Transcranial magnetic stimulation (TMS) inhibits cortical dendrites

Elife. 2016 Mar 18;5:e13598. doi: 10.7554/eLife.13598.

Abstract

One of the leading approaches to non-invasively treat a variety of brain disorders is transcranial magnetic stimulation (TMS). However, despite its clinical prevalence, very little is known about the action of TMS at the cellular level let alone what effect it might have at the subcellular level (e.g. dendrites). Here, we examine the effect of single-pulse TMS on dendritic activity in layer 5 pyramidal neurons of the somatosensory cortex using an optical fiber imaging approach. We find that TMS causes GABAB-mediated inhibition of sensory-evoked dendritic Ca(2+) activity. We conclude that TMS directly activates fibers within the upper cortical layers that leads to the activation of dendrite-targeting inhibitory neurons which in turn suppress dendritic Ca(2+) activity. This result implies a specificity of TMS at the dendritic level that could in principle be exploited for investigating these structures non-invasively.

Keywords: GABAB inhibition; dendritic integration; in vivo; neuroscience; rat; transcranial magnetic stimulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Signaling
  • Dendrites / physiology*
  • Female
  • GABAergic Neurons / radiation effects*
  • Male
  • Optical Imaging
  • Pyramidal Cells / radiation effects*
  • Rats, Wistar
  • Somatosensory Cortex / radiation effects*
  • Transcranial Magnetic Stimulation*

Grant support

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.