Transcranial Magnetic Stimulation (TMS)
Neuromodulation, in the form of transcranial magnetic stimulation (TMS) and transcranial direct/alternating current stimulation (tD/ACS) is a means of non-invasively but directly stimulating the brain.
TMS has many guises. For example, single pulses can be used to briefly and transiently disrupt information processing in the underlying cortex or to measure the excitability of the corticospinal tract. Paired-pulses can be used to examine inhibitory and excitatory circuits in the brain.
Repetitive pulses (rTMS) and tD/ACS can be used to alter the excitability of the cortex and have many possible clinical applications (eg in the treatment of depression, tinnitus, auditory hallucinations, epilepsy and many others). In the CBS, TMS is currently used in the following areas:
- to stimulate motor evoked potentials (MEPs) as an index of mirror neuron system activation
- to modulate EEG oscillations (particularly in the alpha bandwidth) in order to a) explore the functional significance of such oscillatory activity and b) to examine possible future clinical applications
- to investigate the role of the dorsal stream in near/far visual processing
The CBS is equipped with two of the latest Magstim Transcranial Magnetic Stimulation (TMS) systems – the 2002/Bistim2 and the Rapid2. This provides the capability for running a variety of TMS protocols including: single pulse, paired-pulse, repetitive trains (rTMS) and dual coil approaches (e.g. transcallosal inhibition). We also have the Brainsight2, a stereotactic image guidance system that facilitates the positioning of transcranial magnetic stimulator coils over a subject’s brain.
Electrical stimulation of the brain is also possible using the latest Magstim Eldith Transcranial Direct Current Stimulator Plus. With this device, transcranial direct current stimulation (tDCS) is possible in either continuous or pulsed modes. The combination of neuromodulation with our other psychophysiological tools (eg EEG, NIRS) opens an exciting new avenue for research in cognitive neuroscience.