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Updated: May 18, 2026
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Online Transcranial Magnetic Stimulation Protocol for Measuring Cortical Physiology Associated with Response Inhibition
Published on: February 8, 2018
Occipital transcranial magnetic stimulation has an activity-dependent suppressive effect
Francesca Perini1, Luigi Cattaneo, Marisa Carrasco
1Center for Mind/Brain Sciences, University of Trento, 38100 Mattarello (TN), Italy.
Summary
Transcranial magnetic stimulation (TMS) effects on the visual cortex depend on brain state. TMS impaired performance without adaptation but improved it after adaptation, suggesting activity-dependent mechanisms.
Area of Science:
- Neuroscience
- Cognitive Science
- Psychophysics
Background:
- Transcranial magnetic stimulation (TMS) effects are known to be modulated by the brain's state at the time of stimulation.
- Several mechanisms, including virtual lesion and noise generation, have been proposed to explain these context-dependent effects.
Purpose of the Study:
- To investigate the influence of adaptation state on TMS effects in the early visual cortex.
- To test proposed mechanisms of TMS action by examining performance on a contrast-dependent visual task.
Main Methods:
- Human participants performed an orientation discrimination task.
- Contrast adaptation was induced using flickering gratings before trials.
- A single TMS pulse was delivered concurrently with visual targets of varying contrast, with or without prior adaptation.
Main Results:
- Adaptation significantly reduced contrast sensitivity.
- TMS decreased contrast sensitivity in non-adapted states but increased it in adapted states.
- The facilitatory effect of TMS after adaptation, particularly at higher contrasts, was not fully explained by existing models.
Conclusions:
- TMS effects on visual performance are state-dependent, being influenced by prior adaptation.
- A novel hypothesis suggests TMS effects are activity-dependent, modulating the balance between neural excitation and inhibition.
- Existing models of TMS action do not comprehensively explain the observed facilitatory effects in adapted states.
