From mirror neurons to imitation: Facts and speculations

Abstract

Introduction This chapter is composed of two parts. In the first we review the functional properties of an intriguing class of premotor neurons that we discovered in the monkey premotor cortex: the “mirror neurons.” These neurons discharge both when the monkey performs an action and when it observes another individual making a similar action. The second part is basically speculative. It is based on the hypothesis that there is a very general, evolutionary ancient mechanism, that we will name “resonance” mechanism, through which pictorial descriptions of motor behaviors are matched directly on the observer's motor “representations” of the same behaviors. We will posit that resonance mechanism is a fundamental mechanism at the basis of inter-individual relations including some behaviors commonly described under the heading of “imitation.” Functional properties of area F5 Motor properties Area F5 forms the rostral part of inferior area 6 (Matelli et al ., 1985). Microstimulation and single-neuron studies showed that F5 contains a hand and a mouth movement representation (Gentilucci et al ., 1988; Hepp-Reymond, Husler, Maier, & Qi, 1994; Okano & Tanji, 1987; Rizzolatti et al ., 1981; Rizzolatti et al ., 1988). Particularly interesting results were obtained when F5 neurons were studied in a semi-naturalistic context (Rizzolatti et al ., 1988). Awake monkeys were seated on a primate chair and presented with various objects (geometrical solids, pieces of food of different size and shape). The stimuli were introduced in various spatial locations around the monkey, inside and outside its peripersonal space.