Abstract
.SignificanceHemodynamic responses (HRs) are typically averaged across experimental sessions based on the assumption that brain activation is consistent over multiple trials. This may not be a safe assumption, especially in pediatric populations, due to unaccounted effects of inattention, fatigue, or habituation.AimThe purpose of this study was to quantify the consistency of the HR over speech and language brain regions during speech production in typically developing school-aged children.ApproachBrain activity over speech and language regions of interest (ROIs) was recorded with functional near-infrared spectroscopy during a picture description paradigm with 37 children (aged 7 to 12 years). We divided the 30 experimental trials, each 5 s long, into three segments of 10 trials each corresponding with early (trials 1 to 10), middle (trials 11 to 20), and late (trials 21 to 30) trials. We then compared oxygenated (HbO) and deoxygenated (HbR) hemoglobin concentrations averaged across each 10 trial segment to overall concentrations averaged across all 30 trials. We also compared differential hemoglobin (HbD) across ROIs.ResultsHbO and HbR averaged across all experimental trials most strongly correlated with HbO and HbR from early trials. HbD values from channels over most speech and language regions did not appreciably change throughout the experimental session. The exception was HbD values from channels over the dorsal inferior frontal gyrus (dIFG). This region showed significantly higher activation over the left hemisphere during the first segment of the experiment.ConclusionsOur findings suggest that brain activity from speech and language ROIs was relatively consistent over the experimental session. The exception was increased activation of left dIFG during earlier experimental trials. We suggest that researchers critically evaluate the consistency of HRs from different brain regions to determine the reliability of HRs recorded during experimental sessions. This step is instrumental in ensuring that uncontrolled effects do not mask patterns of task-related activation.
Highlights
English-speaking adults produce on average 2 to 3 words per second in connected speech.[1]
Functional nearinfrared spectroscopy has been used increasingly in speech and language paradigms with children because it is less sensitive to speech-related motion artifacts than functional magnetic resonance imaging [see Refs. 14-16], and is a more child-friendly neuroimaging method.[17,18]
We found canonical hemodynamic activation over the left dorsal inferior frontal gyrus and left premotor cortex (PMC) in controls, while children who stutter showed a distinctly different pattern—deactivation in these regions of interests (ROIs).[16]
Summary
English-speaking adults produce on average 2 to 3 words per second in connected speech.[1] Formulating relatively errorless speech is a skill that develops from infancy[2,3,4,5,6] and relies on Neurophotonics. Functional nearinfrared spectroscopy (fNIRS) has been used increasingly in speech and language paradigms with children because it is less sensitive to speech-related motion artifacts than functional magnetic resonance imaging [see Refs. 14-16], and is a more child-friendly neuroimaging method.[17,18] fNIRS does not require time spent in an MRI scanner, which can be fear- or anxiety-inducing for some children.[19] These benefits are of particular relevance for studying many developmental speech and language conditions [see Refs. 20 and 21, for review], including our previous work in the area of developmental stuttering.[16,17] These benefits are of particular relevance for studying many developmental speech and language conditions [see Refs. 20 and 21, for review], including our previous work in the area of developmental stuttering.[16,17]
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