The development of spatial-frequency selectivity in kitten striate cortex.

1. Single units were recorded in the striate cortex of kittens aged between 2 and 12 weeks. Contrast sensitivity measurements made using moving sinusoidal gratings were used to construct spatial-frequency tuning curves. 2. In young kittens cells had low sensitivities, responded only to low spatial frequencies and were unselective for spatial frequency. In addition 30% of the cells recorded in the youngest kittens were unresponsive to visual stimuli. 3. Sensitivity improved to near-adult values within 5-6 weeks. 4. Best spatial frequency improved more gradually, so that even in the oldest kittens best spatial frequencies were lower than adult values. 5. Selectivity for spatial frequency, considered both in terms of the numbers of selective cells and the narrowness of their tuning curves, improved rapidly, and reached adult values within the first 6 weeks. 6. These results are discussed in relation to other developmental studies.