A fNIRS Investigation of Speech Planning and Execution in Adults Who Stutter

Abstract

Our study aimed to determine the neural correlates of speech planning and execution in adults who stutter (AWS). Fifteen AWS and 15 controls (CON) completed two tasks that either manipulated speech planning or execution processing loads.Functional near-infrared spectroscopy (fNIRS) was used to measure changes in blood flow concentrations during each task, thus providing an indirect measure of neural activity. An image-based reconstruction technique was used to analyze the results and facilitate their interpretation in the context of previous functional neuroimaging studies of AWS that used positron emission tomography (PET) or functional magnetic resonance imaging (fMRI). For planning, we compared neural activity associated with high versus low planning load in AWS and CON. For execution, we compared the neural activity associated with overt versus covert naming in AWS and CON. Broadly, group level effects corroborate previous PET/fMRI findings including under-activation in lefthemisphere perisylvian speech-language networks and over-activation in righthemisphere homologues. Increased planning load revealed atypical left-hemisphere activation in AWS, whereas increased execution load yielded atypical right frontotemporo-parietal and bilateral motor activation in AWS. Our results add to the limited literature differentiating speech planning versus execution processes in AWS. Highlights1. This report includes the largest sample of AWS to undergo fNIRS to date.2. AWS showed atypical activation in left speech-language regions for planning and right hemisphere homologues for execution.3. Atypical right hemisphere activation comprises a known inhibitory network 4. Group main effects were generally in line with previous PET/fMRI studies of AWS.

Theta Modulated Neural Phase Coherence Facilitates Speech Fluency in Adults Who Stutter

“…The widely referenced MEG study by Salmelin et al (2000) is an early study that highlighted a potential anomaly in the left hemisphere during speech preparation. Very recently, Jackson et al (2019) added to this evidence in their report that increased planning load elicited left hemisphere blood flow differences preceding fluent utterances.…”

The functional brain networks that underlie visual working memory in the first two years of life

“…Note that these approaches have been validated previously by simultaneously recording fNIRS with other imaging modalities (e.g., fMRI; see Wijeakumar et al., 2017a ; Huppert et al., 2017 ). The methods for our image reconstruction approach have been discussed in previous work ( Putt et al., 2017 ; Wijeakumar et al., 2017a , Wijeakumar et al., 2017b ; see also Jackson et al., 2019 ; Putt et al., 2019 ; Wijeakumar et al., 2019 ; Wijeakumar et al., 2017a , Wijeakumar et al., 2017b ). Briefly, after accommodating for the forward model and beta coefficients from the GLM (see above), the relationship between the hemodynamic response and delta optical density is given by: where, F is the channel-wise sensitivity volumes from the Monte Carlo simulations.…”

Analysis methods for measuring passive auditory fNIRS responses generated by a block-design paradigm

“…For example, if participants are required to provide a verbal response, the act of speech production will increase neural activity in the superior temporal gyrus, 45 and even if the verbal response is delayed relative to the event of interest, the act of speech planning may also induce additional neural activity. 46 A common alternative task in auditory experiments is to have the participant press a button; however, this is undesirable as motor movements may modulate auditory cortical activity. 47 In studies that require active participation from the listeners, modifications to experimental design, such as jittering the response window and additional signal processing, can be used to mitigate undesired systemic and neural components.…”