Understanding Brain- 1

“Let us keep asking What, How and Why for the functionalities we observe in the brain so that we could successfully understand most of the things”

Let us see the big picture first

What Neural System does?

The functionality of the neural system is believed to be maintaining the status quo of the body in general.

How Neural System does this?

Let us start with anatomy of the nervous system

Neural system has

1. Brain
2. Spinal cord
3. Nerves from brain and spinal chord which connect throughout the body

Brain is divided into 3 parts:

1. Cerebrum
2. Cerebellum
3. Brain Stem

You could imagine the segmented nervous in the body to look like below

We will take a look at Cerebrum first and then we’ll move on to cerebellum and brain stem

Cerebrum:

Cerebrum can be divided into many substructures such as

Cerebral cortex ( or just known as cortex ), Hippocampus, olfactory bulb and many others

If we try to divide it based on the functions that sub structures of cerebrum deals with, it would roughly look like this.

Now we shall lookup how the internal structure of the cerebrum

Cerebrum as we know has many internal structures

The largest structure we call as cerebral cortex, the one which we actually see as brain

Cerebral Cortex:

If we remove Cerebral cortex after death, then we could observe parts of white and grey within cerebral cortex. These are known to be white and grey matter regions. These regions are also observed in all parts of the brain including spinal chord which can be seen in the figure below.

In spinal chord Grey matter is at the center and white matter is surrounding it.

But in cerebral cortex, we could see Grey matter is towards outside and the white matter is inside.

We could see the white and grey regions as below:

There are special cells which can be found in the nervous system called neurons

Cerebrum and all other brain structures including nerves connected from brain and spinal chord throughout the body has cells called neurons

Neurons

Neurons have 3 main parts

1. Soma ( neuron body )
2. Dendrite ( Receptors which collect electrical signal )
3. Axon ( most of the times which sends electrical signals to other neurons )

Neurons can be roughly divided into following types according to their structure:

1. Pyramidal cells

2. Stellate cells (star shape body)

3. Rosehip cells ( bush shaped body)

You can refer [5] for more info on this

Neurons can be divided into following types based on its behaviour:

1. Unipolar ( Not found in humans )
2. Bipolar
3. Pseudounipolar ( Found in humans )
4. Multipolar (Most common)

you can refer for further [4] for more info on this

Gray and White Matter

Grey matter contains mostly neuron body and is responsible for the all the functions which humans does like perception, language, etc

White matter mostly contains the axons of these neuron bodies which carry information to other parts of the brain and spinal chord.

You could get to know about this in detail by referring [6]

Grey Matter:

If we take out only the gray matter of the cerebral cortex ( which looks like wrinkles ) and iron it….it actually looks like a thin piece of cloth with 2.5 mm thickness

Within this 2.5 mm thickness, it is believed that we have 6 layers within that

as shown in the diagram, each layer has different distribution of types of neurons.

They can be functionally viewed as below:

Within each of these layers, the neurons are structured in sub structure called mini columns and its debated whether these mini columns has functional importance to it.

Note that the sequence of electrical impulse and activation of neurons is from bottom to top. i.e. Below 6th layer there is white matter. From sensory organs, the signal comes to 6th layer and then passed to 5th, then to 4th and so on

Different parts of this sheet of gray matter in cortical vertex correspond to different behaviours (like part called visual cortex correspond to visual processing region, auditory cortex corresponds to audio processing region)

White Matter:

Between the neurons, there are special cells called Glial cells( which means glue ). They are believed to act as a glue which holds all the neurons in their position. But we now know that it is much more than that. It maintains immunity in the nervous system, it acts as an insulator for axon, it helps in developing neurons, it cleans up dead neurons etc.

White matter contains mostly Glial cells which are acting as insulators (called Myalin Sheath) to axons which carry information.

The ecosystem is not really well understood yet!!! and is an area of research

Other topics yet to be covered involves:

Hippocampus: Memory

Thalamus: Controller

Hypothalamus: Harmones

Basal Ganglia:

Limbic system: Emotions

Amygdala: Fear Emotions

Parahypocampal gyrus: Memory

The flow of data within the brain

parts of other structures within the cerebrum: Hippocampus, thalamus, etc

parts of cerebellum and what does it do

parts of brain stem and its functionalities

parts of spinal chord and its functionalities

How does synapses in neurons work

What are neurotransmitters, types of neurotransmitters and nature of neurotransmitters?

How do harmones work and how does it lead to behaviour

What is plasticity in brain

How does memory work in brain?

How is data represented in brain?

How does behavior kicks in from electrical impulses?

How does Attention work?

System-1 vs System-2…is it real?

Current theories

Conjunction of AI and Neuroscience

So Stay tuned !!! cause you are in for the craziest ride

References:

[1]

Neurons

[2]

Neuroscientifically Challenged

[3]

Brain Science Podcast

[4]

[5]

[6]