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

VERONICA C PIATTI; MARIELA F TRINCHERO; LUCAS A MONGIAT; ALEJANDRO F SCHINDER

San Diego, California, USA

Congreso; Society for Neurosciences- 40th Annual Meeting; 2010

Society for Neurosciences

New neurons continuously develop in the adult hippocampus to become dentate granule neurons that integrate and become functional before reaching complete maturity.  Interestingly, the different steps involved in adult neurogenesis can be regulated by physiological and environmental factors.  We investigated whether the marked anatomical and functional segregation along the dorso-ventral axis of the hippocampus impinge on the development of adult-born neurons.   First, we studied the level of basal activity in the granule cell layer of adult mice by using Arc immunofluorescence, which evidenced a higher level of neuronal activity in the dorsal than the ventral dentate gyrus.  We labeled newborn neurons using a retrovirus expressing GFP and analyzed their morphology, expression of neuronal markers and electrophysiological profile at different ages.  These analyses showed that neurons born in the dorsal region mature faster than those born in the ventral area.   Moreover, voluntary exercise was used as a behavioral tool to increase hippocampal activity and rendered a significant and specific increase of Arc expression in the granule cell layer of the ventral dentate gyrus.  Running accelerated maturation of new neurons born in the ventral but not in the dorsal dentate gyrus.   Therefore, our results demonstrate an activity-dependent timing of neuronal maturation that may further expand the degree of plasticity of the adult hippocampal network.   We propose that the dorsal and ventral dentate gyrus may have different time scales for encoding incoming stimuli that are shaped by the timing of neuronal maturation which is, in turn, modified by animal behavior.