Research report Learned audio-visual cross-modal associations in observed piano playing activate the left planum temporale. An fMRI study

Lip reading is known to activate the planum temporale (PT), a brain region which may integrate visual and auditory information. To find out whether other types of learned audio-visual integration occur in the PT, we investigated ‘‘key-touch reading’’ using functional magnetic resonance imaging (fMRI). As well-trained pianists are able to identify pieces of music by watching the key-touching movements of the hands, we hypothesised that the visual information of observed sequential finger movements is transformed into the auditory modality during ‘‘keytouch reading’’ asis the case during lip reading. We therefore predicted activation of the PT during key-touch reading. Twenty-six healthy righthandedvolunteers were recruited for fMRI. Ofthese, 7subjects hadnever experiencedpiano training(nao¨ve group),10had alittle experience of pianoplaying(less trainedgroup), andtheremaining 9hadbeentrained for morethan8years(welltrainedgroup). Duringtask periods,subjects were required to view the bimanual hand movements of a piano player making key presses. During control periods, subjects viewed the same handssliding from side to side without tapping movements ofthe fingers. Nosound wasprovided. Sequences ofkeypresses during task periods consisted of pieces of familiar music, unfamiliar music, or random sequences. Well-trained subjects were able to identify the familiar music, whereasless-trainedsubjectswerenot.TheleftPTofthewell-trainedsubjectswasequallyactivatedbyobservationoffamiliarmusic,unfamiliar music, and random sequences. The nao¨ve and less trained groups did not show activation of the left PT during any of the tasks. These results suggest that PTactivation reflects a learned process. As the activation was elicited by viewing key pressing actions regardless of whether they constituted a piece of music, the PT may be involved in processes that occur prior to the identification of a piece of music, that is, mapping the complex sequence structure of hand movements onto the sequence of sounds.