Abstract
Recent studies have shown that adult neurogenesis in the dentate gyrus of the hippocampus is required for the behavioral effects of antidepressant drugs in rodents and is possibly involved in the etiology of psychiatric disorders. The synapses between mossy fibers, axons of the dentate gyrus granule cells, and hippocampal CA3 pyramidal cells are characterized by prominent synaptic facilitation, an activity-dependent increase in synaptic efficacy. Changes in mossy fiber synaptic transmission, especially its activity-dependent nature, can greatly affect the operation of CA3 neural circuits. Because the magnitude of this synaptic facilitation has been shown to change during development, the generation of new neurons in the dentate gyrus may affect signal transmission mediated by mossy fibers. Abnormal projection and density of mossy fibers have been demonstrated in patients with psychiatric disorders. For these reasons, alterations in mossy fiber synaptic transmission may be involved in the pathophysiology of psychiatric disorders. The mossy fiber synapse is a potential target for developing new pharmacological treatments for psychiatric disorders.
