A Peak Amplitude Selector for Electrophysiological Data Analysis

This paper describes a peak amplitude selector designed to analyze electrophysiological phenomena ranging from slow (0.1 to 1 Hz) EEG to fast (up to 200 kHz) multiple neuronal units. The selector's minimum window height of 10 mV, when used on input signals of 0.5 to 1 volt allows the selection of interesting impulses out of a group of impulses with nearly the same amplitude. To increase the selector's usefulness, four data outputs are provided: for use with a paper recorder, two low speed outputs are available- one giving a pulse out for every impulse in the window, and one giving a pulse out for every 10 pulses in the window (to overcome the problem of losing counts when a fast pulse train is processed by a slow system); a high speed output giving one pulse for every impulse in the window is available; finally, an analog output proportional to rate of arrival of impulses in the window is provided. In addition, reference outputs are supplied to display the upper and lower thresholds relative to the signal, so that the window is clearly defined. The circuit is designed to use low cost components.