Interocular Transfer Of Visual Discriminations Research Articles

Completing the split in the split-brain rat: transection of the optic chiasm

We describe a stereotaxic technique to transect the optic chiasm in the rat and present illustrative data on the interocular transfer of visual discrimination in chiasm-sectioned and chiasm-plus-forebrain commissure-sectioned animals. Applications of the technique are discussed.

Effects of unilateral thalamic lesion upon interocular transfer of visual discrimination in pigeons. II: lesion in the untrained hemisphere (sensory deficits)

In a previous study, rotundal lesions in the 'trained' hemisphere caused deficits in interocular transfer of visual discrimination when the lesion was made after acquisition of the monocular learning, but not when the lesion was made before the monocular learning. In the present study, a rotundal lesion was made in the 'untrained' hemisphere before and after monocular training. The lesion caused deficits in transfer regardless of the temporal relation between the lesion and the training. Such deficits are likely to be 'sensory deficits' since visual information from the eye goes to the damaged rotundus when tested with the untrained eye. The relation between the 'sensory' versus 'mnemonic' deficits from damage to nucleus rotundus in the trained hemisphere are discussed.

Effects of unilateral thalamic lesion upon interocular transfer of visual discrimination in pigeons. I. Lesion in the trained hemisphere (memory access deficits)

Two groups of pigeons received a unilateral thalamic lesion in the hemisphere contralateral to the eye used for monocular training of a line orientation discrimination. The first group was trained monocularly on the discrimination after the lesion, and the second group received the lesion after the birds were successfully trained on the discrimination task. Then both groups were trained on the same task with their previously untrained eye to examine interocular transfer of discrimination. Lesion in the nucleus rotundus before monocular discrimination retarded acquisition of the original monocular learning but did not cause deficits in interocular transfer, whereas the rotundal lesion after the monocular discrimination learning resulted in deficits in interocular transfer. These results suggest (1) the bird could learn monocular discrimination with the hemisphere ipsilateral to the viewing eye when the contralateral hemisphere was not accessable, and (2) the bird learned monocular discrimination with the hemisphere contralateral to the viewing eye when both hemispheres were intact. Lesion in OPT did not cause deficits in interocular transfer. This result suggests a crucial role of the tecto-fugal pathway in interocular transfer.

Two distinct mechanisms mediating interocular transfer in the goldfish ( Carassius auratus)?

It is known that the postoptic commissures mediate the interocular transfer of visual discriminations in fish. Our experiments demonstrated that information relating to shape crosses in one of these commissures, the horizontal, whereas a completely separate commissure, the minor, mediates the transfer of information relating to color. Such a clear distinction provides a valuable model for the further study of interhemispheric phenomena.

Learning and interocular transfer of visual discriminations by goldfish with retinotectal compression

Visual function mediated by a compressed retinotectal projection was examined by training goldfish with unilateral retinotectal compression to perform red/green and horizontal/vertical discriminations. Fish were trained monocularly via the compressed or the normal visual field using an aversive classical conditioning model. Interocular transfer was then examined to determine if the mechanisms mediating this transfer functioned normally after retinotectal compression and to compare interpretation of visual information via normal and compressed visual fields. Both visual discriminations were learned successfully using the normal or the compressed visual field. Learning deficits (relative to controls) were, however, observed in fish trained with the color discrimination using the compressed visual field, or the horizontal/vertical discrimination using the compressed or the normal visual field. Interocular transfer of the color discrimination from the compressed to the normal visual field or in the reverse direction was demonstrated to occur at approximately normal values. Interocular transfer of the horizontal/vertical discrimination was successful from the compressed to the normal visual field, but was reduced or absent in the opposite direction. The results indicate that analysis of the colors red and green is essentially normal after retinotectal compression, and that the pathways mediating interocular transfer of this color discrimination remain functional. There were, however, abnormalities in the mechanism mediating interocular transfer of pattern discriminations after retinotectal compression.

Learning and interocular transfer of visual discriminations following bilateral ectostriatum lesions in pigeons

Learning and interocular transfer of visual discriminations following bilateral ectostriatum lesions in pigeons

Interocular transfer of visual discriminations in Wulst-ablated pigeons

Interocular transfer (IOT) of monocularly learned pattern, brightness and color discriminations was studied in normal pigeons and in pigeons with a bilateral ablation of the visual Wulst. No significant differences were found between the two groups in terms of both rate of monocular learning and degree of IOT. Pigeons with a Wulst ablation which had shown a normal capacity for IOT, subsequently lost this capacity following a section of the supra-optic decussation (DSO). It is concluded that IOT in pigeons does not require the presence of the binocular neurons of the visual Wulst, and that in absence of this structure, IOT must rely on other centers for binocular interaction which receive fibers from the DSO.

Interocular transfer of visual discriminations in goldfish after selective commissure lesions.

Goldfish with transections of the intertectal commissure learned but failed to transfer interocularly a simple visually cued avoidance task in a shuttle box, whereas posterior commissure lesions had no effect on this simple transfer task. However, fish with tectal commissure lesions could show normal interocular transfer of a shape discrimination, once discrimination pretraining with color cues had been carried out with each eye separately. Lesions of anterior commissure had no effect on either shape or color transfer, but fish with intended cuts of the postoptic commissures showed striking deficits of interocular transfer. As with comparable studies in the pigeon, it is concluded that postoptic, but not tectal, commissures are required for interocular transfer in the goldfish.

Interocular transfer of reversed and nonreversed discriminations via the anterior commissure in monkeys

The function of inferotemporal cortex in monkeys was investigated by testing for interocular transfer of visual discriminations via the anterior commissure. Good transfer was found when the stimulus rewarded during testing was the same as that rewarded during original training. Transfer was disrupted, however, when testing was carried out with the reward values reversed, which shows that the anterior commissure carries information about reward values. Interpretation in terms of two-stage theories of discrimination learning indicates that inferotemporal cortex is not concerned exclusively with selective attention.

Visual perception in cats after environmental surgery.

This report describes a series of experiments testing the behavioral significance of orientation sensitive cells in the cat's visual cortex. Cats used for this purpose were raised with one eye (VE) viewing a field of vertical lines and the other eye (HE) viewing a field of horizontal lines. This experience simplified their cortical physiology, and is thus called “environmental surgery”. Cells with elongated fields were found to be activated monocularly: those driven by the VE had vertically oriented receptive fields, while those activated by the HE had horizontally oriented fields. These animals were tested, using one eye at a time, on a series of visual discriminations: a) flux discrimination, b) tests for selective response to vertical and horizontal lines, c) discrimination between two lines differing only in orientation, d) discrimination between mirror image stimuli, and e) evaluation of inter-ocular transfer on these discriminations. The threshold tests for orientation discrimination gave the clearest results: there were small but consistent differences in performance between the VE and HE which depended on the orientation of the lines being discriminated. There was also evidence that the animals responded to different parts of a stimulus with the VE and HE. As a group, the experimental cats showed less interocular transfer of visual discriminations than the normal controls. However, surprisingly, there was also evidence for much functional equivalence between the two eyes. Possible explanations for this are considered and it is suggested that an animal's ability to make pattern discriminations is not rigidly determined by the shape and orientation of its receptive fields.

Partial interocular transfer of visual discriminations in cats.

AbstractNormally expected visual behavior in the cat, following monocular training, is a full stimulus equivalence when the second eye is used in transfer tests. This expectation has not been tested severely by using competing habits trained separately for each eye. Two groups of cats, normal and with striate cortex ablated, were tested under conditions of training in which opposing habits were used with the two eyes. Using intensity discrimination habits it was found that normal and operated cats failed to show complete interocular transfer. The normal group exhibited more transfer (greater conflict) from one eye to the other than did the operated group. It is suggested that interocular equivalence is partly dependent upon the organism's having learned to use similar kinds of visual cues with both eyes. The data also support the idea that encephalization increases binocularity and interocular equivalence.

PROJECTION OF THE RETINA ON SUPERIOR COLLICULUS OF CATS

PROJECTION OF THE RETINA ON SUPERIOR COLLICULUS OF CATS