ABSTRACT
We turned to the recording of local dendritic potentials, which had been pioneered by Adrian (1950) by a single channel electroencephalogram (BEG) of the bulb, but in our hands with multiple electrodes (64 in an 8 x 8 array) fonning a 4 x 4 mm window fitted onto the bulbar surface. Our prior work (Freeman, 1975) had already established a dose statistical relationship between the spatioremporal patterns of the EEG amplitudes at the bulbar surface and the distributions of relative firing frequencies of the mitral cells within the bulb. We estimated that each surface electrocie gave access to the local mean field of 300 to 500 mitral cells, and that our array accessed about 20% of the bulb in the rabbit. In this way we employed spatial ensemble averaging over neural populations on single trials, instead of time ensemble averaging of measurements from a roving electrode over many trials (Freeman, 1987a).
