Our visual system depends on the use of nerve cells called neurons. The neuron consists of dendrites, where input is received, axons, where output is transmitted, the cell body, where the input is processes, and synapses, which are the connections between neurons.
Neurons generally have several inputs from the dendrites, but only one output through the axon.
Input from the dendrites adds up in the cell body and the cell will only fire once a threshold of activation is reached. Speaking, Moving, etc. Language, Planning, etc. To measure the activity of a neuron, an electrode can be put on its axon. The activity of the neuron can be represented by spikes on a graph.