Statistical properties of near threshold responses to brief sounds in the MES auditory cortex of the anesthetized dog

Abstract

Evoked responses to near threshold p pulses recorded with a 50-channel cathode ray oscilloscope from the MES auditory cortex were analyzed statistically. Observations were taken at 3-msec. epochs for approximately 180 msec. Density functions of the evoked potential at these epochs were essentially normal. The average potential from a single electrode consisted of an initial positive followed by a negative component. The correlation coefficient between the positive and negative components was zero suggesting independence. Standard deviation increased during the positive component of a response decreasing to the zero crossing or was followed by a secondary component. Spatially, in the anterior-posterior direction, the average potentials decremented to approximately zero in 2–4 mm. The decrement was less prominent dorso-ventrally. Spatially, the standard deviation showed the same pattern as the mean.