Does social isolation delay inhibition in the habenula of larval zebrafish?

The lateral habenula (LHb) is a key regulator of dopaminergic and serotonergic pathways involved in motivational and motor functions. It also plays a role in negative reward processing, and changes in LHb function have been linked to depression. During early development, the brain is highly sensitive to environmental inputs, and social interaction is important for normal development. Early-life social isolation can cause long-lasting behavioral changes and has been linked to neuropsychiatric disorders. We aim to study how social isolation during early development affects habenular function in zebrafish. Using in vivo calcium imaging in transgenic zebrafish expressing GCaMP6f, we analyzed habenular neuronal responses to audiovisual stimuli in socially raised and isolated zebrafish between 12 and 17 days old.We and others previously showed that during development habenular responses sharpen and their duration is reduced.This has been linked to a delay in projection of inhibitory vs excitatory inputs. Our results show differences in response duration between age-matched socially raised and isolated animals, with isolated animals showing a tendency toward longer-lasting responses. We are testing the hypothesis that this prolonged activity is similar to the response pattern observed in younger social animals.This could indicate that early social isolation delays the normal development of habenular function and may help explain how early social experience influences later behavior