Binocularly driven neurons in the rostral part of the frog optic tectum

Summary Receptive field (RF) properties of binocular neurons lying in the rostral part of the optic tectum of the frog (Rana esculenta) were studied electrophysiologically using conventional visual stimuli. They were classified into five groups: group 1 neurons have indefinite RF; group 2 neurons are total-field (T6) neurons; group 3 neurons have RFs covering a quadrant of the frontal visual field; group 4 neurons resemble T 1(1) and T 1(3) subclasses described earlier; and finally group 5 neurons look like small-field binocular neurons and are called T7(B). Moreover, RF disparity measurements conducted in all groups suggest that group 4 neurons support the estimation of binocular distance. This problem is discussed.Abbreviation RF receptive field     

Effect of kassinin, neurokinin A and neurokinin B on drinking behaviour in the pigeon

Intracerebroventricular (i.c.v.) injection of kassinin produced a prompt and copious drinking response at doses of 10-1000 ng/pigeon, in the absence of other behavioural alterations or of changes in core temperature. Neurokinin A and B evoked drinking, but they were respectively 10 and 100 times less potent than kassinin. Intraperitoneal injection of kassinin elicited drinking, but at doses about 1000 X larger than the i.c.v. ones. The angiotensin antagonist [Sar1, Leu8]angiotensin II did not reduce drinking induced by i.c.v. kassinin, suggesting that its effect is not due to interaction with the central renin-angiotensin system. Moreover, the effect is apparently independent of the mechanisms controlling hypovolaemic and hyperosmotic thirst since exact additivity was found in the dipsogenic response when i.c.v. kassinin was administered in the presence of a hypovolaemic (subcutaneous (s.c.), polyethylene glycol) or hyperosmotic (s.c. hypertonic NaCl) dipsogenic stimulus. The present findings show that kassinin, neurokinin A and B share with the tachykinins already tested (eledoisin, physalaemin, substance P) a common dipsogenic action in pigeons. However, marked differences exist in their dipsogenic potency. This order of potency, eledoisin = kassinin = physalaemin greater than neurokinin A = substance P greater than neurokinin B, is not consistent with the tachykinin receptor subtypes so far proposed.     

Depth resolution in the pigeon

Summary Pigeons possess a binocular visual field and a retinal region of higher cellular density pointing to the center of this overlap. These features and the precision of pecking behavior suggest that in this lateral-eyed bird cues other than monocular ones might participate in depth judgements.Pigeons were trained with an operant procedure to discriminate between luminous points differing in depth which appeared to the observer as floating in the dark. The accuracy of depth judgements was found to be a function of the ratio between the interstimulus distance and the mean eyes-to-stimulus distance. In a first test (experiment I) no external binocular disparity cues were available, the animal only seeing one luminous point at a time (near or far). In a second test (experiment II) where binocular disparity cues were available, the animal having this time to discriminate a pair of points placed at equal depth from a pair placed at unequal depths, only one pair being visible at a time, depth resolution did not improve. This suggests that, at least within the range of distances explored, the pigeon has no stereoscopic vision. Notwithstanding this, binocular cues do play a role, since when tests were done comparing binocular with monocular viewing (experiment III), monocular depth resolution was significantly worse.     

Dynamic Changes of Serotonin Levels During the First Visual Experience of Binocularly Deprived Kittens

Abstract— Kittens deprived of pattern vision until the 28th day of life received monocular visual experience for 3, 6, 14, and 75 h. Biphasic response of serotonin was found in the visual cortex. Stimulation for 3 h resulted in an increase of serotonin level whereas at 14 h it produced a decrease. The effects are transient, no longer observable after 75 h stimulation. No changes were observed in somatosensory cortex.     

Apomorphine pecking in the pigeon.

Pecking activity elicited by apomorphine was studied quantitatively in intact and thalamic pigeons. While apomorphine pecking is easily observed in the intact pigeon, it is absent in the acute thalamic animal. I reappears, however, in the chronic preparation simultaneously with the recovery of spontaneous pecking. Apomorphine pecking is described by satiation and increased by fasting. Reticular stimulation produces reversible blockade of both apomorphine and spontaneous pecking with the same parameters, without increase in heart rate. Apomorphine pecking can be observed only in the presence of visual contrast, and is always aimed at the contrast points or edges. A decrease in contrast produces a decrease in the number of pecks delivered to the contrast points and an increase in those missing the target, while the total number of pecks delivered in a unit time is unaffected. A lowering of the background luminance is followed by a decrease in the total number of pecks, which is mostly due to a reduction of those aimed at the contrast points. All these findings are discussed and it is concluded that: i) apomorphine exerts an excitatory action (direct or indirect) on the hypothalamic feeding centers; hence apomorphine pecking can be considered as a pharmacologically motivated behavior; ii) visual contrast exerts a dual action on apomorphine pecking, namely it acts both as triggering stimulus and goal object; iii) the decrease in apomorphine pecking induced by lowering the ambient light intensity is probably due to a decrease in the level of the general arousal.     

Food choice in the laboratory pigeon

Although food reward plays a large role in learning and behavioral experiments, there have been few studies examining the most motivating food reward for pigeons. Brown (1969) found that pigeons had a tendency to prefer peas, while Killeen et al. (1993) found pigeons to prefer peas and popcorn in Experiment 1A. We looked to further explore these options as well as expand upon the types of foods examined beyond mainly grains and seeds. Pigeons were presented with six novel foods (granulated peanuts, popping corn, freeze-dried mealworms, bread crumbs, split peas, and sunflower hearts) allocated into two sets of three food items. Once the most consumed food from each food set was determined, they were pooled together with sorghum seeds (a familiar food) to form a third set. Sunflower hearts were the most consumed of all the food items, followed by corn and granulated peanuts. We discuss the potential factors mediating consumption choice, including nutritional profile and food particle size.     

Prolactin and parenting in the pigeon family

The relationship between plasma prolactin and: crop growth; incubation; brooding; and feeding young in Columbiformes is reviewed. There is a good parallel between changes in crop growth and plasma prolactin fluctuations during the breeding cycle. Prolactin does not play a role in the initiation of incubation, though it can maintain the response. Toward the end of breeding, a decline in prolactin precedes the decline in incubation (of infertile eggs) or brooding (of young), while exogenously administered prolactin can prolong the response. There is no evidence of a necessary relationship between prolactin secretion and parental feeding of young, as this behavior can precede and outlast the secretion of the hormone during breeding.     

Spontaneous and deferred imitation in the pigeon

Experimentally-naive pigeons were placed on one side of a clear partition. A pigeon on the other side received food for pecking a ping-pong ball, pulling a rope, or pecking a plastic disk. When given access to a similar object, each naive pigeon pecked or pulled at a low rate for several sessions and two continued to do so forseveral sessions in the absence of the leader. In a second experiment, the latter effect was demonstrated after a delay of 24 hours, even though the naive pigeons had never had access to the object in the presence of the model. A third experiment demonstrated that the effect on the follower was not due merely to the presence of or activity of another pigeon and was at least somewhat specific to the behavior of the model.