DOI: 10.5061/dryad.dbrv15f0j
title: Data from: The music of silence. Part I: Responses to musical imagery encode melodic expectations and acoustics

description: Musical imagery is the voluntary internal hearing of music in the mind
 without the need for physical action or external stimulation. Numerous
 studies have already revealed brain areas activated during imagery.
 However, it remains unclear to what extent imagined music responses
 preserve the detailed temporal dynamics of the acoustic stimulus envelope
 and, crucially, whether melodic expectations play any role in modulating
 responses to imagined music, as they prominently do during listening.
 These modulations are important as they reflect aspects of the human
 musical experience, such as its acquisition, engagement, and enjoyment.
 This study explored the nature of these modulations in imagined music
 based on EEG recordings from 21 professional musicians (6 females and 15
 males). Regression analyses were conducted to demonstrate that imagined
 neural signals can be predicted accurately, similarly to the listening
 task, and were sufficiently robust to allow for accurate identification of
 the imagined musical piece from the EEG. In doing so, our results indicate
 that imagery and listening tasks elicited an overlapping but distinctive
 topography of neural responses to sound acoustics, which is in line with
 previous fMRI literature. Melodic expectation, however, evoked very
 similar frontal spatial activation in both conditions, suggesting that
 they are supported by the same underlying mechanisms. Finally, neural
 responses induced by imagery exhibited a specific transformation from the
 listening condition, which primarily included a relative delay and a
 polarity inversion of the response. This transformation demonstrates the
 top-down predictive nature of the expectation mechanisms arising during
 both listening and imagery.
description:   All participants were chosen to be very well-trained musicians
 and were all professionals or students at Conservatoire National Supérieur
 de Musique (CNSM) in Paris. They were given the musical score of the four
 stimuli in a one-page score and could practice on the piano for about 35
 minutes. The experimenter checked their practice and verified that there
 were no mistakes in the execution. After practice, participants were asked
 to sing the four pieces in the booth with the tactile metronome, the sound
 was recorded in order to check their accuracy offline.
   The experiment consisted of a single session with 88 trials.
 For each condition (listening and imagery) each of the four melodies was
 repeated 11 times. The trial order was shuffled both in terms of musical
 pieces and conditions. In the listening condition, participants were asked
 to passively listen to the stimuli while reading the musical score. For
 the imagery condition, they were asked to imagine the melody in sync with
 the tactile metronome as precisely as they could.    
 Four melodies from the corpus of Bach chorals were selected for this study
 (BWV 349, BWV 291, BWV354, BWV 271). All chorals use similar compositional
 principles: the composer takes a well-known melody from a Lutheran hymn
 (cantus firmus) and harmonizes three lower parts (alto, tenor, and bass)
 accompanying the initial melody on soprano, these cantus firmi were
 usually written during the Renaissance era. Our analysis only uses
 monophonic melodies, we therefore only use these cantus firmi as stimuli
 for our experiment, original keys were kept. The chosen melodies follow
 the same grammatical structures and show very similar melodic and rhythmic
 patterns. Participants were asked to listen to and imagine these stimuli
 at 100 bpm (about 30 seconds each). The audio versions were synthesized
 using a Fender Rhodes simulation software (Neo-Soul Keys). The onset times
 and pitch values of the notes were extracted from the midi files that were
 precisely aligned with the audio versions presented during the
 experiment. The pre-processing has been made with
 filtering between 0.1Hz and 30Hz using Butterworth zero-phase filters and
 down-sampled to 64 Hz. Data were re-referenced to the average of all 64
 channels and bad channels were removed and interpolated using spherical
 spline interpolation. The stimuli onsets that were closer than 500ms from
 a metronome beat were removes.
description: The unique data file contains 3 variables:     <br>     -
 downFs: the sampling rate<br>     - eeg: the EEG data as a
 cell-array (21*2*44*(1803*64)) -&gt;
 (participants*conditions*trials*(time*electrodes)), with conditions as
 (listening, imagery)<br>     - stim: the time-representation of the
 expectation signal (onsets can be extracted from it) following the exact
 same structure as the EEG ((21*2*44*(1803*1))) We also
 include a folder original_stim containing the audio presented during the
 experiment (left channel is the metronome), the midi files, and the pdf
 scores.