Background: Electrical stimulation in the kilohertz-frequency range has gained interest in the field of neuroscience. The mechanisms underlying stimulation in this frequency range, however, are poorly characterized to date.
Objective/hypothesis: To summarize the manifold biological effects elicited by kilohertz-frequency stimulation in the context of the currently existing literature and provide a mechanistic framework for the neural responses observed in this frequency range.
Methods: A comprehensive search of the peer-reviewed literature was conducted across electronic databases. Relevant computational, clinical, and mechanistic studies were selected for review.
Results: The effects of kilohertz-frequency stimulation on neural tissue are diverse and yield effects that are distinct from conventional stimulation. Broadly, these can be divided into 1) subthreshold, 2) suprathreshold, 3) synaptic and 4) thermal effects. While facilitation is the dominating mechanism at the subthreshold level, desynchronization, spike-rate adaptation, conduction block, and non-monotonic activation can be observed during suprathreshold kilohertz-frequency stimulation. At the synaptic level, kilohertz-frequency stimulation has been associated with the transient depletion of the available neurotransmitter pool - also known as synaptic fatigue. Finally, thermal effects associated with extrinsic (environmental) and intrinsic (associated with kilohertz-frequency stimulation) temperature changes have been suggested to alter the neural response to stimulation paradigms.
Conclusion: The diverse spectrum of neural responses to stimulation in the kilohertz-frequency range is distinct from that associated with conventional stimulation. This offers the potential for new therapeutic avenues across stimulation modalities. However, stimulation in the kilohertz-frequency range is associated with distinct challenges and caveats that need to be considered in experimental paradigms.
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http://dx.doi.org/10.1016/j.brs.2021.03.008 | DOI Listing |
J Neural Eng
November 2024
Department of Bioengineering, Phil and Penny Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, OR, United States of America.
J Physiol
November 2024
Spinal Cord Injury Research Centre, Neuroscience Research Australia, Randwick, New South Wales, Australia.
Transcutaneous electrical stimulation with repetitive bursts of a kilohertz carrier frequency is thought to be less painful than conventional pulsed currents by reducing the sensitivity of pain receptors. However, no purported benefit has been shown unequivocally. We compared the effects of carrier-frequency stimulation and conventional stimulation on pain tolerance and the thresholds for sensory and motor axons in twelve participants.
View Article and Find Full Text PDFPhysiol Rep
October 2024
Faculty of Ceilândia, Rehabilitation Sciences Program, Laboratory of Muscle and Tendon Plasticity, University of Brasilia, Brasília, DF, Brazil.
Proc Am Control Conf
July 2024
Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH, USA.
The use of kilohertz-frequency (KHF) waveforms has rapidly gained momentum in transcutaneous spinal cord stimulation (tSCS) to restore motor function after paralysis. However, the mechanisms by which these fast-alternating currents depolarize efferent and afferent fibers remain unknown. Our study fills this research gap by providing a hypothesis-and evidence-based investigation using peripheral nerve stimulation, lumbar tSCS, and cervical tSCS in 25 unimpaired participants together with computational modeling.
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