The brain is one of the most complex and sophisticated systems of the human body. The small region of mass located within your skull is responsible for sending and receiving the messages that allow you to drive a car, have a meal, and elect in conversation. It is what shapes your behaviors, your decisions and emotions, and is what determines your personality as a whole. The brain is an incredibly complicated piece of machinery, and as such, it is a mystery we may never fully understand. However, its implications regarding the structure of our communities, societies, and how our world functions is a vast and immeasurable expanse and thus is a topic that we must attempt to discuss and realize. In my blog post for this week, I will try to explain the chemical processes that lead to addiction and the ways in which drugs interact with our brains.

The first topic we must first begin to understand is the process that is utilized by the brain in order to continuously interact and communicate with the other organs throughout the human body. The brain is composed of a large and complicated network of cells called neurons that send electrical signals via the peripheral nervous system and spinal cord. The peripheral nervous system — as opposed to the central nervous system which is made up of the brain and spinal cord — is composed of smaller arrays of neurons that disperse and branch out throughout our bodies. This entire network of neurons forms an interconnected web that is constantly sending electrical signals back and forth to the brain in the form of neurotransmitters. These chemicals essentially work much like how a key opens a lock. By leaving the synaptic vesicles of their respective neuron and crossing over and attaching to the receptors of the adjacent neuron, neurotransmitters do as their name suggests — they transmit information in the form of positive or negative ions to the next neuron and to the next until a message is finally conveyed. Once a signal is transmitted to the following neuron, the neurotransmitters are recycled and brought back to where they originated and are stored in the synaptic vesicles until they are needed again.

This brings us to the topic of drugs and the two main ways in which neurotransmission is disrupted by these harmful compounds.

• Neurotransmitter reuptake, as it’s often called, is the method by which specific enzymes are capable of bonding with certain free-floating neurotransmitters. This bond essentially serves as the passcode that allows neurotransmitters to enter back into the synapse of their originating neuron. However, some commonly known chemical substances, cocaine, for example, interfere with this process. Cocaine specifically targets transporter enzymes and bonds with them, thereby preventing neurotransmitters from leaving the synaptic cleft and therefore increasing their presence among the adjacent neuron’s receptors. One such neurotransmitter that gets trapped by cocaine is dopamine. Dopamine is classified as an excitatory neurotransmitter that is positively charged and is known as the most prevalent pleasure-inducing neurotransmitter in the human body. Its transmission is what allows us to feel the emotion of happiness and is what drives our motivations and reward-seeking ambitions. By closing the exit way for dopamine to re-enter the synapse, the neurotransmitter is trapped within the synaptic cleft and forced to continuously activate the receptors of the adjacent neuron, thus causing a pleasure signal that is constantly being transmitted throughout the body. This activation sequence continues indefinitely until the effects of the cocaine molecules wear off as they dislodge from the dopamine transporter enzymes.

• Other drugs, on the other hand, can imitate and serve as substitutes for neurotransmitters themselves. Nicotine is one such example as it hijacks the dopamine and acetylcholine receptors along the dendrites of the opposing neuron. Acetylcholine is a specific neurotransmitter such that its responsibility lies in transmitting signals regarding the body’s muscle control and involuntary actions. Scientists believe that it is due to this link that the drunken behavior stereotypically associated with that of alcohol is also characteristic of nicotine. Regardless of that fact, nicotine chemically induces a response that leads to an excess of stimulators built up in the synaptic cleft and thereby causes a cascading effect of the pleasure signal that would typically have been derived from dopamine. Rather than wait for dopamine to build up like how transporter enzyme bonding drugs often do, this process simply adds similar stimulators into the mix of neurotransmitters in order to have that same pleasure effect conveyed.

These two main processes are the ways in which physically consumed drugs affect our brains. Over time as individuals consume more and more of these harmful compounds, our brain learns to decrease its production of dopamine and other neurotransmitters, thereby creating a reliance on the said drug in order to have certain states of feeling. As addicts suddenly end their usage of such substances, they will find that the brain takes time in order to reacclimate to having to produce its neurotransmitters again. This is known as withdrawal and can be incredibly dangerous if not conducted in a professional setting under close observation by a medical professional. Additionally, the patient must gradually decrease their usage of their addicting substance in order to allow the brain to adjust in the safest way possible. Addiction quite literally changes the chemical structure and processes of the brain. Having a developed understanding of the brain and its functions allows us to better realize the ways in which we negatively impact its health and how to avoid those impacts.