Axotomy-induced alterations in the electrophysiological characteristics of neurons

A playback apparatus for reproducing a composite color video signal from a recorded signal of the "color-under" type and having a heterodyne circuit which, in response to a carrier reference signal, frequency reconverts the chrominance component of the reproduced composite color video signal from the low frequency band in which it was recorded to the standard sub-carrier frequency, is further provided with a phase-lock loop circuit for generating the carrier reference signal in response to horizontal synchronizing signals of the reproduced composite color video signal, a time base correcting circuit receiving the reproduced composite color video signal and the carrier reference signal as a clock signal and being operative to compensate for time-base errors in the reproduced composite color video signal from the playback apparatus, a variable phase-shifter through which the carrier reference signal is applied to the heterodyne circuit of the playback apparatus, and a phase comparator for controlling the phase-shifter on the basis of comparison of the phase of color burst signals from the reproduced composite color video signal with the phase of the carrier reference signal from the phase-lock loop circuit.