Abstract
Magnetic methods for localizing evoked neural activity in the human brain have been used to search for evidence of a functional organization in primary somatosensory cortex. We have found that in response to median nerve stimulation the deduced source for the evoked component with a latency of 45 ms lies at a depth in the central sulcus that depends on stimulus repetition rate, whereas the sources of the 20 ms and 24 ms components lie at a fixed depth. Moreover we have identified this 45 ms component with the dominant sinusoidal feature characteristic of steady state response.