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

Summary

Hair type commonly seen in historically underrepresented minorities appears to interfere with transcranial magnetic stimulation (TMS). Here we describe a hair braiding method (The Sol Braiding Technique) that improves TMS.

Abstract

Transcranial Magnetic Stimulation (TMS) is a technique that is frequently utilized in neuroscience for both therapeutic and research purposes. TMS offers critical medical services like treating major depression and is vital in almost every research facility. Because TMS relies on scalp placement, hair is thought to affect efficacy because it varies the distance to the target site. Further, it is presumed that the hair textures and length that are predominantly seen in minoritized persons might pose significant challenges to collecting high-quality data. Here, we present preliminary data demonstrating that TMS may be influenced by hair, particularly in historically underrepresented minoritized groups.

The Sol braiding approach is introduced here as an easy-to-learn, quick-to-implement technique that reduces variability in TMS. Compared across nine participants, it was found that the Sol method significantly increased motor evoked potential (MEP) strength and consistency (p < 0.05). By removing the physical hair barrier that impedes direct coil-to-scalp contact, the Sol approach enhances TMS delivery. The MEP peak amplitude and the MEP area under the curve (AUC) were shown to increase as a result. While preliminary, these data are an important step in addressing diversity in neuroscience. These procedures are explained for non-braiding experts.

Introduction

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....

Protocol

The research presented here was approved by the Institutional Review Board (IRB) committee of Montclair State University initiated in 2001 and updated yearly through 2023. All participants were treated within the ethical guidelines of the American Psychological Association. Typical safety procedures were followed. For example, we recruited nine adults from the general Montclair State University population using flyers and word of mouth. All subjects were screened in person employing TMS guidelines set forth by Wasserman<.......

Discussion

Cornrows should not interfere with the angle (e.g., 45°) of the TMS coil. If they do, one of the cornrows may need to be redone to alleviate this issue. If done correctly, MEPs should be consistent (Figure 6).

By utilizing the characteristics of curly or coarse hair, this method of braiding maintains the integrity of the TMS signal. In this study, we were able to significantly increase the MEP size and found an increased trend for consistency. These data have.......

Materials

Name	Company	Catalog Number	Comments
Android Samsung Tablet (for MEPs)
Cloth Measuring Tape
COVID Appropriate Sanitizers and Safety Masks/Gloves
Figure of 8 Copper TMS Coil
Lenovo T490 Laptop
Magstim 200 Single Pulse
Magstim Standard Coil Holder
Speedo Swim Caps
Testable.Org Account and Software
Trigno 2 Lead Sensor (for MEPs)
Trigno Base and Plot Software (for MEPs)