The cerebral haemodynamics of music perception

Abstract

The perception of music has been investigated by several neurophysiologicaland neuroimaging methods. Results from these studies suggest a righthemisphere dominance for non-musicians and a possible left hemispheredominance for musicians. However, inconsistent results have beenobtained, and not all variables have been controlled by the differentmethods. We performed a study with functional transcranial Dopplersonography (fTCD) of the middle cerebral artery to evaluate changesin cerebral blood flow velocity (CBFV) during different periods ofmusic perception. Twenty-four healthy right-handed subjects wereenrolled and examined during rest and during listening to periodsof music with predominant language, rhythm and harmony content. Thegender, musical experience and mode of listening of the subjectswere chosen as independent factors; the type of music was includedas the variable in repeated measurements. We observed a significantincrease of CBFV in the right hemisphere in non-musicians duringharmony perception but not during rhythm perception; this effectwas more pronounced in females. Language perception was lateralizedto the left hemisphere in all subject groups. Musicians showed increasedCBFV values in the left hemisphere which were independent of thetype of stimulus, and background listeners showed increased CBFVvalues during harmony perception in the right hemisphere which wereindependent of their musical experience. The time taken to reachthe peak of CBFV was significantly longer in non-musicians when comparedwith musicians during rhythm and harmony perception. Pulse rateswere significantly decreased in non-musicians during harmony perception,probably due to a specific relaxation effect in this subgroup. Theresistance index did not show any significant differences, suggestingonly regional changes of small resistance vessels but not of largearteries. Our fTCD study confirms previous findings of right hemispherelateralization for harmony perception in non-musicians. In addition,we showed that this effect is more pronounced in female subjectsand in background listeners and that the lateralization is delayedin non-musicians compared with musicians for the perception of rhythmand harmony stimuli. Our data suggest that musicians and non-musicianshave different strategies to lateralize musical stimuli, with a delayedbut marked right hemisphere lateralization during harmony perceptionin non-musicians and an attentive mode of listening contributingto a left hemisphere lateralization in musicians