[The effect of the systemic administration of neuroleptics on the neuronal background activity of the ventrolateral thalamic nucleus in the cat].

The background activity of 272 neurons of the ventrolateral thalamic nucleus was registered extracellularly in chronic experiments on cats in drowsy state before and after systemic injection of haloperidol and droperidol in cataleptic doses. In intact animals the neuronal activity was characterized by the burst discharges with short duration (5-50 ms) and high intraburst frequency (200-450/s). In 15% of investigated cells the rhythmic sequences of burst discharges with frequency of 2-2.5, rarely 3-4/s were revealed. After injection of haloperidol and droperidol the amount of neurons with rhythmic activity increased to 22% and 30%, respectively. The predominant burst frequency augmented to 3-5/s. In a third of cells long rhythmic discharges lasting for 80-300 ms were registered. After chronic haloperidol administration (10 days) relatively low intraburst frequency (60-170/s) was observed in 37% of cells. It is suggested that the above changes are a result of strengthening of the inhibitory influences on the ventrolateral neurons from substantia nigra and reticular thalamic nucleus because of blockage of the dopamine and alpha-adrenergic receptors.