Amplitude-modulated kilohertz transcranial magnetic perturbation (kTMP) has frequency-specific effects on motor performance
Philipp Reber1 (firstname.lastname@example.org), Christina Merrick2, Daniel Sheltraw2, Cidnee Luu2, Kevin Peter2, Katheryn Thayer-Pham2, Ludovica Labruna2, Richard Ivry1,2; 1University of California Berkeley, 2Magnetic Tides Inc., California, USA
We tested the efficacy of a novel non-invasive brain stimulation method, kilohertz transcranial magnetic perturbation (kTMP) in modulating motor performance. kTMP is a magnetic induction method capable of applying strong subthreshold E-fields in the kilohertz frequency range to superficial cortical structures without eliciting tactile sensations. Amplitude modulation (AM) of the kilohertz carrier waveform can be used to target physiologically relevant frequencies. In the current study, we asked if kTMP over the primary motor cortex impacted performance on a force-tracking task. We targeted two prominent motor rhythms: 1) Beta (15-30 Hz), a rhythm associated with movement idling and shown in previous work with invasive alternating current stimulation to impede motor learning; 2) Low-frequency oscillations (3-6 Hz), a range useful for decoding movement kinematics that has been shown to be disrupted following stroke. kTMP was applied with a carrier frequency of 3.5 kHz with the intensity set to induce a cortical E-field of 4 V/m. In three separate sessions, we employed two AM-kTMP conditions, individualized beta (17-29 Hz) or 3 Hz (fixed for all participants), or sham stimulation in a double-blind repeated-measures design. Within each session, motor performance was measured before, during, and after the application of kTMP. We found that AM-kTMP modulated motor performance in a frequency-dependent manner: Performance improvement during and following beta stimulation was reduced compared to the 3 Hz and sham conditions. These results indicate that kTMP has the potential to expand our non-invasive toolset to investigate brain function and provide new therapies for brain disorders.
Topic Area: PERCEPTION & ACTION: Motor control
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April 13–16 | 2024