Associative conditioning analog selectively increases cAMP levels of tail sensory neurons in Aplysia.

Abstract

Bilateral clusters of sensory neurons in the pleural ganglia of Aplysia contain cells involved in a defensive tail withdrawal reflex. These cells exhibit heterosynaptic facilitation in response to noxious skin stimulation that can be mimicked by the application of serotonin. Recently, it has been shown that this facilitation can be selectively amplified by the application of a classical conditioning procedure to individual sensory neurons. Here it is reported than an analog of this classical conditioning paradigm produces a selective amplification of the c[complementary]AMP content of isolated sensory neuron clusters. The enhancement is achieved within a single trial and appears to be localized to the sensory neurons. Thus, a pairing-specific enhancement of cAMP levels may be a bio-chemical mechanism for associative neuronal modifications and perhaps learning.