High resolution spatiotemporal analysis of the contingent negative variation in simple or complex motor tasks and a non-motor task

Objectives: Since the characteristics of the Bereitschaftspotential (BP) - voluntary movement paradigm of internally-driven movements - have been esta blished recently by our group using high resolution DC-EEG techniques, it w as of great interest to apply similar techniques to the other slow brain po tential - contingent negative variation (CNV) of externally-cued movements - with the same motor tasks using the same subjects. Methods: The CNV for simple bimanual sequential movements (task 1), complex bimanual sequential movements (task 2) and a non-motor condition (task 3) was recorded on the scalp using a 64 channel DC-EEG in 16 healthy subjects, and the data were analyzed with high resolution spatiotemporal statistics and current source density (CSD). Results: (1) The CNV was distributed over frontal, frontocentral, central a nd centroparietal regions; a negative potential was found at the frontal po le and a positive potential was found over occipital regions. (2) CNV ampli tudes were higher for task 2 than for task 1, and there was no late CNV for task 3. (3) A high resolution spatiotemporal analysis revealed that during the early CNV component, statistical differences existed between the motor tasks (tasks 1 and 2) and the non-motor task (task 3), which occurred at f rontocentral, central, centroparietal, parietal and parieto-occipital regio ns. During the late CNV component, additional significant differences were found not only between the motor tasks and the Iron-motor task but also bet ween motor task 1 and task 2 at frontocentral, central and centroparietal r egions. (4) Comparison of the CNV between the frontomesial cortex (situated over the supplementary/cingulate areas, SCMA) and both lateral pre-central areas (situated over the primary motor areas, Mis) showed that there was n o statistically significant difference between the two cortical motor areas except for the early CNV. (5) Comparison of the CNV between the 3 tasks ov er the cortical motor areas showed that there were significant differences between the motor tasks and the non-motor task regarding the auditory evoke d potential (AEP) and the early CNV component, and between all 3 tasks in t he late CNV, the visual evoked potential (VEP2) and the N-P component. (6) The ranges and the densities of the CSD maps were larger and higher for com plex than for simple tasks. The current sinks of the AEP and the early CNV were located at Fz, the late CNV at FCz and surrounding regions. As to be e xpected, current sources of the VEPs were located at the occipital lobes. T he CNV was a current sink (negative) except for the VEP's main component wh ich was a current source (positive). Conclusions: (1) The CNV topography over the scalp varied with the complexi ty of motor tasks and between motor and non-motor conditions. (2) The origi n of the early CNV may rest in the frontal lobes, while the late CNV may st em from more extensive cortical areas including SCMA, MIs, etc. (3) The lat e CNV component is not identical with the BP. (C) 2000 Elsevier Science Ire land Ltd. All lights reserved.