Abstract
We here describe the dc magnetic field over the human head produced by healthy hair follicles when the scalp is lightly pressed. This phenomenon was briefly reported decades earlier, where a double-planar SQUID (Superconducting Quantum Interference Devices) gradiometer at a single location was used. We here perform a larger study, using the dcMEG containing 102 double-planar gradiometers covering the whole scalp. The field is displayed as an on-line arrow map over the head, showing the approximate flow of direct current (dc) in the scalp. Standard sets of five arrow maps per subject were measured, where the subject successively pressed parts of their head against the inside of the helmet. These maps were made for 15 normal subjects (5 females), and 2 with alopecia (non-functioning follicles). The directions of “pressed” generating arrows always followed the natural tilt of the follicles, verifying the follicles as generators, with a time constant of about one second. The maximum generator dipole strength was about 24 µA-cm. Scalp electric potentials corresponding to the magnetic signals were masked by much larger electrodermal potentials. Therefore, this magnetic method, called magnetotrichography, is unique in measuring this follicular electrical activity, with possible applications in studying baldness and hair diseases.
Highlights
We here describe the dc magnetic field over the human head produced by healthy hair follicles when the scalp is lightly pressed
Of the various studies of dc fields of the body, the mapping over the body[3] showed a unique new phenomenon, which is in the head: when the scalp was lightly pressed on a region containing healthy hair follicles, an external dc magnetic field appeared over that region
A standard set consists of five MTG maps: 1. head in lightly, barely touching at the top; 2. head pressing above the left ear; 3. head pressing above the right ear; 4. head pressing at the top; 5. head pressing at the back
Summary
We here describe the dc magnetic field over the human head produced by healthy hair follicles when the scalp is lightly pressed. Of the various studies of dc fields of the body, the mapping over the body[3] showed a unique new phenomenon, which is in the head: when the scalp was lightly pressed on a region containing healthy hair follicles, an external dc magnetic field appeared over that region. We did multiple standard recordings to see repeatability, for a total of about 50 recording sessions In these measurements, we found two new sources of dc fields over the head: one source is magnetite particles in the brains of older subjects[8,9] which could be artifacts in the MTG map, if magnetized in the MRI, or in other ways. This is one long-range plan of the MEG community
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
