The human brain is a very sophisticated collection of nervous pathways that are designed for a rapid transmission of information in the form of chemical and electrical impulses. These numerous pathways are composed of brain cells, scientifically called neurons, which are interconnected with each other and communicate at very high speeds through electrical and chemical methods. This transmission of information is vital for a rapid response, such as muscular contraction that results in body movement, a neuromuscular reflex that helps with defense against potential threats or a signal transmitted to the heart or to the blood vessels to change the parameters of blood circulation, among other functions executed by the nervous system. In other words, the entire nervous system, and the brain specifically, ensure a rapid adaptation of your body to continuously changing circumstances and environments through learning, reasoning, planning and muscular contraction necessary to execute brain commands. The nervous system is divided into the central nervous system, which is just a scientific term for the brain, and the peripheral nervous system, which is composed of the nerves that originate in the brain, travel through the spine and reach throughout the entire body to execute their function.
The neurons are cells located in the brain and peripheral nerve fibers that look like filaments with their prolonged shape that is designed to transmit information very fast. Nervous signals are transmitted electrically through the body of the neuron, which is a process called membrane depolarization that involves sodium and potassium ion currents generated across the cellular membrane. However, once the signal reaches the end of the neuron, it is further transmitted chemically through a special space between neighboring neurons know as a synapse. This space is used to convert the electrical signal into a chemical one through the release of special messengers called neurotransmitters. The electrical current that encodes the nerve impulse is converted into a certain concentration of the neurotransmitter released in the gap between two neighboring neurons. Any type of brain activity or command is transmitted electrically through the body of a neuron and then chemically between different neurons, and these processes are a simplified model of how the human brain is able to execute its functions. However, the detailed mechanisms are more complex due to the differing types of neurons as the connections between them are very sophisticated, and there are many types of neurotransmitters and receptors that are sensitive to their influence.
The Mechanism of Nerve Signal Transmission inside the Synapse
The electrical signal reaching one end of the neuron through a specialized extension of the neuron called its axon is transformed into a precise chemical signal. The neuron has vast storages of neurotransmitters inside the membrane that can be released very quickly in the synaptic space to transmit the signal further to the next neuron. The deposits of neurotransmitters are called vesicles, and they are able to merge with the neuronal cellular membrane allowing the release of its contents into the external space, which is the synapse. These vesicles filled with neurotransmitters are continuously replenished to ensure that chemical messengers are always available for another signal transmission. However, severe mental exhaustion, depression, certain drugs or diseases can cause a considerable depletion of these deposits, which makes the chemical signal transmission more difficult or even impossible. On the other hand, other drugs that influence the nervous system can cause the opposite effect, which is helping with neurotransmitter production and an enhanced packing of chemical messengers into new vesicles ready to be emptied at any time into the synaptic gap between neurons.
Neurotransmitters Influence Target Receptors Located on the Neighboring Neuron
How precisely is the nerve signal transmitted further to the next neuron? Once released into the specialized gap between two brain cells, the neurotransmitters tend to attach to their target receptors situated on the external membrane of the receiving brain cell, which is a method to detect the incoming chemical signal, convert it into an electrical one and propagate it through the body of the receiving neuron until it reaches the next synaptic space. The process continues until the signal reaches its destination, which may be a brain region responsible for memory processing or a muscle cell that will perform a contraction and contribute to a particular type of movement, among other types of targets.
The receptor is critical for the transmission of the chemical signal. Without a target receptor that has a specific structure that matches the released neurotransmitter, the chemical messengers are useless. The neurotransmitter attaches to its receptor and causes precise changes of its structure, which are then converted into an accurate electrical signal transmitted inside the receiving neuron. Besides the availability of various types of neurotransmitters, the process of nerve impulse propagation is further complicated by the ability of the receiving neuron to control the number of receptors that are presented externally for chemical transmission. In other words, depending on various factors, the receiving neuron can add more receptors, which make it more sensitive to chemical stimulation, or “hide” some receptors inside the cell, which cause desensitization. These processes that occur normally in most neurons are known as up-regulation and down-regulation of receptors. Similar events may occur with receptors for hormones, which are not part of the central nervous system, but can be regulated in a similar manner. Some drugs, including nootropics, can cause up or down regulation of receptors, slightly changing their affinity to the released chemical messenger or mimic the effects of a neurotransmitter.
General Methods of Influencing Brain Activity through Drugs or Supplements
Pharmacists learn how to create drugs that would influence various aspects of human physiology, including brain activity. There are multiple interventions that can modify certain parameters by influencing the mechanisms described earlier. It is important to understand that drugs or supplements do not create new processes and do not generate new functions in the brain. All they can do is change the intensity and the emphasis on certain already existing mechanisms that may function deficiently due to disease, exhaustion, poor motivation or previous treatments. In other words, medications or supplements, including nootropics do not change the basic functions of the brain or alter its structure. Some drugs may cause toxicity, which can be prevented with certain supplements like nootropics because they are able to intensify certain brain functions excessively or limit a certain brain mechanism.
Here are the basic methods of influencing brain activity through pharmaceutical remedies or supplements like nootropics:
* Increase the release of neurotransmitters from their deposits, which intensifies the intensity of the nervous signal
* Cause a stimulation of the target receptor on the receiving neuron that is similar to the effect of a neurotransmitter
* Block or slightly inhibit a certain receptor – which makes binding of neurotransmitters difficult or impossible
* Deplete the chemical messenger reserves inside neurons or amplify their production
* Regulate the number of receptors that are presented externally into the synaptic space
* Block and stimulate the reuptake of neurotransmitters back into their internal vesicles once the signal has been successfully transmitted, which may prolong or limit the chemical transmission
* Block the activity of enzymes that neutralize chemical messengers and make them inactive
* Provide nutrients or substances that are used to manufacture new neurotransmitters
* Stimulate the production of certain hormones that influence brain activity (cortisol or adrenaline, for example)
These are the most important mechanisms that allow a modulation of brain activity through medication or supplements. Every described method has certain drugs that utilize this pathway. Some drugs can work through two or more mechanisms. Some of the described pathways influenced through drugs generate powerful influences and brain activity changes, while others cause a less intense effect. Generally, mechanisms like directly blocking receptors or severely depleting neurotransmitter reserves are associated with very powerful drugs or poisons that may cause toxicity. These direct mechanisms like direct receptor blockage, powerful receptor stimulation or a massive release and depletion of neurotransmitter reserves cause immediate effects and take time to reverse. This is why medications that work through these direct pathways are generally used only in hospitals in emergency situations because they can cause considerable adverse effects even in low concentrations.
Nootropic supplements generally work through less direct or collateral mechanisms, such as regulating the number or the sensitivity of receptors, stimulating neurotransmitter production or influencing the enzymes that neutralize the neurotransmitters. It means that nootropics do not brutally intervene in the activity of the brain, but rather cause an indirect stimulation of its potential, provide nutritional support and activate collateral yet safer pathways that result in mental enhancement with minimal undesirable effects. There are numerous neurotransmitter systems that can be influenced directly or indirectly by diseases, drugs or supplements, but nootropics do not influence all of them.
Examples of nootropic influence on neurotransmitter systems in your brain:
* Modulation of acetylcholine pathways in the regions responsible for learning and acquiring new memories, such as the hippocampus.
* Indirect stimulation of glutamate mediated pathways, which stimulate memory strength and improve mental drive or motivation.
* Inhibit enzymes that neutralize acetylcholine, which improves the activity of this neurotransmitter system with noticeable effects on memory.
* Exert a mild stimulation of the norepinephrine neurotransmitter system, which enhance mental alertness and improves attention to details.
You can read more about the specific influence of various classes of nootropics, their safely and how they positively impact cognition in other articles found on this website. The basic understanding of how the brain neurotransmitters systems function and how they can be influenced directly or indirectly allows you to gain valuable insight and experience in combining various nootropics into stacks, which would result in a fine tuned enhancement of various neurotransmitters systems.