Színérzékeny thalamikus idegsejtek jellemzése macskában

Abstract

The domestic cat (Felis catus) is a classic animal model in visual neuroscience. Hence, we know a lot about the anatomical and functional features of its visual system. However, even if the investigation of the cat colour vision has an about 50-year-long history, we can find controversial reports in the literature, and the central mechanism lying behind colour distinction has not been cleared yet. Cats are known as animals having excellent nocturnal vision, but their retina is adapted to daylight conditions as well: in addition to rods, they also have cones, and their retina contains an area (so called area centralis) similar to the primate fovea, where the cones are abundant (25-30.000 cones/mm2, Linberg & al., 2001). These characteristics make this species suitable for further examinations to obtain deeper insight to the dichromatic colour vision of subprimate animals. Thus, we can expand our knowledge on the evolution of the primate trichromatic colour vision. Primary goal of the experiments present in this study were to find and characterise neurones as fully as possible in the cat thalamus, that play a role in colour vision. Some of the early cat experiments failed to show the capability of colour vision (Ducker, 1964) supporting a vulgar error that cats can not discriminate colours. In fact, it has been known for a long time that there are two cone types in the cat retina (Ahnelt & Kolb, 2000; Szél & al., 2000): the S-cones (sensitive in the shorter wavelength range, absorption peak 450 nm, Guenther & Zrenner, 1993) and ML-cones (preferring the medium/long wavelengths, absorption peak 553, Yokoyama & Radlwimmer, 1999) allow dichromatic colour vision (Loop & Bruce, 1978; Loop & al., 1987; Jacobs & al., 2001; van Arsdel & Loop, 2004; Van Hooser & Nelson, 2006).