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Brain 101

Updated: Oct 3, 2021

Parts of the brain and their functions – What happens when each part malfunctions?

Not a second goes by that your brain stops fizzing with activity. While you are busy doing your office chores and when you are asleep, your brain doesn’t take a break. It transmits signals through the neurons via minor gaps between them called synapses.

But do we really appreciate how does the brain work? Not really, until something goes wrong. This is explained by Prof Thomas Südhof, Nobel Laureate who stated at Dublin City University (DCU) regarding the significance of research about brain basics. [1] According to Prof. Sudhof, until now it is not fully understood how the brain works and there is a need for more people to engage in this research in order to develop therapies for challenging conditions.


Anatomy and function of the brain

Most of the brain comprises of cerebrum, which is structured as two halves. In comparison, the other two major compartments are the cerebellum and brainstem. The cerebrum is further divided into lobes that we will discuss below.


Cerebrum

The two halves of the largest chunk of the brain, the cerebrum, are called hemispheres. These hemispheres are divided by a furrow known as the interhemispheric fissure, also referred to as the longitudinal fissure.

There are four lobes in each hemisphere. Their names and functions are as follows.


Frontal lobes

The frontal lobes are found at the front of the brain and form the largest lobes. Their functions include:

· Beginning numerous actions

· Regulating learned motor skills, e.g., playing musical instruments, writing, and tying shoelaces

· Monitoring complex cognitive processes, e.g., thinking, speech, concentration, problem-solving, and future planning.

· Regulating facial expressions and hand gestures

· Harmonizing expressions and motions with mood and sentiments


Parietal lobes

Behind the frontal, the parietal lobes are positioned. Their main function includes the following:

· Interpretation of sensory information obtained from other body parts

· Conjoining impressions of texture, form, and weight into common perceptions

· Modulating mathematical skills and linguistic understanding

· Keeping spatial memories, allowing people to be aware of their orientation, i.e., knowing their place and position and maintaining a sense of direction (knowing where to go)

· Regulating the position of body parts


Temporal lobes

Situated on each side of the head, the temporal lobes have the following functions.

· Regenerating emotions and memory

· Storing events into current and long-term memory

· Keeping and reproducing long-term memories

· Understanding images and sounds, allowing people to identify objects and people as well as integrate speech.


Occipital lobes

The back of the head above the backside of the neck houses the occipital lobe. Their functions include:

· The ability to read and identify printed words

· Allowing people to create visual memories


Cerebellum

The cerebellum is found at the backside of the brain, underneath the occipital lobes. Its functions involve fine motor skills, i.e., coordination of smaller movements, particularly the ones related to the hands and feet. Also, it supports the body in maintaining its posture, balance, and equilibrium.


Diencephalon

Located at the base of the brain, the diencephalon comprises the thalamus, epithalamus, and hypothalamus


The thalamus is involved with signal relaying, sleep, consciousness, and memory.


The epithalamus connects the limbic system and other brain parts. The limbic system is the brain’s portion involved with long-term memory, emotions, and behavior.


The hypothalamus is involved with maintaining homeostasis (body balance), controlling appetite, sleep, body temperature, and hormone release.


Brain stem

Found in front of the cerebellum, the brainstem serves as a connection with the spinal cord and consists of the midbrain, pons, and medulla oblongata.


Midbrain – controls eye movement and modulates auditory and visual information.


Pons - The biggest section of the brain stem is situated below the midbrain. It serves as a group of neurons that connect different brain parts and houses some cranial nerves.


Medulla oblongata – it is the lowest part of the brain and controls heart and lung activity. It regulates breathing, swallowing, and sneezing.




What happens when a brain part is damaged?

As seen above, different functions are performed by each brain portion. Thus, injury to any part leads to imparity in the specific function.


Frontal lobe damage

Injury to the frontal lobes typically leads to problem-solving issues and problems in planning and initiating actions, e.g., answering a difficult question or crossing the road. However, more precise impairments may differ depending upon the part of the frontal lobe affected.


Dorsal portion damage causes issues involuntary movements, weakness, or paralysis. As one side of the brain controls the movement in the opposite side of the body, when the left hemisphere is damaged, the symptoms appear in the right side of the body, and so forth.


Damage to the middle part of the frontal lobe leads to apathy (lack of interest and emotion), inattentiveness, demotivation, slow thinking, and responses to questions. Particularly, if the injury is in the middle back left frontal lobe called the Broca area, difficulty in expression in words occurs. This condition is known as Broca (expressive) aphasia. [2]


Injury to the front part of the frontal lobe can cause

· Loss of working memory

· Reduced fluency of speech

· Inattentiveness

· Apathy

· Slow response time to questions

· Poor behavioral control



Parietal lobe damage

The left parietal lobe is considered dominant and controls language, while the right one is non-dominant and controls functions, including the spatial relationship of their body with the surroundings.


Front part injury of the parietal lobe unilaterally leads to numbness and impaired sensation on the opposite body side. Affected individuals find it difficult to identify the location and type of sensation such as heat, pain, cold, or vibration.

Damage to the middle part of the parietal lobe leads to right-left disorientation, meaning that the person cannot distinguish between the right and left sides. They may also have difficulty with writing, calculations, and sensing the position of their body parts called proprioception.


Injury to the right side (generally non-dominant) parietal lobe causes the inability to perform simple skilled tasks, including combing hair or dressing up— a condition known as apraxia.



Temporal lobe damage

If the portion of the left temporal lobe that regulates language is damaged, memory for words might get impaired, along with difficulty understanding a language—called Wernicke (receptive) aphasia.

Damage to other specific sites may affect memory for sounds. Thus, resulting in trouble singing.


Occipital lobe damage

Bilateral damage to the occipital lobe will lead to difficulty recognizing objects by sight. Although the eyes are functioning well, referred to as cortical blindness.

Damage to certain parts of the occipital lobe can also cause visual hallucinations and seizures. [3]






Bottomline

The brain has a complex structure and carries out executive function yet is sensitive. Nature has thus, given it protection, through the skull. Disturbance in a single portion of the brain would lead to problems in diverse body activities performed by that part, having a significant impact on one’s life.






[H2] References

1. Nobel Laureate, Thomas Südhof, speaks at DCU. DCU. Sep, 2020. https://www.dcu.ie/news/news/2015/09/nobel-laureate-thomas-sudhof-speaks-at-dcu

2. Huang J. Aphasia. Sep, 2020.https://www.msdmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/brain-dysfunction/aphasia

3. Huang J. Brain Dysfunction by Location. Sep, 2020. https://www.msdmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/brain-dysfunction/brain-dysfunction-by-location

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