Chapter 41: Modulation of information processing in thalamocortical systems: Chairman's introductory remarks

Abstract

Publisher Summary The modulation of afferent signals by ascending regulatory systems was initially reported in two studies independently carried out in Bremer's and Dell's laboratories, showing that midbrain reticular stimulation potentiates cortical field potentials evoked by synchronous stimuli applied to prethalamic pathways. These observations demonstrated that the desynchronization of spontaneous electroencephalographic (EEG) rhythms elicited by brainstem reticular stimulation indeed reflects an activation of the cerebral cortex. At the same time, it was shown that stimulation of the mesencephalic reticular core also facilitates light-induced responses in the visual thalamus, whereas the simultaneously recorded potentials in the optic tract remained unchanged. These data indicated that the information processing through thalamocortical systems is facilitated by an ascending regulatory system and that the thalamus is the first station where significant alterations in excitability occur during shifts in the state of vigilance. The listing of the issues given in this chapter indicates how many crucial aspects of the modulation of information processing by cholinergic systems are now open to further exploration at the analytical and more global levels.