Inferior colliculi

PAM crosses the blood-brain barrier with difficulty. 2-PAM in rat brain, 10 min after injection, is only about 5-12% of that in plasma higher percentages are in the more heavily vascularized areas, such as cerebral and cerebellar cortex and inferior colliculi.34 This low brain-to-blood ratio persists, but over the next 6 h the brain and blood come closer to equilibrium as the blood... 

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). 

Inferior colliculi (ko- lik-yu-lT) Midbrain structures that control sound localization (Chapter 3). 

Malmierca, M. S., Rees, A., Le Beau, F. E., and Bjaalie, J. G. (1995). Laminar organization of frequency-defined local axons within and between the inferior colliculi of the guinea pig. J. Comp. Neuro. 357(1), 124-44. 

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. 

Results in newborn kittens showed a selective nuclear staining by bilimbin in thalamic nuclei, subthalamic nuclei, inferior colliculi, cuneate nuclei, and cochlear nuclei. The intensity of staining correlated with the time of exposure. Histologically, changes were seen in some neurons, and consisted of vacuoladon and pyknotic nuclei. 

IC (inferior colliculi), 5-11-5-12 IC (inspiratory capacity), 7-6 ICC (interstitial cells of Cajal), in gastrointestinal system, 6-4,6-8... 

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