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Biomedical subjects

J D Delius

Publications and source records attributed to J D Delius.

At least 37 records · Page 2Linked to original sources
PubMed1988

Preventing a feature-positive effect in pigeons.

The feature-positive effect (FPE) is a widespread and robust phenomenon in the context of discrimination learning. It refers to the fact that a distinctive feature associated with a stimulus that is reinforced leads to efficient discrimination learning, whereas the same feature associated with the nonreinforced stimulus inhibits discrimination learning. Two experiments with pigeons showed that the FPE also occurs with a simultaneous discrimination paradigm involving brief discrete trials and no intertrial intervals. A pre-training treatment unexpectedly prevented the expression of the FPE in this discrimination task. The pretraining consisted of having pigeons discriminate the feature/nonfeature visual shapes from a plain background disc. Rewarding responses to the shapes, or alternatively to the blank disc, had the same FPE-preventing effect. A reversal of a feature/nonfeature stimulus discrimination led to an analogous erasure of the FPE. The results are discussed in terms of the concurrence or interference between the various associations that the subjects formed on the basis of the different stimulus-reward correlations they experienced in the different phases of the experiments.

Animals↗
PubMed1987

Apomorphine-induced pecking in pigeons classically conditioned to environmental cues.

The dopamine agonist apomorphine elicits protracted pecking when injected systemically (1 mg/kg) into pigeons. In two experiments it was investigated whether apomorphine would function as an unconditioned stimulus in the classical conditioning of pecking in these animals. An experimental design based on a differentiation procedure was used so that possible pseudoconditioning effects were controlled. Two differently coloured test chambers served as negative (CS-) and positive conditioned (CS+) stimuli. During the training phase the subjects experienced the former while injected with saline, and the latter while injected with apomorphine. In later tests not involving any injections the pigeons made significantly more pecks (conditioned response) in the CS+ chamber than in the CS- chamber. In the first and second experiments the conditioned stimuli were, respectively, discrete and diffuse visual cues, but both had similar effects. The conditioning obtained may explain sensitization effects that are observed with repeated apomorphine injections. Apomorphine probably also functions as a positive reinforcer for instrumental conditioning in pigeons.

Animals↗
PubMed1987

Orientation invariance of shape recognition in forebrain-lesioned pigeons.

Pigeons were trained to perform a visual orientation invariance task consisting of shape matching-to-sample or oddity-from-sample discriminations where the comparison forms differed in orientation from the sample forms, and the odd comparison forms were always a mirror image of the sample. They then received lesions affecting the visual projection area within the anterior hyperstriatum or the dorsal neostriatum, a control area with no known visual function. Both groups of birds evinced minor transient postoperative deficits of similar magnitude during the shape recognition task under orientation invariance conditions when the habitual training forms were used. When novel forms were introduced, the performance of hyperstriatal pigeons was significantly worse than that of the neostriatal pigeons, but still well above chance. The introduction of a delay between the offset of the sample and the onset of the habitual comparison stimuli did not yield any differential effect. It is concluded that orientation invariance of pattern recognition performance of birds, in contrast to that in mammals, is probably a midbrain, optic tectum function.

Animals↗
PubMed1986

Sensory projections to the nucleus basalis prosencephali of the pigeon.

The afferent pathways to the nucleus basalis prosencephali of the pigeon were studied by use of the horseradish peroxidase (HRP) technique. It was confirmed that this nucleus receives a direct pathway from the nucleus sensorius principalis nervi trigemini and that, as in the starling, it receives a direct input from the nucleus lemnisci lateralis, pars ventralis, an auditory relay. Totally novel is the finding that the nucleus basalis prosencephali is the target of a direct pathway originating in the medullary nucleus vestibularis superior. All three pathways bypass the thalamus. From within the telencephalon the nucleus basalis prosencephali also receives fibres from the tuberculum olfactorium and the peri-ectostriatal belt, suggestive of olfactory and visual input. Marked cell bodies were also found in the neostriatum frontolaterale. It is assumed that these arose from HRP uptake by axons of the tractus fronto-archistriatalis that course through the nucleus basalis prosencephali to the anterodorsal archistriatum. Marked fibres and bouton-like formations were observed in the latter structure. The afferents to the nucleus basalis prosencephali are discussed in conjunction with the probable role of the nucleus as a sensorimotor coordinator of the pecking/feeding behaviour of the pigeon.

Afferent Pathways↗
PubMed1986

Sensory inputs to the nucleus basalis prosencephali, a feeding-pecking centre in the pigeon.

Evoked potentials were recorded from the nucleus basalis prosencephali (Bas) of the pigeon through chronically implanted electrodes. The auditory sensitivity of the Bas was assessed by the amplitude of the potentials. Audiograms thus obtained were comparable to those similarly measured from stations of the orthodox auditory pathway and resembled those obtained by others with behavioural techniques from the same species. The sensitivity to vibration applied to the beak was also measured. The vibrogram revealed two separate optima, one located in the lower frequency and another in the higher frequency region. These were shown to be due to trigeminal mechanoreceptive sensitivity and to bone/cochlea mediated sound sensitivity, respectively. Evoked potentials of the Bas in response to vestibular stimulation are described for the first time. The possibility that they were artefacts was excluded with several control procedures. These findings confirm recent anatomical evidence of a direct pathway from the vestibular nucleus to the nucleus basalis prosencephali. All afferents to the Bas are discussed in conjunction with the probable function of the nucleus as a sensorimotor coordinator of the pigeon's pecking/feeding behaviour.

Acoustic Stimulation↗
PubMed1985

Scanning electron microscopy of the lateral ventricle of the pigeon brain.

Adult pigeons of both sexes were used for this study. Depending upon the distribution of various surface profiles, for example cilia, microvilli and blebs, ependymal areas with differing surface patterns were distinguished in the lateral ventricle. The topographical locations of these areas with respect to the underlying forebrain nuclei were determined in accord with the atlas of Karten and Hodos (1967). The medial surface (A) of the ventricle was much more densely ciliated than the lateral surface (B). There did not appear to be any correlation between a given surface pattern and a specific type of underlying nervous tissue. Comparison of the cell patterns seen in the pigeon brain with those seen in the analogous areas of the rat brain showed that it is not feasible to extrapolate from one zoological group to another. With the exception of the Kolmer cells populating the choroid plexus, there were remarkably few supraependymal cells in the pigeon lateral ventricle. Supraependymal nerve fibers were also extremely rare. Particular attention was given to the ependyma associated with the nucleus stria terminalis, to that of the lateral septal organ and to the choroid plexus. The possible classification of these areas into the group of the circumventricular organs is considered.

Animals↗
PubMed1984

Lateral telencephalic lesions affect visual discriminations in pigeons.

The importance of the lateral telencephalon of the pigeon for visual performance was examined. Lesions in this area markedly impaired both the acquisition and the retention of instrumentally learned hue, intensity and pattern discriminations. Comparable lesions of the thalamofugal visual projection in the dorsoanterior telencephalon did not have an appreciable effect. Laterally lesioned pigeons showed only a minor, non-significant impairment in an instrumental auditory discrimination task. These results generally agree with findings of other authors on domestic chicks but disagree with previous work on pigeons. The visual discrimination performance of laterally lesioned subjects improved gradually over the course of days and weeks without specific experience being necessary, and after 3 months the recovery was virtually complete. The effect of lateral telencephalic lesions is discussed in connection with known visual projections within the avian endbrain and their relationship with other functional systems.

Animals↗
PubMed1982

Rotational invariance in visual pattern recognition by pigeons and humans.

Pigeons and humans chose which one of two alternative visual forms was identical to, or a mirror image of, a previously presented sample form. The two comparison forms were presented in various orientations with respect to the sample. The two species yielded similar accuracies, but although human reaction times depended linearly on the angular disparities, those of the pigeon did not. Humans appeared to apply a well-known, thoughtlike, mental rotation procedure to the problem, whereas pigeons seemed to rely on a more efficient automatic process that humans can use only in simpler rotational invariance tasks. Mirror-image forms may be better discriminated by the pigeon's visual system than by the human one.

Animals↗
PubMed1982

A contribution to the study of the afferents to the pigeon optic tectum.

The origins of several afferent pathways to the pigeon's tectum were studied using the horseradish peroxidase tracing technique. The results confirm the presence of several previously described afferents, and add further data on intertectal and hyperstriatofugal projections. Two new sources of afferents to the tectum, located in the hypothalamus and the septum, were identified. The latter is described in greater detail.

Afferent Pathways↗
PubMed1981

Discrepant effects of unilateral and bilateral forebrain lesions on the visual performance of pigeons.

The monocular and binocular performance of pigeons with bilateral, unilateral or sham lesions in the telencephalic Wulst was tested with visual discrimination tasks. Unilateral lesions yielded a marked deficit when the animals could only use the eye contralateral to the lesion. Otherwise the accomplishments of the ablated animals did not differ from that of the controls. The reciprocal inhibition of symmetrical visual brain stem centers is thought to have been unbalanced through the one-sided interruption of a known pathway descending from the Wulst.

Animals↗
PubMed1981

Short-term modulation of domestic pigeon (Columbia livia L.) behaviour induced by intraventricular administration of ACTH.

The behavioural responses induced in adult domestic pigeons by intraventricular injections of 0 to 6 IU of ACTH 1-39 are reported. The frequency of 10 different behaviour patterns was recorded for 90 min after administration of the peptide. The effect that was induced was complex, the frequency of some patterns increasing (yawning, headshaking, body shaking, wing-flapping), or some others decreasing (feeding, one-wing stretching, eye closing) or remaining unchanged (preening). The frequency of several patterns was maximal during the first 30 min following the injections but this was shown in some cases to be independent on the hormone administration.

Adrenocorticotropic Hormone↗
PubMed1976

Polarized light discrimination by pigeons and an electroretinographic correlate.

Pigeons placed in a multiple-key Skinner-box could be trained to choose reliably keys that were aligned in a specific way with the polarization axis of an overhead, randomly rotating light source. On the basis of these results and those of additional control experiments, it is concluded that pigeons can discriminate the axis orientation of linearly polarized light and, furthermore, that they can orient themselves spatially by this cue. Electrophysiological recording experiments showed that the shape of the b-wave of the pigeons' electroretinogram is affected by the axis orientation of linearly polarized flash stimuli. This phenomenon seems to be due to the presence of retinal polarization analyzers that may be tied to color vision mechanisms.

Animals↗