unimodal neural activity to the putative crossmodal face-name responses. About 30% of the response occurring at the frequency of crossmodal identity change over the left occipito-temporal cortex could not be accounted for by the linear sum of unimodal responses. Finally, intracerebral recordings in the left ventral anterior temporal lobe (ATL) in 7 epileptic patients tested with this paradigm revealed a small number of "pure" crossmodal responses, i.e., with no response to changes of identity for faces or names only. Altogether, these observations provide evidence for integration of verbal and nonverbal person identity-specific information in the human brain, highlighting the contribution of the left ventral ATL in the automatic retrieval of face-name identity associations.

Highlights

Putting a name to a familiar face is a highly common activity in our daily life, which greatly enriches social interactions
In the Face Only condition (FO), names of the base identity were replaced by other famous names in order to isolate unimodal face responses that potentially contribute to the neural response observed in the Face Name condition
Using an original frequency-tagging approach with mixed modalities of stimulation while recording scalp EEG and intracerebral EEG (SEEG), we found a neural response at the specific frequency at which different famous identities, either as a written name or a face picture, interrupted the successive presentation of a repeated specific identity, presented in either format

Summary

Introduction

Putting a name to a familiar face is a highly common activity in our daily life, which greatly enriches social interactions. This association is often automatic—i.e., names are retrieved even without the intention to do so—and yet quite difficult: often, someone’s name cannot be remembered, or can take a few seconds to be evoked from one’s face [1,2,3]. These difficulties increase with ageing, with people being often concerned with a reduced ability to retrieve specific names associated with familiar faces [4,5,6,7]. These findings have been interpreted within cognitive models of person recognition, in which person-related semantic representations act as a gateway to name retrieval [20,21,22,23]

Methods

Results

Conclusion