Sleep affects higher-level categorization of speech sounds, but not frequency encoding

Aurélien de la Chapelle, Marie Anick Savard, Reyan Restani, Pouya Ghaemmaghami, Noam Thillou, Khashayar Zardoui, Bharath Chandrasekaran, Emily B.J. Coffey*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Sleep can increase consolidation of new knowledge and skills. It is less clear whether sleep plays a role in other aspects of experience-dependent neuroplasticity, which underlie important human capabilities such as spoken language processing. Theories of sensory learning differ in their predictions; some imply rapid learning at early sensory levels, while other propose a slow, progressive timecourse such that higher-level categorical representations guide immediate, novice learning, while lower-level sensory changes do not emerge until later stages. In this study, we investigated the role of sleep across both behavioural and physiological indices of auditory neuroplasticity. Forty healthy young human adults (23 female) who did not speak a tonal language participated in the study. They learned to categorize non-native Mandarin lexical tones using a sound-to-category training paradigm, and were then randomly assigned to a Nap or Wake condition. Polysomnographic data were recorded to quantify sleep during a 3 h afternoon nap opportunity, or equivalent period of quiet wakeful activity. Measures of behavioural performance accuracy revealed a significant improvement in learning the sound-to-category training paradigm between Nap and Wake groups. Conversely, a neural index of fine sound encoding fidelity of speech sounds known as the frequency-following response (FFR) suggested no change due to sleep, and a null model was supported, using Bayesian statistics. Together, these results support theories that propose a slow, progressive and hierarchical timecourse for sensory learning. Sleep's effect may play the biggest role in the higher-level learning, although contributions to more protracted processes of plasticity that exceed the study duration cannot be ruled out.

Original languageEnglish (US)
Pages (from-to)27-45
Number of pages19
JournalCortex
Volume154
DOIs
StatePublished - Sep 2022

Funding

The authors thank Caroline Holden and Camille Bouhour for assisting with data collection; Casey Roark, G. Nike Gnanateja and Fernando Llanos Lucas for sharing code and materials, some of which are credited to Jessica Roeder for the development of the dual-task and Erika Skoe for providing the MATLAB codes to create the autocorrelograms and implement the F0 tracking analysis; Monika Schönauer for advice concerning the nap design; Robert Zatorre and Giovanni Beltrame for discssion; and Aaron Johnson for advice on Bayesian statistics. We thank the International Laboratory for Brain, Music and Sound Research (BRAMS) for loan of the EEG equipment. Funding was provided by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant to EC. The authors thank Caroline Holden and Camille Bouhour for assisting with data collection; Casey Roark, G. Nike Gnanateja and Fernando Llanos Lucas for sharing code and materials, some of which are credited to Jessica Roeder for the development of the dual-task and Erika Skoe for providing the MATLAB codes to create the autocorrelograms and implement the F0 tracking analysis; Monika Schönauer for advice concerning the nap design; Robert Zatorre and Giovanni Beltrame for discssion; and Aaron Johnson for advice on Bayesian statistics. We thank the International Laboratory for Brain, Music and Sound Research (BRAMS) for loan of the EEG equipment. Funding was provided by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant to EC.

Keywords

  • Categorical learning
  • Consolidation
  • Frequency-following response
  • Sleep
  • Speech

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Neuropsychology and Physiological Psychology
  • Cognitive Neuroscience

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