MAGNETIC BRAIN IMAGING OF EXTINCTION PROCESSES IN HUMAN CLASSICAL-CONDITIONING

BY recording neuromagnetic events during aversive classical conditioni ng, we examined the extinction of a previously described conditioned r esponse. Averaging over non-reinforced exposures to the conditioned st imulus revealed magnetic activity in the secondary somatosensory and i nsular cortices, appearing between 110 and 140 ms after the omitted un conditioned electric shock. We suggest this activity to be elicited by the discrepancy between shock expectancy and perceptual processes ass ociated with the omission of the unconditioned stimulus, reflecting on e of several brain processes in extinction.