Factors that influence the amplitude of the bereitschaftspotential

The Bereitschaftspotential (BP) is a slow negative-going deflection in the scalp electrical potential that appears before self-initiated movements that has been considered a neural sign of motor preparation. Besides neuroscience, this brain potential has also generated significant interest in philosophy regarding free will, in law concerning culpability discussions, and in sociology for shaping views on agency and responsibility. Its amplitude varies considerably across tasks and populations, and is influenced by diseases, stage of development, and cognitive factors. However, the factors relevant to this variation have never been systematically reviewed. There have been many studies on some aspects of the BP and fewer on others. In this narrative review, we analyze whether there might be a general factor, explaining most results, despite their differences of purpose. A structured literature search on PubMed revealed many peer-reviewed studies that used a task that might illuminate the significance of the amplitude. We found studies comparing different types of movement and different populations. We conclude that the factor of attention appears to be the most consistent across the studies reviewed.