Tickling the body & the brain: TMS and tactile perception

14. Mai 2018
UHG C01-142

Transcranial magnetic stimulation (TMS) is a potentially very powerful method to temporarily interfere with brain function.
The vast majority of TMS research has been aimed at understanding motor behaviour, for example by stimulating primary motor cortex (M1), which produces direct, measurable outputs in the form of muscle contractions.
Other brain areas and systems pose great challenges for TMS research due to the lack of direct, measurable outputs following each pulse of TMS.
For the last five years, I've been working under the assumption that, of all the non-motor cortical areas accessible to TMS, the most likely to yield its mechanisms is primary somatosensory cortex (S1).
S1 is aligned with M1, both anatomically and functionally; it is highly topographic and body-part-specific. This makes it an ideal candidate for TMS research.

In this talk, I'll describe the methods we've used, the problems we've run into, and the findings of 18 experiments designed to understand how the peripheral nerves and S1 process very simple tactile stimuli applied to the fingertips.
Along the way, I'll review TMS literature on tactile perception.
Failures to replicate, generally low methodological quality, and systematic use of inappropriate heuristics to localise S1 have led, I suspect, an anonymous reviewer to state that 'S1 is notoriously hard to TMS'.
My talk aims to show that it is not.