Neurons are the main type of cells that make up each part 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 have the same structure and shape, the truth is that not all neurons are not identical. different types depending on their shape, where they send information, or even their relationship to other neurons. In this article we will focus on pyramidal neurons and their functions.
Pyramidal neurons are one of the different types of neurons found in our nervous system. It is one of the most common types of multipolar neurons, making up around 80% of neurons in the cortex (not in vain, two of the layers of the cortex are called inner and outer pyramids) and are among the most relevant. in the body. They are generally considered to be projection neurons. In other words, they act by sending the message to cells far away and separate from the region where they were born.
Discoveries of Santiago Ramón i CajalThe name of this type of neuron refers to the shape of its soma, triangular or pyramidal in appearance. Most are glutamatergic neurons, with glutamate being the neurotransmitter that activates them, and they generally act as excitatory-type neurons. They can come in different sizes, the largest of which are giant pyramid cells or Betz cells.
Like other neurons, the structure of this type of neuron consists of soma, which, as we said, has a pyramidal shape, axon, and dendrites. However, they have a peculiarity: as for dendrites, they have a prolonged strength compared to others, called apical dendrite, And many basal and shorter dendrites that will 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 certain specific areas. These include the following
1. Cerebral cortex
Pyramidal neurons are largely found in the cerebral cortex, forming part of most of it, and in five of the six layers that make up this brain region. Specifically, they can be observed in both the outer and inner granular and pyramidal layers.
They emphasize especially in the third and fifth layers (that are in fact those that in fact are denominated external pyramidal and internal pyramidal), being of greater size more deeply in the crust. Within the crust there are also areas where its existence has been detected more often.
2. Motor cortex
In the motor cortex, we find a large number of pyramidal-type neurons, and it is mainly related to motor control. In this area of the bark those known as Betz cells aboundGiant, pyramidal neurons that carry motor information from the brain to areas of the spinal cord where they synchronize with motor neurons that activate movement.
3. Prefrontal cortex
Pyramidal neurons can also be found in the prefrontal cortex, influencing higher mental processes. These cells are seen are the main neurons of the primary excitation of the prefrontal, Participate in many functions and consider-paramount for the existence of driving control.
4. Corticospinal route
Pyramidal neurons are particularly visible along the corticospinal tract, which sends motor information from different brain nuclei. in charge of motor neurons which will generate a muscle contraction, passing through the spinal cord.
Not only in the cortex we can find pyramidal neurons, but also the we can find in subcortical structures. One of them is the hippocampus, related to aspects such as memory and orientation.
Another structure in which these neurons are found is in the cerebral amygdala, an area of the limbic system related to emotional memory.
Functions of pyramidal neurons
Like the rest of neurons, those of the pyramidal type are structures that they transmit information in the form of electrochemical pulses which will be picked up by other neurons until they reach their final destination. Being such a widespread type of neuron in the cortex, pyramidal neurons are activated and linked to a large part of the functions and processes performed by human beings. Examples of these functions are as follows.
Motor control is one of the functions most traditionally associated with pyramidal neurons. More precisely, these neurons are deeply associated with the voluntary motor control of muscles.
2. Cognition and executive functions
The excitatory role of pyramidal neurons in the prefrontal cortex makes it possible to link their activation to very relevant cognitive processes, like executive functions or cognition.
The activity of pyramidal neurons in the prefrontal cortex is related to the connection of these areas with different subcortical regions, among them the limbics. In this sense, the amygdala and the hippocampus play a key role.
4. Memory and orientation
Memory and special orientation are other functions in which great activation occurs in pyramidal neurons, in this case those of the hippocampus.
- Kandel, ER; Schwartz, JH and Jessell, TM (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Inter-American. Madrid.
- McDonald, AJ (1992). Cell types and intrinsic connections of the amygdala. Program. Neurobiol. 55: 257-332.