Musicians at the cocktail party: Neural correlates of bottom-up and top down mechanisms
Montreal Neurological Institute
Segregating sound mixtures makes demands on multiple cognitive and neural mechanisms that musical training may enhance or exploit. In a series of studies we have documented the music-related enhancement behaviorally in the context of speech in noise, and also in a selective attention context with competing speech streams. Using functional MRI, we observed that musicians’ enhanced speech-in-noise perception was associated with better decoding of speech in auditory areas at high signal-to-noise ratios (SNR), whereas under low SNR conditions the enhancement was associated with decoding in frontal and motor cortical regions. We interpret this finding as indicating a shift from bottom-up to top-down mechanisms depending on the quality of the input, with musicians being better able to deploy either mechanism as a function of the conditions. We then used MEG to look at the neural representation of competing speech streams via decoding of the neural signature (amplitude envelope) of attended vs unattended items. The behavioral advantage associated with musical training was related to enhanced ability to represent both streams in auditory cortex, consistent with their capacity to follow multiple sound streams in music. These cognitive neuroscience approaches help us to develop better models to explain why musicians are good at cocktail parties (apart from their reputed drinking abilities).
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