We are thrilled to dedicate this article to the exploration and understanding of the human brain. For centuries, this magnificent yet complex organ has drawn the attention and curiosity of many, but more so of scientists. A network made- up of billions of neurons, each responsible for sending, processing information and performing different functions within the human body. Our senses, emotions, movements and thinking processes are dominated and controlled by this fascinating organ. Diseases or malfunction of the brain, can alter our ability to process information, perform everyday task and enjoyments. Why is this organ so vital to our human existence, because we need it to survive and interact with our environment. For example to touch, see, taste, hear learn, work, eat, plan, dream, reason, remember, exercise, play and dance. Life-sustaining activities on the other hand, such as breathing and heart rate, are automatically controlled by the Medulla oblongata, located at the base of the skull. Thankfully to this mechanism, breathing and heart rate are regulated and so, we do not have to take care of this function entirely on our own. Except when serious injuries to the spinal cord occurs, leading to paralysis and needing human intervention to sustain-life through the use of artificial methods such as a ventilator.
The proper care and support of the human brain is important. Proper nutrition, exercise and adequate sleep can help our brains stay healthy, improve and maintain our memory. In contrast, substances like drugs, alcohol and malnutrition can have a negative and adverse effect on how well our brain continues to work. This brings us to the main reason we wrote this article. We want to broaden your understanding about the brain and the biological and physiological changes it undergoes with continual use of harmful substances such as cocaine, methamphetamine, heroine, marijuana and alcohol. In addition, We want our readers to appreciate its value and contribution to our human existence and enjoyment.
How Does My Brain Really Works
Like we said in the beginning, the brain is made-up of billions of neurons. Neurons are specialized cells which process information. This is accomplished through a process called Neurotransmission. Neurons receive and send messages to one another and back and forth to the brain through electrical impulses traveling along the axon of each neuron. An axon is a narrow tube at the end of the cell body which connects one neuron to another (fig.1 ). The axon is coated with a fatty-acid called myelin. This is important because myelin allows information to travel back and forth to your brain from up to speeds of 268 MPH !. The protection or coating over the nerve fiber or axon, almost resembles that of the coating found in insulated wires ( fig. 2). This protective system, is one of the reasons our brain can communicate with the rest of the body. But diseases like Multiple Sclerosis produce inflammation which destroys and damage the myelin, causing lesions or scars along the nerve fiber. As a result, neurons are not able to communicate properly and transfer information to other parts of the nervous system and symptoms like, numbness, weakness, loss of vision and lack of coordination soon develop.
fig. 1 Biology.StackExchange.com fig.2
Types of Neurons
There many different types of neurons. For this article we will focus primarily on two, sensory and motor neurons. Sensory neurons, receive sensory signals and send it via the axon to the central nervous system. They tell your brain that a particular action requires an immediate reaction. For example, when you place your hand on a hot surface the sensory neurons send messages to the brain along the spinal cord, HOT! The brain immediately responds by sending a message to your motor neurons which then contract the muscles and the hand is quickly removed or risks a burn. This is particular a problem for people who have Diabetes and which suffer from a condition called Peripheral neuropathy, a disease or dysfunction of one or more peripheral nerves, causing numbness and loss of sensation in the hands and feet. This is another example of how disruption and a breakdown of communication between neurons affects functionality.
Drugs in the Brain
Now that you understand how neurons communicate and work, let’s look closely at where and how drugs of abuse bind in the brain and how they ultimately affect the brain. The brain has natural chemicals called Neurotransmitters. Neurotransmitters are brain chemicals that communicate information throughout our brain and body. Some excite while others inhibit function. You maybe familiar with a few of them, for example, serotonin, dopamine, nor epinephrine and epinephrine ( adrenaline).These chemicals are housed inside the neurons and released in response to a electrical impulse generating from the cell body along the axon, across a space called synapse, then on to the next adjoining cell. Remember, once they reach across this space, these neurotransmitters; attach themselves to specific receptors in the adjoining cell almost like a puzzle piece (fig.3). Receptors are structures on the surface of a cell that selectively receives and binds a specific substance like, hormones, antibodies, drugs, viruses and etc… The next electrical impulse activates the adjoining neuron, causing it to transmit and process information on to other neurons. This signal continues to travel along the entire network of neurons, communicating and affecting different bodily functions in an excitatory or inhibitory way, as we will soon learn.
Fig.3
“Dopamine, The Feel Good Chemical”
There is a specific neurotransmitter which is of great importance called, dopamine. Dopamine is responsible for behavior, cognitive thinking, motivation, focus, reward, movement and mood. Dopamine is a chemical which is involved in our sense of well being and in anticipation of pleasurable activities such as eating, sex, and other activities which we enjoy and look forward to. Dopamine is also released by drugs which are abused by humans including nicotine, alcohol, heroin, cocaine and marijuana.
Cocaine, targets the brain’s “Reward Center” , where dopamine is stored and released. Under normal conditions, dopamine is released in small amounts in response to normal activities and then taken back up inside the neuron to be reused again. Unfortunately, once cocaine enters the brain, it blocks this reuptake process and the result leads to a rapid rise in abnormally high levels of dopamine in the brain causing feelings of intense pleasure, alertness, sense of energy, elevated mood, feelings of power, excitement, and also feelings of irritability, restlessness, anxiety, and paranoia.
A recent visit with Joanna Fowler, an award winning scientist at the US Department of Energy’s Brookhaven National Laboratory in New York, provided some more insight on how drugs like cocaine affect the human brain. She and her colleague Nora Volkow ( now Director of the National Institute on Drug.Abuse) used brain imaging to study where cocaine binds in the human brain and how the revealed areas in the brain targeted specifically by drugs. Cocaine, the mood altering drug, its seeing in targeting the “Reward Center,” and flooding the brain with dopamine (fig.4).
Their brain imaging studies also revealed that people who abused drugs over time had fewer dopamine receptors.This results in a weakened dopamine system and the inability to experience normal pleasure, joy with natural reinforces like food and needing to use an external stimuli like drugs to compensate. Other scans involving highly addictive drugs also produce the same similar findings in the brain (fig.5).
- (fig.5).
