Abstract
The ferret is one of the primary animal models for studying the development of visual cortex. Indeed, ferrets do not open their eyes until around postnatal day 32; thus the development of ferret visual cortex before and after eye-opening is accessible to experimental investigation and manipulation. Yet, despite the significance of the ferret model for visual development research, relatively little is known about the adult ferret’s behavioral visual capabilities. Here, we used two-alternative forced-choice psychophysical tasks to evaluate the ferret’s visual acuity, motion perception, and form perception. Visual acuity was assessed by determining contrast sensitivities for detection and orientation discrimination tasks at different spatial frequencies. Additionally, just-noticeable-differences were measured for fine orientation discriminations about vertical and oblique reference orientations. Form integration was evaluated based on discriminations between horizontal and vertical Glass patterns at different coherence levels, and similarly, motion integration was evaluated with random-dot kinematograms at different coherence levels. Ferrets performed above 90% on the easiest condition on all tasks, and psychometric curves were fit to their performance with high fidelity. To complement our psychophysical assessment of motion integration, we performed anesthetized extracellular recordings from neurons in PSS, a higher-order visual area that has been shown to be involved in motion processing in the ferret, and used this data to estimate neurometric motion coherence thresholds. We found that our psychometric motion integration threshold estimates agreed well with the constraints suggested by our neurometric threshold estimates. Taken together, this work provides a comprehensive characterization of visual psychophysics in the adult ferret. Hence, this work broadens the possibilities for future visual development research, as investigators could study both how these visual capabilities develop normally, as well as the impact of manipulations during development on any of these visual capabilities.