The main cells that perform the functions of the nervous system are neurons.

Here's why:

* Neurons are specialized cells that transmit information throughout the nervous system. They do this by sending electrical and chemical signals.

* Glial cells are another type of cell found in the nervous system, but they primarily support neurons. They provide insulation, nutrition, and protection.

So, while glial cells are important, neurons are the key players in the nervous system's communication and function.