THE AEP T-COMPLEX TO SYNTHESIZED MUSICAL TONES - LEFT-RIGHT ASYMMETRYIN RELATION TO HANDEDNESS AND HEMISPHERE DOMINANCE

Auditory evoked potentials were recorded to onset and offset of synthe sised instrumental tones in 40 normal subjects, 20 right-handed for wr iting and 20 left-handed. The majority of both groups showed a T-compl ex which was larger at the right temporal electrode (T4) than the left (T3). In the T4-T3 difference waveforms, the mean potential between l atencies of 130 and 165 ms was negative in all right-handed subjects e xcept two for whom the waveforms were marginally positive-going. Among st the left-handers, however, this converse asymmetry was seen in 7 su bjects, 5 of them more than 2 standard deviations from the mean of the right-handed group. The degree of asymmetry was not significantly cor related with the degree of left-handedness according to the Edinburgh Handedness Inventory. Asymmetry of the T-complex to instrumental tones appears to reflect the lateralisation of auditory 'musical' processin g in the temporal cortex, confirming evidence from other sources inclu ding PET that this is predominantly right-sided in the majority of ind ividuals. The proportion of left-handers showing the converse laterali ty is roughly in accordance with those likely to be right-hemisphere-d ominant for language. If linguistic and 'musical' processes are consis tently located in opposite hemispheres, AEPs to complex tones may prov e a useful tool in establishing functional lateralisation. (C) 1998 El sevier Science Ireland Ltd. All rights reserved.