RESUMO
Steady-state critical flicker-fusion frequencies (CFFs) were determined for four beagle dogs using the psychophysical technique of conditioned suppression. The CFFs obtained demonstrated that the dog can discriminate flicker at much faster rates than has been suggested by ERG data. In addition, dog rods may support the discrimination of flicker at much higher rates than can human rods. An indication of a psychophysical rod-cone break occurred at a luminance level intermediate to those previously reported in ERG CFF studies. This level is similar to that in the cat, but much higher than that in man. The high CFFs provide the first psychophysical evidence of a well-developed functioning cone system in the dog.
Assuntos
Comportamento Animal/fisiologia , Condicionamento Psicológico , Fusão Flicker/fisiologia , Animais , Limiar Diferencial , Cães , Estudos de Avaliação como Assunto , Feminino , Masculino , Métodos , Estimulação Luminosa , Psicofísica , Percepção Visual/fisiologiaRESUMO
The effect of light-induced retinal damage on the behaving rat's critical flicker-fusion frequency (CFF) was studied by determining the CFF at scotopic and photopic luminances both before and after exposure to damaging light. The CFF was reduced but not abolished following damaging light exposure. The shapes of the functions relating CFF to luminance before and after exposure suggested that scotopic visual function may have survived the light damage better than did photopic function. Anatomical and biochemical measures of retinal damage indicated that 91-93% of the outer nuclear layer (ONL) and 99% of the rodopsin had been lost.
Assuntos
Fusão Flicker/fisiologia , Retina/fisiologia , Privação Sensorial/fisiologia , Animais , Masculino , Nervo Óptico/fisiologia , Células Fotorreceptoras/fisiologia , Psicofísica , Ratos , Rodopsina/metabolismo , Limiar SensorialRESUMO
In order to provide some detailed information on the feeding behavior of freely-feeding dogs, four adult beagles were maintained in an isolated outdoor environment where food and water were freely available. Observations across an 8-month period indicated that the dogs are episodically (in "meals") and that the total daily intake of food and water changed as the observation period progressed, most likely as a consequence of change in the ambient environmental conditions across seasons. Within-day changes in ambient temperature, and the timing of daily maintenance activities in the animal's runs influenced the temporal distribution of meals with the day.
