Aphasia patients were subjected to psychophysiological tests by means
of cognitive demands. We hypotesize, that the amplitude of the semanti
cal evoked potentials correlates with the synchronization among the sp
eech processing neuronal areas and that the presence of oscillating po
tentials indicates an intact function of the neuronal structures. A mo
del is presented to understand the different types of aphasia and the
change of syndromes during rehabilitative treatment.