Animal Welfare Synergy Series: Dr Tom Smulders on hippocampal neurogenesis

Adult hippocampal neurogenesis, the continuous production of new neurons in the dentate gyrus, shows bidirectional responses to experiential valence—chronic stress decreases neurogenesis while positive experiences like environmental enrichment or tickling increase it, making it a potential biomarker for assessing animal welfare states; however, recent findings suggest it may primarily reflect resilience capacity rather than direct valence, as demonstrated by the interaction between rearing history and stress response in chickens where dark brooder-reared birds showed opposite neurogenesis responses to chronic stress compared to conventionally reared birds.