Biomedical subjects
Publications and source records attributed to W H de Vos-Korthals.
The possible effect of overtraining on interocular transfer of striated pattern discrimination was studied in Chinchilla rabbits. Over-training did not improve the low level of interocular transfer generally found in rabbits.
In the rabbit, unilateral ablation of the occipital lobe leads to a severe impairment of striated pattern discrimination with the eye contralateral to the lesion. In the present report it is studied whether the acute reduction of the overall visual field, due to closure of the eye contralateral to the intact hemisphere shortly before each testing session, leads to results which underestimate the animal's capability to discriminate striated patterns via the ipsilateral fibres. The experiment described in the present report suggests that this is not the case and that there is a genuine visual discrimination deficit after unilateral ablation of the visual cortex.
Rats had access to water for 15 min per day. After an adaptation period of 14 days the animals were given water and apple juice on alternate days. In half of the animals the first presentation of apple juice was followed by a 15-min period of hypobaric hypoxia. Taste neophobia was found in both groups of animals. In the animals which were not made hypoxic considerable attenuation of this neophobia was seen during the second presentation. In the animals which were made hypoxic after the first presentation of apple juice, apple juice intake was significantly reduced during the following presentations.
Interocular transfer of mirror image striation discrimination was studied in rabbits in such a way that uninterrupted series of monocular trials were avoided. It was found that the results were not different from those obtained in a previous study in which one eye was occluded by a textile mask. It was concluded that the low level of interocular transfer was not due to position habit developed during prolonged monocular training.
The contribution of the rewarded and unrewarded stimulus in two-choice pattern discrimination after a unilateral ablation of the occipital lobe was studied in 14 rabbits. With the eye contralateral to the intact hemisphere the correct decision is mainly based on avoidance of the unrewarded stimulus. The results with the eye contralateral to the lesion suggest that both the unrewarded and rewarded stimulus play a role in the decision.