Mechanoafferent neurons innervating tail of Aplysia. II. Modulation by sensitizing stimulation

作者：Edgar T. Walters, John H. Byrne, Thomas Carew, Eric R. Kandel · 发表于：Journal of Neurophysiology · 年份：1983 · DOI：10.1152/jn.1983.50.6.1543 · 被引用次数：195 · 研究领域：Neurobiology and Insect Physiology Research、Neural dynamics and brain function、Photoreceptor and optogenetics research

The tail-withdrawal reflex of Aplysia can be sensitized by weak stimulation of a site outside the site used to test the reflex or by repeatedly stimulating the test site itself. The sensitization of tail-withdrawal responses is associated with enhanced activation of the tail motor neurons and heterosynaptic facilitation of the monosynaptic connections between the tail sensory neurons and tail motor neurons. This synaptic facilitation can occur under conditions in which neither posttetanic potentiation nor generalized changes in postsynaptic input resistance contribute to the facilitation. In addition to producing monosynaptic excitatory postsynaptic potentials (EPSPs), action potentials in tail sensory neurons often recruit longer latency polysynaptic input to the tail motor neurons during sensitization. Strong, noxious tail shock similar in intensity to that used previously for sensitization and aversive classical conditioning of other responses in Aplysia produces more heterosynaptic facilitation than does weak sensitizing stimulation. Heterosynaptic facilitation builds up progressively with multiple trials and lasts for hours. Very strong shocks to the tail can change the response characteristics of tail sensory neurons so that a prolonged, regenerative burst of spikes is elicited by a brief intracellular depolarizing pulse. This bursting response produced by sensitizing stimulation has not been described previously in Aplysia sensory neurons and can greatly amplify the sy...