FNIRS pre-processing and processing methodologies are very important—how a researcher chooses to process their data can change the outcome of an experiment. The purpose of this review is to provide a guide on fNIRS pre-processing and processing techniques pertinent to the field of human motor control research. One hundred and twenty-three articles were selected from the motor control field and were examined on the basis of their fNIRS pre-processing and processing methodologies. Information was gathered about the most frequently used techniques in the field, which included frequency cutoff filters, wavelet filters, smoothing filters, and the general linear model (GLM). We discuss the methodologies of and considerations for these frequently used techniques, as well as those for some alternative techniques. Additionally, general considerations for processing are discussed.

Ovarian hormones influence the propensity for short-term plasticity induced by repetitive transcranial magnetic stimulation (rTMS). Estradiol appears to enhance the propensity for neural plasticity. It is currently unknown how progesterone influences short-term plasticity induced by rTMS. The present research investigates whether the luteal versus follicular phase of the menstrual cycle influence short-term plasticity induced by intermittent theta-burst stimulation (iTBS). We tested the hypothesis that iTBS would increase motor evoked potentials (MEPs) during the follicular phase. Further, we explored the effects of the luteal phase on iTBS-induced neural plasticity. Twenty-nine adult females participated in a placebo-controlled study that delivered real and sham iTBS to the left primary motor cortex in separate sessions corresponding to the follicular phase (real iTBS), luteal phase (real iTBS), and a randomly selected day (sham iTBS). Outcomes included corticospinal excitability as measured by the amplitude of MEPs and short-interval intracortical inhibition (SICI) recorded from the right first dorsal interosseous muscle before and following iTBS (612 pulses). MEP amplitude was increased following real iTBS during the follicular condition. No significant changes in MEP amplitude were observed during the luteal or sham visits. SICI was unchanged by iTBS irrespective of menstrual phase. These findings suggest women experience a variable propensity for iTBS-induced short-term plasticity across the menstrual cycle. This information is important for designing studies aiming to induce plasticity via rTMS in women.

Purpose: Complex regional pain syndrome (CRPS) is a debilitating chronic pain condition characterized by sensory, motor, and autonomic dysfunction with a world-wide prevalence of 26.2 per 100,000 people per year and is 3 to 4 times more prevalent in females. Repetitive transcranial magnetic stimulation (rTMS) has shown to be beneficial for pain relief in neuropathic pain and initial evidence in CRPS is promising, but studies are limited. The objective of this study was to investigate the feasibility of using rTMS in CRPS patients, to improve pain intensity and quality of life. Patients and Methods: Six participants (5 lower limb, 1 upper limb, 42 ± 9 yr) took part in an open-label rTMS study comprised of a 9-week intervention and 6-month follow-up. Participants took part in a 4-week induction period (5 days per week) followed by a 5-week tapering period whereby the frequency of rTMS sessions per week was reduced. rTMS was delivered at 10 hz for 2000 pulses at 80% of resting motor threshold over the primary motor cortex. Feasibility was assessed as compliance of attending treatment sessions. Clinical outcomes included pain intensity using the numerical ratings scale, Pain Catastrophizing scale-EN-SF, PROMIS-29 v2.0 profile, and Rainbow Pain Scale. Results: All participants tolerated the study procedures and 83% of participants completed the 9-week intervention, deeming the protocol feasible. At six months follow-up, data was obtained from 3 individuals. Exploratory analysis revealed a significant reduction in pain intensity (~20%) immediately following the intervention. Categorical improvements in allodynia were observed in four patients immediately following the intervention. Conclusion: This study demonstrates that rTMS delivered over 9 weeks is feasible and well tolerated in individuals living with CRPS. However, there are challenges in collecting follow-up data for six months and appropriate measures must be taken in randomized controlled trials to ensure follow-up retention.

Ipsilateral motor pathways projecting from primary motor cortex (M1) to the distal upper limb exist in humans, and activation of these ipsilateral pathways also facilitate corticomotor excitability of the contralateral homologous muscle. Handedness and biological sex potentially influence the motor cortical representations, however their influence on ipsilateral representations remain largely unexplored. Here, we investigated the effects of ipsilateral contraction on hand motor representation size and excitability, and examined whether these effects were dependent on handedness and/or biological sex. In 80 individuals (40 right-handed, 40-left handed, equal males and females), we performed transcranial magnetic stimulation (TMS) to obtain motor threshold and motor map area of the contralateral first dorsal interosseus (FDI) muscle of each hemisphere, at (1) rest and during (2) ipsilateral FDI muscle contraction at approximately 10% of maximum voluntary contraction. Results showed that ipsilateral contraction increased motor map area and decreased motor threshold within M1. These changes were independent of handedness and biological sex, and similar between hemispheres. Our findings demonstrate that an ipsilateral hand contraction increases the size and excitability of motor representations within ipsilateral M1, and these increases are irrespective of one's handedness and biological sex.

This case series highlights the feasibility and tolerability of using controllable pulse parameter Transcranial Magnetic Stimulation (cTMS) in individuals with painful diabetic neuropathy (pDN). cTMS delivers repetitive monophasic pulses, which allows for greater and longer lasting effects compared to traditional repetitive TMS (rTMS). All participants (N = 2) tolerated 10 sessions of cTMS over a two-week period (five days per week) with no discomfort from the stimulation. They reported no pain from the stimulation despite their heightened pain sensitivity as a result of pDN. The cTMS intervention improved their pain and quality of life as determined through questionnaires evaluating pain, depression, anxiety, and other related measures. Notably, cTMS has never been evaluated in diabetic neuropathy, and our data suggest that it is feasible and tolerable in this clinical population. It further proposes a potential therapeutic treatment option for individuals with pDN.