determining the motor threshold on non-braided hair during transcranial magnetic stimulation (tms)

Enhancing TMS Efficacy with Sol Braiding Technique in Diverse Populations

Neuroscience research, by its very nature, involves paradigm shifts and innovations for understanding brain function, neurological disabilities, and psychiatric disorders1. Despite much progress, the discipline of neuroscience has fallen short in some aspects. For example, there exist racial disparities, both in the number of researchers, but also in the representation of subjects and patients in research. Numerous underrepresented persons from minority groups are absent from experiments and clinical studies2. Only 5 publications out of 81 peer-reviewed scalp-based EEG articles from September to October 2019 specifically indicated having a sample that included minoritized individuals. Furthermore, recent studies demonstrated that individuals from underrepresented minority groups were often misdiagnosed or failed to trust the researchers. Assari et al. found that the healthcare community, specifically half of White medical students and residents, believed that African Americans have thicker skin than Whites, which influenced their medical judgment and treatment strategies3,4. Owing to the absence of data from minority participants, research findings are less generalizable and show disparities for minority populations. To ensure that the trial population is representative of the patients who will use the medication or medicinal product and that the results are generalizable, clinical trials must include a diverse group of participants5.
Of interest to scalp-based neuroscience is the distinct shape, thickness, styling, and density that is often seen in underrepresented minority hair. The follicle shape, for example, is one feature that makes African hair distinctive. African hair comes from smaller, more elliptical, and flat follicles while Caucasian and Asian hair follicles are more circular and large6. When minorities wash their hair, it curls, causing difficulties for researchers in their experiments. Minority groups are sometimes advised to wash and straighten their hair using hair products before coming in for scalp-based imaging, but doing so can have an impact on the accuracy of the data. Data are skewed because fewer participants of minority groups would volunteer and data from them might be discarded for being a lower quality. Moreover, due to their typical hairstyles (such as cornrows and braids), minoritized individuals are sometimes perceived as being difficult to recruit and retain2. Rosen et al. studied a man of African descent who wore dreadlocks, a style worn by underrepresented minoritized individuals, and presented with disfluency in spontaneous speech7. He wanted to receive treatment using scalp-based imaging since it had emerging evidence for efficacy and was tolerable.
One of the scalp-based imaging techniques that is used widely is transcranial magnetic stimulation (TMS). TMS is a surface-based imaging technique that is used in a non-invasive way to induce localized increases in brain activity. The ability to control neuronal activity in the human brain makes TMS a crucial tool for both experimental and therapeutic neuroscience8. To set standard safety recommendations, when represented as a percentage of the motor threshold (MT), TMS intensity provides a generalizable indicator of applied stimulation that may be used with any coil shape or kind of stimulator9. The motor evoked potential (MEPs) used in determining MT can also be a measure of cortico-excitability, which is elicited by TMS over the human motor cortex10,11,12,1,3,14,15,16. TMS is delivered to the motor cortex, which causes activation in the contra-lateral regions. Typically, regions of the hand are targeted as the stimulating target is not difficult to find on the motor cortex, and attaching electrodes or visually monitoring hand/digit responses is simple. The mechanisms governing motor output can be more fully comprehended using MEPs. Since MEPs are used to measure individual differences in MT, they are now a part of practically every TMS application. In general, it is dangerous to utilize TMS without gauging some aspect of MT. If TMS is delivered above the appropriate MT, seizures may result. If TMS is delivered below MT, results may be reduced or absent (i.e., targeted neurons may not be depolarized). Accurate MT reporting is also critical in comparing studies. For example, many of the studies in our lab use a 90% value, which tells other researchers that a 110% application may result in a greater effect.
Stokes et al. examined different distances between the target region and the stimulating coil and subsequently found a direct linear relationship between the distance and the individuals&#39; MT8,17. Therefore, minority groups, some with thicker natural hair might have less accurate MTs/MEP measurements. In a survey targeting the TMS community of published authors,we found when we asked open-ended questions such as &#34;does hair play a role in impedance?&#34; experts in the field replied: &#34;It increases thresholds. Moving hair aside, compressing it, etc.;&#34; We try to use gel to bridge that contact, but not a lot that can be done;&#34; &#34; Thick hair also makes contact difficult; same as above&#34;; &#34; More hair makes stimulation more difficult-especially if it prevents good scalp contact with the coil18. Dense hair growth makes it challenging to achieve contact between the TMS coil and the scalp, leaving minimal to no contact and impeding the signal. Previous research has shown that braiding thick, coarse hair reduces impedances in scalp-based imaging6. Using the characteristics of coarse or curly hair, Etienne et al. found that braiding a participant&#39;s hair into cornrows maintains signal integrity when using EEG.
We are introducing the Sol &#34;Sun&#34; method to offer a solution to manage the hair in underrepresented minorities. Due to the thickness and coarseness of their hair, we predicted that hair that is typically seen in underrepresented minorities will respond better to this procedure since it will preserve the hair (i.e., no shaving) and allow for long-term measurement. These methods are easy to teach, learn, and perform; require no additional equipment; do not increase safety risks; honor and respect the participants&#39; natural hair; and promote pride in the participant (and researchers) who may have felt previously discouraged by scalp-based techniques.

Author Spotlight: Increasing TMS Accessibility Through Braiding Techniques for Diverse Hair Types

경두개 자기 자극 중 두꺼운 모발을 다루기 위한 Sol Braiding 방법: 뇌 자극의 잠재적 편향에 대한 주소

경두개 자기 자극(TMS) 중 땋아지지 않은 모발의 운동 임계값 결정

시작하려면 70mm 8자 코일의 온도를 모니터링합니다. 필요한 경우 즉시 교체할 수 있도록 백업 코일을 준비하고 액세스할 수 있습니다. 그런 다음 지울 수 있는 매직 마커를 사용하여 Cz nasian 또는 inion 라인 영역과 중간점을 표시합니다.또한 귓불이나 귓바퀴 지점을 측정하고 표시하십시오. 오른쪽 반구의 1/3을 측정하여 abductor pollicis brevis 또는 APB를 활성화하기 위한 최적의 위치를 찾습니다. 코일 트리거와 풋 스위치를 사용하여 TMS 장치를 활성화하고 기계 전면에서 안전 장치를 해제합니다.모든 검색 및 TMS 전달을 위해 TMS 코일을 45도 각도로 배치합니다. 이제 기계 전면의 다이얼을 사용하여 총 기계 출력의 30%에서 자극 출력을 시작합니다. 움직임이 나타날 때까지 강도를 2%씩 점진적으로 높입니다.모터 임계값 결정을 시작하기 전에 정확한 배치를 용이하게 하려면 수영 모자에 코일 팁 위치를 표시하십시오. 매직 마커를 사용하여 코일의 전체 앞 부분의 윤곽을 그립니다. 육안 검사 방법의 경우 다이얼을 사용하여 기계 강도의 20%에서 시작하여 약 20개의 펄스를 전달합니다.응답의 50%가 얻어지면 강도를 개인의 운동 임계값으로 기록합니다. 모터 유발 전위 방법의 경우 APB와 엄지 힘줄에 일회용 전극을 부착합니다. 손목 뒤쪽에 접지 전극을 두르고 육안 검사 대신 기록 장치에서 양의 모터 유발 전위가 관찰되는지 확인합니다.포지티브 모터 유발 전위 응답을 피크 대 피크 진폭이 50마이크로볼트 이상인 응답으로 정의합니다.

Research

JoVE Journal

Neuroscience

Determining the Motor Threshold on Non-Braided Hair During Transcranial Magnetic Stimulation (TMS)

The Sol Braiding Method for Handling Thick Hair During Transcranial Magnetic Stimulation: An Address for Potential Bias in Brain Stimulation

Transcranial Magnetic Stimulation (TMS) is a technique that is frequently utilized in neuroscience for both therapeutic and research purposes. TMS offers ...

연구

신경과학

The Sol Braiding Method for Handling Thick Hair During Transcranial Magnetic Stimulation (TMS)

경두개 자기 자극(TMS) 중 두꺼운 모발을 다루기 위한 솔 브레이딩 방법