Human cerebellar activity reflecting an acquired internal model of a new tool

Abstract

Theories of motor control postulate that the brain uses internal models of the body to control movements accurately. Internal models are neural representations of how, for instance, the arm would respond to a neural command, given its current position and velocity. Previous studies have shown that the cerebellar cortex can acquire internal models through motor learning. Because the human cerebellum is involved in higher cognitive function as well as in motor control, we propose a coherent computational theory in which the phylogenetically newer part of the cerebellum similarly acquires internal models of objects in the external world. While human subjects learned to use a new tool (a computer mouse with a novel rotational transformation), cerebellar activity was measured by functional magnetic resonance imaging. As predicted by our theory, two types of activity were observed. One was spread over wide areas of the cerebellum and was precisely proportional to the error signal that guides the acquisition of internal models during learning. The other was confined to the area near the posterior superior fissure and remained even after learning, when the error levels had been equalized, thus probably reflecting an acquired internal model of the new tool.

Emergence of rhythm during motor learning

“…It is an open question whether the cerebellar contribution to motor sequence learning is related to chunking [47,57] (see also Box 2 for other future research questions). The shift of activation from the posterior cerebellar lobe to the anterior lobe is also observed during learning how to use a computer mouse with a novel rotational transformation, a skill that does not involve learning a specific sequence [58]. A learningrelated transition from controlled to automatic mode has been proposed previously by Fitts [59] and Anderson [60], and a recent model has stressed the parallel mechanisms between the two modes of processing [2,61].…”

Maintaining rotational equilibrium during object manipulation: linear behavior of a highly non-linear system

“…An integration of sensory information with previous experience has been suggested as a possible mechanism underlying such finger force adjustments (Kording et al 2004). Several brain structures have been recently implicated in anticipatory force control including the cerebellum and the frontal and parietal cortices (Imamizu et al 2000(Imamizu et al , 2004Yamamoto et al 2002). A recent study has suggested, in particular, the importance of cortico-cortical projections in producing motor cortical outputs in relation to the properties of an object manipulated by the hand (Cattaneo et al 2005).…”

Explicit contextual information selectively contributes to predictive switching of internal models

“…Internal models are neural mechanisms that mimic the inputoutput properties of controlled objects (Wolpert et al 1995;Brashers-Krug et al 1996;Kawato 1999;Imamizu et al 2000). Empirically, two types of information are crucial for the switching of internal models: contextual information such as color or shape of the objects that can be perceived before movement execution, and information about the difference between actual and predicted sensorimotor Electronic supplementary material The online version of this article (doi:10.1007/s00221-007-0940-1) contains supplementary material, which is available to authorized users.…”