What is the synaptic space and how does it work?

This place of communication between neurons is known as the synapse and holds many secrets.

The nervous system is made up of an extensive network of nerve connections, the basic component of which is the neuron.. These connections allow the control and management of the different mental processes and behaviors of which the human being is capable, allowing us to stay alive, run, talk, relate, imagine or love.

Nerve connections occur between different neurons or between neurons and internal organs, generating electrochemical impulses that are transmitted between neurons until they reach their target. However, these nerve cells are not hooked to each other. Between the different neurons that form part of the nervous system we can find a small space through which communication with the next neuron or neurons takes place. These spaces are called synaptic spaces.

Synapses and synaptic space

The synaptic space or synaptic cleft is the small space that exists between the end of one neuron and the beginning of another neuron.. It is an extracellular space between 20 to 40 nanometers and filled with synaptic fluid that forms part of the neuronal synapse, together with the pre- and postsynaptic neurons. Thus, it is in this space or synaptic cleft where the transmission of information from one neuron to another takes place.The neuron that releases the information is called presynaptic, while the neuron that receives it is called postsynaptic neuron.

There are different types of synapsesThe synaptic space may connect the axons of two neurons between them, or directly the axon of one and the soma of the other. However, the type of synapse in which the axon of one neuron and the dendrites of another communicate, called axodendritic synapse, is the most common. It is also possible to find both electrical and dendritic synapses, it is also possible to find electrical and chemical synapses, the latter being much more frequent and of which I will speak in this and of which I will speak in this article.

Transmission of information

The involvement of the synaptic space, although passive, is essential in the transmission of information. Upon the arrival of an action potential (caused by depolarization, repolarization and hyperpolarization in the cone of the axon) to the final end of the presynaptic axon, the terminal boutons of the neuron are activated, which eject outwards.which expel a series of proteins and neurotransmitters, substances that exert a chemical communication between neurons, which the next neuron will pick up at the end of the axon. that the following neuron will capture through the dendrites. (although in electrical synapses this does not occur).

It is in the synaptic space where neurotransmitters are released and radiated, and from there they will be taken up by the postsynaptic neuron. The neuron that has emitted the neurotransmitters will recapture the excess neurotransmitter that remains in the synaptic space and that the postsynaptic neuron does not allow to pass, taking advantage of them in the future and maintaining the balance of the system (it is in this reuptake process that many psychotropic drugs, such as SSRIs, interfere).

Potentiating or inhibiting electrical signals

Once the neurotransmitters have been taken up, the postsynaptic neuron will react in this case to the continuation of the nerve signal by generating excitatory or inhibitory potentials, which will allow or not the propagation of the action potential (the electrical impulse) generated in the axon of the presynaptic neuron by altering the electrochemical balance.

And the fact is that the synaptic connection between neurons does not always involve the passage of the nerve impulse from one neuron to another.It can also cause it not to replicate and to be extinguished, depending on the type of connection that is stimulated.

To understand it better, it is necessary to think that nerve connections do not involve only two neurons, but that we have a great multitude of interrelated circuits that can cause a signal that a circuit has emitted to be inhibited. For example, in the event of an injury, the brain sends Pain signals to the affected area, but another circuit temporarily inhibits the sensation of pain to allow the injured stimulus to escape.

What is the purpose of synapses?

Considering the process of information transmission, we can say that the main function of the synaptic space is to allow communication between neurons, regulating the passage of the electrochemical impulses that govern the functioning of the organism..

Moreover, thanks to it, neurotransmitters can remain for a time in the circuit without the need for the presynaptic neuron to be activated, so that although they are not initially captured by the postsynaptic neuron, they can be used later.

In an opposite sense, it also allows excess neurotransmitter to be reuptaken by the presynaptic neuron, or degraded by different enzymes that can be emitted by the membrane of neurons, such as MAO.

Finally, the synaptic space facilitates the possibility of removing from the system the residues generated by the nervous activity, which could lead to the intoxication of the neurons and their death.

Synapses throughout life

The human being as an organism is continuously active throughout the life cycle, whether performing an action, feeling, perceiving, thinking, learning.... All these actions mean that our nervous system is permanently activated, emitting nervous impulses and transmitting the neurons of the nervous system.The nervous system is permanently activated, emitting nervous impulses and transmitting orders and information from one neuron to another through synapses.

When a connection is formed, the neurons come together thanks to neurotrophic factors that make it easier for them to attract or attract each other. that make it easier for them to attract or repel each other, although without ever touching. When they connect, they leave a small intermediate gap, the synaptic space, thanks to the modulating action of the same neurotrophic factors. The creation of synapses is called synaptogenesis, and is particularly important in the fetal stage and in early childhood.. However, synapses are formed throughout the life cycle, through the continuous creation and pruning of neuronal connections.

Life's own activity and the different actions we carry out have an effect on synaptic activity: if the activation of a circuit is repeated to a great extent, it is strengthened, while if it is not exercised for a long time, the connection between neuronal circuits is weakened.

Bibliographical references:

• Bear, M.F.; Connors, B.W. & Paradiso, M.A. (2002). Neuroscience: exploring the brain. Barcelona: Masson.

• Kandel, E.R.; Schwartz, J.H. & Jessell, T.M. (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamericana. Madrid.