INFLUENCE OF HANDEDNESS ON PERIPHERAL AUDITORY ASYMMETRY

It is well established that in humans many differences between right- and left-handers, anatomical, physiological and functional, exist. Lef t- and mixed-handedness is associated with greater bihemispheric repre sentation of cognitive functions than in right-handers. Several studie s indicate a left-right asymmetry in the function of hearing pathways between cochlea and auditory cortex, and furthermore, that this asymme try is associated with handedness. Our investigation focuses on the me dial olivo-cochlear system, which has been demonstrated to be more eff ective in the right than left ear in right-handers. The aim of the stu dy was to investigate this auditory efferent system asymmetry accordin g to handedness, gender, eyedness, footedness and the presence of spon taneous otoacoustic emissions. The medial efferent system has been fou nd to be more effective in the right than left ear in right-handers, w hile functioning symmetrically in left-handers. Furthermore, the olivo -cochlear system, assumed to be involved in basic language processing, shows an asymmetrical pattern of functioning influenced by handedness as well as by hemispheric language representation. Reverse medial eff erent system asymmetry was observed in left-handers compared to that i n right-handers, on condition that only left-handed males were conside red, or that the left-handers were also left-eyed, or that spontaneous otoacoustic emissions were present in the left ear of the left-hander s, or when only left-handers without mixed-handers were considered.