Inhibitory motor control in stop paradigms: review and reinterpretation ofneural mechanisms

What is the neurophysiological locus of inhibition when preparation for a m anual response is countermanded? This paper evaluates data and models that pertain to inhibitory mechanisms operating in stop paradigms. In a model of De Jong, Coles and Logan (1995), (Strategies and mechanisms in nonselectiv e and selective inhibitory motor control. Journal of Experimental Psycholog y: Human Perception and Performance, 21, 3, 498-511), a mechanism for nonse lective inhibition operates peripheral to the motor cortex, while a selecti ve mechanism operates at a central cortical level. We argue, however, that a peripheral mechanism of inhibition is incorrectly inferred from inhibitio n data available to date. Neurophysiological and psychophysiological data s uggest that inhibitory processes always involve the cortex, and inhibitory effects are exerted upstream from the primary motor cortex. The prefrontal cortex and basal ganglia are candidate agents of response inhibition, where as possible sites of inhibition are the thalamus and motor cortex. (C) 1999 Elsevier Science B.V. All rights reserved. PsycINFO classifications: 2260; 2330; 2530; 2540; 2560.