Hemispheric asymmetry of feedback-related potentials in a positioning task: comparison of right- and left-handed...

Previous research has demonstrated that delayed nonverbal information feedback (IF) about the correctness of a positioning movement is preceded by a contingent negative variation (CNV) which is larger over the right hemisphere independent of movement side. It was hypothesized that this asymmetry is a manifestation of functional hemispheric specialization, and that, therefore, the distribution of the differences between CNV amplitude measures of the two hemispheres should be different in right-handed and left-handed subjects. The latter group should show a mean asymmetry score closer to zero, and a larger between-subject variance of the asymmetry scores. The present investigation was intended to test these assumptions in samples of rigorously defined right-handers (n = 12) and left-handers (n = 8). The results revealed the expected group differences of the CNV asymmetry scores. In addition, the P1-N1 peak-to-peak amplitude of the IF-evoked potentials was similarly lateralized as the pre-IF CNV and showed the same group differences. In contrast, the handedness groups did not differ in the contralateral lateralization of the movement-related potential shift in the same task.