Learning about learning: The Basics of Neuro-Science -The Brain Cell

In the first post, I described the different parts of the brain and their different, mostly overlapping, functions. To understand neuro science, one also needs to understand the brain cell or neuron and its structure. In this post I talk about the two types of cells in the brain. Then focusing neurons, I will use a hand and arm analogy to explain the two parts of neuron before going into the technical details of the neuron structure and how information can be lost or retained and passed on. I will tell you a cool fact at the end of the post.  

The brain is composed of trillions of cells. These are of two types: the nerve cells or neurons and the glial cells. The brain is mostly of glial cells. Gail cells act as blood-brain barrier and protects the neuron from the blood substance that may disrupt the neural activities. These glial cells hold the neurons together and keep harmful substance out of reach of the neurons. It also regulates the neuron signals.

The neurons are just a tenth of the total cell. Neurons the most sensitive and functional center of the brain. Neurons are of different sizes. Each neuron has tens of thousands of branches emerging from its body called the dendrites. Dendrites and axons are the two most important parts of the neuron. Let’s try and understand dendrite and axon of a neuron with the analogy of hand and arms.

David Sousa (2017)

Consider the image of the hand and arm as a neuron cell. Let’s say the fingers are the dendrites and the arm is the axon. The fingers of one neuron are connected to the arms of the neighboring neuron. These finger connections can be strengthened and at the same time the number of the fingers can be increased. The more the fingers the better the information processing and the strong the memory. Let’s get to the more technical explanation of this.

So the dendrites are branches emerging from the cell body. The dendrites are connected to the axon of the next cell. The exiting connections of the dendrites to the axon of the next neuron can be strengthened and new dendrites can be formed. The more the dendrites, the more connections with other neurons. The more the dendrites, the more the connection, the more the intelligence of a person. This connection is strengthened and improved through challenging tasks or jobs. Studies have found that the more complex and demanding the job or task, the greater the number of dendrites. There are different ways to strengthen and increase these connections. I will talked in a separate post but for now why is such high connection link to intelligence? 

The high number of dendrites and its connection helps the brain process the data continuously coming from the senses. It stores decades of memories, faces and places, helps in learning languages and combines information in ways no other creature can do. The stronger this connection, the more learning and retention of information occurs.

David Sousa (2017)

Each neuron has one axon (the arm in the analogy). The dendrites receiving electrical impulses from other neurons transmits them along this long fiber called the axon. A myelin sheath surrounds the axon. This sheath insulates the axon from other cells i.e it helps retain the information within the cell. If the information leaves the cell, it is lost or forgotten. So again the better the myelin sheath, the better retention and processing of information. The insulin sheath also prevents the electric charge from leaking into the environment and increases the speed of transmission. This transmission can be as speedy as in two tenths of a second through the entire body of a 6 foot adult. Each second the neurons transmit thousands of impulses simultaneously. 

As I said, the dendrites of one neuron is connected to the axon of the next neuron, but they are not directly attached. There is a very small gap between the dendrites and the axon of two neurons. This gap is called a synapse. The information passed from the dendrites of one neuron to the axon of the next neuron has to go through this synapse. A neuron sends electrical impulse through the axon to its end terminal at the synapse which releases the chemicals stored in sacs at the end of the axon so it could be passed through to the dendrites of the other neuron crossing the synapse. These chemicals are called neurotransmitters that move across the synapse and either exit or inhibit at the end of the neighboring neuron. If it exits, information is lost, if it inhibits to the neighboring neuron, information is retained. The impulse moves along this neuron’s axon to other neurons and so on. 

Here is a video by Hashim Al-Ghaili on how your brain looks when the neurons fire.

A COOL FACT: have you ever observed a person’s expression observing someone else working intensely on something.  Although the observer is not performing the action but his/her impression are similar to what the performer is experiencing. Sit in the front seat of a car and while the driver is driving, you seem to be controlling the movement of the car just by watching ahead. Scientists have discovered that a set of neurons fired both when the person performed an action and when observed a similar action performed by someone else. For example the firing patter of these neurons that preceded the person grasping a cup of coffee was identical to the pattern when the person saw someone else do that. Thus, similar brain areas process both the production and the perception of movement. This is called mirror neuron.  Mirror neurons allow us to recreate the experience of others within ourselves and understand others’ emotions and empathize. Seeing the look of sadness or joy on other people’s face cause mirror neurons to trigger similar emotions in us. We start to feel their actions and sensation as though we were doing them. You should smile next time you see someone to make them happy.

The next post will discuss information processing model of learning.