 Another possible explanation of facilitation is synaptic potentiation within an attractor neural network model where repetition decreases the settling time as the attractor basin deepens and so increases the overall speed of processing.When a stimulus is repeated top-down feedback modulates the neural response of earlier processing regions, with reduced neural activation and improved behavioural responses reflecting fulfilled expectations.The idea for this comes from predictive coding theories and Bayesian statistics and has some support in fMRI studies manipulating stimulus expectation.