The theoretical model of theta burst form of repetitive transcranial magnetic stimulation

Clin Neurophysiol. 2011 May;122(5):1011-8. doi: 10.1016/j.clinph.2010.08.016.


Objective: Theta burst stimulation, a form of repetitive transcranial magnetic stimulation, can induce lasting changes in corticospinal excitability that are thought to involve long-term potentiation/depression (LTD/LTD)-like effects on cortical synapses. The pattern of delivery of TBS is crucial in determining the direction of change in synaptic efficiency. Previously we explained this by postulating (1) that a single burst of stimulation induces a mixture of excitatory and inhibitory effects and (2) those effects may cascade to produce long-lasting effects. Here we formalise those ideas into a simple mathematical model.

Methods: The model is based on a simplified description of the glutamatergic synapse in which post-synaptic Ca(2+) entry initiates processes leading to different amount of potentiation and depression of synaptic transmission. The final effect on the synapse results from summation of the two effects.

Results: The model using these assumptions can fit reported data. Metaplastic effects of voluntary contraction on the response to TBS can be incorporated by changing time constants in the model.

Conclusions: The pattern-dependent after-effects and interactions with voluntary contraction can be successfully modelled by using reasonable assumptions about known cellular mechanisms of plasticity.

Significance: The model could provide insight into development of new plasticity induction protocols using TMS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain / physiology*
  • Electric Stimulation / methods*
  • Evoked Potentials, Motor / physiology
  • Humans
  • Models, Neurological*
  • Motor Cortex / physiology
  • Neuronal Plasticity / physiology
  • Transcranial Magnetic Stimulation / methods*