Encyclopedia of Psychology Alan E. Kazdin, PhD, Editor-in-Chief
LEARNING
...Learning is said to have taken place if an organism’s response to a particular situation or problem is shaped or determined by its earlier experiences with that type of situation.
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This “synaptic plasticity” received increased attention after it was demonstrated in the 1960s that (I) experience during development regulated the number of synapses in the visual system, and (2) new synapses could “sprout” in the damaged brain. Shortly thereafter, studies indicated that synapses could also change in size, shape, and number as a result of behavioral experience and learning. Subsequently, both synapse formation and synapse alteration have received sufficient support to render them likely mechanisms, independently or in combination, in many aspects of learning and memory.
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In one paradigm, motor skill learning was compared with motor activity in a treadmill or running wheel that did not involve learning: animals that learned showed synapse number increases, whereas animals that exercised increased the amount of capillaries but added no synapses. Thus, the synaptic changes appear to be specific to learning and not caused by mere neuronal activity.
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