Spontaneous firing of hypothalamic neurones over a narrow temperature interval

Abstract

THE search for the central mechanism of thermoregulation in mammals has been narrowed down to a study of neurones in particular regions of the hypothalamus^1,2. The experimental work has mainly been carried out in vivo and thus reflects not only the properties of a single neurone but also the influence of the neuronal network in which it is connected. We are currently measuring spontaneous electrical potentials in dissociated hypothalamic cells grown in culture to determine the thermal behaviour of individual neurones freed from their original synaptic connections. Our primary intention was to measure the temperature-dependence of the firing rate and relate it to published in vivo data^1,3, but our initial experiment produced the unexpected result that a significant proportion of hypothalamic neurones that survive in culture are silent between 30 and 40 °C except inside a narrow temperature range, only about 2° wide, where they show spontaneous electrical activity.