A novel developmental critical period of orexinergic signaling in the primary visual thalamus

The orexinergic system of the lateral hypothalamus plays crucial roles in arousal, feeding behaviour, and reward modulation. Most research has focused on adult rodents, overlooking orexins' potential role in the nervous system development. This study, using electrophysiological and molecular tools, highlights importance of orexinergic signalling in the postnatal development of the rodent dorsolateral geniculate nucleus (DLG), a primary visual thalamic centre. Orexin activation of DLG thalamo-cortical neurons occurs in a brief seven-day window around eye-opening, concurrent to transient OX2 receptor expression. Blocking OX(2) receptors during this period reduces sensitivity of DLG neurons to green and blue light and lowers spontaneous firing rates in adulthood. This research reveals critical and temporally confined role of orexin signalling in postnatal brain development, emphasising its contribution to experience-dependent refinement in the DLG and its long-term impact on visual function.