FIGURE 2.

Timecourse illustrating visual function development in the ferret, monkey and human. A schematic illustrating the developmental timing of different visual functions reflecting relative onset and duration of maturation in different species. Eye opening in ferrets is around P30, and at birth in monkeys and humans. Cortex responds to visual stimuli as early as P20 in ferret whereas it is present at birth in both monkeys and humans. Unlike in both monkeys and humans, development of direction preference requires visual experience in the ferret. Orientation selectivity in ferret is present at the onset of visual experience by P20 and is fully mature by P45. Monkeys can detect motion direction discrimination responses as early as 3–5 weeks postnatally and these complex form cues continue to mature up to 3 years of age. In ferrets and humans, spatial frequency appears at a later stage of postnatal development, whereas, it is present at a relatively earlier timepoint of about 2 months of age in the monkey.