Brain Basics

Problems people experience with language and learning are directly related to their brain’s ability to communicate. To understand how brain communication can be improved, we need to understand how brain communication works.

In Brain Basics:

 

Anatomy of the Brain

The brain is made of three main parts: the forebrain, midbrain, and hindbrain.

  • The forebrain consists of the cerebral cortex, thalamus, and hypothalamus.
  • The midbrain consists of the tectum and tegmentum.
  • The hindbrain is made of the cerebellum, pons and medulla.

The Cerebral Cortex 

The cerebral cortex spreads over the brain like a helmet and is the largest part of the human brain. It is associated with higher brain function such as thought and action. The cerebral cortex is divided into four sections, called "lobes". 

 

  •  Frontal Lobe: The Frontal lobe contains the motor cortex and is associated with muscle movement and parts of speech.
  •  Parietal Lobe: The parietal lobe contains the sensory cortex and is associated with movement, orientation, recognition, perception of stimuli.
  •  Occipital Lobe: The occipital lobe contains the visual cortex and is associated with receiving and processing visual information.
  •  Temporal Lobe: The temporal lobe contains the auditory cortex and is associated with perception and recognition of auditory stimuli, memory, and speech.

Within each lobe there are special regions that undertake different language and learning tasks. These regions do not work in isolation, but rather are connected by a series of neurons that allow information to be relayed between regions.

Read more in How the Brain’s Neurons Communicate

 

Angular Gyrus  

The angular gyrus is located at the point where the temporal lobe (sound), occipital lobe (visual) and parietal lobe (perception) meet. This specialized region is involved in converting visual information into audio information and vice versa.

  

Wernicke’s area

Wernike’s area is contained in the temporal lobe. It is the area of the brain associated with language inputs (for example, processing words that have been spoken). People who have problems with neuronal connections in Wernicke's area can generally speak fluently but since they have less ability to comprehend or process language inputs, the speech may make little sense.

 

Broca’s Area

Broca’s area is contained in the frontal lobe. It is the area of the brain that is involved in speech production and control. Therefore, people who have problems with neuronal connections in Broca's area can generally comprehend language properly, but cannot produce their thoughts in complex or coherent sentences. Broca's area is connected to the Wernicke’s area of the brain by a pathway of neurons called the arcuate fasciculus.

  

Anatomy of a neuron

The neuron is a type of cell found in the brain that specializes in communication.A neuron is made up of a cell body, dendrites, an axon and axon terminal. Using all these different parts, a neuron can send and receive information.

 

Cell body

The cell body (called the soma) contains a nucleus. The nucleus stores DNA and is the control centre of the neuron. In certain situations the DNA can reproduce itself and the nucleus can split into two. This is how new neurons are formed.

 

Dendrite

Dendrites branch off the cell body. The main function of dendrites is to RECEIVE messages from other neurons and relay those messages to the cell body. 

 

Axon

The axon is a long thin fiber that extends away from the cell body (like a string on a balloon). Axons carry information away from the cell body and SEND that information to the axon terminal. The message that is sent down the axon is in the form of an electrical current, which is called an action potential. The axon is surrounded by fatty tissue called the myelin sheath, which keeps the axon insulated so that electrical messages can be sent quickly and easily.   

 

Axon terminal

At the end of the axon are the axon terminals (these are also sometimes called synaptic terminals). The axon terminals contain hundreds of sacs containing different chemicals called neurotransmitters.


Synapse
Each axon terminal is separated from the next neuron by a tiny gap called the synapse. Although they are close, neurons never actually touch, so the electrical message sent by the axon has to be able to cross the synapse. In order to do this, the electrical message (action potential) must be converted into a chemical message (neurotransmitter). 

 

Neurotransmitters

When the action potential arrives at the axon terminal, it causes sacs to release chemicals called neurotransmitters. In order to relay information to the next neuron, these chemicals cross the synapse and attach to the dendrites of the next neuron.  

 

There are many different types of neurotransmitters in the brain. Some of the common ones include dopamine, acetyelcholine and serotonin (otherwise known as 5-HT).

 

Receptors

A receptor is simply the site on the neuron that the neurotransmitter chemical attaches itself to. When it attaches, the receptor becomes activated, causing the neuron to fire an action potential down the axon of the neuron. The receptor and neurotransmitter are like a lock and key – only certain neurotransmitters can activate certain receptors. This controls the type of message that is sent by the neuron.   

 

Depolarisation

The electrical message sent down the axon is called an action potential. An action potential is formed in response to a stimulus from either outside the body (light, heat, sound) or inside the body (chemical neurotransmitter). When the stimulus hits the neuron, it causes the inside of the neuron to change its charge and the neuron become more positive. This change in charge is called depolarisation. When there is enough positive charge inside the neuron, the action potential is generated and the electric current is sent down the axon.

 

Brain Facts
The Human brain has 100 billion neurons
The average adult human brain weighs 1.3 kilograms