Interocular Transfer in Parallel Visual Pathways in Pigeons

Abstract

Pigeons were trained to perform intensity, color and pattern tasks monocularly. After their training was completed, a unilateral electrolytic lesion was made either in the nucleus rotundus or in the nucleus opticus principalis thalami (OPT). The lesion was made in the trained hemisphere (contralateral to the trained eye) in half of the subjects and in the untrained hemisphere in the other half. After a 7-day recovery period the birds were retrained on the same tasks with the previously untrained eye. A rotundal lesion, on either side, resulted in the loss of interocular transfer of discrimination, whereas neither contralateral nor ipsilateral OPT lesions affected discrimination. These results suggest that the tectofugal visual pathway plays a crucial role in the interhemispheric transfer of visual information in pigeons.

Ascending and descending mechanisms of visual lateralization in pigeons

“…As a consequence of these anatomical and functional properties of the interhemispheric commissures, the more bilateral information might then be transposed to the forebrain, giving the left hemisphere a more bilateral representation of the monocular discrimination task. As demonstrated in several bird species (Catania 1965;Ogawa 1966;Mello 1968;Meier 1971;Green 1978;Francesconi et al 1982;Remy & Watanabe 1993), interhemispheric transfer of information can only be accomplished through one of the subtelencephalic commissures, and it seems to be sensitive to lesions in the tecto-but not in the thalamofugal system (Watanabe et al 1986). More specifically, interocular transfer of pattern, brightness and colour discrimination was impaired by section of supra-optic decussation but not by the tectal commissure (Catania 1965;Cuénod & Zeier 1967;Meier 1971;Cuénod 1974;Burkhalter & Cuenod 1978).…”

Visual wulst influences on flash evoked responses in the ectostriatum of the zebra finch

“…Therefore, these studies suggest an integrative role for the cctostriatum in visual processing in the same way as our physiological recordings do. In addition, the described thalamotectofugal connectivity may contribute to visual discrimination learning and visual transfer learning [27,28]. If the visual wulst mainly facilitates ectostriatal processing, it is easy to understand that visual wulst lesions are more effective in combined thalamo-tectofugal lesion experiments.…”

Limits of intraocular and interocular transfer in pigeons

“…However, in an experiment in which the stimuli were displayed on a vertical screen above ground level, interocular transfer was not observed [1]. Two hypotheses were proposed to explain these contradictory results: the "sensorimotor integration" hypothesis [46,45] and the "retinal locus" hypothesis [23][24][25]10,26].…”

“…To test the "sensorimotor integration" hypothesis, pigeons were trained in three spatial tasks employing two pecking keys arranged either vertically or horizontally [46]. No matter whether the keys were arranged horizontally or vertically, if response key and stimulus were located in the same pecking key, there was a perfect interocular transfer of information.…”