Mossy Fiber Sprouting in the Dentate Gyrus

Excerpt

Aberrant sprouting of granule cell axons (mossy fibers) into the inner molecular layer of the dentate gyrus was first described nearly 40 years ago in lesion studies designed to evaluate reactive synaptogenesis. Later, mossy fiber sprouting was discovered in patients with temporal lobe epilepsy. The cause/effect relationship between mossy fiber sprouting and epileptogenesis is unclear and controversial. Some propose it creates a positive-feedback seizure-generating circuit. Others argue that sprouted mossy fibers preferentially excite inhibitory interneurons, thereby controlling seizure activity. This chapter reviews the literature on mossy fiber sprouting with respect to the following questions: Under what circumstances does it occur? How does it develop? And, what are the functional consequences?