Functions of the dentate gyrus

The hippocampus is known to play an important role in various types of memory both in humans and rodents. The dentate gyrus is a sub-region of the hippocampus and one of two places in the adult brain where new neurons are continuously added to existing ne tworks. The function of these adult born neurons remains an enigma. The purpose of this project is to understand the function of the dentate gyrus including the newborn neurons by studying rats. The project has started in Trondheim, Norway and collaborati ons with University of Lethbridge in Canada will be necessary to perform complementary projects to answer questions regarding functions of the dentate gyrus. Employing methods not available in Trondheim will help us understand how the dentate gyrus and th e new neurons operate. We will for example use different techniques to abolish the mature cells or the formation of new neurons and subsequently investigate recent neural activity (gene imaging) in the dentate gyrus and adjacent regions, to observe how di fferent environmental contexts affect the dentate gyrus. Gene imaging enables us to examine and quantify recent neural activity in an entire structure not possible with micro electrodes used in Trondheim. One possible outcome is that lack of new neurons w ill completely silence the dentate gyrus (cells cease to fire) indicating that the new neurons are the active cells of the dentate gyrus (the mature ones being silent or simply "retired"). The region receiving input from dentate gyrus might also be affect ed by lack of mature cells (or new neurons) in that similar input will be difficult to differentiate. One of our challenges is detecting a correlation between newborn neurons and function in an extremely silent structure as the dentate gyrus. However, by knowing more what regulates adult born cells generated from stem cells, may enable us to apply this knowledge in future therapeutic contexts, for example in regeneration of brain tissue after damage.