Daniela Musumeci

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.

Binocular interactions measured by choice reaction times in pigeons

In 7 pigeons binocular interactions were studied by recording monocular and binocular choice reaction times (RTs) to a pattern discrimination task. In all the animals binocular responses were found to be significantly faster than monocular RTs. In order to assess whether binocular advantage might be ascribed to a neural interaction between the two eyes, monocular and binocular performances were evaluated according to a probability summation model. The results indicate that in the great majority of animals, probability summation alone can account for binocular superiority.

Apparatus for quantitative evaluation of visually guided pecking in the pigeon.

An apparatus using a phase-locked loop is described which allows automated, differential counts of correct and incorrectly oriented pecks, elicited by apomorphine in the pigeon. This apparatus provides a unique and precise means for the study of this characteristic, visually guided behavior.

An automated apparatus for the study of visual discriminations in pigeons

A fully automated apparatus for the study of visual discriminations in pigeons is described. The apparatus allows the presentation of a single stimulus for successive discriminations and of two or more stimuli at the same time for simultaneous discriminations. It has proven advantageous for comparing successive and simultaneous discriminations in tests of interocular transfer.

Visuomotor Coordination in Behaviour of Pigeons Following Post-Hatching Monocular Experience: An Image Analysis Study

We investigated the role of visual binocular inputs during the development on visuo-motor coordination in conditioned key-pecking responses to differently sized spots. Five groups of pigeons were used: monocular control group; two early groups (retinal ablated -ERA-, and eyeball enucleated -EEE) operated in two days post-hatching; two late groups (adult pigeons, retinal ablated — LRA-, and eyeball enucleated -LEE). The most substantial results occurred in early groups: the impairment of visual performance at small size spot, the loss of bill gape/spot size coordination and the permanent inaccurate reaching trajectory, particularly in the EEE group. On the contrary, late groups did not show any significant difference compared with the control group. The present data indicate that binocular interactions are crucial during the development of the visual system and, in addition, prove the differential role played by retinal and extraretinal inputs on the development of the visuomotor coordination. Once the maturation stage is accomplished (late groups) the eyes can work independently one from the other in conditioned key-pecking responses.