Data from: Perceptually relevant speech tracking in auditory and motor cortex reflects distinct linguistic features

During online speech processing, our brain tracks the acoustic
fluctuations in speech at different timescales. Previous research has
focused on generic timescales (for example, delta or theta bands) that are
assumed to map onto linguistic features such as prosody or syllables.
However, given the high intersubject variability in speaking patterns,
such a generic association between the timescales of brain activity and
speech properties can be ambiguous. Here, we analyse speech tracking in
source-localised magnetoencephalographic data by directly focusing on
timescales extracted from statistical regularities in our speech material.
This revealed widespread significant tracking at the timescales of phrases
(0.6–1.3 Hz), words (1.8–3 Hz), syllables (2.8–4.8 Hz), and phonemes
(8–12.4 Hz). Importantly, when examining its perceptual relevance, we
found stronger tracking for correctly comprehended trials in the left
premotor (PM) cortex at the phrasal scale as well as in left middle
temporal cortex at the word scale. Control analyses using generic bands
confirmed that these effects were specific to the speech regularities in
our stimuli. Furthermore, we found that the phase at the phrasal timescale
coupled to power at beta frequency (13–30 Hz) in motor areas. This
cross-frequency coupling presumably reflects top-down temporal prediction
in ongoing speech perception. Together, our results reveal specific
functional and perceptually relevant roles of distinct tracking and
cross-frequency processes along the auditory–motor pathway.