The nervous system is formed from four differentiated cell populations during embryonic development.the prosencephalon, the midbrain, the rhombus and the cells of the spinal cord.
The prosencephalon in turn is divided into two distinct cellular populations, the innermost that will form the diencephalon, and the outermost that form the telencephalon.
The telencephalon is the part of the central nervous system that includes the cerebral cortex, one of the most developed structures in human beingsin comparison with other nearby species. Together with the cerebellum, the telencephalon coordinates practically all the voluntary actions of the human body.
In this article we will talk to you about the telencephalon at a structural and functional level, to better understand where the different parts of the central nervous system come from.
The different parts of the telencephalon and their functions
The telencephalon in vertebrates is the portion of the central nervous system that is furthest from the beginning of the spine, either horizontally or vertically – as in the case of humans.
This includes different structures, placed not only in the outermost part of the brain, but also forming internal structures.
The different functions of the parts of the telencephalon vary greatly depending on the area we’re talking about.. In the following, we review the different structures of the telencephalon, briefly summarizing its function.
1. The cerebral cortex
The cerebral cortex is the part most people think of when they imagine a brain: A structure above the rest of the nervous system, with a topography full of wrinklesas if it were a walnut.
The cerebral cortex is composed of gray matterwhich differs from the white matter of the brain by its proportion of neuronal bodies to the neuronal axons. Grey matter is rich in neuronal bodies and has a greater capacity to process information, while white matter is richer in axons of neurons, allowing a rapid distribution of nerve information.
Brain cortex covers the rest of the prosencephalon, in the form of a helmet. This structure full of peaks and valleys – called turns and furrows – is divided into two hemispheres, which in turn are divided into 4 main types of brain lobes. Its wrinkled structure allows a greater brain volume without an exaggerated increase in the size of the head, which already causes problems for human reproduction with its current size.
The functions of the cerebral cortex are various, depending on the area we are studying. To learn more about the functions of the lobes, we recommend our article about The 6 lobes of the human brain.
2. The hippocampus
The hippocampus is a brain region that lies deep within each of the temporal lobes. It has an elongated shape, with a very high neuronal concentration. It is also known as the “memory organ” at the colloquial level because of its important role in collecting and accessing long-term memory.
In addition to its memory level functions, the hippocampus is known to influence behavior -inhibiting maladaptive behaviours for the individual in society, as well as being key in learning processes and navigation in three-dimensional space.
3. The cerebral amygdala
The amygdala represents a small neuronal zone with a distinctive almond shapelocated in the most central part of the temporal lobe. This structure has a lot to do with the processing of emotions, being part of the limbic system.
This means, for example, that the cerebral amygdala is related to the response to fear or pleasure, as well as to aggressiveness. Its size in men is 30% larger by the effect of sex hormones, such as testosterone. Interestingly, this enlargement disappears in case of castration.
Some psychological and psychiatric illnesses, such as autism, depression or post-traumatic stress disorder are related to amygdala dysfunction, either at the structural level or its balance of neurotransmitter activity.
4. The striatum
The striatum –also known as striated nucleus– is another group of subcortical neurons of the telencephalon, in this case related to the basal ganglia. It is a fundamental part of the motor response and reward mechanisms-the way our bodies motivate us to act-as well as serving as the “antenna” of the basal ganglia, through which they receive signals from the rest of the nervous system.
It’s a telencephalon zone. important for conscious processessuch as planning or the ability to make decisions. Its name comes from its “striated” appearance, due to its composition of white and grey matter.
Their dysfunction is related to disorders such as autistic disorder or addictions, as well as diseases that also affect movement, such as Parkinson’s disease.
5. The olfactory bulb
The olfactory bulb represents one of the most conserved brain structures among animals. It allows the processing of olfactory information, partly thanks to its privileged position: It is located just above the nasal neurons and the olfactory nerve.
6. Basal ganglia
Basal ganglia are subcortical nuclei of neurons that are also found just below the cerebral cortex. They relate to such important functions as voluntary motor control, learning or emotions. Its major component is the striatum, which receives signals from other brain areas to communicate to the rest of the components of the basal ganglia.
Bibliographic references
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Amunts K, Kedo O, Kindler M, Pieperhoff P, Mohlberg H, Shah NJ, Habel U, Schneider F, Zilles K (December 2005). “Cytoarchitectonic mapping of the human amygdala, hippocampal region and entorhinal cortex: intersubject variability and probability maps. Anatomy and Embryology. 210 (5-6): 343-52. doi:10.1007/s00429-005-0025-5.
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Sniffing out the contributions of the olfactory tubercle to the sense of smell: hedonics, sensory integration, and more? Neurosci. Biobehav. Rev. 35 (3): 655-668. doi:10.1016/j.neubiorev.2010.08.004.
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Cameron IG, Watanabe M, Pari G, Munoz DP (June 2010). “Executive impairment in Parkinson’s disease: response automaticity and task switching”. Neuropsychology. 48 (7): 1948-57. doi:10.1016/j.neuropsychologia.2010.03.015