Brain and Cognition 44, 280–302 (2000) doi:10.1006/brcg.2000.1231, available online at http://www.idealibrary.com on Neural Representation for the Perception of the Intentionality of Actions T. Jellema, C. I. Baker, B. Wicker, and D. I. Perrett School of Psychology, University of St. Andrews, St. Andrews, Fife, Scotland, United Kingdom Published online August 15, 2000 A novel population of cells is described, located in the anterior part of the superior temporal sulcus (STSa, sometimes called STPa) of the temporal lobe in the macaque monkey. These cells respond selectively to the sight of reaching but only when the agent performing the action is seen to be attending to the target position of the reaching. We describe how such conditional selectivity can be generated from the properties of distinct cell populations within STSa. One cell population responds selectively to faces, eye gaze, and body posture, and we argue that subsets of these cells code for the direction of attention of others. A second cell population is selec- tively responsive to limb movement in certain directions (e.g., responding to an arm movement to the left but not to an equivalent leg movement or vice versa). The responses of a subset of cells sensitive to limb movement are modulated by the direction of attention (indicated by head and body posture of the agent performing the action). We conclude that this combined analysis of direction of attention and body movements supports the detection of intentional actions.  2000 Academic Press INTRODUCTION This article describes the response properties of several distinct but interre- lated cell populations within the anterior part of the superior temporal sulcus (STSa), a high-level visual-processing area within the temporal cortex of the macaque monkey. The term STPa applies to the upper bank of STSa, which receives polysensory input (Bruce et al., 1981). Since we recorded from both the upper and lower bank, we use the term STSa. Section I of this article investigates the properties of cells responsive to faces, eye gaze, and body posture. We argue that subsets of these cells show characteristics compatible with the notion that the cells code for the direction of attention of the per- We thank Dr. L. Fogassi for drawing our attention to the interaction between attention and action in the control of cell responses. T.J. is supported by HFSP, C.I.B. by St. Leonard’s College and the University of St. Andrews, and B.W. by MNESR. Address Correspondence and reprint requests to T. Jellema, University of St. Andrews, School of Psychology, St. Andrews, Fife KY16 9JU, Scotland, United Kingdom. 280 0278-2626/00 $35.00 Copyright  2000 by Academic Press All rights of reproduction in any form reserved.