Thalamus Lateral geniculate nucleus

Figure 22.3 Possible links in the induction of circadian rhythm between daylight, the suprachiasmatic nucleus and melatonin release from the pineal gland. Some fibres in the optic nerve, projecting from the eye to the lateral geniculate nucleus (LGN) in the thalamus, innervate the suprachiasmatic nucleus (SCN) in the anterior hypothalamus, via the retinohypothalamic tract (RHT). Others project to the SCN from the LGN in the geniculohypothalamic tract (GHT). The release of melatonin into the circulation from the pineal gland (PG) is maximal at night and appears to be controlled partly by noradrenaline released from sympathetic nerves originating in the superior cervical ganglion (SCG). Melatonin receptors are found in the SCN, the removal of which dampens melatonin secretion...

Selemon LD, Begovic A. 2007. Stereologic analysis of the lateral geniculate nucleus of the thalamus in normal and schizophrenic subjects. Psychiatry Res 151 1-10. 

A cross-section through the human visual pathways can be seen in Figure 5.4. One may note that the predominant pathway leads from the eye to the lateral geniculate nucleus (LGN) of the thalamus, and from there to the occipital part of the cortex, while less important numbers of fibers branch off to a tectal area, the superior colliculus (SC), and to a number of pre-tectal nuclei. We will briefly discuss these subcortical pathways below. 

Clinical evidence, lesion, and stimulation studies all point toward the participation of vitally important neural sites in the control of saccades, including the cerebellum, superior colliculus (SC), thalamus, cortex, and other nuclei in the brain stem, and that saccades are driven by two parallel neural networks [Enderle, 1994, 2002]. From each eye, the axons of retinal ganglion cells exit and join other neurons to form the optic nerve. The optic nerves from each eye then join at the optic chiasm, where fibers from the nasal half of each retina cross to the opposite side. Axons in the optic tract synapse in the lateral geniculate nucleus (a thalamic relay), and continue to the visual cortex. This portion of the saccade neural network is concerned with the recognition of visual stimuli. Axons in the optic tract also synapse in the SC. This second portion of the saccade neural network is concerned with the location of visual targets and is primarily responsible for goal-directed saccades. 

Medium-high density of D3 mRNA was described in the septal area, in the medial division of the bed nucleus of the stria terminalis, in the nuclei of the horizontal and vertical limbs of the diagonal band, in the nucleus gelatinous and paracentral nucleus of the thalamus, in the medial and ventral lateral geniculate nuclei, and in the lateral portion of the SNc. 

The areas of the brain that retained the greatest concentrations of the label after intravenous Injection of [ H]BZ Into cats (16) were motor cortex, sensory cortex, caudate nucleus, lateral geniculate, and medial geniculate Smaller concentrations were retained In thalamus, hippocampus, hypothalamus, medulla oblongata, colliculi, cerebellar cortex, the pyramids of the medulla, cerebral white matter, and cerebellar white matter ... 

Within the prosencephalon, FGF-1 positive neurons are sparse in the cerebral cortex and hippocampus, but abundant in the septal area, nucleus basalis, and select nuclei of the thalamus (paraventricular, anterodorsal, lateral geniculate) and hypothalamus (lateroanterior). Other areas including pallidum and many thalamic and hypothalamic nuclei contain smaller but still substantial numbers of FGF-1 im-munoreactive neurons (Stock et al., 1992). 

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