Brain lobes

Brain Lobes and What Part of it Makes You?

The human brain is the most elegant, complicated, and beautiful thing in the universe. This is so because it is the universe, capable of understanding itself. There are no other things in this world that we know of that surpasses the capacities of the human brain. And the brain lobes and their functions have been divided to some degree.

The human brain can be divided into many parts based on different criteria. But for the sake of simplicity and considering neither you nor me have the time to explain and understand all the complexities of the brain, we’ll keep it to the anatomical division. The explanation of some portions will be brief, forgive me in advance. It is the most complicated thing we are talking about. 

Before we move to the brain lobes and their functions, we have to explain, in brief, some jargon so that you can easily understand when these terms come up. These are the hemispheres, bumps and grooves, and medical staff. 

The Wavy Brain Lobes 

If you see the brain of a human, you’ll notice that it is very weird. Instead of being a plain and smooth organ, like most organs are, our brain is like a pink colored snake coiled to fit inside our skull. Nature may be a slow worker, but she is a brilliant designer. There is a reason for all those folds and crevices. Here are some jargons. The bumps on the brain are called gyri (singular: gyrus) and the grooves are called sulci (singular: sulcus). 

Brain lobes
The Human Brain

This uneven surface of the brain is because of the increased cerebral cortex. The cerebral cortex of humans is quite advanced and it is the major area where complicated thinking and processes occur. This cerebral cortex is present on the surface of the brain. So increasing the surface area of the brain would also increase the cerebral cortex.
This is why the size of the brain is not an important factor in intelligence, but it is the grooves and bumps that matter. Apart from this, the brain is also divided into some major regions. Let’s take a look at that. 

Components of Brain.

The brain is divided into three major parts, the Forebrain, the Mid-brain, and the Hindbrain. The Forebrain is the part of the brain that has the brain lobes. The midbrain connects the forebrain to the hindbrain. The midbrain contains parts such as tectum, cerebral peduncle, etc. Diving into these topics will be unnecessary to the core of this article. So we will leave it here. The hindbrain contains pons and cerebellum which connect the forebrain with the spinal cord. This was the basic division of the complete brain. 

The Hemispheres of the brain.

The brain is further divided (anatomically) by a long fissure in the middle. This creates two hemispheres of the brain, called the cerebral hemisphere. The groove that divides the two hemispheres is called the longitudinal fissure. 

Brain Hemispheres
The left and right hemispheres of the brain. Image: Blausen.com staff (2014)
CC-BY-SA 3.0

Now that you are familiar with the basic anatomy of the brain and the jargons associated with it, let’s come to the brain lobes and their functions. 

Brain Lobes and their functions. 

According to Terminologia Anatomica, there are six different brain lobes in the human brain.  While that is the number, usually four brain lobes are commonly known to the general public. These lobes are Frontal lobe, Parietal lobe, Temporal lobe, Occipital lobe, Limbic lobe, and Insular Cortex. 

Brain lobes, main sulci and boundaries
The lobes of the brain labeled. Image: Sebastian023
CC-BY-SA 3.0

The first four brain lobes are regarded as true lobes by many authors. The last two lobes, limbic and insular cortex are not considered to be “true lobes.” Nevertheless, we have added a tiny bit of information about them too. 

We have presented a labeled diagram of the brain lobes and described their function in later sections. You can refer to the diagram in case you forget which lobe is where. But it is very easy to understand the anatomy of the brain lobes. 

Frontal Lobe 

The frontal lobe of the brain is the largest of the four lobes. This lobe, as the name suggests, is present at the front of the brain. So for visualization, the frontal lobe is behind your forehead. This lobe is separated from the parietal lobe (which is next to it) by a groove called the central sulcus. It is separated from the temporal lobe by a lateral sulcus, also called the Sylvian fissure.

Functions of the frontal lobe :

Many functions are controlled or affected by the frontal lobe. This lobe is involved in reasoning, emotions, language, etc. The posterior (back) part of the lobe has the primary motor cortex which controls voluntary movement.

The frontal lobe also has a prefrontal cortex which is responsible for high-level cognitive functioning. It is known to control executive functions like problem-solving, planning, making decisions, etc. 

This lobe also has Broca’s area which is essential for language production. This area is needed to form words. People who have their Broca’s area affected can understand words easily, but cannot speak or even write words. 

The frontal lobe also has dopamine receptors which are involved in attention, short-term memory task, motivation, etc.

Damage of Frontal Lobe :

Damage to the frontal lobe has shown a multitude of changes in the suffering. The symptoms include difficulty in recognizing faces, places, etc. Sufferers also experience reading difficulty, short-term memory difficulty, and increased aggression. 

The most famous case of damage to the frontal lobe in the case of Phineas Gage who got into an accident which resulted in an iron rod piercing his frontal lobe. He survived, but he never came back the way he used to be. From being calm and friendly, he became impulsive and angry. This shows how much the frontal lobe affects our personality. 

In the case of frontotemporal dementia, personality change is the first sign of the disease. So a major portion of your personality is influenced by your frontal lobe. 

Parietal Lobe 

Right behind the frontal lobe is the parietal lobe. It would be right to say that the parietal lobe’s function is mainly sensory reception. It is the sensory zone of the brain and is essential for spatial sense and navigational ability. How far things are, how to avoid obstacles, how much speed must you walk with are all influenced by this lobe of the brain?

Parietal lobe
The Parietal lobe (colored yellow) Public domain

The parietal lobe has the somatosensory cortex that is responsible for the sense of touch (mechanoreception). So the sense of touch, temperature, pain, etc are all because of the parietal lobe. It gives us the feel of an object, whether it is cold or warm, smooth or sharp, firm or soft, etc. It also has areas that are involved in language processing.

An interesting thing about the parietal lobe is that it has the somatosensory cortex homunculus. This is the pictorial representation of the neurological map of the brain. The regions that are responsible for controlling the part of the body are placed next to each other. Take a look at the image and you’ll understand. So the section which controls the legs has a leg next to it. Same with the hands and the fingers. Notice how the control area for the fingers is the same as our fingers. 

The dedicated area for each finger is as much as the area for the entire leg. This is because of the meticulous use of fingers that is required for complex tasks. Legs are mostly for walking.

 cortical sensory homunculus
The parts of the brain controlling parts of the human body.
Image : OpenStax College CC-BY-SA 3.0

So the human would look like this if the body parts were arranged the same way the control center for the body part are arranged in the brain

Damage of Parietal lobe : 

Since the parietal lobe is important for spatial awareness, damage to this lobe shows a decreased ability in spatial awareness, depth perception, hand-eye coordination, self-awareness, etc.

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Temporal Lobe 

The temporal lobe is the lobe that is situated at the side of the brain. It is behind your temples, hence the name. One of the most important functions of this lobe is the creation of long-term memory. It works with the hippocampus and associates sensory input with emotions. This helps in making long term memory. So if you have a pleasant memory from your past, thank your temporal lobe.

Temporal Lobe.
The green-colored part is the temporal lobe.

Some areas in the temporal lobe are associated with high-level auditory processing. It has the primary auditory cortex that is essential for hearing and language recognition. Not just that, but it is also responsible for understanding the semantics or the meaning of words and their relation with each other. It also helps you to understand different sounds like a dog barking, baby’s crying, etc.

The temporal lobe, along with the parietal lobe has Wernicke’s area. This area works with Broca’s area and is responsible for understanding words and language. People with damaged Wernicke’s area can speak and write words but they cannot understand language and words. 

Occipital Lobe.

The occipital lobe sits at the backside of the head and in the region for vision. It has the most of the primary visual cortex that enables us to see. The visual nerve that runs from the retina of the eye connects to this area.

the occipital lobe
The pink-colored part is the occipital lobe. Image: Public Domain

The primary visual cortex is called the Brodmann area 17 or V1 (Visual 1). This part of the lobe is responsible for moving and stationary objects as well as pattern recognition. A fun fact about the V1 area is that if you look at the human brain, you could see this area because there is a large sheath of myelin called the stria of Gennari. 

The occipital lobe has other areas called the extrastriate cortex that is involved in other visual processes like color differentiation, motion perception, etc.

Damage to the Occipital lobe can cause loss of vision, hallucinations, blurry vision, difficulty in analysis colors.

The Limbic Lobe or the Limbic System. 

There is a lot of disagreement in the medical science community to put a clear boundary on the things that comprise the limbic lobe. The area is not well defined and is comprised of multiple components. The lobe is confined to a horseshoe-shaped area and is crucial in the functioning of the human brain. 

The Limbic lobe (colored Orange).
Image: John A Beal
CC-BY-SA 2.5

The limbic system is comprised of Amygdala, Hippocampus, Parahippocampus gyrus, Cingulate cortex, Septal Nuclei, Mammillary body, Hypothalamus, Fornix. We are venturing into the world of detail and complexities. So I must restrict myself to go back to simplicity. 

Here are the general functions of these systems:

  • Amygdala. – Fear and anxiety.
  • Hippocampus – Memory 
  • Parahippocampal gyrus – Memory 
  • Cingulate cortex – emotion and memory.
  • Septal Nuclei – Pleasure, reward.
  • Mammillary body – memory 
  • Hypothalamus – controls the release of various hormones.
  • Fornix – It is a fibrous bundle that carries information from the hippocampus to the mammillary body and then to the thalamus. 

Insular Cortex 

This is a small portion of the cerebral cortex. While more research is needed, this part is believed to be involved in consciousness and emotions. This part also is believed to control cognitive function, self-awareness, interpersonal experience, motor control, etc. 

The insular lobe or the insular cortex
The Insular cortex. Image John A Beal CC-BY 2.5

Some Misconceptions about the function of the brain. 

You may have noticed that while the brain lobes have some specie functions, they aren’t unitary. This means that they aren’t solely responsible for the entire function. The motor control is a major function of the frontal lobe, but the temporal lobe as well as the parietal lobe play a crucial part in the complete motor movement of humans. This reveals a major aspect of the functioning brain. 

The brain and its lobes are interconnected and need each other to work. The frontal lobe cannot work alone. It can’t even complete the function that it majorly controls. There is no clear cut division of labor in the lobes of the brain and that is what makes the brain such a complicated and unique creation of the universe.

Where is consciousness located in the brain?

Another important thing to note is the presence of consciousness. There is not a single section of the brain that has consciousness housed in it. You cannot remove the part of the brain and get rid of consciousness. While it has been seen that advanced animals like humans have a highly developed frontal cortex and the frontal context is responsible for self-awareness, one cannot argue that the frontal lobe is where consciousness sits.

Consciousness can be attributed to the seamless working of the different lobes of the brain, but again, we cannot say where consciousness is because we do not know what consciousness is. But we all can appreciate the fact that the congregation of cells and billions of years of evolution has created an organic machine that uses electricity, blood, nutrients to transfer hormones, electrical pulses, and is aware of its environment. And the same organic machine has become so advanced that it has started asking, “What am I?” 

Sources

Frontal pole, Temporal brain, Parietal lobe, Cerebral Sulci and Gyri, Understanding Brain evolution, Brain Lobes.

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