Interaction between the Reticular Nucleus of the Thalamus and Different Brainstem Structures

The reticular nucleus of the thalamus (TRN) has attracted special attention among diencephalic structures, which are specially related to the genesis of the electrical activity of brain. Brain stem formations also appear to be able to change the activity of other parts of the brain. The aim of this investigation was to study the mechanisms of the relationship between TRN, mesencephalic reticular formation (MRF) and nucleus of the solitary tract (NTS). It has been shown, for the first time, that: firstly, TRN and MRF are functionally interrelated and affect each other reciprocally - activation of TRN mainly inhibits the activity of MRF neurons and vice versa; secondly, stimulation of NTS led to the activation of TRN neurons. Moreover, when recording the activity of TRN and MRF neurons with two microelectrodes, it was shown that, upon NTS stimulation, deep inhibition of MRF neurons occurred in parallel with the activation of TRN neurons. Based on our results, it is possible to make some adjustments to the scheme of the relationship between the synchronizing and desynchronizing structures when changing the functional state of the brain and the place of TRN in this activity. Taken together, these findings indicate that the brainstem exerts substantial control over the activity of TRN neurons, possibly to globally modulate the level of arousal for preparing for consciousness.