The contribution of sensory experience to the maturation of orientation selectivity in ferret visual cortex

Sensory experience begins when neural circuits in the cerebral cortex are s till immature; however, the contribution of experience to cortical maturati on remains unclear. In the visual cortex, the selectivity of neurons for or iented stimuli at the time of eye opening is poor(1-5) and increases dramat ically after the onset of visual experience(3-8). Here we investigate wheth er visual experience has a significant role in the maturation of orientatio n selectivity and underlying cortical circuits(9-12) using two forms of dep rivation: dark rearing, which completely eliminates experience, and binocul ar lid suture, which alters the pattern of sensory driven activity(13). Ori entation maps were present in dark-reared ferrets, but fully mature levels of tuning were never attained. In contrast, only rudimentary levels of orie ntation selectivity were observed in lid-sutured ferrets. Despite these dif ferences, horizontal connections in both groups were less extensive and les s clustered than normal, suggesting that long-range cortical processing is not essential for the expression of orientation selectivity, but may be nee ded for the full maturation of tuning. Thus, experience is beneficial or hi ghly detrimental to cortical maturation, depending on the pattern of sensor y driven activity.