Zoekresultaten

Cerebral activations in highly-skilled keyboard performers

Recognition of action, goals and intentions has been shown to be mediated by a multimodal mirror-neuron system, not only in monkeys, but also in humans. A fronto-parietal network of brain areas has been identified where these neurons are located. We should expect musical actions, goals and intentions to be mediated by this system as well. In this fMRI study, we present audio recordings of music composed in two-part harmony to 10 professional, improvising keyboard performers. The first task (Motor Imagery) was to imagine playing the piece, the second task (Judgment) to listen attentively while assessing the performance . Half of the pieces were familiar, the other half unfamiliar. A group of musically unskilled subjects participated as controls. As hypothesized, a fronto-parietal network of cerebral areas was activated, not only during Motor Imagery, but also during Judgement, including activity in left, ventral PMC. In a behavioral test, the ability of these performers to recognize musical actions, goals and intentions was corroborated. Performers listened to various excerpts, played them by ear, harmonized them and transposed them, demonstrating that they not only could replicate, but also manipulate them in a musically plausible manner, suggesting that the cerebral activations observed could indeed be ascribed to recognition of musical action, goals and intentions.

The role of cerebral resonance behavior in the control of music performance

Mirror neurons in the cerebral cortex have been shown to fire not onlyduring performance but also during visual and auditory observation ofactivity. This phenomenon is commonly called cerebral resonance behavior.This would mean that cortical motor regions would not only beactivated while singing, but also while listening to music. The sameshould hold true for playing a music instrument. Although most individualsare able to sing along when they hear a melody, even highlyskilled instrumentalists, however, are frequently unable to play by ear.They are score-dependent—i.e. they are only able to play a piece of musicwhen they have access to the notes—while musicians who are able to playby ear and improvise are non score-dependent; they are able to playwithout notes. Our hypothesis is that score-dependent instrumentalistswill exhibit less cerebral resonance behavior than non score-dependentmusicians while listening to music. Using fMRI to measure BOLD response,subjects listen to two-part harmony presented with headphones.The following experimental conditions are distinguished: (1) well-knownvs. unknown music (2) motor imagery vs. attentive listening. A voxelbasedanalysis of differences between the condition-related cerebral activationsis performed using Statistical Parametric Mapping.

Differential parietal and temporal contributions to music perception in improvising and score-dependent musicians, an fMRI study

Using fMRI, cerebral activations were studied in 24 classically-trained keyboard performers and 12 musically unskilled control subjects. Two groups of musicians were recruited: improvising (n=12) and score-dependent (non-improvising) musicians (n=12). While listening to both familiar and unfamiliar music, subjects either (covertly) appraised the presented music performance or imagined they were playing the music themselves. We hypothesized that improvising musicians would exhibit enhanced efficiency of audiomotor transformation reflected by stronger ventral premotor activation. Statistical Parametric Mapping revealed that, while virtually 'playing along' with the music, improvising musicians exhibited activation of a right-hemisphere distribution of cerebral areas including posterior-superior parietal and dorsal premotor cortex. Involvement of these right-hemisphere dorsal stream areas suggests that improvising musicians recruited an amodal spatial processing system subserving pitch-to-space transformations to facilitate their virtual motor performance. Score-dependent musicians recruited a primarily left-hemisphere pattern of motor areas together with the posterior part of the right superior temporal sulcus, suggesting a relationship between aural discrimination and symbolic representation. Activations in bilateral auditory cortex were significantly larger for improvising musicians than for score-dependent musicians, suggesting enhanced top-down effects on aural perception. Our results suggest that learning to play a music instrument primarily from notation predisposes musicians toward aural identification and discrimination, while learning by improvisation involves audio-spatial-motor transformations, not only during performance, but also perception.

Behavioral quantification of audiomotor transformations in improvising and score-dependent musicians

The historically developed practice of learning to play a music instrument from notes instead of by imitation or improvisation makes it possible to contrast two types of skilled musicians characterized not only by dissimilar performance practices, but also disparate methods of audiomotor learning. In a recent fMRI study comparing these two groups of musicians while they either imagined playing along with a recording or covertly assessed the quality of the performance, we observed activation of a right-hemisphere network of posterior superior parietal and dorsal premotor cortices in improvising musicians, indicating more efficient audiomotor transformation. In the present study, we investigated the detailed performance characteristics underlying the ability of both groups of musicians to replicate music on the basis of aural perception alone. Twenty-two classically trained improvising and score-dependent musicians listened to short, unfamiliar two-part excerpts presented with headphones. They played along or replicated the excerpts by ear on a digital piano, either with or without aural feedback. In addition, they were asked to harmonize or transpose some of the excerpts either to a different key or to the relative minor. MIDI recordings of their performances were compared with recordings of the aural model. Concordance was expressed in an audiomotor alignment score computed with the help of music information retrieval algorithms. Significantly higher alignment scores were found when contrasting groups, voices, and tasks. The present study demonstrates the superior ability of improvising musicians to replicate both the pitch and rhythm of aurally perceived music at the keyboard, not only in the original key, but also in other tonalities. Taken together with the enhanced activation of the right dorsal frontoparietal network found in our previous fMRI study, these results underscore the conclusion that the practice of improvising music can be associated with enhanced audiomotor transformation in response to aurally perceived music.

The effect of centralized financial and social incentives on cooperative behavior and its underlying neural mechanisms

Incentives are frequently used by governments and employers to encourage cooperation. Here, we investigated the effect of centralized incentives on cooperation, firstly in a behavioral study and then replicated in a subsequent neuroimaging (fMRI) study. In both studies, participants completed a novel version of the Public Goods Game, including experimental conditions in which the administration of centralized incentives was probabilistic and incentives were either of a financial or social nature. Behavioral results showed that the prospect of potentially receiving financial and social incentives significantly increased cooperation, with financial incentives yielding the strongest effect. Neuroimaging results showed that activation in the bilateral lateral orbitofrontal cortex and precuneus increased when participants were informed that incentives would be absent versus when they were present. Furthermore, activation in the medial orbitofrontal cortex increased when participants would potentially receive a social versus a financial incentive. These results speak to the efficacy of different types of centralized incentives in increasing cooperative behavior, and they show that incentives directly impact the neural mechanisms underlying cooperation.

Combining EEG and fMRI to investigate the post-movement beta rebound.