The reticular thalamus nucleus forms a thin capsule on the outside of the thalamus itself. The nucleus contains primarily GABA-ergic (i.e. slowing/inhibitory) neurons.
The nerve fibers that convey the signal traffic between different thalamus nuclei and the cerebral cortex, both in and out of, emit lateral branches to and excite, i.e. "push", the GABA-ergic neuron of the reticular thalamus nucleus, which in turn inhibit the thalamic nucleus that the signal traffic affects. The coupling dampens the tendency of the "irritable" thalamus neurons to overreact.
The different specific thalamus nuclei, each of them, through their afferent and efferent cortical signal flows, activate only a limited area of the reticular thalamus nucleus.
The nonspecific thalamic nuclei, on the other hand, due to their scattered and overlapping cortical target areas, activate neuron groups scattered throughout the reticular thalamus nucleus.
The reticular thalamic nucleus also contains local neural networks that are believed to coordinate the activity of different thalamic nuclei, underscoring the influence of the reticular nucleus on various cortical functions.
The reticular thalamus nucleus is part of the subthalamus (ventral thalamus) where it is connected to the zona incerta and is sometimes considered an offshoot of the brainstem formatio reticularis.