Synapses - Plastic plasticity

The connections between neurons (synapses) can adapt to changing circumstances of nervous transmissions, a phenomenon known as activity-dependent plasticity. Moreover, such plasticity is itself regulated, but little is known about the mechanisms or behavioural consequences of this metaplasticity. New work on the mollusc Aplysia, involving study of the neural circuits that respond to stimulation of the siphon and tail, unveils connections and feedback systems that provide a handle on the regulation of metaplasticity.