AN ANALOGUE CROSS-CORRELATOR TO STUDY NATURALLY INDUCED ACTIVITY IN INTACT NERVE TRUNKS

Abstract

An analogue cross-correlator has been devised to sort peripheral nerve traffic as to velocity and direction. This is done by the simultaneous recording of intact nerve activity from at least two sets of electrodes. The recorded data are then fed into the cross -correlator which performs the task of displacement, multiplication and integration. A cross-correlogram is plotted which relates activity to decay time. Natural stimuli only are used to induce activity; thus, the instrument is capable of giving the spectrum of afferent and efferent fibers responding to a "physiological" stimulus such as touch, pressure, noxious stimulus, etc. The validity of the method was demonstrated by the use of various differential blocks such as pressure, temperature and local anesthetic. In addition, the cross-correlogram showed the typical pattern of temporal dispersion. In response to mechanical stimuli, three peaks were shown and identified as alpha, delta and C. Noxious stimuli were especially effective in inducing C activity.