Fig. 7.

Summary of learning-induced plasticity in behavioral circuits of Aplysia. a In reflexive pathways, the functioning of which is strictly dependent on extrinsic activation by sensory stimuli, learning intensifies (or reduces) otherwise fixed motor responses by modifying the linear through-flow of impulse activity from the sensory input to motor output stages via changes in synaptic connectivity and/or membrane excitability in chains of passively conducting neurons. b In neuronal pathways generating autonomous (motivated) behaviors, which partly depend on the intrinsically driven impulse to act, learning regulates the initiation of, and selection between, different motor patterns by rigidifying the underlying multifunctional CPG network into a fixed functional configuration though changes in the active membrane properties and reciprocal connections of constituent neurons