Movement-related potentials and intelligence.

The relationship between intelligence and brain electrical activity has long aroused the interest of many researchers. Quantified EEG and event-related potentials have contributed significantly to the development of this topic. Conversely, movement-related potentials have contributed little for both adults and children. This study analyses possible relationships between intelligence and movement-related potentials. One hundred and ten normally developing boys performed a skilled performance task (SPT) that required adaptive programming, learning proper timing and performance improvement by providing real time knowledge of results and feedback. The EEG was recorded with Ag/AgCl electrodes over Fpz, Cz, Pz, right and left precentral (RPC, LPC), P3 and P4. Intelligence was tested using the Wechsler Intelligence Scale for Children-Revised (WISC-III-R). Linear and multiple linear regressions were used to test the association between intelligence quotients (IQ) and readiness potential or Bereitschaftspotential (BP) and skilled performance positivity (SPP). BP onset was significantly and positively related to verbal IQ, and BP amplitude was significantly related to all three IQs (verbal, performance and full) in all cerebral areas. Children with higher IQ had a greater BP amplitude. SPP latency was significantly and negatively related to age but not to IQ, while SPP amplitude was significantly and negatively related to all three IQs and smaller in children with higher IQ. BP and SPP amplitudes seem to reflect the efficiency of cognitive processes associated with the task.