Recurrent mossy fibers preferentially innervate parvalbumin-immunoreactiveinterneurons in the granule cell layer of the rat dentate gyrus

Detection of vesicular zinc and immunohistochemistry against markers for di fferent interneuron subsets were combined to study the postsynaptic target selection of zinc-containing recurrent mossy fiber collaterals in the denta te gyrus. Mossy fiber collaterals in the granule cell layer selectively inn ervated parvalbumin-containing cells, with numerous contacts per cell, wher eas the granule cells were avoided. Under the electron microscope, those bo utons made asymmetrical contacts on dendrites and somata. These findings su ggest that, in addition to the hilar perforant path-associated (HIPP) inter neurons, the basket and chandelier cells also receive a powerful feed-back drive from the granule cells, and thereby are able to control population sy nchrony in the dentate gyrus. On the other hand, the amount of monosynaptic excitatory feed-back among granule cells is shown to be negligible. NeuroR eport 11:3219-3225 (C) 2000 Lippincott Williams & Wilkins.