Modulation of Auditory Responses to Speech vs. Nonspeech Stimuli during Speech Movement Planning.

Ayoub Daliri,Ludo Max

doi:10.3389/fnhum.2016.00234

Abstract

Previously, we showed that the N100 amplitude in long latency auditory evoked potentials (LLAEPs) elicited by pure tone probe stimuli is modulated when the stimuli are delivered during speech movement planning as compared with no-speaking control conditions. Given that we probed the auditory system only with pure tones, it remained unknown whether the nature and magnitude of this pre-speech auditory modulation depends on the type of auditory stimulus. Thus, here, we asked whether the effect of speech movement planning on auditory processing varies depending on the type of auditory stimulus. In an experiment with nine adult subjects, we recorded LLAEPs that were elicited by either pure tones or speech syllables when these stimuli were presented prior to speech onset in a delayed-response speaking condition vs. a silent reading control condition. Results showed no statistically significant difference in pre-speech modulation of the N100 amplitude (early stages of auditory processing) for the speech stimuli as compared with the nonspeech stimuli. However, the amplitude of the P200 component (later stages of auditory processing) showed a statistically significant pre-speech modulation that was specific to the speech stimuli only. Hence, the overall results from this study indicate that, immediately prior to speech onset, modulation of the auditory system has a general effect on early processing stages but a speech-specific effect on later processing stages. This finding is consistent with the hypothesis that pre-speech auditory modulation may play a role in priming the auditory system for its role in monitoring auditory feedback during speech production.

Highlights

The central nervous system (CNS) modulates its response to sensory inputs that are consequences of self-produced movements
We suggested that, during speech planning, the CNS uses an efference copy of planned control signals to prime the auditory system for its role in processing the upcoming auditory feedback resulting from execution of those control signals
In the current study, we hypothesized that if pre-speech modulation plays a role in priming the auditory system for its role in monitoring auditory feedback during speech production, the N100 and P200 components might be differentially affected when the stimuli used to probe the auditory system during speech planning are pure tones vs. speech syllables

Summary

Introduction

The central nervous system (CNS) modulates its response to sensory inputs that are consequences of self-produced movements. Auditory Modualtion cortical responses evoked by self-produced speech sounds are modulated in comparison with those evoked by hearing a playedback version of the same speech sounds (EEG: Ford et al, 2001; Liotti et al, 2010; MEG: Curio et al, 2000; Houde et al, 2002; Beal et al, 2010; ECoG: Towle et al, 2008; Greenlee et al, 2011; single unit recordings: Creutzfeldt et al, 1989). Animal studies have further confirmed this phenomenon in the auditory-motor system of monkeys, rodents, bats, and crickets (Suga and Schlegel, 1972; Suga and Shimozawa, 1974; Muller-Preuss and Ploog, 1981; Poulet and Hedwig, 2002, 2007; Eliades and Wang, 2003; Nelson et al, 2013; Schneider et al, 2014)

Objectives

Results

Conclusion