Fig. 3.

Similarity of initial signals for induction of long-term neuronal plasticity in molluscan and mammalian nociceptors (left side) and mammalian neurons that form memories within the CNS (right side). In each case local signals include intense depolarization of an injured segment or synaptic region (darkened areas), Ca²⁺ influx, and modulation by various neuroactive substances released from nearby cells. In addition, global signals released during injury or memorable events can influence the soma and other parts of the neuron, at least in part by regulating gene transcription. These initiating events for nociceptive sensitization and memory are mediated by common sets of highly conserved intracellular signals (see text).