The inhibition of somatosensory inputs prevents pups from finding nipples. (A) The experimental procedure. After ION section was performed, pups were separated from their mothers for 21 hours, and then nipple attachment latencies were examined. (B and C) The percentage of pups that were able to attach to a nipple within 180 sec. ION-sectioning at P7 and P10 resulted in pups being unable to find and attach to nipples within 180 sec, while sham-operation did not apparently affect suckling behavior.