Unit Activity of Thalamic and Hypothalamic Neurons During Thalamic Spreading Depression in Rats

Abstract

The effect of thalamic spreading depression (SD) on the extracellularly recorded activity of thalamic and hypothalamic neurons was studied in unanesthetized curarized rats. In 81 % thalamic neurons (n = 31) SD caused a reduction of the spontaneous firing rate, preceded in 55 % of cases by a brief discharge. This reaction was essentially similar to those described in other structures directly invaded by SD. Also in the subthalamic and hypothalamic units (n = 39) the most common reaction was a deep decrease of spontaneous activity (69 %) which was preceded by a short lasting increase of firing in 26 % cases only. Pure increase reactions were observed in 1 thalamic and 6 hypothalamic units, while 5 thalamic and 7 hypothalamic units remained unaffected.