An electroencephalogram (EEG) is a recording of the electrical activity that occur in the brain and across its surface. Electrodes are applied to a subjects scalp, filled with a conductive gel, and then plugged into a recording device. The minute electrical pulses of the brain are monitored and amplified for observance via a computer.
EEG is a non-invasive technique which offer the advantage of a good temporal resolution.
Functional magnetic resonance imaging (fMRI)
When a certain brain area becomes particularly active (e.g. during a mental task such as language processing) it consumes more oxygen. This leads to an increase in blood flow to that active area. fMRI detects such minute changes in blood oxygenation and flow and, by this means, can display areas of altered brain activity as the result of some stimulus or condition.
fMRI is a non-invasive technique which offer the advantage of a good spatial resolution.
Transcranial magnetic stimulation (TMS)
TMS is a non-invasive method for focal cortical stimulation by means of a coil positioned on the scalp. It delivers brief, strong electric pulses. These create a local magnetic field, which induces a current in the surface of the cortex that temporaly changes local neural activity.
Participants of a behavioral experiment typically sit at a computer where they receive visual or auditory stimuli and press response buttons according to the instructions they received from the experimenter.
The measurements of the participant's behavior are recorded and through the analysis of reaction times and errors it is possible to draw conclusions about brain´s activity .