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It has several functions, such as the relaying of sensory and motor signals to the cerebral cortex [1] [2] and the regulation of consciousness, sleep, and alertness. [3] [4] Anatomically, it is a paramedian symmetrical structure of two halves (left and right), within the vertebrate brain, situated between the cerebral cortex and the midbrain.
It is a small, ovoid, ventral projection of the thalamus where the thalamus connects with the optic nerve. There are two LGNs, one on the left and another on the right side of the thalamus. In humans, both LGNs have six layers of neurons (grey matter) alternating with optic fibers (white matter).
In mammals, where it becomes so large as to dominate the brain, it takes over functions from many other brain areas. In many mammals, the cerebral cortex consists of folded bulges called gyri that create deep furrows or fissures called sulci. The folds increase the surface area of the cortex and therefore increase the amount of gray matter and ...
Matrix cells of the thalamus, or calbindin-immuno-reactive neurons (CIR neurons), are widely distributed and diffusely dispersed in each of the nuclei of the dorsal thalamus. In comparison, parvalbumin immuno-reactive neurons ( PIR neurons ) can be found only in principal sensory and motor relay nuclei, and in the pulvinar nuclei as well as the ...
Its function is modulatory on signals going through the thalamus (and the reticular nucleus). The thalamic reticular nucleus receives massive projections from the external segment of the globus pallidus , thought to play a part in disinhibition of thalamic cells, which is essential for initiation of movement (Parent and Hazrati, 1995).
The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses.
The cells also send axons directly to many parts of the brain, including nuclei of the limbic system such as the lateral nucleus of the amygdala, the anterior cingulate, and the hippocampus. This part of the sensory system, known as the non-classical or extralemniscal system is less accurate, and less detailed in regards to sensory signal analysis.
The thalamocortical loop starts with oscillatory thalamic cells. These cells receive both sensory input from the body as well as input from feedback pathways in the brain. In a sense, these cells serve to integrate these multiple inputs by changing their inherent oscillatory properties in response to depolarization by these many different inputs.