TCProbe (Thalamo-CorticalProbe) – Software Package to extract from TMS EEG data syntactic indexes of cortical excitability and connectivity for research and clinical purposes.

The combination of transcranial magnetic stimulation (TMS) and high-density electroencephalography (hd-EEG) allows directly stimulating a subset of cortical neurons and measure, with good spatial-temporal resolution, the effects produced by this perturbation in the rest of the brain. In principle, this perturb-and-measure approach has important advantages compared to current electrophysiological and neuroimaging techniques.

First, TMS/hd-EEG by-passes sensory pathways, subcortical structures and probes directly the cerebral cortex. Thus, at difference with peripherally-evoked potentials and event-related metabolic activations, it does not depend on the integrity of sensory and motor systems and can access any subject (de-afferentated, paralyzed, unconscious) and any cortical area (primary and associative).

Second, with TMS/hd-EEG it is possible to perturb the cerebral cortex with a wide range of intensities, beyond the limited bandwidth of peripheral receptor and nerves. In this way it is possible to obtain a full excitability profile, from threshold to saturation, of the stimulated cortical area.

Third, TMS/hd-EEG, by recording the effects of the activation of the stimulated neurons on distant cortical areas, can provide an unambiguous measure of cortical effective connectivity, an important parameter for recovery of function, consciousness and cognition.

Given its unique characteristics, TMS/hd-EEG may represent a powerful tool to probe thalamocortical circuits in the lab and at the patient’s bedside. However, while this technique allows probing human thalamocortical circuits with an unprecedented degree of freedom, it also faces us with the challenge of dealing with a black box. At difference with peripheral nerve stimulation, when we apply TMS to perturb directly one of the several accessible cortical sites at one of the several possible intensities, we have very little a priori knowledge about whether, where and when we should expect relevant activations.