Adult-born granule cells (ABGCs) are involved in certain forms of hippocampus-dependent
learning and memory. It has been proposed that young but functionally integrated ABGCs
(4-weeks-old) specifically contribute to pattern separation functions of the dentate
gyrus due to their heightened excitability, whereas old ABGCs (>8-weeks-old) lose
these capabilities. Measuring multiple cellular and integrative characteristics of
3-10 weeks old individual ABGCs, we show that ABGCs consist of two functionally distinguishable
populations showing highly distinct input integration properties (one group being
highly sensitive to narrow input intensity ranges while the other group linearly reports
input strength) that are largely independent of the cellular age and maturation stage,
suggesting that 'classmate' cells (born during the same period) can contribute to
the network with fundamentally different functions. Thus, ABGCs provide two temporally
overlapping but functionally distinct neuronal cell populations, adding a novel level
of complexity to our understanding of how life-long neurogenesis contributes to adult
brain function.
