In the central nervous system, a pyramidal neuron is a type of nerve cell that is so named due to the shape of its cell body. The cell body, or soma, of pyramidal neurons has a distinct shape that gives them their name. They are also referred to as pyramidal cells and have been seen in fish, birds, reptiles and mammals. A pyramidal neuron has the same basic structure as all other types of neurons, so it is made up of a cell body attached to an axon and dendrites. What makes a pyramidal neuron unique is how the dendrites are arranged and the fact that both the axon and dendrites undergo extensive branching.
Within the central nervous system, pyramidal neurons are found within different regions of the forebrain only. In particular, these types of neurons send and receive nerve impulses within the cerebral cortex, hippocampus and the amygdala. In mammals, it is thought that pyramidal neurons play a key role in cognitive functions, such as perception, reasoning, remembering, thinking and understanding.
A pyramidal neuron has two distinct groups of dendrites — one found on the bottom of the cell body and one from the top of the cell body. These groups of dendrites are referred to as the basal and apical dendrites, respectively. This is the basic structure of a pyramidal neuron and it can vary based on where the cell is found within the central nervous system. Not only can the structure of pyramidal neurons differ based on what part of the brain they are found in, but also the exact location where they are found within the structure.
At the base of pyramidal neurons, there are usually several basal dendrites that branch extensively. As such, the basal dendritic tree looks more like a bush with a lot of branches. From the apex of the cell body, a single apical dendrite usually extends for some distance before branching. In some cases, this dendrite may split into two separate dendrites that extend and branch at the end.
Each pyramidal neuron contains many dendrites that are branched considerably so it can communicate with hundreds and even thousands of other neurons. Many studies have investigated how nerve impulses are received by pyramidal neurons. This is not well understood as nerve impulses are often received at one or the other of the dendritic trees, and can also be received by specific parts of each tree.