Limbic system final explanation part #1

January 23 / 2018

Stage: c) taking action

Approaches to learning: Transference skills

LIMBIC SYSTEM: The limbic system is located right in the center of the brain, it contributes to  specific vital human functions such as emotions, memories and instincts. It's structure is based upon parts such as the hypothalamus, the amygdala, and the hippocampus amongst others.

HYPOTHALAMUS: First of all, we have the hypothalamus, a very important part of the limbic system, it is located in the middle of the brain along with other different parts such as the hippocampus and the amygdala, it’s exact location is right under thalamus. It's main functions consist of the production of hormones and the housing of hormone producers, it is involved in endocrine functions, and most importantly, it aids in the maintenance of homeostasis.

Regarding hormones, the hypothalamus is in charge of housing the pituitary gland, and together, they both aid the endocrine system in order for it to work at its best. The hypothalamus secrets hormones such as an anti diuretic hormone (it’s job is to increase the level of water absorbed into the blood by the kidneys), corticoprotin releasing hormones (that help regulate the metabolism and immune responses through releasing certain steroids), gonadotropin releasing hormones (they tell the pituitary gland to produce hormones that make sure the sexual organs are working correctly), the hormone and neurotransmitter oxytocin (involved in child labour and in the production and release of breast milk, sleep cycles and body temperature. It is released during sex, (specially during orgasms), lactation and childbirth), prolactin controlling hormones (they tell the pituitary gland wether to stop or continue breast milk production in mothers), and finally, thyrotropin releasing hormones (they are the hormones in charge of regulating the metabolism, and the energy levels).

In contributes to homeostasis though the hormones it secretes, when something in the body is not right and results in the alteration of homeostasis, the hypothalamus responds through releasing specific hormones into the bloodstream that will make sure the body regains it's stability, in other words, it's homeostasis back again.

Disorders present in the hypothalamus that alter it's ability to work correctly are known as hypothalamic diseases. The most common causes for this disease are radiation, tumors, surgeries or impacts to the head that affect the hypothalamus, some times the disease might be inherited, however it tends to happen very rarely. Symptoms include sensitivity to cold, depression, hair loss, constipation and lower mental capacity amongst others.

In order to support the proper functionality of your hypothalamus, you should include vitamin rich fruits and vegetables, vitamin C  and vitamin B to your daily diet.

THALAMUS: The thalamus is another part of the limbic system, it is a subdivision of the diencephalon (a part of the brain), it is located below the corpus callosum right in the center of the brain. It’s main functions consist of relaying motor and sensory sygnals to the cerebral cortex, as well as regulating sleep, alertness, some types of memory and wakefulness.

Regarding inputs, the thalamus is mostly in charge of receiving the sensory inputs from all around the body and then passing them down to the cerebral cortex where the inputs shall be processed, in other words, it is like a relay center for sensory inputs. The thalamus receives 98% of all sensory inputs coming from all around the body, the only sensory information the thalamus does not relay are the inputs related to smell.

The thalamus is made up of different parts (also known as thalamic nuclei), and each one is in charge of dealing with a specific type of information, some of the most important and distinct parts are; the anterior nucleus, it is located at the anterior part of the thalamus, and it is connected to the hippocampus and is thought to be involved in memory formation. The dorsomedial nucleus is involved in emotional behavior and memory. The ventral anterior nucleus and the ventrolateral nucleus are both thought to be involved in motor functions. The ventral posterolateral nucleus (also known as VPL) and the ventral posteromedial nucleus (also known as VPM) are both in charge of acting as relay nuclei for the somatosensory cortex. The lateral posterior nucleus is in charge of integrating the sensory input being received and associating it with cognitive functions. The pulvinar nucleus is involved in the processing of visual stimuli. The medial geniculate nucleus and the lateral geniculate nucleus are relay centers for auditory and visual information. And finally, the reticular nucleus is like a sheet that covers most part of the thalamus, it influences the activity of other nuclei present in the thalamus.

The thalamus is a very important part of the brain because if it weren't for it, the incoming sensory stimuli from the whole body would not be properly organized and then sorted out to the areas of the brain in charge of different specific functions, it would not be set up properly for further processing, meaning everything would literarily turn into a gigantic mess.

EPITHALAMUS: The epithalamus is a subdivision of a part of the brain known as the diencephalon, it also makes a part of the limbic system.

The function of the epithalamus is to connect the limbic system to other parts of the brain, it also aids in the secretion of melatonin (a hormone  produced by the pineal gland that inhibits melanin formation) and finally, in the regulation of emotions.

AMYGDALA: The amygdala is also a part of the limbic system, it is located at the end of the hippocampus in the medial temporal lobe, in a very wide description, it can be said to be an almond shaped set of neurons.

It is in charge of the way the body processes and responds to emotions, such as anger, sadness, and most importantly, fear. What the amygdala does is that it processes the memory of an experience (either happy or sad), and it stores the memory for future reference, and in the future when you experience the situation again, you will consult the memory and the amygdala will tell you the way in which you should act upon it.

Regarding fear, the amygdala is responsible for your memory of fear, meaning that if you take it away, you will no longer have the ability to be afraid of the things that are out of your control such as that one test or of the snake you just saw.

Many people might say they would rather live their life in a fearless way, without ever being worried about those tiny little things that tend to terrify and keep them from doing the things they would love to do but don't dare to, believe me, I have been there too. However those that say that, may not be entirely right, because even though a life in which you don't fear the tiny little things such as being embarrassed or encountering a spider, may not be the optimal form of life, why? because fear is one of the most important variables for self preservation, when we feel fear, we heighten our awareness in order to be able to protect ourselves or flee from imminent danger, meaning that fear is the reason why we are able to live as long as we do, because if it weren't present in our lives, we would jump of a cliff just to see what could happen without even thinking it twice, and possibly end up dead or badly injured. 

CINGULATE GYRUS: The cingulate gyrus a part of the limbic system, it is a fold that covers the corpus callosum, located between the cingulate sulcus and the corpus callosum sulcus. It is present in both brain hemispheres (right and left).

The cingulate gyrus is involved in processing emotions and in regulating behavior and autonomic motor functions, as well as emotional responses to pain, maternal bonding, decision making and communication.

It can be divided into the anterior and posterior segments, the anterior cingulate gyrus has connections with speech and vocalization areas in the frontal lobe (more specifically in Broca's area), and has connections with the amygdala as well.
The posterior cingulate gyrus plays a role in spatial memory, and just like the thalamus, relays some signals between the spinal cord and the brain.

Damage can result in emotional, cognitive and behavioral disorders such as depression, anxiety and obsessive compulsive disorders.