Diencephalon


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diencephalon

(dī'ənsĕf`əlŏn): see brainbrain,
the supervisory center of the nervous system in all vertebrates. It also serves as the site of emotions, memory, self-awareness, and thought. Anatomy and Function
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Diencephalon

 

the section of the brain that consists of the most anterior (in man, the topmost) part of the brain stem, over which the cerebral hemispheres are located.

Inferiorly and posteriorly, the diencephalon borders on the mesencephalon (midbrain). The central portion of the diencephalon, around which the other parts are grouped, is the thalamus. These other parts are the epithalamus, which includes the epiphysis; the hypothalamus, which is connected to the pituitary, or hypophysis; and the subthalamic nucleus. The formations of the diencephalon perform a number of very important functions: they participate in the organization of the body’s sensory processes (sensitivity), motor functions, and autonomic (visceral) activities. The diencephalon plays a very important role in processes related to emotional reactivity and the states of sleep and wakefulness, as well as in the autoregulatory processes of the brain, which are reflected in the overall electrical activity of its higher areas, as recorded in the electroencephalogram. The diencephalon processes and switches the currents of neural impulses that enter from the various sense organs and signal shifts in the body’s external and internal environments. It does the same with impulses from various brain structures and directs them to other areas of the brain, including the cerebral cortex.

L. P. LATASH


Diencephalon

 

the section of the brain at the base of the large hemispheres that is the extreme anterior part (in humans the superior part) of the brain stem. The different portions of the diencephalon are the thalamus, hypothalamus, and subthalamus. Together they have very important functions; for example, they participate in the organization of the sensory processes of brain analyzers and in the performance of autonomic functions. Other bodily functions they affect are sleep, memory, instinctive behavior, and emotional and motivational processes. The structures of the diencephalon are associated with the perception of pain sensations and with the integration of the processes that maintain homeostasis. The functions of the glands of internal secretion are regulated through releasing hormones (releasing factors) produced by the neurosecretory cells of the hypothalamus. Aldosterone is produced, for example, by the adrenal cortex with the participation of a special polypeptide from the hypothalamus.

L. P. LATASH

diencephalon

[¦dī·en′sef·ə‚län]
(embryology)
The posterior division of the embryonic forebrain in vertebrates.
References in periodicals archive ?
Diencephalon. The diencephalon ventral anterior is the optic nerve, and its ventral posterior has a flat of the pituitary gland which continuously extends until the myelencephalon abdomen (Fig.
The main regions impaired by binge drinking are the limbic system, diencephalon, frontal, and middle and inferior temporal lobes.
So that genes for the synthesis and storage have expression in structures of mesencephalon while genes that are related wiht inactivation are expressed in the diencephalon in general.
After brain injury, there are blood-brain barrier breakdown and neurodegeneration in areas including the injured cortex, hippocampus, and a portion of the diencephalon. Microglia, monocytes, macrophages, and neutrophils invade areas exhibiting blood-brain barrier damage (Figure 1) [8], which is also associated with extensive upregulation of neutrophil adhesion factors [9], including integrin receptors (Figure 1) and immunoglobulin superfamily members [10-12].
The cZI has widespread afferent and efferent projections amongst the cerebral cortex, diencephalon, brainstem, cerebellum, and spinal cord, the majority of which are GABAergic [26].
Each hypertext contained seven sections (spinal cord, brain stem, cerebellum, mesencephalon, diencephalon, telencephalon, and prefrontal cortex), which could be navigated via the use of a navigation menu on the left side of the screen, the forward and backward buttons of the browser, or the key words of each section, which were linked with other sections.
In 1878, Broca pointed out that a general feature of a mammalian brain was a horseshoe-shaped rim of cortex surrounding the junction between the diencephalon and each cerebral hemisphere, which at the base of the brain ends of this arc, are joined by olfactory areas so that a complete loop is formed with the olfactory tract and bulb extending anteriorly.
Shape: The shape features are extracted over the lobes (frontal lobe, parietal lobe, occipital lobe, temporal lobe, and limbic lobe), brain stem (medullar, pons, and midbrain) [156], diencephalon [157], cerebellum [158], ventricles (lateral ventricles, third ventricle, fourth ventricle), tracts [159], vessels (artery and vein) [160], and even the whole brain.
The second section details neuroanatomy, including the histology of nerve and glial cells, the autonomic nervous system, meninges of the brain and spinal cord, the ventricular system and cerebrospinal fluid, the telencephalon, the diencephalon, the brainstem, the cerebellum, blood vessels, the spinal cord, sectional anatomy of the brain, and functional systems.
Patients with pituitary cancers frequently show behavior alterations arising from upward extension of the tumor to other structures, especially those in the diencephalon, commonly noted in patients with craniopharyngioma.
McKee noted neuropathological features of CTE include "generalized atrophy of the cerebral cortex, medial temporal lobe, diencephalon and mammillary bodies with enlarged ventricles; cavum septum pellucidum, often with fenestrations; extensive p-tau-immunoreactive neurofibrillary tangles and astrocytic tangles in the frontal and temporal cortices, particularly around small cerebral vessels and at the depths of cerebral sulci; extensive p-tau- immunoreactive neurofibrillary tangles in limbic regions, diencephalon and brainstem nuclei; extensive degeneration of axons and white matter fibre bundles; TAR DNA-binding protein 43 (TDP-43) immunoreactive intraneuronal and intraglial inclusions and neurites in most cases and a relative absence of amyloid-[beta] peptide deposits." Id.
(5), the sensory deficit in stroke patients is related to the disruption of an ascending protection pathway transmitting sensory information from the laryngopharynx mucosa to the diencephalon and cortex.