Superior colliculi

Localization CNS Hippocampus (CA1, CA3, DG), septum, amygdala, raphe nuclei CNS Striatum, hippocampus (CA1), substantia nigra, globus pallidus, superior colliculi, spinal cord, raphe nuclei CNS like 5-HT1B but at lower densities. CNS Caudate putamen, parietal cortex, fronto-parietal motor cortex, olfactory tubercle, amygdala CNS Cortex, Thalamus, olfactory bulb (rat), claustrum (g-pig), hippocampus (CA3), spinal cord. 

In this cell, the tonic firing of the neuron during this behavior is increased by amphetamine. This result is consistent with our finding that neostriatal units projecting to the pars reticulata are inhibited by amphetamine. The resulting disinhibition of these nigral units may, in turn, increase their tonic inhibitory control over their target stmetures, such as the deep layers of the superior colliculis (Chevalier et al. 1985). the thalamus (Deniau and Chevalier 1985) and the PPN. These output stmetures are known to affect the motor behaviors that amphetamine influences (Di Chiara et al. 1979). 

Location Area postrema Cortex (low density) vagal efferents Superior colliculi Hippocampus Cortex, Hippocampus Olfactory bulb Cerebellum Habenula Hippocampus Striatum Amygdala Cortex Hypothalamus Hippocampus Cortex Olfactory bulb... 

Substantia nigra, globus pallidus, dorsal subiculum, superior colliculi Non-selective pinodol, propanolol selective partial agonists CP-93, 129 Possible clinical use of antagonists antidepressants 5-HTj25 receptors... 

Medium-high density of D2 receptors was found in the islands of Calleja, ventral pallidum, zona incerta, GP, central amygdala, in some cells of the anterior lobe of the pituitary, and at several sites in the forebrain the laterodorsal septal area, hippocampus, subiculum, lateral habenula, STh, lateral mammillary bodies. D2 receptors were also found with a medium-high density in various cortical fields prefrontal, anterior cingulate, entorhinal and perirhinal cortices. In the brain stem, medium-high density of D2 receptors was found in the VTA, SNc, ventral SNr, parabrachial nucleus, superior and inferior colliculi, dorsal raphe nucleus and locus coeruleus. 

Part of the brain that includes the inferior and superior colliculi and the substantia nigra. 

The midbrain consists of a number of structures, including the inferior colliculi, the superior colliculi, and tlic substantia nigra. The inferior colliculi form part of the auditory system. The superior colliculi function in localization of visual stimuli. These structures are specifically involved with localization of stimuli and mediation of reflexes. The actual recognition and interpretation of visual and auditory stimuli take place elsewhere in the brain (sec the section on the cerebral cortex). 

Superior colliculi Midbrain structures that control visual localization (Chapter 3). 

HT RECEPTORS 5-HT receptors are widely distributed throughout the body. In the CNS, the receptors are found on neurons of the superior and inferior colliculi and in the hippocampus. In the GI tract, 5-HT receptors are located on neurons of the myenteric plexus and on smooth muscle and secretory cells. The 5-HT receptor is thought to evoke secretion in the alimentary tract and to facilitate the peristaltic reflex. 5-HT receptors couple to G to activate adeny-lyl cyclase, leading to a rise in intracellular levels of cyclic AMP, possibly accounting for the utility of prokinetic benzamides in GI disorders (see Chapter 37). 

HT receptors occur on neurons within the inferior and superior colliculi and in the hippocampus. Activation of5-HT receptors stirmilates the G -adenylyl cyclase-cyclic AMP pathway. 

At the hippocampal level, the distribution is clearly laminar, following the CA3, CA2, CAl pyramidal cell layers and dentate gyrus. As expected from our previous work, superior colliculi, and to a lesser extent, inferior colliculi express, 5-HT4-RS. We performed a less extended analysis in human that however confirmed the high density of 5-HT4-RS in the nigro-striatal pathway and hippocampus (Figure 5) [56]. 

The superior colliculus is a small pair of bumps on the dorsal surface of the midbrain. Another pair, the inferior colliculus, is found just below it. Stimulation of the superior colliculus results in contralateral eye movement. Anatomically, output tracts from the superior colliculus run to areas that control eye and neck movement. Both the inferior and superior colliculi are apparently involved in locating sound. In the bat, the inferior colliculus is enormous, crucial to that animal s remarkable echolocation abihties. The superior colhculus processes information from the inferior colliculus, as well as from the retina, allowing the eyes to quickly find and follow targets based on visual and auditory cues. 

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