Reafferent copies of imitated actions in the right superior temporal cortex

^aAhmanson-Lovelace Brain Mapping Center, Neuropsychiatric Institute, Departments of ^bPsychiatry and Biobehavioral Sciences, ^cNeurology, ^gPharmacology, and ^hRadiological Sciences, University of California Los Angeles School of Medicine, 660 Charles E. Young Drive South, Los Angeles, CA 90095; ^dDepartment of Cognition and Action, Max Planck Institute for Psychological Research, Leopoldstrasse 24, D-80802 Munich, Germany; and ⁱInstitute of Human Physiology, University of Parma, Plesso Biotecnologico Integrato, Via Volturno, 39, I-43100 Parma, Italy

Communicated by James M. Sprague, University of Pennsylvania School of Medicine, Philadelphia, PA (received for review August 9, 2001)

Abstract

Imitation is a complex phenomenon, the neural mechanisms of which are still largely unknown. When individuals imitate an action that already is present in their motor repertoire, a mechanism matching the observed action onto an internal motor representation of that action should suffice for the purpose. When one has to copy a new action, however, or to adjust an action present in one's motor repertoire to a different observed action, an additional mechanism is needed that allows the observer to compare the action made by another individual with the sensory consequences of the same action made by himself. Previous experiments have shown that a mechanism that directly matches observed actions on their motor counterparts exists in the premotor cortex of monkeys and humans. Here we report the results of functional magnetic resonance experiments, suggesting that in the superior temporal sulcus, a higher order visual region, there is a sector that becomes active both during hand action observation and during imitation even in the absence of direct vision of the imitator's hand. The motor-related activity is greater during imitation than during control motor tasks. This newly identified region has all the requisites for being the region at which the observed actions, and the reafferent motor-related copies of actions made by the imitator, interact.

Footnotes

↵ e Present address: Department of Neurology, Max Planck Institute of Cognitive Neuroscience, Stephanstrasse 1A, D-04103 Leipzig, Germany.
↵ f Present address: Department of Experimental and Work Psychology, Grote Kruisstraat 2/1, 9712 TS, Groningen, The Netherlands.
↵ j To whom reprint requests should be addressed. E-mail: fisioum{at}symbolic.parma.it.
↵ k Fogassi, L., Gallese, V., Fadiga, L. & Rizzolatti, G. (1998) Soc. Neurosci. Abstr. 24, 654.
↵ l Iacoboni, M., Woods, R. P., Brass, M., Bekkering, H., Mazziotta, J. C. & Rizzolatti, G. (2000) Neuroimage 5, S821 (abstr.).
Abbreviation:

STS,

superior temporal sulcus