Effect of whisker removal on defensive behavior in rats during early ontogenesis.

The effects of restriction of sensory afferentation in rats by vibrissectomy performed daily on days 9 to 20 of life on the formation of defensive reactions in early postnatal ontogenesis were studied. Vibrissectomized and control rat pups were assessed in terms of the extent of motor defensive reactions in response to touching the skin from days 10 to 18 of life, the duration of the freezing reaction at age 20 days, and behavior in the open field at age 25 days. Vibrissectomized rat pups showed the following significant differences from controls: a decrease in the extent of early withdrawal from a potentially dangerous stimulus (at age 12 and 13 days), a decrease in the duration of the freezing reaction, and decreases in that extents of the flight reaction and emotional reactivity in the open field test.