Lateralized readiness potential

In neuroscience, the lateralized readiness potential (LRP) is an event-related brain potential, or increase in electrical activity at the surface of the brain, that is thought to reflect the preparation of motor activity on a certain side of the body; in other words, it is a spike in the electrical activity of the brain that happens when a person gets ready to move one arm, leg, or foot. It is a special form of bereitschaftspotential (a general pre-motor potential). LRPs are recorded using electroencephalography (EEG) and have numerous applications in cognitive neuroscience. Kornhuber and Deecke's discovery of the Bereitschaftspotential (German for readiness potential) led to research on the now extensively used LRP, which has often been investigated in the context of the mental chronometry paradigm. In the basic chronometric paradigm, the subject experiences a warning stimulus, followed by an interval (foreperiod), and then an imperative stimulus that the subject must respond to (see chronometric paradigm). During this foreperiod, the subject may be able to prepare a unimanual response, based on information from the warning stimulus. Part of this preparation includes a slow negative wave bilaterally distributed over pre- and post-central sites, the readiness potential. Vaughan, Costa, and Ritter (1968) noted that the readiness potential was larger contralateral to the side of the body where the muscle contraction occurred. The only RPs that do not seem to be lateralized are face and tongue movements which have symmetrical distribution over both hemispheres with the maximum of the potential located in the lower half of the central sulcus. That the lateralized aspect of the readiness potential in general might be used to measure the amount of motor preparation for a direct specific action, termed "corrected motor asymmetry", was highlighted by De Jong and Gratton et al. The LRP is elicited whenever a subject initiates a voluntary movement with his/her hand (or feet). Typically, a subject may be given a task requiring a button press (or squeeze) response.