Synaptic efficacy rises via potentiation or falls via depression in experience

Evidence

The efficacy of the synapse (its capacity to transmit signals from neuron to neuron) either rises, which is called ”long-term potentiation” (LTP), or diminishes, which is ”long-term depression” (LTD). This can be verified even in an animal like the aplysia. Its central nervous system is simple, composed of eight pairs of ganglia situated around its esophagus and one large abdominal ganglion. The aplysia has a small set of stereotypical behaviors, among them a number of protective maneuvers, such as retracting its siphon and its gills. But the intensity of its self-defense reflex is modulated by experience. Repeated innocuous stimulation of its mantle results in a diminution of the reflex (a habituation), which manifests as a decrease in the size of the retracting motion. This habituation is accompanied by a depression in synaptic activity correlated to the amount of neurotransmitter emitted at the level of the motor-sensory synapse. — Catherine Malabou, What Should We Do with Our Brain?, 85

Categorization

• DEFINE: Defines LTP and LTD with the aplysia habituation case as concrete evidence.