Stimulation of the lateral geniculate, superior colliculus, or visual cortex is sufficient for eyeblink conditioning in rats

Abstract

The role of the cerebellum in eyeblink conditioning is well established. Less work has been done to identify the necessary conditioned stimulus (CS) pathways that project sensory information to the cerebellum. A possible visual CS pathway has been hypothesized that consists of parallel inputs to the pontine nuclei from the lateral geniculate nucleus (LGN), superior colliculus (SC), pretectal nuclei, and visual cortex (VCTX) as reported by Koutalidis and colleagues in an earlier paper. The following experiments examined whether electrical stimulation of neural structures in the putative visual CS pathway can serve as a sufficient CS for eyeblink conditioning in rats. Unilateral stimulation of the ventral LGN (Experiment 1), SC (Experiment 2), or VCTX (Experiment 3) was used as a CS paired with a periorbital shock unconditioned stimulus. Stimulation was delivered to the hemisphere contralateral to the conditioned eye. Rats in all experiments were given five 100-trial sessions of paired or unpaired eyeblink conditioning with the stimulation CS followed by three paired sessions with a light CS. Stimulation of each visual area when paired with the unconditioned stimulus supported acquisition of eyeblink conditioned responses (CRs) and substantial savings when switched to a light CS. The results provide evidence for a unilateral parallel visual CS pathway for eyeblink conditioning that includes the LGN, SC, and VCTX inputs to the pontine nuclei.

Classical eyeblink conditioning using electrical stimulation of caudal mPFC as conditioned stimulus is dependent on cerebellar interpositus nucleus in guinea pigs

“…The threshold stimulation of CS required to establish the CR in the present study was lower than that in most previously studies (50-200 mA in current study vs 180-250 µA for visual cortex stimulation [34] ). This difference may in part due to differences in current spread at different sites of stimulation, but may also relate to differences in the numbers of cells which must be excited for the CS to be effective [45] .…”

“…The current findings combined with the results of previous studies may indicate that one brain area at which an effective and sufficient stimulation CS for establishing CR was applied can not be interpreted as an essential area for classical eyeblink conditioning. For instance, lesions of the visual cortex did not prevent acquisition of CRs with a light CS [73] , suggesting that the visual cortex is not involved in the process of CR acquisition, whereas stimulation of the visual cortex can be successfully used as a CS to establish CR [34] . Moreover, although lesions of the pretectal nuclei [73] and hippocampus [22][23][24]68] retarded acquisition of eyeblink conditioning, stimulation of the anterior pretectal nucleus [11] and of the CA1 layer of hippocampus [74] can not be served as effective CSs for establishing eyeblink conditioning.…”

Purkinje cell activity during classical conditioning with different conditional stimuli explains central tenet of Rescorla–Wagner model

“…Animals can acquire conditioned blink responses to a wide range of stimuli, including tones and light stimuli (30), forelimb stimulation, whisker stimulation (31), lateral geniculate nucleus stimulation, superior colliculus stimulation (32), and mossy fiber stimulation (33). Consistent with their purported role in eyeblink conditioning, Purkinje cells can also acquire conditioned pause responses to different CSs, including stimuli applied to the forelimb, mossy fibers (21), superior colliculus (34), and parallel fibers (35).…”

The Role of Norepinephrine in Amygdala Dependent Fear Learning and Memory

“…2) of conditioned and unconditioned stimuli (CS and US), the latter can be also shown in experimental animals by employing diverse parameters depending on the area of interest (Halverson et al, 2009;Kwapis et al, 2009). A particular Pavlovian training or conditioning that has been widely used in research, enables experimental animals to associate the neutral CS with the US of a negative valence.…”