Hand cortical representation at rest and during activation: Gender and age effects in the two hemispheres

Objective: To characterize the age- and gender- dependence of sensory hand cortical representation in the two hemispheres in healthy population. Methods: In 57 adults, the cerebral activity from rolandic areas as detected by magnetoencephalography was considered both in a resting state (spectral power properties) and in response to the electrical stimulation of the contralateral median nerve (M20 and M30 cortical sources). Results: We found a dependence of rest and evoked activity on age (alpha rhythm slowing, high frequency power increase, M20 latency increase, M20 strength increase, no change in M30) and on gender (higher alpha frequency, higher beta power, higher spectral entropy, lower M20 amplitude in women). These changes were quite symmetrical in the two hemispheres, making the interhemispheric differences non-dependent on age and gender. Moreover, lower total power and faster alpha rhythm appeared in the dominant hemisphere. Conclusions: Age and gender have a significant effect on spontaneous and evoked activity at the primary sensorimotor cortex. Significance: The results consolidate the reference base in healthy population, to study pathological conditions. Inter-hemispheric asymmetries are confirmed as a sensitive indicator for the early identification of possible neuronal rearrangements due to unilateral brain injuries. © 2006 International Federation of Clinical Neurophysiology.