On the neuronal processing of movement dynamics

The thesis collects five essays on how neurons in four motor areas of the frontal lobe process the movement dynamics. In the experiments described, monkeys executed visually instructed reaching movements while holding the handle of a robotic arm. Motors attached to the robot allowed turning on and off perturbing forces that deviated the hand of the monkeys. After some exposure, the monkeys adapted to the perturbation. The experiments were designed to dissociate the activity related to the desired kinematics from that related to the dynamics. Furthermore, the experiments dissociated the activity related to motor performance (desired kinematics and dynamics) from that related to motor learning (learning a new dynamics). The thesis describes the following results. 1. During motor execution, the movement dynamics is processed across multiple areas. Specifically, dynamics-related activity is found in all areas projecting to the spinal cord under study, namely the primary motor cortex (M1), supplementary motor area (SMA), dorsal premotor (PMd), and ventral premotor area (PMv). 2. Dynamics-related activity is also present during motor planning in both PMd and SMA, but not in M1 and PMv. This suggests that the dynamics is processed "upstream" of M1. The activity of SMA reflects during motor planning a kinematics-to-dynamics transformation. Neuronal correlates of that transformation are observed both at the level of the population and for single cells. 3. Extensive neuronal plasticity is observed in these areas when monkeys learn a new dynamics. The activity of single neurons modifies as monkeys adapt to the force, and changes outlast the exposure to the perturbation.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Brain and Cognitive Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Padoa-Schioppa, Camillo, 1970-

Advisor dc:contributor.advisor

• Emilio Bizzi and Nancy Kanwisher.

• Brain and Cognitive Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8354

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8354