Neural Activity in the Somatic Primary Receiving Area of the Human Brain and Its Relation to Perceptual Estimates

Experiments were performed to establish the relation between scales of perceived intensity and primary cortical potentials obtained under identical stimulation conditions. When the maximal positive-negative deflection of the primary component of the averaged evoked potential was plotted against stimulus displacement, all data were well represented by power functions with exponents of nearly the same size as those of the psychophysical functions. The results indicate also that spatial summation takes place when two neighboring locations are stimulated with an increase in apparent intensity of only about ¿2 of that corresponding to monodigital stimulation.