AP Action potential BOLD Blood level-dependent EEG Electroencephalography EM Electrical stimulation of the median nerve ERF Event-related field ERP Event-related potential ET Electrical stimulation of the tibial nerve fMRI Functional magnetic resonance imaging fT Femtotesla Fig Figure GMFP Global mean field power ICA Independent component analysis MEG Magnetoencephalography mm Millimeter ms Millisecond MSR Magnetically shield room PM Pneumatic stimulation of the median nerve PSP Post-synaptic potential PT Pneumatic stimulation of the tibial nerve SD Standard deviation SEF Somatosensory evoked field SEP Somatosensory evoked potential SI Primary somatosensory cortex SII Secondary somatosensory cortex SQUID Superconducting quantum interference devices T Tesla