EXTRARETINAL MODULATION OF GENICULATE NEURONAL-ACTIVITY BY CONDITIONING

The transmission of signals from the retina to the visual cortex is gated by the dLGN in relation to the state of the organism, and to its attention to the visual environment. The dLGN serves as an integrative center, incorporating a variety of modulatory influences upon the visual signal. The intense innervation of the dLGN by non-retinal afferents, especially the feedback inhibition from nucleus reticularis thalami (TR), and various features of geniculate neurons are the basis of this gating process. It is shown that dLGN neurons, e.g., of cats or pigeons change their responses to light during conditioning that is by pairing light with a reward or with aversive stimuli. The chapter discusses experiments that aim to evaluate the role of appetitive and aversive conditioned light stimuli in the determination of the response pattern of dLGN neurons in rats. The chapter discusses mechanisms leading to the observed response changes. The role of the TR and its cholinergic afferents as well as of the direct cholinergic input to the dLGN in mediation of the conditioning-related changes in single unit activity of the dLGN was of special interest. © 1993, Academic Press Inc.