His contribution to neuroscience is the part he played in establishing the concept of neuronal plasticity, the capacity of the brain to reorganise itself as a result of the pattern of activity passing through its connections. Blakemore was one of the first, in the late 1960s, to demonstrate that the visual part of the cerebral cortex undergoes active, adaptive change during a critical period shortly after birth, and he argued that this helps the brain to match itself to the sensory environment. He went on to show that such plasticity results from changes in the shape and structure of nerve cells and the distribution of nerve fibres, and also from the selective death of nerve cells.