Oztop, Erhan
Coauthors(s): Michael Arbib USC
USC
Computer Science
University of Southern California Hedco Neuroscience Building Los Angeles, CA 90089-2520
www-scf.usc.edu/~oztop

Mirror Neuron System in Monkey: A computational modeling approach

The experimental data accumulated in recent years indicate that, in monkey, AIP (anterior intra- parietal area) and premotor area F5 form a cortical circuit that transforms visual information of the objects into hand movements to allow animal to manipulate objects (Jeannerod et al. 1995; Rizzolatti et al. 1996). Fagg & Arbib studied the circuitry involved in detail and developed the FARS (Fagg, Arbib, Rizzolatti, Sakata) model (Fagg & Arbib 1998). The model gave a computational account for the visuo-motor transformation in primate brain for the control of grasping. Recently Rizzolatti and his co-workers (Rizzolatti et al., 1996; Gallese et al., 1996) discovered an interesting set of neurons in area F5, which they named mirror neurons. These neurons are activated when the monkey observes meaningful actions done by the experimenter. The mirror neurons look like the usual motor-related F5 neurons with respect to their motor properties. However, in addition they have visual response properties that qualify them to have their name. A mirror neuron that responds for a particular action becomes active also when the monkey observes the experimenter do the same action. The mirror neurons to be triggered require an interaction between the experimenter and the object. The sight of the experimenter or the object alone does not trigger any mirror activity. In most of the mirror neurons, there is a clear relation between the coded observed and executed action (Rizzolatti et al.1996; Gallese et al. 1996). The actions studied so far include grasping, manipulating and placing. This paper presents the simulation results we obtained during our study towards a unified computational model of the primate mirror neurone system. To do so we describe the model in its detail with its bonds to biology. The model focuses on the formation of the mirror neuron system during infancy and show how, in the developed state, observed actions can be represented as internal (pre)motor patterns. The mirror neuron system formation process is based on the hypothesis that the observation of self-actions is the training stimulus for the mirror neuron system. By associating the motor actions with the visual stimuli created, the animal forms a basic 'vocabulary' of actions that it can (visually) recognize and represent (as internal neuronal activity). Then the animal extends his repertoire by observing other individual's actions. From a computational viewpoint, the simulation results that will be presented will introduce our recognition system which is capable of recognising different grasp actions given the time series data (such as hand speed, aperture and distance to target) which are extracted during the vision of the hand in action. References Fagg AH, Arbib MA , Modeling parietal--premotor interactions in primate control of grasping, Neural Networks (11)7-8 (1998) pp. 1277-1303 Gallese V, Fadiga L, Fogassi L, Rizzolatti G. (1996) Action recognition in the premotor cortex. Brain, 119: 592-609 Jeannerod M, Arbib MA, Rizzolatti G, Sakata H, Grasping objects: Cortical mechanisms of visuomotor transformations. Trends in Neuroscience (1995). Rizzolatti G, Fadiga L, Gallese V, Fogassi L, (1996) Premotor cortex and the recognition of motor actions. Cognitive Brain Research, 3(2):131-141