Memory of fearful events: the role of fibroblast growth factor-2 in fear acquisition and extinction.

Research during the past decade has led to a tremendous growth in our understanding of how fear memories are acquired and subsequently inhibited on a neural and molecular level. Such research has contributed to significant developments in the treatment of anxiety disorders, and has considerably advanced our understanding of the neurobiology of learning and memory in general. A number of recent studies have examined the role of growth factors in the formation of long-term memory for fearful events, due to their ability to cause morphological neural changes in response to environmental stimulation. In this review we first describe physiological evidence that fibroblast growth factor-2 (FGF2) receptors are highly expressed in the neural circuitry regulating fear acquisition and extinction, and that FGF2 modulates the molecular signals known to be involved in the formation of fear memories. Then we present emerging behavioral research that demonstrates that exogenous FGF2 can enhance the formation of fear conditioning and extinction memories. Finally, we briefly discuss how research into the role of FGF2 in learning and memory may be of clinical benefit, particularly in the treatment of anxiety disorders.