Stability of brain potentials, mental abilities, and cortical thickness

The purpose of the study was to test whether trial-to-trial variation in amplitude of the brain potentials P3a and P3b is related to age, intelligence (verbal and performance abilities), and brain volumetry. One hundred and thirty-three participants underwent neuropsychological testing and an event-related potential task, whereas a subgroup (n=72) also had magnetic resonance scans. Trial-to-trial variation in P3a amplitude correlated positively with age, and negatively with verbal and performance intelligence. Trial-to-trial variation in amplitude also correlated negatively with thickness in the temporoparietal junction and the precentral gyrus of the cerebral cortex, but these relationships were dependent on the influence of age. The results indicate that intraindividual variability should be used as a variable in the study of central nervous system function.