Figure 1.

Delta waves and brain plasticity.

In physiological conditions with preserved interneuronal connections, background electroencephalography (EEG) activity oscillates in alpha frequency (8–12 Hz) band (A). When cortical plasticity is locally stimulated (as in Assenza et al., 2014) new connections are created and larger groups of neurons start oscillating simultaneously generating delta waves (B). When a lesion hit the brain, spared neurons on the boundaries of the lesion try to connect each other according to novel networks in the attempt to overcome the occurred neuronal deficit and start oscillating in delta frequency band.