Network activity determines dorso-ventral differences in neuronal maturation in the adult hippocampus

PIATTI VC; TRINCHERO MF; MONGIAT LA; SCHINDER AF

Congreso; Society for Neuroscience Annual Meeting; 2010

Newneurons continuously develop in the adult hippocampus to become dentate granuleneurons that integrate and become functional before reaching complete maturity.Interestingly, the different steps involved in adult neurogenesis can beregulated by physiological and environmental factors. We investigated whetherthe marked anatomical and functional segregation along the dorso-ventral axisof the hippocampus impinge on the development of adult-born neurons. First, westudied the level of basal activity in the granule cell layer of adult mice byusing Arc immunofluorescence, which evidenced a higher level of neuronalactivity in the dorsal than the ventral dentate gyrus. We labeled newbornneurons using a retrovirus expressing GFP and analyzed their morphology,expression of neuronal markers and electrophysiological profile at differentages. These analyses showed that neurons born in the dorsal region maturefaster than those born at the ventral area. In addition, voluntary exercise wasused as a behavioral tool to increase hippocampal activity and rendered asignificant and specific increase of Arc expression in the granule cell layerof the ventral dentate gyrus. Interestingly, running accelerated maturation ofnew neurons born in the ventral but not in the dorsal dentate gyrus. Therefore,our results demonstrate an activity-dependent timing of neuronal maturationthat may further expand the degree of plasticity of the adult hippocampalnetwork. We propose that the dorsal and ventral dentate gyrus may have differenttime scales for encoding incoming stimuli that are shaped by the timing ofneuronal maturation which is, in turn, modified by animal behavior.