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 ?
The tract of the habenular commissure (THC) projected axons from the telencephalon to the dorsal diencephalon to form the habenular commissure ([16]; Figures 3(a) and 3(b).
one of those structures, the diencephalon , located right above the brain stem (Duvernoy & Bourgouin, 1999), includes the thalamus, hypothalamus, and the pineal gland.
The secondary vesicles arise from the primary vesicles: the prosencephalon divides into the telencephalon anteriorly and the diencephalon posteriorly; the rhombencephalon divides into the anterior metencephalon and the posterior myelencephalon.
Designed as a study guide for the USMLE but also useful as a refresher and course supplement, this compact treatment covers a range of topics, including development, gross anatomy, blood supply, cytology, the spinal cord, the brain stem, the cerebellum, basal ganglia, diencephalon and limbic systems, visual system, papillary reflexes, the cerebral cortex and higher functions.
Most of our attention is focused on the diencephalon, especially the hypothalamus, a small area that surrounds the third ventricle in the ventral portion of the brain.
Intraventricular administration of Al-maltolate to rabbits developed widespread neurofibrillary degeneration involving pyramidal neurons of the isocortex and allocortex, projection neurons of the diencephalon, and nerve cells of the brain stem and spinal cord (37).
The pineal gland, also known as pineal body, is a medium and odd endocrine organ, which originates in the second month of intrauterine life (Macchi & Bruce, 2004) as a diencephalon roof evagination with a conical shape (Bertolucci & Foa, 2004), is aimed antero-posterior and rests on the path that separates the upper colliculus of the posterior wall of the third ventricle and is joined habenular and posterior commissures (Rouviere & Delmas, 1999).
Using [123I]beta-CIT tropane-2beta-corboxylate, Kugaya and colleagues (2004) were able to correlate serotonin transporter availability in the diencephalon to positive SSRI response in depressed patients.
11) Symmetric, low-density abnormalities in the diencephalon, midbrain, and periventricular regions that enhance following contrast injection may be seen on CT scan.
Staley et al (20) found that depressed women show a significantly greater decrease in 5-HTT availability in the diencephalon (forebrain region containing the thalamus, hypothalamus, and part of the pituitary gland) when compared with healthy women and depressed men.
Wire in the monkey's diencephalon prints out a wave most beautiful.
These EEG responsive disorders appear to have a common characteristic in that they seem mediated through the physical structures in the diencephalon within which the limbic system functions.