Mapping the functional organization of the temporal lobes with fMRI

Overview

This project investigated through functional Magnetic Resonance Imaging how the brain processes changes in facial expression and changes in facial position both of which have implications for social communication.

The study found that patterns of response to expression and viewpoint were largely unaffected by changes in facial identity. The resulting data will provide a normative range with which to compare individuals with disabling disorders such as autism and schizophrenia which are associated with abnormalities in processing faces.

In detail

Despite the fact that highly disabling disorders, such as autism and schizophrenia, are associated with abnormalities in processing faces, the functional organization of face responsive regions in the brain is not fully understood. Movements of the face are often considered to be non-rigid or rigid. Non-rigid movements give rise to different facial expressions. In contrast, rigid movements of the head create up and down movements indicating dominance or submissiveness and rotational movements that usually signal a shift in a person's focus of attention. All of these movements can be subsumed under the broad heading of changeable aspects of faces, but their implications for the perceiver are clearly quite different. The aim of this study was to determine how facial cues involved in social communication are represented in the brain using functional magnetic resonance imaging (fMRI).

In this study, fMRI was used to investigate the neural representations underlying changes caused by rigid (viewpoint) and non-rigid (expression) movements of the face. Participants viewed sequences of faces that varied in either facial expression or viewpoint. Each sequence of images could be from the same identity or could contain different identities. Using multivariate pattern analyses, the researchers found distinct patterns of response for facial expression and viewpoint within face-selective regions. Larger responses to changes in expression were evident in the superior temporal sulcus and inferior frontal gyrus, but larger responses to changes in viewpoint were found in the intra-parietal sulcus. These patterns of response to expression and viewpoint were largely invariant to changes in facial identity and were consistent across participants.

These investigations have revealed distinct, topographic patterns of response for rigid and non-rigid movements in face-selective regions of the human brain. The data will provide a normative range with which to compare individuals with disabling disorders such as autism and schizophrenia.