INTRODUCTION: Twice a day, at dawn and dusk, animals experience considerable changes in the amount and spectral composition of light. Interestingly, both of them, so irradiance as well as colour, contribute to photoentrainment and are used by rodents to encode the time of the day. The olivary pretectal nucleus (OPN) is a retinorecipient midbrain structure responsible for pupillary light reflex and is suggested to play a role in photoentrainment. AIM(S): The aim of the study was to investigate whether cutting off the short wavelengths of light resulting in color changes influences light‑induced neuronal activity in the rat OPN. METHOD(S): To address this issue multielectrode in vivo recordings from the OPN of urethane anesthetized Long Evans rats were performed. Recordings were combined with light stimulations of different irradiance and spectral composition: full light spectrum provided by xenon lamp (“white light”) vs. blockade of blue light by yellow filter (“yellow light”; cut off at 490 nm). RESULTS: Both light stimulations induced a robust increase in multiunit activity across the pretectum area, with three differenttypes of neuronalresponses clearly seen:sustained, transient ON and OFF. Interestingly, sustained cells were able to encode light intensities independently of yellow filter usage. However, their mean activity during light pulses decreased in yellow light across all irradiances. CONCLUSIONS: To our knowledge this is the first study showing that spectral composition of light matters not only for the suprachiasmatic nucleus where the main biological clock is localised, but also for other structures of the non-image forming visual system. FINANCIAL SUPPORT: Supported by the grant 2013/08/W/NZ3/00700 obtained from the National Science Centre in Poland.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.