Journal of Neuroscience, Vol 13, 1820-1829, Copyright © 1993 by Society for Neuroscience
Effects of posterior association cortex lesions on brain potentials preceding self-initiated movements
J Singh and RT Knight
Department of Psychology, Northwestern University, Evanston, Illinois 60208.
To assess the role of subregions of the posterior association cortex in
movement control, we recorded movement-related potentials (MRPs) in
patients who had lesions centered in the temporal-parietal junction (T-
PCx; damaged areas 22, caudal 39, 40, and 42; n = 7), superior parietal
cortex (ParCx; damaged areas 5, 7, rostral 39, and 40; n = 5), and
posterior association cortex lesions involving both the temporal- parietal
junction and the superior parietal structures (PosCx; damaged areas 7, 22,
39, 40, 41, and 42; n = 5) and in 14 age-matched normal controls. MRPs were
recorded in a self-paced button-press task in which subjects performed a
switch closure with the right, left, or both hands (experiment I,
experiment II, and experiment III, respectively) under counter-balanced
experimental conditions. Data epochs beginning 1400 msec prior to and
extending to 600 msec after each motor response were recorded from scalp
sites over the precentral, central, and parietal regions. Normal controls
and patients with T-PCx lesions generated comparable vertex maximal,
symmetrical readiness potentials (onset 1000 msec), contralaterally
enhanced NS' values (onset 500 msec), and MP values (onset 100 msec)
preceding voluntary self-paced movements. Extensive lesions involving the
posterior association cortex reduced MRP amplitudes. Patients with
selective ParCx lesions also had marked reduction of MRPs under all
experimental conditions. The MRP findings coupled with clinical and
behavioral data on patients with parietal- cortex lesions indicate that the
superior parietal regions are part of a neural system necessary for
movement preparation.