Anatomic.us > Nervous System > Brain > Hypothalamus

Suprachiasmatic Nucleus

The suprachiasmatic nucleus (SCN) is a tiny region located in the anterior part of the hypothalamus and is situated directly above the optic nerve. It is immediately dorsal (in or toward the back), or superior (hence, supra) to the optic chiasm (CHO) bilateral to (on either side of) the third ventricle. It is responsible for controlling circadian rhythms.

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Suprachiasmatic Nucleus

The neuronal and hormonal activities it generates regulate many different body functions in a 24-hour cycle. It uses about 20,000 neurons. The SCN is shaped like a pinecone and is approximately the size of a grain of rice.

It interacts with many other parts of the brain. It has within it many types of cells and several different peptides (including vasopressin and vasoactive intestinal peptide) and neurotransmitters.

These elements found within the suprachiasmatic nucleus are what allows the dynamics of the circadian (rhythmic events that happen to the human body within a 24-hour period, such as sleep, homeostasis) cycle to happen. This role the SCN plays in control of hypothermic conditions to maintain body temperature is still under study.

There have been some very interesting studies developed to explain the interaction of the retina having its’ own polysynaptic pathway that transmits light information through this pathway which travels from the retina to the suprachiasmatic nucleus. The SCN is considered to be the mind’s clock of the hypothalamus.

 

ANATOMY OF THE SCN-PINEAL PATHWAY  

A study conducted and published in April 1999 from the National Institute of Health (NIH) demonstrates how this pathway works. The various points that follow are not the complete comprehensive results of that study, the points made  are only some of the highlights from the study of the NIH that reflect the anatomical connection of the SCN to other parts of the brain including the pineal gland and hypothalamus:

  • A powerful transneuronal tracer, pseudorabies virus (PRV), was used for a detailed description of this study.

  • PRV was injected into the pineal gland, subsequently labeled the superior cervical ganglion, the intermediolateral column of the upper thoracic cord, the autonomic division of the paraventricular nucleus of the hypothalamus (PVN), and the SCN.

  • Neurons in the autonomic division of the PVN were the only pseudorabies (PRV)-labeled neurons in the hypothalamus shown to receive input from the SCN as demonstrated by the presence of vasoactive intestinal peptide axonal contacts.

  • The present study of these interactions between the SCN, pineal gland, and hypothalamus provides the anatomical basis for the circadian control melatonin secretion.

The neuronal and hormonal activities it generates regulate many different body functions in a 24-hour cycle. It uses about 20,000 neurons. The SCN is shaped like a pinecone and is approximately the size of a grain of rice.

It interacts with many other parts of the brain. It has within it many types of cells and several different peptides (including vasopressin and vasoactive intestinal peptide) and neurotransmitters.

These elements found within the suprachiasmatic nucleus are what allows the dynamics of the circadian (rhythmic events that happen to the human body within a 24-hour period, such as sleep, homeostasis) cycle to happen. This role the SCN plays in control of hypothermic conditions to maintain body temperature is still under study.

There have been some very interesting studies developed to explain the interaction of the retina having its’ own polysynaptic pathway that transmits light information through this pathway which travels from the retina to the suprachiasmatic nucleus. The SCN is considered to be the mind’s clock of the hypothalamus.

 

ANATOMY OF THE SCN-PINEAL PATHWAY  

A study conducted and published in April 1999 from the National Institute of Health (NIH) demonstrates how this pathway works. The various points that follow are not the complete comprehensive results of that study, the points made  are only some of the highlights from the study of the NIH that reflect the anatomical connection of the SCN to other parts of the brain including the pineal gland and hypothalamus:

  • A powerful transneuronal tracer, pseudorabies virus (PRV), was used for a detailed description of this study.

  • PRV was injected into the pineal gland, subsequently labeled the superior cervical ganglion, the intermediolateral column of the upper thoracic cord, the autonomic division of the paraventricular nucleus of the hypothalamus (PVN), and the SCN.

  • Neurons in the autonomic division of the PVN were the only pseudorabies (PRV)-labeled neurons in the hypothalamus shown to receive input from the SCN as demonstrated by the presence of vasoactive intestinal peptide axonal contacts.

  • The present study of these interactions between the SCN, pineal gland, and hypothalamus provides the anatomical basis for the circadian control melatonin secretion.
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