Brain–Speech Alignment Enhances Auditory Cortical Responses and Speech Perception

Abstract

Asymmetry in auditory cortical oscillations could play a role in speech perception by fostering hemispheric triage of information across the two hemispheres. Due to this asymmetry, fast speech temporal modulations relevant for phonemic analysis could be best perceived by the left auditory cortex, while slower modulations conveying vocal and paralinguistic information would be better captured by the right one. It is unclear, however, whether and how early oscillation-based selection influences speech perception. Using a dichotic listening paradigm in human participants, where we provided different parts of the speech envelope to each ear, we show that word recognition is facilitated when the temporal properties of speech match the rhythmic properties of auditory cortices. We further show that the interaction between speech envelope and auditory cortices rhythms translates in their level of neural activity (as measured with fMRI). In the left auditory cortex, the neural activity level related to stimulus-brain rhythm interaction predicts speech perception facilitation. These data demonstrate that speech interacts with auditory cortical rhythms differently in right and left auditory cortex, and that in the latter, the interaction directly impacts speech perception performance.

Asymmetric sampling in human auditory cortex reveals spectral processing hierarchy

“…Patients were implanted with an average of 11 (range [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]) depth electrodes (0.8 mm), composed of 5-15 contacts. Contacts were 2 mm long and spaced by 1.5 mm.…”

“…Such temporal multiplexing allows the system to process in parallel acoustic information using 2 complementary algorithmic strategies, optimized to encode complementary spectrotemporal characteristic of sounds. This prediction-that sounds are processed at preferred and specific timescales-has received support from both auditory and speech-specific paradigms [7][8][9][10][11][12][13][14][15].…”

Asymmetric sampling in human auditory cortex reveals spectral processing hierarchy

“…Such temporal multiplexing allows the system to process in parallel acoustic information using two complementary algorithmic strategies, optimized to encode complementary spectrotemporal characteristic of sounds. This prediction - that sounds are processed at preferred and specific timescales - has received support from both auditory and speech-specific paradigms [8–16].…”

Reliability of early cortical auditory gamma-band responses

“…Abnormalities in neural timing at any level of the auditory system can contribute to impairments in processing complex auditory information, including speech, at the level of the cortex (Zeng et al, 1999; King et al, 2002; Warrier et al, 2004; Saoud et al, 2012). Examining the time course of cortical gamma-band responses within and between brain regions may provide useful information about normal and impaired auditory processing (Gilley and Sharma, 2010; Chang et al, 2011; Cervenka et al, 2011b).…”