The Effects of Phenobarbitone on the Spinal Segmental Cord Potentials in Man

The effects of phenobarbitone on the spinal segmental cord potentials elicited by stimulation of the posterior tibiul nerve were investigated in 10 subjects. Intrathecal recording technique was used to obtain the spinal potentials. The major ellects of phenobarbitone were to be on the N2 COMponent of the CD potantials, and the amplitudes of the N2 romponent derreased to 45 % of the first value, though the N1 and P2 com-ponents were deereased about 6 % and 25 % of the first value. It was conluded that the NI component of CD potential arise from the presynaptic activily via the dorsal roots and intrameduller extentions of these afferents, and the post postsynaptir activity in the posterior horn relis. The P2 cornponent rep-resents presynaptic inhibition in the primer af-ferents, and postsynaptir activity of the posterior horn rells. The N2 components of the CD po-tentials are due to synaptic and postsynaptic ac-tivity of the spinal cord neurons.