Functional Anatomy of Biological Motion Perception in Posterior Temporal Cortex: An fMRI Study of Eye, Mouth and Hand Movements

TLDR

Passive viewing of biological motion activates extensive posterior temporal‑occipital cortex, especially the superior temporal sulcus, yet its functional specificity remains poorly understood, with some studies proposing intentionality as an organizing principle and others suggesting limb‑based somatotopy. The study aimed to compare neural responses to eye, mouth, and hand movements during passive viewing. An event‑related fMRI experiment was conducted to measure activation patterns elicited by each movement type. All three movements produced robust right posterior temporal‑occipital activation, but spatial distribution differed: mouth movements activated mid‑posterior STS, eye movements activated more superior and posterior STS, and hand movements activated inferior‑posterior STS and extended into inferior temporal, middle occipital, and lingual gyri, suggesting motion‑specific topography linked to functional roles.

Abstract

Passive viewing of biological motion engages extensive regions of the posterior temporal-occipital cortex in humans, particularly within and nearby the superior temporal sulcus (STS). Relatively little is known about the functional specificity of this area. Some recent studies have emphasized the perceived intentionality of the motion as a potential organizing principle, while others have suggested the existence of a somatotopy based upon the limb perceived in motion. Here we conducted an event-related functional magnetic resonance imaging experiment to compare activity elicited by movement of the eyes, mouth or hand. Each motion evoked robust activation in the right posterior temporal-occipital cortex. While there was substantial overlap of the activation maps in this region, the spatial distribution of hemodynamic response amplitudes differentiated the movements. Mouth movements elicited activity along the mid-posterior STS while eye movements elicited activity in more superior and posterior portions of the right posterior STS region. Hand movements activated more inferior and posterior portions of the STS region within the posterior continuing branch of the STS. Hand-evoked activity also extended into the inferior temporal, middle occipital and lingual gyri. This topography may, in part, reflect the role of particular body motions in different functional activities.