Modulation of evoked potentials by interfering mental activity

Non-specific influences (attention, mental set, mental imagery) take part in modulation of information processing in the human central nervous system at various levels of central hierarchy.

To broaden knowledge concerning the conjunction of motor control and cognition as well as to discuss some possible psychophysiological mechanisms.

Somatosensory evoked potentials, motor related cortical potentials and the saccadic eye movement related potentials were recorded over frontal and parietal cortices in the control condition and compared with those registered under the influence of a mental imagery task introduced as a modulatory factor. Special focus was devoted to their early components.

Early components of the above potentials, which are assumed to represent the coding of physical characteristics of evoking stimuli, are changed under the influence of mental activity. Frontal evoked potentials are markedly modulated as compared to those recorded parietally. In general, the results support the view that the preparation for both, real movements and mentally simulated movements share probably some common mechanisms at the cortical level.

Modulatory effects of mental activity upon the used evoked potentials point to the possible participation of the central gating mechanism, attention focussing and some other psychophysiological mechanisms related to internal representation of sequence of events. The results suggest that experimental conditions need to be exactly specified and examined subjects must be properly instructed. (Fig. 3, Ref. 12.)