APPLYING jolts of electricity to the brain can prompt both the desire to move a limb and the sensation that you have just done so.
Angela Sirigu of the CNRS Cognitive Neuroscience Centre in Bron, France, and colleagues electrically stimulated the brains of seven patients undergoing brain surgery while awake, and then asked them what they felt. Lightly stimulating a particular region of the parietal cortex made patients want to wiggle their finger, while other regions made them want to roll their tongue or move a limb. Stronger pulses to the same regions convinced them they had actually performed these movements, though their bodies had not moved (Science, ).
Sirigu speculates that this electrical stimulation mimics signals that the parietal cortex produces naturally to initiate movement or produce the feeling that movement has taken place. 鈥淭hat鈥檚 extremely interesting because up to now it has been very difficult for neuroscientists to deal with the idea of intentions or wishes or will,鈥� says Patrick Haggard, a neuroscientist at University College London.
Advertisement