ABSTRACT
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.
Subject(s)
Discrimination Learning/physiology , Form Perception/physiology , Pattern Recognition, Visual/physiology , Animals , RabbitsABSTRACT
In 5 groups of rabbits (0-1, 2-3, 4-5, 6-7 and 12-13 weeks old) the left frontal, parieto-temporal and occipital cortex were removed. Beginning two weeks after the operations the hopping reaction was tested during 15 weeks. It was found in the groups operated 0-1, 2-3 and 4-5 weeks after birth, that the hopping reaction developed normally. This was not the case in the animals operated 6-7 and 12-13 weeks after birth. Brightness discrimination with the left and right eye was tested in the same animals, beginning 12 weeks after the operation. Contrary to the motor system, no age-dependent recovery was found in the visual system. In all age groups, brightness discrimination with the eye contralateral to the lesion was impaired.
Subject(s)
Aging/physiology , Cerebral Decortication , Discrimination Learning/physiology , Motor Activity/physiology , Visual Pathways/physiology , Animals , Frontal Lobe/physiology , Occipital Lobe/physiology , Parietal Lobe/physiology , Photic Stimulation , Rabbits , Visual Pathways/growth & developmentABSTRACT
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.
Subject(s)
Discrimination Learning/physiology , Dominance, Cerebral/physiology , Form Perception/physiology , Occipital Lobe/physiology , Pattern Recognition, Visual/physiology , Sensory Deprivation/physiology , Animals , Orientation/physiology , Rabbits , Visual Pathways/physiologyABSTRACT
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.
Subject(s)
Discrimination Learning/physiology , Form Perception/physiology , Functional Laterality/physiology , Pattern Recognition, Visual/physiology , Reward , Visual Cortex/physiology , Animals , Rabbits , Reaction Time/physiologyABSTRACT
After bilateral removal of the occipital lobe rabbits were studied in an enriched environment. At first their behaviour was severely impaired. After eight weeks the animals had learned to avoid obstacles, climb up ramps and jump from tables. It was shown that this recovery was due to the use of remaining visual structures. For this the pressure of an enriched environment was essential. In spite of this recovery the animals were incapable of striated pattern discrimination. Although black-white discrimination was apparently normal, the brightness threshold was found to be increased.
Subject(s)
Occipital Lobe/physiology , Psychomotor Performance/physiology , Animals , Brain Mapping , Discrimination Learning/physiology , Environment , Light , Pattern Recognition, Visual/physiology , Rabbits , Visual Perception/physiologyABSTRACT
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.
Subject(s)
Avoidance Learning/physiology , Hypoxia, Brain/physiopathology , Taste/physiology , Animals , Association Learning/physiology , Atmospheric Pressure , Drinking , Male , RatsABSTRACT
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.
Subject(s)
Discrimination Learning/physiology , Dominance, Cerebral/physiology , Form Perception/physiology , Pattern Recognition, Visual/physiology , Retina/physiology , Animals , Orientation/physiology , Rabbits , Visual Pathways/physiologyABSTRACT
Previous studies in rabbits have shown that a unilateral ablation of the occipital lobe leads to a severe impairment of the ability to discriminate striated patterns. Considerable retraining is required in order to reach the 90% correct level with the eye contralateral to the lesion. In the present study the effects of a unilateral and bilateral ablation are compared. It is concluded that the rudimentary ability to discriminate patterns with the eye contralateral to a unilateral ablation of the occipital lobe is mediated by the remaining ipsilateral cortical projection and not by subcortical structures.
