title: Adult-born hippocampal neurons are more numerous, faster maturing, and more involved in behavior in rats than in mice.
abstract: Neurons are born throughout adulthood in the hippocampus and show enhanced plasticity compared with mature neurons. However, there are conflicting reports on whether or not young neurons contribute to performance in behavioral tasks, and there is no clear relationship between the timing of maturation of young neurons and the duration of neurogenesis reduction in studies showing behavioral deficits. We asked whether these discrepancies could reflect differences in the properties of young neurons in mice and rats. We report that young neurons in adult rats show a mature neuronal marker profile and activity-induced immediate early gene expression 1-2 weeks earlier than those in mice. They are also twice as likely to escape cell death, and are 10 times more likely to be recruited into learning circuits. This comparison holds true in two different strains of mice, both of which show high rates of neurogenesis relative to other background strains. Differences in adult neurogenesis are not limited to the hippocampus, as the density of new neocortical neurons was 5 times greater in rats than in mice. Finally, in a test of function, we find that the contribution of young neurons to fear memory is much greater in rats than in mice. These results reveal substantial differences in new neuron plasticity and function between these two commonly studied rodent species.
authors.affiliation: Unit on Neuroplasticity, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA. snyderjason@mail.nih.gov
authors.forename: Jason S
authors.initials: JS
authors.lastname: Snyder
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Choe
authors.forename: Meredith A
authors.initials: MA
authors.lastname: Clifford
authors.forename: Sara I
authors.initials: SI
authors.lastname: Jeurling
authors.forename: Patrick
authors.initials: P
authors.lastname: Hurley
authors.forename: Ashly
authors.initials: A
authors.lastname: Brown
authors.forename: J Frances
authors.initials: JF
authors.lastname: Kamhi
authors.forename: Heather A
authors.initials: HA
authors.lastname: Cameron
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D055495:Neurogenesis / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity