Associative sequence learning: the role of experience in the development of imitation and the mirror system

Abstract

A core requirement for imitation is a capacity to solve the correspondence problem; to map observed onto executed actions, even when observation and execution yield sensory inputs in different modalities and coordinate frames. Until recently, it was assumed that the human capacity to solve the correspondence problem is innate. However, it is now becoming apparent that, as predicted by the associative sequence learning model, experience, and especially sensorimotor experience, plays a critical role in the development of imitation. We review evidence from studies of non-human animals, children and adults, focusing on research in cognitive neuroscience that uses training and naturally occurring variations in expertise to examine the role of experience in the formation of the mirror system. The relevance of this research depends on the widely held assumption that the mirror system plays a causal role in generating imitative behaviour. We also report original data supporting this assumption. These data show that theta-burst transcranial magnetic stimulation of the inferior frontal gyrus, a classical mirror system area, disrupts automatic imitation of finger movements. We discuss the implications of the evidence reviewed for the evolution, development and intentional control of imitation.

Understanding intentions from actions: Direct perception, inference, and the roles of mirror and mentalizing systems

“…Recent data on imitative compatibility (the tendency to perform an action faster when observing the same action than a different action; Heyes, 2011;Stürmer, Aschersleben, & Prinz, 2000), a behavioural effect that is thought to index mirror neuron function (Catmur, Walsh, & Heyes, 2009;Heiser, Iacoboni, Maeda, Marcus, & Mazziotta, 2003;Hogeveen et al, in press), supports the conclusion that mirror responses can occur with limited attention. Catmur (under review) used an imitative compatibility design to demonstrate that the mapping of an observed movement onto the motor program for that movement occurs under conditions of limited attention (however see Chong, Cunnington, Williams, & Mattingley, 2009, for an alternative finding); and Dainton, Catmur, and Marsh (in preparation) showed that attention affects spatial, but not imitative, compatibility.…”

Time course analyses confirm independence of imitative and spatial compatibility.

“…Mirror neurons, discovered in the macaque monkey (di Pellegrino, Fadiga, Fogassi, Gallese, & Rizzolatti, 1992;Gallese, Fadiga, Fogassi, & Rizzolatti, 1996), fire both when the monkey executes a particular movement and when it passively observes the same movement. Converging evidence for a homologous mirror system in the human brain (Fadiga, Fogassi, Pavesi, & Rizzolatti, 1995;Hari et al, 1998;Iacoboni et al, 1999;Iacoboni & Mazziotta, 2007) has led to renewed interest in imitation as a behaviour which may rely on the key property of the mirror system: its ability to perform perceptual-motor translations between observed and executed movements (Catmur, Walsh, & Heyes, 2009;Heiser, Iacoboni, Maeda, Marcus, & Mazziotta, 2003).…”

“…That is, that they provide a specific measure of the extent to which observation of a movement facilitates or interferes with the performance of the same or a different movement, where the similarity between movements depends on the configural spatial relationship between body parts. Such facilitation or interference is assumed to result from perceptual-motor translations between sensory and motor representations of movements: a necessary step during imitation, and one that may be performed by the mirror system (Catmur et al, 2009;Heiser et al, 2003).…”

“…In this context, it is regarded as a relatively pure measure because, in comparison with intentional imitation tasks, imitative compatibility tasks minimise demands on motivational and working memory processes (Catmur et al, 2009). …”

Sensorimotor learning and the ontogeny of the mirror neuron system

“…In lieu of such data, researchers have investigated the imitation of facial gestures in neonatal macaques [24]. Imitation can be used as an indirect index of mirror neuron responses due to the requirement to map the observed action on to the motor program used to perform that action -a mapping which mirror neurons perform; this is supported by findings that repetitive transcranial magnetic stimulation to mirror neuron areas in humans disrupts imitation [11,32,50].…”