Topic: pupillary dilation

Orexin neurons originate in the lateral hypothalamus, receive many inputs, and project throughout the brain. This puts them in an ideal position to integrate large amounts of information and signal them toward desired targets. We hypothesized that arousal, which impacts a variety of internal states and behaviours, could be one of these signals that orexin neurons transmit. To test this, we investigated the causal and correlative links between orexin neurons and pupil size, which is often taken as a readout of arousal. Optogenetic stimulation, 2-photon imaging, photometry, ablation, and pharmac