Early Selective Visual Experience and Pattern Discrimination in Hooded Rats JAMES G. CORRIGAN DAVID L. CARPENTER Department of Psychology St. Bonaventure University St. Bonaventure, New York The early visual experience of hooded rats was restricted to either vertical or horizontal stripes. In a discrimination task pairing a gray surface and stripes of either the same orientation or an orientation orthogonal to that experienced during rearing, the rats made significantly fewer correct choices with the orthogonal orientation. However, the relatively lower overall performance of the vertically reared-horizontally tested animals was a major factor in the main effect of testing condition. We conclude that functional modification of the rat visual system through early selective visual experience is possible.
Studies involving restriction of the early visual experience of kittens to patterned stimulation of 1 orientation (either horizontal or vertical) followed by testing with patterns of the orthogonal orientation, have demonstrated physiological and behavioral modifications (Blakemore & Cooper, 1970; Blakemore & Mitchell, 1973; Hirsch & Spinelli, 1970; Muir & Mitchell, 1973). The physiological modifications have been a lack of orientation-specific cortical cells with receptive fields for the orthogonal orientation, whereas the behavioral modifications have ranged from acuity deficits to apparent blindness for the orthogonal Orientation. Freeman and Thibos (1 973) have suggested that the reduced acuity of human astigmats for orientations which were blurred prior t o correction is the result of a process similar to that observed with the cat. Generalization to the visual systems of other mammalian species, however, needs empirical support. In addition to the lack of evidence in support of generalizability, Mize and Murphy (1973), using the rabbit, failed to produce the type of physiological alterations observed in the cat, and Stryker and Sherk (1975) have questioned the conditions required to produce the physiological changes in the cat. We used the hooded rat in a test of the generalizability of the specific behavioral modifications that have been observed as a consequence of early selective visual experience. The rat visual system has the capacity for discrimination on the basis of orientation (DodweLl & Nienii, 1967; Jander & Quadagno, 1974; Lashley, 1938) and, also, has some sensitivity to environmental manipulation (Tees, 1968, 1974). In
Reprint requests should be sent t o James G. Corrigan, Research Department, E. R. Johnstone Training and Research Center, Bordentown, New Jersey 08505, U.S.A. Received for publication 5 April 1977 Revised for publication 26 September 1977 Developmental Psychobiology, 12(1): 67-72 (1979) 0 1 9 7 9 by John Wiley & Sons, Inc.
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addition, orientation-specific cells, siinilar to those observed in the cat, have been found in the rat visual cortex (Shaw, Yinon, & Auerbach, 1975; Wiesenfeld & Kornel, 1975). Our manipulation of selective experience and subsequent discrimination testing were similar to those used by Muir and Mitchell (1973) with the cat: following early experience with stimuli of 1 orientation (horizontal or vertical), the rats were tested for ability to discriminate between contours identical to or orthogonal to those previously experienced and a gray surface of the same mean luminance.
Method Subjects Sixteen hooded Long-Evans rats (Rattus nowegicus), 7 males and 9 females, were used. Litters were housed in separate wire mesh cages. After weaning a t 33 days of age, all rats were housed individually.
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Studies involving restriction of the early visual experience of kittens to patterned stimulation of 1 orientation (either horizontal or vertical) followed by testing with patterns of the orthogonal orientation, have demonstrated physiological and behavioral modifications (Blakemore & Cooper, 1970; Blakemore & Mitchell, 1973; Hirsch & Spinelli, 1970; Muir & Mitchell, 1973). The physiological modifications have been a lack of orientation-specific cortical cells with receptive fields for the orthogonal orientation, whereas the behavioral modifications have ranged from acuity deficits to apparent blindness for the orthogonal Orientation. Freeman and Thibos (1 973) have suggested that the reduced acuity of human astigmats for orientations which were blurred prior t o correction is the result of a process similar to that observed with the cat. Generalization to the visual systems of other mammalian species, however, needs empirical support. In addition to the lack of evidence in support of generalizability, Mize and Murphy (1973), using the rabbit, failed to produce the type of physiological alterations observed in the cat, and Stryker and Sherk (1975) have questioned the conditions required to produce the physiological changes in the cat. We used the hooded rat in a test of the generalizability of the specific behavioral modifications that have been observed as a consequence of early selective visual experience. The rat visual system has the capacity for discrimination on the basis of orientation (DodweLl & Nienii, 1967; Jander & Quadagno, 1974; Lashley, 1938) and, also, has some sensitivity to environmental manipulation (Tees, 1968, 1974). In
Reprint requests should be sent t o James G. Corrigan, Research Department, E. R. Johnstone Training and Research Center, Bordentown, New Jersey 08505, U.S.A. Received for publication 5 April 1977 Revised for publication 26 September 1977 Developmental Psychobiology, 12(1): 67-72 (1979) 0 1 9 7 9 by John Wiley & Sons, Inc.
00 12-163O/79/0012-0067$01 .OO
68
CORRIGAN AND CARPENTER
addition, orientation-specific cells, siinilar to those observed in the cat, have been found in the rat visual cortex (Shaw, Yinon, & Auerbach, 1975; Wiesenfeld & Kornel, 1975). Our manipulation of selective experience and subsequent discrimination testing were similar to those used by Muir and Mitchell (1973) with the cat: following early experience with stimuli of 1 orientation (horizontal or vertical), the rats were tested for ability to discriminate between contours identical to or orthogonal to those previously experienced and a gray surface of the same mean luminance.
Method Subjects Sixteen hooded Long-Evans rats (Rattus nowegicus), 7 males and 9 females, were used. Litters were housed in separate wire mesh cages. After weaning a t 33 days of age, all rats were housed individually.
A ppar a t 11s I
