What is the function of a dendrite?

The different parts of neurons tell us a lot about how these tiny brain cells work.

Neural axons, for example, with their elongated wire-like shape allow electricity to travel through them, regardless of whether or not they are accompanied by myelin sheaths. The dendrites, in turn, fulfill another function that we will see now.

In this post we are going to answer the question ‘’What is the function of a dendrite?’’ we will discover what a dendrite is, how it is formed and what is its role within the brain.

What is the function of a dendrite?

Its main function is to receive impulses from other neurons and send them to the neuron’s soma.

Dendrites are parts of neurons that are found throughout the body, that is, both in the brain and spinal cord and in those that are in the ganglia, internal organs, muscles, etc.

Specifically, dendrites are small branches that come out of the cell body (the part of the neuron where the cell nucleus is located). Compared to the axon, dendrites are usually shorter and thinner, so that they end closer to the cell body.

In addition, there is still another class of microscopic processes on the surface of the dendrites. These are small formations called dendritic spines, which are, in turn, the places where the dendrites fulfill their main function, as we will see.

Dendritic spines and synapses

Since the time of the famous Spanish neurologist Santiago Ramón y Cajal, it has been known that neurons are relatively independent small bodies, that is, there is a separation between them.

A part of this space that separates neurons from each other are the so-called synaptic spaces, which are the points through which these nerve cells pass information through substances called neurotransmitters.

The function of the dendrites in general, and of the dendritic spines in particular, is to act as the main contact of the neurotransmitters that arrive from outside. In other words, the dendritic spines act as terminals to which the stimuli arrive from the other neuron that sends neurotransmitters through the synaptic space.

Thanks to this it is possible that the transmission of nerve impulses is established that allows the functioning not only of the brain, but of the entire nervous system, since there are neurons distributed throughout the body.

On the other hand, the potential of the brain to adapt to circumstances (for example, learning from experience) is also possible thanks to the work of dendrites.

It is these that regulate the chances that two nerve cells come into contact with more or less frequency, so they decide the “route” that the nerve impulses take.

With the passage of time, the degree of affinity that the dendrites of one neuron gain with the terminals of another causes a habitual communication path to be created, a fact that affects, even minimally, the progress of the mental operations that are going away conducting.

Of course, this effect multiplied by the number of synapses in the nervous system is not minimal, and not only affects the functioning of the brain and the rest of the system, but is, in itself, the basis of it.

On the surface of dendritic spines there are a series of structures called receptors that are responsible for capturing certain types of neurotransmitters and activating a specific mechanism.

In this way, a neurotransmitter such as dopamine will reach a receptor compatible with it and will cause it to activate a process in the receptor neuron.

Your role in brain communication

If the axons are responsible for making nerve impulses travel through two points in the nervous system, the dendrites are responsible for capturing the chemicals that come out from the tip of the axons and for making these chemical signals transform or not in electrical impulses, although this process can also be initiated in the body of the neuron.

That is, it is in the dendrites and in the neuronal body where the electrical signals are born (also called action potentials) that run through the neurons and that will end up at the tips of the axons, causing this part of the neuron to release chemical substances.

When the right amount of neurotransmitters reach the dendrites, depolarization occurs, which is the process that generates nerve impulses.

Dendrites are very sensitive to the slightest variations in the type and quantity of neurotransmitters that they collect, and that means that depending on the chemical substances they detect, they initiate one or another pattern of electrical impulses, or that an electrical signal is not generated directly, if conditions are met.

That means that the dendrites don’t need to pick up any neurotransmitters so they don’t produce an electrical impulse; This can also happen if they capture a certain amount of a certain type of chemical.

That is why some psychotropic drugs act on the dendrites of neurons, to make them not generate electrical signals as they would if it were not for the effect of this active principle.

Ultimately, the molecular traces that lived experiences leave in dendrites and neuron terminals are the basis for the functioning of the nervous system and its ability to make its activity vary dynamically.

At the same time, they are a fundamental part of the process of managing memories, which are patterns printed in those molecular fingerprints with which the nerve cell works.

So, what is the function of a dendrite?

As discussed above, the most basic function of dendrites is to establish functional contact with other cells in order to achieve a change in their behavior.

This can be its stimulation or inhibition, processes that can be expressed in numerous aspects, such as changes in the state of muscle contraction and increase or decrease in the transmission of nerve impulses, for example.

In a huge number of cases in the human body, this is achieved through the release of substances called neurotransmitters, which achieve important changes in adjacent cells. This process is known as a chemical synapse.

There is another small variation known as an electrical synapse, which has some disadvantages because it is not very present in the cells of the human body.

These neurotransmitters also allow the adequate transmission of nerve impulses, a complex process characterized by variations in the intra and extracellular levels of various ions (chemical elements with positive or negative charges).

What types of neurotransmitters are there?

Actually, the orders and responses in which the nervous system participates depend entirely on the neurotransmitters released at chemical synapses and the receptors found on postsynaptic receptors.

That is why, to properly understand the physiology of the different nervous circuits, it is vital to consider the neurotransmitters involved.

For example, the main excitatory neurotransmitter in the central nervous system is glutamate.

This interacts with a varied amount of receptors (proteins) anchored in the plasma membrane of the postsynaptic cell, generating a large number of intracellular changes characterized by variations in electrolyte levels that, in the long run, produce the transmission of the nerve impulse of cell to cell (which, although a laborious process, really does happen in a very short time).

On the other hand, the main inhibitory neurotransmitter is GABA, which is also involved in the aforementioned mechanisms (release and interaction with specific postsynaptic receptors) but which causes different changes at the intracellular level, greatly reducing the emission of nerve impulses. in the following neurons.

Dendrites: the beginning of a revolution

For many years, neuroscience has used different tools to try to “listen” to the conversations of neurons. In the same way that linguists decipher an unknown language, scientists try to decode neural firing patterns to try to figure out the grammar of the brain.

In these attempts, it seems that new stars have been born: the dendrites.

The latest research seems to be showing that neuroscience, when it comes to estimating our brain’s capacity, has only been scratching the surface.

The University of UCLA discovered a hidden layer of neural communication through dendrites. This means that the brain’s capacity could be up to 100 times greater than previously thought.

This discovery can significantly change the foundations of conventional neuroscience. Until a few months ago, the foundations of neuroscience were supported by the belief that dendrites were something like a passive wiring that carried electrical signals to the neural body, the soma.

But this research showed that dendrites are much more than just passive conductors. The dendrites generate their electrical signals, in peaks five times larger and more frequent than the peaks that come from the nuclei of neurons.

Brain capacity: research

The research team of Dr. Mayank R. Mehta devised a system that allows electrodes to be placed near rat dendrites.

This system allows to capture electrical signals from the animal during the time it is awake and carrying out its daily activities, as well as during sleep. In this way, they were able to listen to the electrical activity of the dendrites for four days in a row and transmit it live to the computers.

The electrodes were implanted in the area of ​​the brain linked to movement planning, the posterior parietal cortex. What they managed to capture was that during periods of sleep the electrical signals looked like irregular waves, each signaling a peak.

That is, while the rats slept, the dendrites chatted with each other, and they did so in electrical shots up to five times faster than those originating in cell bodies. During waking periods, the rate of fire increased tenfold.

 

Dendrites: measurers of the here and now

Another shocking discovery during this research was found in the type of signal emitted by dendrites. The electrical signals from the dendrites could be digital, but they also showed large fluctuations, almost twice as large as the spines themselves.

This type of wide-range fluctuation demonstrates that the dendrite also exhibited analogue computing activity. Something that had not been seen before in any pattern of neural activity.

What this type of emission from the dendrite calculates appears to be related to time and space. Observing the rats behaving in a maze, two types of signals were distinguished. One in the form of spikes from the cell body in anticipation of a behavior.

In this case, it was before turning a corner. While the dendrites emitted their calculation signals just as the animal turned the corner.

It seems that neuroscience has been underestimating the computational power of the brain. From the perspective of volume alone, and because dendrites are 100 times larger than soma, we could assume that the brain actually has a hundred times more processing power than previously thought.

It seems that the neuron will no longer be the basic computational unit of the brain, the dendrites having taken over.

FAQS: What is the function of a dendrite?

What is a dendrite and what does it do?

Dendrites are segmented protoplasmic extensions of a nerve cell that propagate electrochemical stimulus to the cell body, or soma, of the neuron from which the dendrites project, obtained from other neural cells.

What is the function of the dendrites of a neuron?

They receive chemical signals from the axon termini of other neurons.

What is the function of a dendrite quizlet?

Dendrites grow to make synaptic connections with other neurons.

What does Dendrite mean?

1. Arborescent mineral concrete that usually occurs in cracks and rock joints.

2. Metallic crystal, generally produced by solidification, characterized by a structure analogous to that of a tree with multiple branches

What do dendrites receive?

Dendrites receive communications from other cell

In this post we answered the question ‘’What is the function of a dendrite?’’ we discovered what a dendrite is, how it is formed and what is its role within the brain.

If you have any questions or comments please let us know!

References

Moore, J. J., Ravassard, P. M., Ho, D., Acharya, L., Kees, A. L., Vuong, C., & Mehta, M. R. (2017). Dynamics of cortical dendritic membrane potential and spikes in freely behaving rats. Science, 355(6331), eaaj1497. https://doi.org/10.1126/science.aaj1497

‌Stuart, G., Spruston, N., & Häusser, M. (Eds.). (2016). Dendrites. Oxford University Press.

Rall, W. (1962). Theory of physiological properties of dendrites. Annals of the New York Academy of Sciences, 96(4), 1071-1092.