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PubMedDate not supplied

[Formation of passerine (Passeriformes) vocalization in ontogeny: the current state of the problem].

It the acoustic signal system of birds, songs and calls are distinguished. Up to the late 1970s, the attention of researchers was focused primarily on studying the process of song formation; the patterns of the call system formation remained virtually unstudied. In this field, the prevailing notion was that, since all calls are hereditary, their formation in the repertoire of all birds is similar. This notion was based on non-passerine birds, for which calls constitute most of the vocal communication. Most calls can, indeed, be formed without learning, even in nestlings raised in isolation. Yet some calls remain and are transferred in populations only through learning. The stages of sound repertoire development reflect crucial reorganizations of the acoustic behaviour of nestlings and are distinctly recognizable in most of the studied birds. The first three stages coincide with the periods of postnatal development of altricial birds distinguished by researchers from other fields (based on morphological, behavioural, and physiological characters). These are the early nestling, later nestling, and post-nestling periods. Two more periods may, however, be distinguished in the formation of vocalization: the fourth, confined to the period of hormonal reorganization of the organism during the autumn moult, and the fifth, coinciding with the beginning of the first reproductive cycle of the young bird. The formation of calls in representatives of different systematic groups (to families inclusive) can follow three principal paths: independent, successive, or explosive. Data on the development of the specific repertoire of acoustic signals in ontogeny can serve as a reliable taxonomic criterion, assisting in reconstructing and specifying phylogenetic relationships between different bird lineages.

Age Factors↗
PubMed1988

Effects of unilateral thalamic lesion upon interocular transfer of visual discrimination in pigeons. I. Lesion in the trained hemisphere (memory access deficits).

Two groups of pigeons received a unilateral thalamic lesion in the hemisphere contralateral to the eye used for monocular training of a line orientation discrimination. The first group was trained monocularly on the discrimination after the lesion, and the second group received the lesion after the birds were successfully trained on the discrimination task. Then both groups were trained on the same task with their previously untrained eye to examine interocular transfer of discrimination. Lesion in the nucleus rotundus before monocular discrimination retarded acquisition of the original monocular learning but did not cause deficits in interocular transfer, whereas the rotundal lesion after the monocular discrimination learning resulted in deficits in interocular transfer. These results suggest (1) the bird could learn monocular discrimination with the hemisphere ipsilateral to the viewing eye when the contralateral hemisphere was not accessable, and (2) the bird learned monocular discrimination with the hemisphere contralateral to the viewing eye when both hemispheres were intact. Lesion in OPT did not cause deficits in interocular transfer. This result suggests a crucial role of the tecto-fugal pathway in interocular transfer.

Animals↗
PubMed2006

Increased expression of 5-HT6 receptors in the rat dorsomedial striatum impairs instrumental learning.

A number of studies have shown that systemic 5-HT(6) receptor antagonists can improve learning and memory, but the mechanism for these observations is not known. As striatum normally expresses 5-HT(6) receptors abundantly and is important in consolidating stimulus-response learning, we used targeted gene delivery to further increase the expression of 5-HT(6) receptors in rat striatum and then examined learning. Increased 5-HT(6) expression had no effect on performance in the Morris water maze, a hippocampal-dependent learning paradigm, and did not alter the latency to approach or consume sucrose tablets. However, rats with increased 5-HT(6) expression failed to acquire a reward-based instrumental learning task, a striatum-dependent learning model, during 3 days of successive sessions as compared to sham surgery or GFP-expressing control rats. This behavioral deficit was observed in rats overexpressing 5-HT(6) receptors in the dorsomedial striatum, but not in rats with increased dorsocentral striatal expression. The 5-HT(6) receptor-associated deficit was reversed by administration of a 5-HT(6) antagonist, SB-258585, before each training session. When animals learned the instrumental learning task before gene transfer, increased 5-HT(6) receptor expression had no effect on long-term recall or performance of the task or on extinction of operant responding. Thus, 5-HT(6) receptor activity in rat striatum disrupts acquisition of new instrumental learning but does not impair memory or performance of reward-motivated behavior once established.

Animals↗
PubMed2003

Cartilage regeneration by gene therapy.

Damage of articular cartilage is a frequent clinical problem and is commonly considered to be irreversible. Full-thickness defects may lead to the formation of fibrous repair tissue of minor mechanical quality, while partial-thickness lesions hardly show any repair response. Surgical approaches often fail to restore the articular surface, facing the problem of incomplete chondrogenesis or rapid degradation of the repair tissue. However, advances in molecular biology have revealed the potential of growth factors, differentiation factors, and cytokines in directing cellular differentiation and metabolic activity. Anabolic factors including members of the TGF-beta superfamily, IGF-1, FGF, or HGF have proven their potential to stimulate chondrogenesis and synthesis of cartilage-specific matrix components, allowing the formation of a hyaline cartilage-like repair tissue in experimental studies. In addition, anti-catabolic or anti-inflammatory molecules, such as IL-4, IL-10, IL-1Ra, and TNFsR may also exert beneficial effects by inhibiting excessive cartilage degradation. Although it is questionable whether regeneration of hyaline cartilage implying a complete restoration of the articular surface by a tissue that is identical with the original can ever be achieved, all these molecules have been considered as suitable tools for cartilage repair. The transfer of the respective genes into the joint, possibly in combination with the supply of chondroprogenitor cells, might be an elegant method to achieve a sustained delivery of such therapeutic factors at the required location in vivo. This review focuses on the therapeutic molecules, the suitability of different viral and non-viral vectors for intraarticular gene transfer and the lessons learned from gene therapy studies on various animal models.

Adenoviridae↗
PubMed1998

What is improved if a mental rotation task is repeated--the efficiency of memory access, or the speed of a transformation routine?

The present study contrasts 3 theories which provide explanations for performance improvement in mental rotation tasks. Wallace and Hofelich conjectured that the process as such may be executed more rapidly after training, while Bethell-Fox and Shepard attributed practice effects to the fact that images may be transformed first elementwise, but later as a Gestalt. In contrast, Tarr and Pinker assumed that a transformation of an image will no longer be computed after training but simply be retrieved from memory. Thirty-seven subjects participated in 3 test sessions in which they had to decide on the parity of 3-D block figures presented from different perspectives. Experimental group subjects underwent 4 additional practice sessions in which a subset of the figures and a subset of perspective views were used. Tests adapted to the predictions of the 3 theories revealed specific learning effects but no transfer, neither to old objects presented in new perspectives nor to new objects. This supports an instance-based explanation of practice effects which states that objects are represented in multiple perspective views.

Adult↗
PubMed1999

Assessment of technical skills transfer from the bench training model to the human model.

BACKGROUND: This study examines whether technical skills learned on a bench model are transferable to the human cadaver model. METHODS: Twenty-three first-year residents were randomly assigned to three groups receiving teaching on six procedures. For each procedure, one group received training on a cadaver model, one received training on a bench model, and one learned independently from a prepared text. Following training, all residents were assessed on their ability to perform the six procedures. RESULTS: Repeated measures analysis of variance revealed a significant effect of training modality for both checklist scores (F(2,44) = 3.49, P <0.05) and global scores (F(2,44) = 7.48, P <0.01). Post-hoc tests indicated that both bench and cadaver training were superior to text learning and that bench and cadaver training were equivalent. CONCLUSIONS: Training on a bench model transfers well to the human model, suggesting strong potential for transfer to the operating room.

Cadaver↗
PubMed1996

Coordination between posture and movement in a bimanual load-lifting task: is there a transfer?

The present experimental series was designed to test the possibility that an anticipatory postural adjustment learned during the performance of a bimanual load lifting task may be transferred between the upper extremities. Eight seated subjects were asked to maintain horizontally one forearm (postural arm) loaded with a 1-kg load, which was fixed to the arm by means of an electromagnet. The unloading was triggered either by the experimenter pressing a switch (control) or by the subjects making a voluntary movement with their other arm (moving arm). In the latter case, the subject lifted a 1-kg load resting on a force platform with the moving hand, and the switching off was triggered when the force level reached a threshold of 0.5 kg. The maximum amplitude (MA) and the maximum velocity (MV) of the postural forearm elbow joint rotation occurring after the unloading were measured at each trial. The learning process was estimated by performing a regression analysis on each series of trials, using an exponential model, and from the intercept of the regression curve with the ordinate. 1. During the original learning session (three series of 20 trials), a decrease in MA and MV was found to occur both within the series and between the series during a session. 2. After the initial learning session, the sides of the postural and moving arm were interchanged to test whether any transfer had occurred. The first series of trials in the second session (transfer) and the last series of trials in the original learning session were compared and found to be significantly different in terms of the intercept (seven subjects in the case of MA, five subjects in the case of MV) and the slope (five subjects), indicating a lack of transfer. 3. The data recorded during the second transfer learning session indicated that learning occurred in all eight subjects in the case of MA and in six subjects in the case of MV. It was observed that the original learning session did not facilitate the second one. 4. The lack of transfer of the anticipatory postural adjustment observed in this task is discussed with reference to the data in the literature.

Conditioning, Psychological↗
PubMed1993

Reduced feedback frequency enhances generalized motor program learning but not parameterization learning.

The purpose of the study was to examine the effects of a reduced feedback frequency on the learning of generalized motor programs and movement parameterization. Subjects practiced three movement patterns with the same relative timing and the same relative amplitude, but with varied movement time (Experiment 1) or varied movement amplitude (Experiment 2). KR was given either on 100% or 63% of the trials, with learning being assessed by retention and transfer tests. In both experiments, reduced KR frequency enhanced GMP learning but generally degraded parameter learning. These data provide converging evidence for the dissociation of the program and parameterization processes postulated in GMP theory.

Adult↗
PubMed2005

Shape-specific perceptual learning in a figure-ground segregation task.

What does perceptual experience contribute to figure-ground segregation? To study this question, we trained observers to search for symmetric dot patterns embedded in random dot backgrounds. Training improved shape segmentation, but learning did not completely transfer either to untrained locations or to untrained shapes. Such partial specificity persisted for a month after training. Interestingly, training on shapes in empty backgrounds did not help segmentation of the trained shapes in noisy backgrounds. Our results suggest that perceptual training increases the involvement of early sensory neurons in the segmentation of trained shapes, and that successful segmentation requires perceptual skills beyond shape recognition alone.

Discrimination, Psychological↗
PubMedDate not supplied

Median nerve palsy following claw finger correction in leprosy: effect of M. leprae or a consequence of surgery.

Median nerve palsy, though not a frequent occurrence after claw finger correction, does exist as a post-operative complication after claw finger correction. A retrospective study was carried out to examine the occurrence of post-operative median palsy, in cases of isolated ulnar palsy, where the transferred motor tendon was routed through the carpal tunnel. We noted that six patients developed median nerve palsy following claw finger correction. Median palsy developed at different times after surgery--the "early onset" type developing within three weeks post-operatively, "reactional" type developed when patient was undergoing physiotherapy exercises and learning to use the transfer and "delayed insidious" type presenting six months or more after operation. We could not succeed to get the true prevalence of such occurrences because all the operated hands could not be re-examined.

Adolescent↗
PubMed2002

Creatine kinase B-driven energy transfer in the brain is important for habituation and spatial learning behaviour, mossy fibre field size and determination of seizure susceptibility.

Creatine kinases are important in maintaining cellular-energy homeostasis, and neuroprotective effects have been attributed to the administration of creatine and creatine-like compounds. Herein we examine whether ablation of the cytosolic brain-type creatine kinase (B-CK) in mice has detrimental effects on brain development, physiological integrity or task performance. Mice deficient in B-CK (B-CK-/-) showed no gross abnormalities in brain anatomy or mitochondrial ultrastructure, but had a larger intra- and infrapyramidal mossy fibre area. Nuclear magnetic resonance spectroscopy revealed that adenosine triphosphate (ATP) and phosphocreatine (PCr) levels were unaffected, but demonstrated an apparent reduction of the PCr left arrow over right arrow ATP phosphorus exchange capacity in these mice. When assessing behavioural characteristics B-CK-/- animals showed diminished open-field habituation. In the water maze, adult B-CK-/- mice were slower to learn, but acquired the spatial task. This task performance deficit persisted in 24-month-old, aged B-CK-/- mice, on top of the age-related memory decline normally seen in old animals. Finally, a delayed development of pentylenetetrazole-induced seizures (creating a high-energy demand) was observed in B-CK-/- mice. It is suggested that the persistent expression of the mitochondrial isoform ubiquitous mitochondrial CK (UbCKmit) in the creatine/phospho-creatine shuttle provides compensation for the loss of B-CK in the brain. Our studies indicate a role for the creatine-phosphocreatine/CK circuit in the formation or maintenance of hippocampal mossy fibre connections, and processes that involve habituation, spatial learning and seizure susceptibility. However, for fuelling of basic physiological activities the role of B-CK can be compensated for by other systems in the versatile and robust metabolic-energy network of the brain.

Animals↗
PubMed1984

Global and local control of choice behavior by cyclically varying outcome probabilities.

Subjects asked to simulate decision makers in a competitive bidding situation chose repeatedly between two alternatives; reward probability varied according to a sine wave function of time for one alternative but was held constant over time for the other. Learning functions for choice probability exhibited the wavelike pattern predicted by a statistical learning model. However, on later transfer trials, when success probability was independent of subjects' choices, their choice behavior continued to follow a wavelike function rather than approaching the constant .5 level predicted by the learning model. A possible basis in memory for the transfer performance was revealed in subjects' sketches of the remembered pattern of variation in reward probabilities. It is concluded that choice performance is controlled by a mixture of local feedback, in a manner described by the learning model, and more global information encoded in an abstract memory representation, with the balance of the influence shifting toward the latter when local feedback becomes uninformative.

Adult↗
PubMed2005

Origins of group coordination: nonlinear dynamics and the role of verbalization.

Coordination occurs when two or more people do the same or complimentary tasks simultaneously; its explanation game theory, nonlinear dynamics, and implicit learning theory. In the experiment, 12 four-person groups were allowed to discuss the coordination (card game) task while performing it; 12 other groups worked nonverbally. One to three group members were replaced during the game. Split-plot ANOVA showed that verbalizing groups performed better than nonverbalizing groups overall and showed more acute coordination learning curves, but verbalization did not compensate for the replacement of personnel. Groups that changed one or two players showed positive coordination transfer, but groups that changed three players did not. Nonlinear regression for temporal dynamics within verbalizing and nonverbalizing groups showed asymptotic stability for initial coordination learning and transfer to a difficult rule, a chaotic function when replacements were introduced, and asymptotic stability again when the team with replacements switched to the difficult rule.

Cooperative Behavior↗
PubMed1985

Extent and limits of the matching concept in monkeys (Cebus apella).

In Experiment 1, 8 monkeys, experimentally naive with regard to visual stimuli, were trained on identity matching with a two-sample set based on two-dimensional stimuli. On a subsequent test employing two new samples, 4 of the 8 applied the matching rule to the new sample stimuli (as defined by our transfer criterion), and 3 showed substantial savings in learning to match the new samples. Two of these 3 transferred the matching rule when given a second test with two new samples, and the third showed immediate and complete transfer when tested with a third pair of new stimuli. These results indicate a much stronger representation of the matching concept in monkeys than in pigeons, even when the conditions of assessment are reasonably comparable. In Experiment 2, however, 4 monkeys from Experiment 1 failed to transfer the matching rule to steady versus flashing green samples, indicating that the matching concept did not immediately extend beyond the general class of visual stimuli with which it was developed. These and related results in the literature suggest that representation of the matching concept in animals varies along a specificity-abstractness dimension, reflecting the degree to which the concept is tied to the conditions and context of its development.

Animals↗
PubMed1986

Survival of a conditioned inhibitory avoidance response after decerebration.

There is evidence that inhibitory avoidance learning is still possible after removal of the telencephalic forebrain. However, it is not known whether subtelencephalic storage of such a conditioned response takes place when the brain is intact. To investigate this possibility, rats received one training trial in the "up-hill avoidance" task, and 8 h later the entire forebrain except the hypothalamus was bilaterally ablated. When tested 24 h later, the decerebrate rats still exhibited the learned response, demonstrating a transfer of the conditioned response from the intact to the postlesion state. This result indicates that memory-storage for this avoidance task takes place, at least in part, subtelencephalically.

Animals↗
PubMedDate not supplied

The operant and the classical in conditioned orientation of Drosophila melanogaster at the flight simulator.

Ever since learning and memory have been studied experimentally, the relationship between operant and classical conditioning has been controversial. Operant conditioning is any form of conditioning that essentially depends on the animal's behavior. It relies on operant behavior. A motor output is called operant if it controls a sensory variable. The Drosophila flight simulator, in which the relevant behavior is a single motor variable (yaw torque), fully separates the operant and classical components of a complex conditioning task. In this paradigm a tethered fly learns, operantly or classically, to prefer and avoid certain flight orientations in relation to the surrounding panorama. Yaw torque is recorded and, in the operant mode, controls the panorama. Using a yoked control, we show that classical pattern learning necessitates more extensive training than operant pattern learning. We compare in detail the microstructure of yaw torque after classical and operant training but find no evidence for acquired behavioral traits after operant conditioning that might explain this difference. We therefore conclude that the operant behavior has a facilitating effect on the classical training. In addition, we show that an operantly learned stimulus is successfully transferred from the behavior of the training to a different behavior. This result unequivocally demonstrates that during operant conditioning classical associations can be formed.

Animals↗
PubMed1994

Aging and skill acquisition: learning-performance distinctions.

This research examined the hypothesis that a conservative response bias in older persons interferes with the acquisition and mastery of cognitive skill. Twenty younger and 20 older Ss performed both consistent mapping and varied mapping versions of a memory search task. Half of the Ss in each group performed under speed stress instructions, whereas the remaining Ss performed under accuracy stress instructions. Older Ss exhibited less skilled performance than did younger Ss. A power function analysis attributed this to both age-related differences in the rate of associative learning and differences in asymptotic levels of performance. These results are at odds with A. D. Fisk and W. A. Roger's (1991) hypothesis that age-related differences in automatization do not occur in memory search tasks. Results are interpreted in terms of a learning vs. performance distinction.

Adolescent↗