Measurement of evoked potential in recognition of faces and buildings.

In the functional neuro-imaging, it is known that the activation to the second stimulus is suppressed when two stimuli are given successively with a short interval as sensory inputs. This kind of suppressive phenomenon has been observed in event-related potential (ERP) signals as well as functional MRI signals of primary auditory, somatosensory and visual cortices. However, we rarely find reports to ERP suppression in higher-order areas of the brain. In this study we used a paired stimulus paradigm. The paired stimulus paradigm consisted of successively presented two stimuli in one trial. We recorded ERP related to recognition of faces and buildings to investigate the suppressive phenomenon in higher-order areas of the brain. We used the paired stimulus paradigm which was comprised of face, building and gray-colored-plain (gray) pictures. The inter-stimulus interval of two stimuli was 200 ms. On the points of O2 and T6, we observed that the ERP for the latter stimulus (face picture) was suppressed severely when a face-gray stimulus pair was presented. On the other hand, when a gray-building stimulus pair was presented, the ERP for the latter stimulus (building picture) was not suppressed on the points of O2 and T6. The similar suppression was observed with a face-face stimulus pair.