Hebbian Theory

Hebbian theory is a neuropsychological theory holding that an increase in synaptic efficacy arises from a presynaptic cell's repeated and persistent stimulation of a postsynaptic cell, an attempt to explain synaptic plasticity, the way neurons adapt during learning. It was introduced by Donald Hebb in his 1949 book The Organization of Behavior, and is also called Hebb's rule, Hebb's law, Hebb's postulate or cell assembly theory; Hebb held that when a cell repeatedly or persistently helps fire another nearby cell, a growth process or metabolic change occurs in one or both cells that increases the first cell's efficiency in firing the second. The theory is often summarized as neurons that fire together wire together, though Hebb specified that the first cell must fire just before, not at the same time as, the second, a form of causal timing that foreshadowed what is now known as spike-timing-dependent plasticity. Hebbian theory explains associative learning, in which the simultaneous activation of cells produces a marked increase in the synaptic strength between them, provides a biological basis for errorless learning methods used in education and memory rehabilitation, and is often treated as the neuronal basis of unsupervised learning in the study of neural networks.