Neural activation while perceiving biological motion in dynamic facial expressions and point-light body action animations

BACKGROUND: The interpretation of non-verbal social signals relies heavily on the ability to perceive biological motion. The posterior superior temporal sulcus is an important part of a network involved in biological motion processing. However, the underlying functional organization remains poorly understood. Several studies have suggested topographical representation of motion from different body parts within this region. However, other studies have shown that the posterior superior temporal sulcus responds equally to any body part. OBJECTIVE: Through the use of functional magnetic resonance imaging, the effects of socially relevant biological motion stimuli to activate a specific cortical area within posterior superior temporal sulcus, even if different body parts are involved in motion, will be analyzed. DESIGN, TIME AND SETTING: A functional magnetic resonance imaging, block-design was performed at the Magnetic Resonance Imaging, Surgical Medical Investigation Center, Havana, Cuba between 2004 and 2005. PARTICIPANTS: Thirteen healthy volunteers, from 19 to 55 years of age and comprising eight males and five females, were included in the study. METHODS: A conjunction analysis of responses to natural, dynamic, fearful, facial expressions and point-light, body-motion animations. MAIN OUTCOME MEASURES: The corresponding functionally specialized areas, as well as neural areas significant for both types of stimuli, were identified. RESULTS: One region within the posterior superior temporal sulcus of the right hemisphere was equally activated by facial and body complex motion. CONCLUSION: A site of common neural activity existed within the posterior superior temporal sulcus, which was not specific to a biological motion type. In addition, the activity was not related to a topographically organized body-part map, which suggested high-level visual representation of biological motion in this region.