Macefield V G, Johansson R S
Department of Physiology, University of Umeå, Sweden.
Neuroreport. 1994 Nov 21;5(17):2229-32. doi: 10.1097/00001756-199411000-00006.
Evoked potentials were recorded in 10 subjects to assess cortical involvement in automatic control of grip force during restraint of a manipulandum held between finger and thumb. Brisk pulling loads elicited an increase in first dorsal interosseous EMG after 60.6 +/- 2.4 ms. Preceding this response were several time-locked scalp potentials, the most significant being a widespread negativity that appeared first over the frontal cortex and peaked 19.5 +/- 1.8 ms before the EMG peak, and a positivity that followed the EMG by 24.3 +/- 5.4 ms. The slope of the negativity and the amplitude of the positivity were greater than during passive conditions, suggesting that these potentials reflect cortical processes associated with automatic regulation.