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 types of multipolar neurons, accounting for about 80% of the neurons in the cortex (not surprisingly, two of the layers of the cortex are called the internal and external pyramid) and are among some of the most relevant in the body. They are generally considered to be 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 Cajal , the 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, with 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 cells or Betz cells.

Like other neurons, the structure of this type of neuron consists of soma, which as we have said has a pyramidal shape, an axon and dendrites. However, they have a peculiarity: as far as dendrites are concerned, they have a fairly long one in comparison with the rest, called apical dendrite , and numerous basal and shorter dendrites that are going to branch out.

Location of these nerve cells

Pyramidal neurons can be found at different points in the nervous system, but are much more prevalent in some specific areas. Among them, the following stand out.

1. Cerebral cortex

Pyramidal neurons are largely found 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 the granular and pyramidal layers both external and internal.

They stand out especially in the third and fifth layers (which are in fact those called external pyramidal and internal pyramidal), being of greater size the deeper they are in the crust. Within the crust, 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 there are many so-called Betz cells , giant pyramidal neurons that carry motor information from the brain to the areas of the spinal cord where they synapse with the motor neurons that activate movement.

3. Prefrontal cortex

Pyramidal neurons can also be found in the prefrontal cortex, influencing higher mental processes. It is considered that these cells are the main neurons of primary excitation of the prefrontal , participating in numerous functions and being considered primordial for the existence of behavioral control.

4. Corticospinal tract

Pyramidal neurons are especially visible along the corticospinal tract, which sends motor information from the different brain nuclei in charge of motor function to the motor neurons that will generate muscle contraction, passing through the spinal cord.

4. Hippocampus

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

5. Amygdala

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

Pyramidal neuron functions

Like the rest of the neurons, the pyramidal type are structures that transmit information in the form of electrochemical pulses 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 humans. 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 these areas 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 pyramidal neurons, in this case those of the hippocampus, are highly activated.

Bibliographic references

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