Pyramidal neurons: functions and location in the brain

This type of nerve cell has some unique features, such as a giant dendrite.

Neurons are the main type of cells that make up each of the elements of the nervous system. These structures are well known to most people today.

But although in the collective imagination we have a typical image or representation of what a neuron is, and many people imagine that all or almost all of them have the same structure and shape, the truth is that not all neurons are the same: there are very different types depending on their shape, where they send the information or even their relationship with other neurons. In this article we will focus on pyramidal neurons and their functions..

Pyramidal neurons

Pyramidal neurons are one of the different types of neurons present in our nervous system.. It is one of the most common multipolar neuron types, accounting for about 80% of the neurons of the cortex (not in vain, two of the layers of the cortex are called internal and external pyramidal) and are among some of the most relevant in the organism. They are generally considered projection neurons. That is, they act by sending the message to cells far away and separated from the area where they are born.

Discovered by Santiago Ramón y Cajalthe name of this type of neuron refers to the shape of its soma, which is triangular or pyramidal in appearance. They are mostly glutamatergic neurons, glutamate being the neurotransmitter that activates them, and they usually act as excitatory neurons. They can have different sizes, the largest being the giant pyramidal or Betz cells.

Like other neurons, the structure of this type of neuron consists of the soma, which as we have said has a pyramidal shape, an axon and dendrites. However, they have a particularity: as far as the dendrite is concerned, they have a rather long dendrite compared to the rest, called apical dendriteand numerous basal and shorter dendrites that will branch out.

Location of these nerve cells.

Pyramidal neurons can be found in different parts of the nervous system, but are much more prevalent in some specific areas. These include the following.

1. Cerebral cortex

The pyramidal neurons are found to a large extent in the cerebral cortex, forming part of most of it and being found in five of the six layers that make up this brain region. Specifically, they can be observed in both the outer and inner granulosa and pyramidal layers.

They are particularly prominent in the third and fifth layers (which are in fact called external pyramidal and internal pyramidal), and the deeper they are in the cortex, the larger they are. Within the cortex, there are also areas where their existence has been detected more often.

2. Motor cortex

In the motor cortex we can find a large number of pyramidal neurons, being especially linked to motor control. In this area of the cortex known as Betz cells abound in this area of the cortex.These are giant pyramidal neurons that carry the motor information from the brain to the areas of the spinal cord where they synapse with the motor neurons that activate the movement.

3. Prefrontal cortex

Pyramidal neurons can also be found in the prefrontal cortex, influencing higher mental processes. These cells are considered to be are considered to be the main primary excitatory neurons of the prefrontal cortex, participating in numerous functions andThese cells are considered to be the main primary excitatory neurons of the prefrontal cortex, participating in numerous functions and considered essential for the existence of behavioral control.

4. Corticospinal tract

The pyramidal neurons are especially visible along the corticospinal tract, which sends the motor information from the different brain nuclei responsible for motor functions to the corticospinal tract. responsible for motor function to the motor neurons that generate that will generate Muscle contraction, passing through the spinal cord.

4. Hippocampus

Not only in the cortex we can find pyramidal neurons, but also in subcortical structures. can also be found in subcortical structures. One of them is the hippocampus, linked to aspects such as memory and orientation.

5. Amygdala

Another of the structures in which these neurons are found is in the cerebral amygdala, an area of the limbic system linked to emotional memory.

Functions of pyramidal neurons

Like other neurons, pyramidal neurons are structures that transmit information in the form of pulses. transmit information in the form of electrochemical pulses, which are that will be captured by other neurons until they reach their final destination. Being such a prevalent type of neuron in the cortex, pyramidal neurons are activated and linked to a large part of the functions and processes carried out by the human being. Examples of such functions are the following.

1. Movement

Motor control is one of the functions most traditionally associated with pyramidal neurons. Specifically, these neurons are deeply associated with voluntary motor control of muscles.

2. Cognition and executive functions

The excitatory role of pyramidal neurons in the prefrontal cortex means that their activation can be linked to highly relevant cognitive processes, such as executive functions or cognition..

3. Emotion

The activity of pyramidal neurons in the prefrontal cortex is linked to the connection of this area with different subcortical regions, including limbic regions.. In this sense, the amygdala and the hippocampus play a fundamental role.

4. Memory and orientation

Memory and special orientation are other functions in which there is a great activation in the pyramidal neurons, in this case those of the hippocampus.

Bibliographical references

• Kandel, E.R.; Schwartz, J.H. & Jessell, T.M. (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamericana. Madrid.
• McDonald, A.J. (1992). Cell types and intrinsic connections of amygdala. Prog. Neurobiol. 55: 257-332.