Hebb connected the biological function of the brain as an organ together with the higher function of the mind. He studied how the function of neurons contributed to psychological processes such as learning. In this work he introduced the theory of Hebbian learning, a neuroscientific theory claiming that an increase in synaptic efficacy arises from a presynaptic cell's repeated and persistent stimulation of a postsynaptic cell. This was an attempt to explain synaptic plasticity, the adaptation of brain neurons during the learning process.
Hebb has been described as the father of neuropsychology and neural networks.