Linking actions and their perceivable consequences in the human brain

Voluntary action is goal-directed and therefore depends on the ability to learn associations between movements and their perceivable consequences. The neural substrate of this ability was investigated with (H2O)-O-15 positron emission tomography (PET). Healthy adults first learned that self-initiated keypresses were consistently followed by certain tones (i.e., action effects). During PET imaging, participants listened to varied ratios of action-effect tones and neutral tones without performing any movement. The caudal supplementary motor area and the right hippocampus increased their activity with the frequency of action-effect tones, suggesting that both cortical areas play a role in linking the consequences of an action and the action itself. This integration process represents a highly flexible mechanism that helps to promote the learning, automatization, and control of voluntary actions. (C) 2002 Elsevier Science (USA).