In vivo imaging of adult human hippocampal neurogenesis: progress, pitfalls and promise

Abstract

New neurons are produced within the hippocampus of the mammalian brain throughout life. Evidence from animal studies has suggested that the function of these adult-born neurons is linked to cognition and emotion. Until we are able to detect and measure levels of adult neurogenesis in living human brains—a formidable challenge for now—we cannot establish its functional importance in human health, disease and new treatment development. Current non-invasive neuroimaging modalities can provide live snapshots of the brain’s structure, chemistry, activity and connectivity. This review explores whether existing macroscopic imaging methods can be used to understand the microscopic dynamics of adult hippocampal neurogenesis in living individuals. We discuss recent studies that have found correlations between neuroimaging measures of human hippocampal biology and levels of pro- or anti-neurogenic stimuli, weigh whether these correlations reflect changes in adult neurogenesis, detail the conceptual and technical limitations of these studies and elaborate on what will be needed to validate in vivo neuroimaging measures of adult neurogenesis for future investigations.

Adult Neurogenesis in Humans

“…Such parameters include enriched environment and learning, physical activity, aging, stress, depression, and antidepressant treatments. Correlations of these parameters to changes in hippocampal volume have been reported, leading investigators to suggest that a decrease/increase in hippocampal volume relates to changes in hippocampal neurogenesis (for a review on hippocampal volume and major depressive disorder [MDD], see McKinnon et al [2009]; for a comprehensive review of in vivo imaging of adult human hippocampal neurogenesis, the reader is referred to Ho et al [2013]). Definitive studies, however, that link imaging outcome measures to adult neurogenesis are yet to be established.…”

Untitled

“…U novije vrijeme istraživanja su usmjerena u pravcu razvoja metoda mjerenja razine neurogenetske aktivnosti u ljudskom mozgu in vivo, npr. koristeći neinvazivnu magnetsku rezonanciju 17 . Istraživanja u čovjeka pokazuju razlike u intenzitetu stvaranja novih neurona u germinativnim regijama mozga u usporedbi s drugim sisavcima.…”

Adult neurogenesis: mechanisms and functional significance

“…To overcome this apparent gap between animal and human studies, a number of groups currently aim to develop novel methods to measure levels of neurogenesis in the human brain, for example by using non-invasive magnetic resonance imaging (Ho et al, 2013).…”