Scalp electroencephalography (EEG) is a non-invasive mean to sample human brain activity. The recorded signals are hypothesized to result from synchronized changes in postsynaptic activity, occurring in the apical dendrites of pyramidal neurons.
Intracerebral EEG is performed using electrodes implanted in the brain for the diagnostic workup of patients with partial intractable epilepsy. As compared to scalp EEG, intracerebral EEG offers the advantage of a much higher spatial resolution.
Letswave is a Matlab EEG signal-processing toolbox developed to perform fast multi-subject analyses of electrophysiological data, in particular, stimulus-evoked EEG responses such as event-related brain potentials (ERPs), event-related synchronization and desynchronisation (ERD and ERS), and EEG frequency tagging.
Magnetic resonance imaging (MRI) uses radio waves and a strong magnetic field to provide images of internal organs and tissues. It does not use X-rays. Functional MRI is a procedure that uses MRI to indirectly measure the neural activity occurring in the brain of humans (or other animals).
In 1975, Mor and Carmon introduced infrared laser stimulators as tools to explore nociception in humans. Allowing brief, synchronous, and selective activation of cutaneous Adelta- and C-fibre nociceptors, laser heat stimulators are now used extensively to study nociception in humans. Recently, we have collaborated to the development of a novel CO2 laser stimulator whose power is regulated using a feedback control based on an online measurement of skin temperature at the site of stimulation (Laser Stimulation Device, SIFEC, Belgium).
Transcranial magnetic stimulation (TMS) is used to briefly activate nerve cells in a small area on the surface of the brain. The stimulator device uses the principle of electromagnetic induction. An electrical current is passed very briefly through a coil of copper wires held on the surface of the scalp. This current induces a magnetic field around the coil which, in turn, induces an electrical current in the underlying nerve cells on the surface of the brain.
Transcranial direct current stimulation (tDCS) is non-invasive technique to modulate neuronal excitability. The stimulation is generated by a direct current stimulator and delivered through a pair or an array of surface electrodes placed on the scalp. Depending on the electrode polarity, the stimulation can either decrease or increase excitability, probably by hyperpolarization or depolarization of the underlying neuronal populations.