Herrmann B, Henry MJ, Grigutsch M, Obleser J (2013). Oscillatory phase dynamics in neural entrainment underpin illusory percepts of time. The Journal of Neuroscience 33:15799-15809.
This study investigated the role of entrained neural oscillations in perpection of time. We used frequency modulated sounds that changed in modulation rate over time (speeding up vs. slowing down) and simultaneously changed in pitch (increase vs. decrease in mean carrier frequency) over time. Although listeners were instructed to only judge whether sounds were speeding up or slowing down and to ignore pitch changes, listeners perceived a sound as speeding up when it actually increased in pitch and as slowing down when the sound was actually decreasing in pitch. (The figure below shows the frequency modulation of the sounds and the behavior ratings).
We recorded magnetoencephalography (MEG) while participants listened to the sounds. We specifically investigated changes in the strength of neural synchronization (quantified as inter-trial phase coherence [ITPC]) in auditory cortex.
Neural synchronization was strongest when sounds congruently changed in frequency modulation and pitch (e.g., speeding up and increasing in pitch), and was relatively weaker when sounds incongruently changed. We separated participants into two groups based on the degree their modulation rate percept was influenced by pitch. The interaction (shown in the figure above) was only significant for participants that were strongly influenced by changes in pitch.