Absence of coherence between cervical and lumbar spinal cord dorsal surface potentials in the anaesthetized cat

Recordings of spontaneous cord dorsum potentials (CDPs) along the longitudinal axis of the spinal cord were made. These recordings were obtained from the surface of the dorsal horn at different points along the spinal cord caudally and cranially in relation to the point giving spontaneous potentials of maximal amplitude. We found two curves (lumbar and cervical) for the longitudinal distribution of the area of the power spectra of these recordings. Each of these curves had a symmetrical decrement on both sides of the position of the point for the maximal area of power. Such points were discovered on the L5-L7 and C3-C4 spinal segments. Spectral analysis of the spontaneous CDPs simultaneously recorded in both regions indicates no evidence of coherence, thus suggesting that the spontaneous CDPs recorded in the lumbar and cervical regions of the pentobarbitone-anaesthetized cat are generated by two independent populations of neurones not functionally interconnected between them.