Neurons are the cells of nerve tissue.
A neuron consists of a main portion, which contains the nucleus, and cell extensions called axons and dendrites . Neurons communicate with each other by means of electrical and chemical signals, transmitted across a synapse , or gap, between the axon of one neuron and the dendrites of another. Neurotransmitters are molecules that relay signals by moving from one neuron to the next. Billions of neurons are packed into the cerebral cortex , the part of the brain that receives, processes, and stores memory of sensory information as well as originates ideas. Many recent advances in understanding the brain are due to the development of techniques that allow scientists to see connections among neurons throughout the body.