Changes in spectral measures of brain electrical activity in rats after transection of the sciatic nerve.

Electrophysiological measures of brain electrical activity were studied in rats during the development of neurogenic pain syndrome induced by transection of the sciatic nerve. At the peak of development of pain syndrome, three weeks after deafferentation, rearrangements in the spectra of electrical activity were seen in the limbic structures of the brain (hippocampus, amygdala, nucleus accumbens), in the frontal areas of the neocortex, and in the caudate-putamen complex: changes consisted of increases in the relative power of the delta and alpha ranges as compared with controls, along with a decrease in relative power in the beta-2 range. Changes in spectral measures of electrical activity in the limbic structures of the brain occurred independently of the clinical manifestations of neurogenic pain syndrome (autotomy). The increase in relative power in the alpha range of the spectrum of electrical activity in all the structures studied suggests that the reticular nucleus of the thalamus is involved in the pathogenetic mechanisms of neurogenic pain syndrome.