Binaral Rivalry in the Presence of Visual Perceptual and Semantic Influences

When two different odorants are presented simultaneously to the two nostrils, we experience alternations in olfactory percepts, a phenomenon called binaral rivalry. Little is known about the nature of such alternations. Here we investigate this issue by subjecting unstable and stable olfactory percepts to the influences of visual perceptual or semantic cues as participants engage in simultaneous samplings of either two different odorants (binaral) or a single odorant and water (mononaral), one to each nostril. We show that alternations of olfactory percepts in the binaral setting persist in the presence of visual perceptual and semantic modulations. We also show that perceptual cues have a stronger effect than semantic cues in the binaral case, whereas their effects are comparable in the mononaral setting. Our findings provide evidence that an inherent, stimulus-driven process underlies binaral rivalry despite its general susceptibility to top-down influences

Melanopsin (Opn4) Requirement for Normal Light-Induced Circadian Phase Shifting

like the latter two groups, mammals lack functional extraocular photoreceptors (28); thus, redundancy in photoreception is confined to the retina. One challenge is to determine the relative contributions of melanopsin, rod/cone opsins, cryptochromes, and other currently uncharacterized photopigments in communicating photic information to the circadian system. Fluorescent lights (Philips F32T8/TL741 Hi-Vision, 4100 K) were used both for light pulses and for overhead lighting in the activity recording room. Light intensity on the cage floor ranged from 20 to 60 W⅐cm Ϫ2 or 70 to 280 lux for light pulses and from 10 to 30 W⅐cm Ϫ2 or 30 to 120 lux for LD and LL conditions, depending on the location of the sensor in the cage. Light was measured in both radiometric (International Light, model IL-1405 Radiometer System) and photometric (Iso-Tech, ILM 350) units of measure to facilitate comparison between traditional photoreception and circadian studies. Mice used for in situ hybridization were sacrificed at the end of the light or dark pulse and their brains were frozen on dry ice. In situ experiments were performed as described in (16). Small sample sizes precluded statistical evaluation of c-fos levels