Objective: The contingent negative variation (CNV) is a widespread electroencephalographic (EEG) potential that occurs during the interval between a warning stimulus and a subsequent imperative stimulus if a mental or motor response is required. The present study was designed to explore the impact of the previous trial on the CNV of the forthcoming trial, that is, how a previous movement affects brain activation preparing the next movement. Effects of alteration of finger (from index to middle, and vice versa) and hand (from left to right, and vice versa) were examined independently from each other.
Methods: CNV was recorded in 20 right-handed healthy subjects with electrodes placed at F7, F5, F3, F4, F6, F8, FC5, FC3, FC1, FC2, FC4, FC6, T7, C5, C3, C1, C2, C4, C6, T8, CP5, CP1, CP2, CP6, P7, P3, P4 and P8. In a visual/visual S1-choice paradigm, an earlier informative (S1) stimulus which instructed for side and finger of the following movement was followed 3 s later by an imperative (S2) stimulus providing the command to move. Subjects had to respond to each imperative stimulus with an appropriate button press made by brisk flexion movements with the index or middle finger of each hand. The CNV recorded in the interval between the informative and the imperative stimulus was analysed with respect to finger and hand of the present and the preceding movement.
Results/conclusions: (1) A change of the side of movement is associated with a widespread increase of negativity contralateral to the currently prepared movement. (2) A change of finger is associated with a focal increase of negativity contralateral to the side of the current movement over temporoparietal and mid-parietal areas. (3) A change of finger results in a widespread increase of negativity over the left hemisphere.