The caterpillars of the butterfly Methona themisto (Nymphalidae: Ithomiinae) are conspicuously coloured and feed exclusively on Brunfelsia uniflora (Solanaceae), a plant that is rich in secondary plant substances, which suggests the caterpillars are chemically protected against predators. Results of experiments indicate that predators determine the survival of Methona themisto caterpillars in the field and laboratory bioassays that this organism is eaten by ants and spiders but not chicks. Both the conspicuous orange and black striped colouration and chemical compounds of Methona themisto caterpillars seem to be related to protection against predation by visually hunting predators. Chicks ate proportionally more of the cryptically coloured 1st instar caterpillars than of the conspicuously coloured later instar caterpillars. That Methona themisto caterpillars are chemically defended is supported by the activity of the dichloromethanic extract of 5th instars in preventing predation by chicks. Caterpillars of Methona themisto are aposematic as they are both (1) unpalatable, and (2) their warning signal is easily recognized by potential predators. Chicks learned to avoid the aposematic 3rd or 5th instar caterpillars after one encounter. Mealworms painted to look like caterpillars were also rejected by chicks that had previously encountered Methona caterpillars. Naïve chicks did not avoid eating the painted mealworms, which indicates they do not innately avoid this specific colour pattern.
The paper deals with a description of a constructive neural network based on gradient initial setting of its weights. The network has been used as a pattern classifier of two dimensional patterns but it can be generally used to n x m associative problems. A network topology, processes of learning and retrieving, experiments and comparison to other neural networks are described.
Extremely low-frequency magnetic field (ELF-MF) has been suggested to influence the cognitive capability but this should be dynamically evaluated in a longitudinal study. Previous training can affect performance, but the influence under magnetic field is unclear. This study aims to evaluate the effects of previous training and ELF-MF exposure on learning and memory using the Morris water maze (MWM). Sprague-Dawley rats were subjected to MWM training, ELF-MF exposure (50 Hz, 100 μT), or ELF-MF exposure combined with MWM training for 90 days. Normal rats were used as controls. The MWM was used to test. The data show that the rats exposed to training and ELF-MF with training performed better on spatial acquisition when re-tested. However, during the probe trial the rats showed no change between the training phase and the test phase. Compared with the control group, the ELF-MF group showed no significant differences. These results confirm that previous training can improve the learning and memory capabilities regarding spatial acquisition in the MWM and this effect can last for at least 90 days. However, this improvement in learning and memory capabilities was not observed during the probe trial. Furthermore, ELF-MF exposure did not interfere with the improvement in learning and memory capabilities., Y. Li, C. Zhang, T. Song., and Obsahuje bibliografii
During the early postnatal age environmental signals underlie the development of sensory systems. The visual system is considered as an appropriate system to evaluate role of sensory experience in postnatal development of sensory systems. This study was made to assess the effect of visual deprivation on strategy of arm selection in navigation of radial arm maze. Six-week-old light- (LR, control) and dark-reared (DR) rats were trained for correct choices and adjacent arms tasks. Our results showed that both the LR and DR animals equally selected correct arms. In the adjacent arms task, however, the control group significantly outperformed the DR animals. While the LR males and females displayed some differences in performing the tasks, no sex dependency was found in the performance of the DR group. These findings indicate that the lack of visual experience is likely to influence the strategy selection as well as sex differences. Thus the difference in the performance of LR and DR animals seems to be due to the male rather than female behavior., M. Salami., and Obsahuje bibliografii a bibliografické odkazy
This contribution provides insights into learning research conducted at the University of Innsbruck, Austria, where vignette research was developed in a grant-funded project still in progress. It has been designed to gain access to students' learning experiences in the classroom as they occur rather than measuring learning by its outcome. The authors frame the research need out of which this lived experience methodology developed and describe its theoretical foundations in phenomenology. The vignette research is illustrated by a hermeneutic phenomenological vignette reading which explores the impact that explicit and implicit ascriptions have on children's learning as well as on the pedagogical practice of the teacher. The significance of the Innsbruck Vignette Research for research into teaching and learning is presented as well as the relevance of vignette work for teaching and learning and teacher education.
Aphelinus abdominalis Dalman (Hymenoptera: Aphelinidae), a solitary endoparasitoid of cereal aphids [e.g. Sitobion avenae (F.)] and aphids in greenhouses [e.g. Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas)] is available as biological control agent against aphid pests in greenhouses. As little is yet known about its long-range host location after release, the in-flight orientation of female A. abdominalis was investigated with regard to the effects of post-emergence experience, using a wind tunnel bioassay. In no-choice tests experienced females responded to the odour of M. euphorbiae-infested sweet pepper and aubergine plants while naive females exhibited mostly random flights. In a choice test, offering infested and uninfested plants of the same species, experienced wasps were able to recognize the plant-host complex (PHC) and selected it as landing site. In contrast to uninfested plants, host-damaged plants (infested plants with aphids removed) attracted experienced females just as well as infested plants. When the responses of groups of parasitoids with experience on two different plant-host complexes were studied, specifically trained wasps were observed to orientate significantly better towards the infested target plant than wasps with previous experience on the non-target plant. A final choice test, with an infested pepper and an infested aubergine plant as odour sources, showed that females trained on one of the offered plant-host combinations significantly preferred the odour of the learnt PHC to that of the different PHC. The results suggest that A. abdominalis females employ specific volatile signals emitted by host-infested plants (synomones) during long-range host location. These odours must be learnt, e.g. in association with a successful oviposition.
Spatial navigation comprises a widely-studied complex of animal behaviors. Its study offers many methodological advantages over other approaches, enabling assessment of a variety of experimental questions and the possibility to compare the results across different species. Spatial navigation in laboratory animals is often considered a model of higher human cognitive functions including declarative memory. Almost fifteen years ago, a novel dry-arena task for rodents was designed in our laboratory, originally named the place avoidance task, and later a modification of this approach was established and called active place avoidance task. It employs a continuously rotating arena, upon which animals are trained to avoid a stable sector defined according to room-frame coordina tes. This review describes the development of the place avoidance tasks, evaluates the cognitive processes associated with performance and explores the application of place avoidance in the testing of spatial learning after neuropharmacological, lesion and other experimental manipulations., A. Stuchlík ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Neurotransmitter substrate of spatial cognition belongs to current topics in behavioral neuroscience. The present study examined the effects of serotonin depletion with p-chlorophenylalanine on learning of rats in active place avoidance, a spatial task requiring allothetic mapping and cognitive coordination and highly dependent upon hippocampus. Serotonin depletion transiently increased locomotor activity in response to footshocks, but it did not change the avoidance efficiency measured by three spatial parameters. These results suggest that serotonin neurotransmission is not crucial for cognitive coordination and allothetic learning, i.e. the processes, which are crucial for active place avoidance performance., T. Petrásek, A. Stuchlík., and Obsahuje seznam literatury
Spatial navigation and memory is considered to be a part of the declarative memory system and it is widely used as an animal model of human declarative me mory. However, spatial tests typically involve only static settings, despite the dynamic nature of the real world. Animals, as well as people constantly need to interact with moving objects, other subjects or even with entire moving environments (flowing water, running stairway). Therefore, we design novel spatial tests in dynamic environments to study brain mechanisms of spatial processing in more natural settings with an interdisciplinary approach including neuropharmacology. We also translate data from neuropharmacological studies and animal models into development of novel therapeutic approaches to neuropsychiatric disorders and more sensitive screening tests for impairments of memory, thought, and behavior., A. Stuchlik ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy