Analisi automatica dell'attivita' emisferica EEG durante compiti verbali e non-verbali

Interhemispheric EEG changes have been observed to accompany the performance of functionally asymetric tasks. The analysis of bilateral samples of EEG, taken while a subject performs tasks presumed to engage differentially the two sides of the brain, shows a relative activation of one or the other hemisphere. The present study was designed to investigate whether these task-dependent hemispheric changes interest different frequency bands and different derivations. Ten right-handed normal subjects, 8 males and 2 females were involved. The age range was 24-28. Recordings from frontal leads (F4 , F3 ) and temporal leads {T4 , T3 } referred to the vertex {Cz} were subjected to automatic analysis. The Righ/Left ratios of EEG power in conventional frequency bands were compared under three successive uninterrupted conditions: eyes open, performing a visual task, and performing an arithmetic task. In seven subjects a relatively lower power was found in the left side during arithmetic task in frontal leads; it shifted for all the bands in the right during visual task. This right/left hemispheric relationship was also observed in the temporal leads.