Electrophysiological properties of dorsal lateral geniculate neurons in brain slices from ME7 scrapie-infected mice

Electrophysiological recordings using conventional intracellular techniques were obtained from dorsal lateral geniculate nucleus (dLGN) neurons in brain slices from ME7 scrapie-infected mice at specific time points throughout the incubation period of the disease. Comparisons were made with age-matched control mice. A number of dLGN neurons from control and scrapie-infected mice were injected with biocytin in order to examine their cellular morphology. Mice were infected with ME7 scrapie by an intraocular route and the mean (+/- SEM) incubation period of the disease was 276 +/- 3.5 days. Our results indicate that there were no differences in the electrophysiological or morphological parameters of neurons recorded in ME7 scrapie-infected and age-matched control mice at any stage of the disease up to 240 days postinoculation. After this time, however, no detectable electrical activity was recorded in the dLGN. This study demonstrates that in the ME7 scrapie-infected dLGN, relay neurons with normal physiological and morphological properties are present even at an advanced stage of the disease at a time when the dLGN is known to be subject to marked pathological changes and a profound neuronal loss.