Tracking differential activation of primary and supplementary motor cortex across timing tasks: An fNIRS validation study

Abstract

Functional near-infrared spectroscopy (fNIRS) provides an alternative to functional magnetic resonance imaging (fMRI) for assessing changes in cortical hemodynamics. To establish the utility of fNIRS for measuring differential recruitment of the motor network during the production of timing-based actions, we measured cortical hemodynamic responses in 10 healthy adults while they performed two versions of a finger-tapping task. The task, used in an earlier fMRI study (Jantzen et al., 2004), was designed to track the neural basis of different timing behaviors. Participants paced their tapping to a metronomic tone, then continued tapping at the established pace without the tone. Initial tapping was either synchronous or syncopated relative to the tone. This produced a 2 × 2 design: synchronous or syncopated tapping and pacing the tapping with or continuing without a tone. Accuracy of the timing of tapping was tracked while cortical hemodynamics were monitored using fNIRS. Hemodynamic responses were computed by canonical statistical analysis across trials in each of the four conditions. Task-induced brain activation resulted in significant increases in oxygenated hemoglobin concentration (oxy-Hb) in a broad region in and around the motor cortex. Overall, syncopated tapping was harder behaviorally and produced more cortical activation than synchronous tapping. Thus, we observed significant changes in oxy-Hb in direct relation to the complexity of the task.

Cerebral hemodynamic response during a live action-observation and action-execution task: A fNIRS study

“…The hemodynamic response function was then generated for each channel during each condition for each participant by averaging the response curves from all trials within a condition into a single hemodynamic curve. For each participant at each channel, the maximum change in HbO (increase in chromophore concentration) and HbR (decrease in chromophore concentration) between 5 and 20 seconds in response to each experimental condition (observation and execution) were computed to be used as the dependent variable in subsequent analyses as in previous fNIRS studies [56,57] Due to a greater signal to noise ratio and similarly to previous fNIRS studies we only used HbO signal for remaining analysis [58,59].…”

Observation and motor imagery balance tasks evaluation: An fNIRS feasibility study

“…This model iteratively reweights all error terms to minimize the effect of outliers using both pre-whitening and robust regression, thus making the algorithm robust to physiological noise and motion artifacts as well. Therefore, using any pre-processing technique (such as principal component analysis or band-pass filtering) was not explicitly required to remove these components [ 58 – 60 ]. Furthermore, in order to remove the strong noise component presented at very low frequencies, a high pass filter based on a discrete cosine transform, with a 120s cut-off period, was utilized in this study [ 61 , 62 ].…”

An fNIRS Study of Brain Lateralization During Observation and Execution of a Fine Motor Task

“…For each channel, the maximum change in HbO (increase in chromophore concentration) and HbR (decrease in chromophore concentration) between 5 and 20 s in response to each experimental condition (observation and execution) were computed to be used as the dependent variable in subsequent analyses. Due to a greater signal-to-noise ratio, and consistent with previous fNIRS studies, we only used the HbO signal in the remaining analyses (Yamamoto and Kato, 2002 ; Rahimpour et al, 2020 ).…”