Localization of the "visual memory system" in the white rat.

Position reversal learning as affected by occipital, posterior thalamic, and rubral lesions in the white rat

“…Several lesion studies dealing with the performance of visual discrimination tasks in the white rat (Thompson & Massopust, 1960;Thompson, 1963Thompson, , 1969 have discIosed that only three general areas of the brain are crucial for normal retention. These areas, which presumably make up the core of a "visual memory system," include the occipital cortex, posterior diencephalon, and ventromedial mesencephalon.…”

Nucleus cunieformis lesions: Amnestic effects on visual pattern discrimination in the rat

“…It must also be noted that lesions dorsal (Group DNC) or posterior (Group PNC) to the critical region did not produce a significant deficit on Problem HV. The finding that the integrity of the ventral half of the midbrain as opposed to the dorsal half is considerably more important for the execution of discriminative responses to visual cues has been reported in several previous studies (McNew, 1968;Thompson, 1963Thompson, ,1969; Thompson & Massopust, 1960). …”

“…"Significant run" errors referred to the number of errors committed prior to the ftrst attainment of a series of correct responses that had a probability of occurrence of less than .05 (see Thompson, 1969). From these data, two error savings scores were determined : a criterion run savings score and a significant run savings score.…”

“…Details of the apparatus and preliminary training procedures have been presented elsewhere (Thompson, 1969),…”

“…Since rats readily survive extensive unilateral damage to the NC, it was decided to construct an experimental design that would utilize this capability. The design that was finally settled upon was based on the neuropsychological findings that bilaterally occipitalectomized rats , while being able to relearn a white-black (brightness) discrimination problem, cannot relearn a horizontal-vertical (pattern) discrimination problem (Horel, Bettinger, Royce, & Meyer, 1966;Lashley, 1950;Thompson, 1969) and upon the neuroanatomical findings that the occipitoreticular pathway described by Valverde is largely homolateral. If the occipitoreticular pathway is indeed critical for the performance of visual discrimination habits in the rat, then it would follow that rats trained on a brightness habit and a pattern habit with only the right occipital cortex intact would show considerable retardation in relearning the pattern habit after damage to the right NC, but would have little difficulty relearning the pattern habit after damage to the left NC.…”