Cognitive neuroscience is the study of physiological basis of cognition. Neurons are the building blocks and transmission lines of the nervous system. Neuron doctrine is the idea that individual cells transmit signals in the nervous system and that these cells are not continuous with other cells as proposed by nerve net theory. The cell body contains mechanisms to keep the cell alive. Dendrites branch out from the cell body to receive signals from other neurons, and the axon or nerve fiber transmits signals to other neurons. The neuron has a receiving end and a transmitting end. In addition to neurons in the brain, there are also neurons that pick up information from the environment such as the neurons in the skin, eye, and ear. Usually many neurons are connected together to form neural circuits. Nerve impulses and action potentials deflect the dot up (if positive) and then back down (if negative). size.