Through the lens of adult neurogenesis, our overarching question is how the brain stores information and uses it to guide future behavior.
Just like all the other parts of your body, your brain is capable of producing new cells throughout life. However, unlike all the other parts of your body, adding new cells to the brain is not such a trivial task. If you cut yourself, new skin cells are grown and laid out to replace what has been lost. The cells are all the same, and they just have to fill in the hole. In the brain, each cell forms very specific connections with other cells, through a complex interplay between developmental programming and experience. This precise connectivity is the basis of memory, it determines behavioral outputs, and underlies, well, everything we think and do! What is the impact of adding new neurons and new connections to an experienced and finely-tuned brain? This is the major question we aim to address and there are many angles. For example…
What is the behavioral function of new neurons?
Behavior is the ultimate functional readout and at this point we still know very little about what adult-born neurons are doing. Do they function just as older neurons? Or do they have a distinct function? Currently, we are blocking adult neurogenesis in transgenic rats and examining how behavior is altered. We are investigating the role of neurogenesis in both the memory and mood related functions of the hippocampus, including the possibility that memory-related functions may be dependent on emotional factors such as stress.
Do adult-born neurons have properties that may give them unique or enhanced functions in the brain?
Inhibiting adult neurogenesis can lead to behavioral changes but, inconveniently, it doesn’t always change behavior. It is possible that a loss of function is masked by compensatory effects of other neurons. One way around the compensation problem is to acutely silence new neurons at the time of testing, for example with optogenetics or pharmacogenetics. However, to date, enhanced plasticity and distinct physiological properties are some of the best evidence suggesting new neurons might have a unique and powerful function in the brain. We are therefore interested in how experience alters the structure and function of adult-born vs. developmentally-born neurons.
Are there enough new neurons to make a difference?
An uncomfortable truth is that neurogenesis declines substantially with age and so it is unclear whether new neurons continue to play a significant role throughout the entire adult life. On the other hand, over 1000 new neurons per day, every day, in humans may have a powerful effect. We are therefore investigating the cumulative impact of neurogenesis and relationships between the large number of neurons that are born during early development and adulthood. We believe that characterizing both of these populations is necessary to understand the function of the dentate gyrus as a whole.