Features of the dynamics of the forebrain EEG of Emys orbicularis during the solving of an extrapolation problem

Sharp EEG changes are recorded in bioelectrical activity of the dorsal cortex and dorsal ventricular edge in marsh tortoises in conditions of free movement during solving of an extrapolation task (a test of elementary reasoning ability). These changes of a pathological character, accompanied by neurotic states, were observed in some animals having correctly solved the task several times in succession (2-5), beginning with the first presentation. Such changes of EEG and behaviour were not found in tortoises that committed errors at first presentations of the task and only gradually learned correct solving. Formation of the adequate behaviour can proceed by two means: on the basis of elementary reasoning ability and learning. Disturbance of adequate behaviour in the experiment with characteristic changes of EEG testifies to a difficult state of the animal during solving of the extrapolation task.     

Problem solving of wild animals in the Wet Tropics of Queensland,Australia

While many species of animals can solve food-baited problems, most studies are conducted in captivity, which may not reflect the natural behavioural and cognitive abilities of wild animals. As few studies have explored problem solving of Australian animals generally, we investigated the problem solving abilities of native Australian species in natural rainforest in the Wet Tropics of Queensland. We baited multiple types of puzzles (matchbox task, cylinder task, and tile and lever tasks on a Trixie Dog Activity Board) with different food types (seeds, fruit, sardines) and placed the puzzles in front of trail cameras. We noted the species captured on camera, whether or not individuals interacted with the puzzles, the number of interactions with puzzles, and whether or not different animals solved them. We found that seven species from multiple taxa (mammals, birds, reptiles) could solve food-baited problems in the wild, providing the first evidence of problem solving in these native species. As problem solving may help animals cope with anthropogenic threats, these results provide some insights into which Wet Tropics species may potentially be more vulnerable and which ones might be better at coping with changing conditions.     

Problem-solving of the cylinder,tile and lever tasks by wild animals in Dryandra National Park,Western Australia

Problem-solving is an important ability that allows animals to overcome environmental challenges. As such, it is a useful measure of behavioural flexibility and could be beneficial for conservation work. However, there is currently little known about the solving abilities of many Australian species, despite the high threat of environmental degradation and loss that they face. We therefore measured the problem-solving abilities of native Australian species living in the Dryandra National Park, Western Australia using food-baited puzzles (cylinder task, tile task and lever task) placed in front of camera traps. We recorded 12 species on cameras, with 10 species interacting with at least one puzzle. Of these species, woylies and koomal solved all tasks across multiple sites and using multiple behaviours, suggesting that they may be capable of adapting to novel conditions or environments. We also recorded a chuditch solving the tile task at one site. Regardless of species and puzzle type, animals had a higher chance of solving puzzles with increasing interactions. Our results document the first occurrence of problem-solving in woylies and chuditch, and highlight the potential for problem-solving measures to be incorporated into conservation management.     

Behavior of fish in groups presented with an extrapolation problem

Grouped carps as well as isolated fishes were shown to be uncapable to extrapolate the direction of movement of an alimentary stimulus after its disappearance from the visual field. Differences in behaviour of isolated fishes and grouped ones as well as those between the groups of different size and composition were revealed in repeated performance of the same extrapolation task. Groups of six fishes exhibited higher behavioural plasticity in comparison to isolated fishes and groups of two unlearned animals: in the former orienting-exploratory activity was higher and the process of learning more stable. At minimal group size (two animals) learning was accelerated only in the case if one of the fishes had been previously learned. Some decrease in efficiency of task solving was observed in a learned fish after its grouping with unlearned one.     

Food search by mice solving an extrapolation problem after suppression of smell by zinc sulfate

Anosmia induced by intranasal zinc administration to mice capable of solving an extrapolation problem (search for food which disappears from animal sight in definite direction), led to disturbance of normal food searching behaviour. In anosmic mice the percentage of task solutions (correct as well as incorrect) in which the trajectory was the shortest ("goal-directed"), was significantly lower than in controls. At the same time the percentages of correct "goal-directed" choices were equal in both groups. The main differences in the number of correct task solutions were among those trials in which non-goal-directed behaviour was delivered. Thus zinc induced anosmia provokes rather severe deteriorations of food searching behaviour. The investigated group of mice possessing Robertsonian translocation Rb(8, 17) 1 IEM, reveals no disturbance of extrapolation capacity during first 20 s after task presentation. This signifies that this capacity which in this group is higher than in other mice, is not determined by peculiarities of their olfaction.     

Nonspecific grooming in rats during the solution of an extrapolation task

Grooming behavior in laboratory brown rats was analysed in the course of extrapolation task solving. Cases of task solution (correct and incorrect) were compared with those when animal "refused" to turn round the screen during search of food bait. In latter cases grooming episodes were more numerous, their latency and duration being higher than during former cases. At the same time the latest stages of experiment (when 8-13 trials a day twice a week were presented) were characterized by more frequent grooming occurrence as well as by longer latencies and duration of grooming episodes. When rats were given I trial a day with one week intervals grooming incidence as well as "refusals" occurrence decreased. The possible participation of animal grooming in arranging the defense reactions against excessive and inadequate activity is discussed.     

The learning characteristics of rats under free-choice conditions]

The ability to organize a four-link operant food-procuring habit in a multiple alternative maze using the free-choice method was studied in albino rats. Three types of animals were observed which were different in the character of learning. The learning curve of 20% of rats had of exponential character (type I). Some animals (37%) acquired the skill through "insight" and the process of learning in these cases could be described by a logistic regression function (type II). The remaining rats (43%) refused from solving the intricate task and were able to acquire only the simplest form of a response, i.e., running to feeders. It is suggested that learning differences between the I and II types of animals may be associated with different strategies of problem solving: "procedural" (algorithmic) and "conceptual" (semantic).     

Effect of destruction of the frontal and parietal regions of the neocortex on the ability of dogs to solve extrapolation problems

Parietoectomized dogs (n = 8), like intact ones (n = 102), are able to extrapolate the direction of the movement of an alimentary stimulus when presented with a complex task variant. In this they differ from animals with a prefrontal lobectomy (n = 10) in which, according to the authors' previous data (1971), the ability to elementary rational activity in Krushinsky extrapolation test (1977), is impaired.     

Learning an operant conditioning task differentially induces gliogenesis in the medial prefrontal cortex and neurogenesis in the hippocampus

Circuit modification associated with learning and memory involves multiple events, including the addition and remotion of newborn cells trough adulthood. Adult neurogenesis and gliogenesis were mainly described in models of voluntary exercise, enriched environments, spatial learning and memory task; nevertheless, it is unknown whether it is a common mechanism among different learning paradigms, like reward dependent tasks. Therefore, we evaluated cell proliferation, neurogenesis, astrogliogenesis, survival and neuronal maturation in the medial prefrontal cortex (mPFC) and the hippocampus (HIPP) during learning an operant conditioning task. This was performed by using endogenous markers of cell proliferation, and a bromodeoxiuridine (BrdU) injection schedule in two different phases of learning. Learning an operant conditioning is divided in two phases: a first phase when animals were considered incompletely trained (IT, animals that were learning the task) when they performed between 50% and 65% of the responses, and a second phase when animals were considered trained (Tr, animals that completely learned the task) when they reached 100% of the responses with a latency time lower than 5 seconds. We found that learning an operant conditioning task promoted cell proliferation in both phases of learning in the mPFC and HIPP. Additionally, the results presented showed that astrogliogenesis was induced in the medial prefrontal cortex (mPFC) in both phases, however, the first phase promoted survival of these new born astrocytes. On the other hand, an increased number of new born immature neurons was observed in the HIPP only in the first phase of learning, whereas, decreased values were observed in the second phase. Finally, we found that neuronal maturation was induced only during the first phase. This study shows for the first time that learning a reward-dependent task, like the operant conditioning, promotes neurogenesis, astrogliogenesis, survival and neuronal maturation depending on the learning phase in the mPFC-HIPP circuit.     

Use of cloprostenol as an abortifacient in the llama (Lama glama)

As part of a larger project investigating the development and heritability of choanal atresia glama), it was necessary to develop a protocol for aborting llamas at various stages of gestation. Twenty-seven animals between 4 and 7 mo of gestation were successfully aborted a total of 53 times following two 250 microg intramuscular injections of cloprostenol at 24 h intervals. Abortion was induced once in 10 animals and multiple times (range 2 to 5) in 17 animals. Twenty-four animals (45.2%) aborted 3 d following the first injection, with 20 animals (37.7%) aborting 4 d post prostaglandin administration. Other animals aborted at 2 d (n=6, 11.3%), 5 d (n=2, 3.8%), and 7 d (n=1, 1.9%) following drug administration. Forty-nine (92.5%) of the abortions occurred following a single series of injections, while 4 animals (7.5%) aborted following a second series of injections. No confirmed pregnant animals failed to abort following the second series of cloprostenol injections. Conception rates in animals rebred 2 to 4 wk following an abortion were comparable to those of untreated animals in the research herd. Unlike the severe hypertension and death that has been reported following dinoprost tromethamine administration in the llama, no adverse reactions were observed in this study following cloprostenol administration. The results demonstrate that llamas can be safely and effectively aborted up to 7 mo of gestation (normal full term gestation = 342 +/- 10 days) without adverse effects on subsequent fertility.     

Effect of amizil and the ACTH4-10 fragment on the ability of mice to extrapolate the direction of movement

Mice possessing the ability to extrapolate the direction of movement (100% of correct choices) were injected i.p. with different doses of m-cholinolytic amizil 2 hours before experiment. Doses of 2-5 mg/kg reduced the percentage of correct choices, the adequate solving strategy being replaced by stereotyped unidirectional reactions or stereotyped alternating responses. Doses of 8-12 mg/kg induced "refusals" to solve extrapolation problem. When amizil treated mice were intraventricularly injected with 1 mg/kg of ACTH4-10, their extrapolation ability was restored. This compensatory action of peptide could be mediated by its influence on cholinergic as well as on other neurotransmitter systems.     

The relationship between plumage colouration,problem‐solving and learning performance in great tits Parus major

Recent studies suggest that individuals with better problem‐solving and/or learning performance have greater reproductive success, and that individuals may thus benefit from choosing mates based on these performances. However, directly assessing these performances in candidate mates could be difficult. Instead, the use of indirect cues related to problem‐solving and/or learning performance, such as condition‐dependent phenotypic traits, might be favored. We investigated whether problem‐solving and learning performance on a novel non‐foraging task correlated with sexually selected plumage colouration in a natural population of great tits Parus major. We found that males successful in solving the task had darker blue‐black crowns than non‐solvers, and that males solving the task more rapidly over multiple attempts (i.e. learners) exhibited blue‐black crowns with higher UV chroma and shorter‐wavelength hues than non‐learners. In contrast, we found no link between behavioural performance on the task and the yellow breast colouration in either sex. Our findings suggest that blue‐black crown colouration could serve as a signal of problem‐solving and learning performance in wild great tit males. Further research remains necessary to determine whether different sexually selected traits are used to signal cognitive performance for mate choice, either directly (i.e. cognitive performance influencing individual's health and ornamentation through diet for example) or indirectly (i.e. due to a correlation with a third factor such as individual quality or condition).     

Solution of Revecz-Krushinskii test by animals of different taxonomic groups

There has been compared behavior of rats, corvid birds, and monkeys of different species at their performance of the Revecz-Krushinskii test (RKT) developed by L.V. Krushinskii to estimate the human capability for revealing rule of discrete translocation of hidden target object. RKT was introduced as an addition to the test for extrapolation of the movement direction of the lure seen only at the initial pathway fragment; this test is close to Piaget’s test (stage 6) evaluating the capability for mental representation and location of the moving hidden object. During RKT, the lure, hidden from animals, was placed, near where it was previous time: at the first test presentation—under the 1st cylinder, at the 2nd one—under the 2nd cylinder, etc. The animals were tested once. It was shown that they did not catch the necessary for successful solution rule of the lure translocation, direction and step of its translocation at each presentation. Only some of the animals solved RKT, found the lure 3 and more times in succession with no errors or with one error. Nevertheless, in all groups the number of errors was lower than that in the model situation of random search. Such optimization was a consequence of universal for all groups’ strategy of search in the places where the lure was found recently. With the similar number of errors, rats, birds, and monkeys performed the search differently. Rats were looking for lure mainly among the cylinders where they had found it previously, whereas monkeys and birds the first the new cylinders located near the target one, which implies the existence, to the weak extent, of elements of prognosis. For all groups of animals, RKT turned out to be more difficult both of the test for extrapolation and of the Piaget’s test.     

Craniotopic updating of visual space across saccades in the human posterior parietal cortex

The neural mechanisms underlying the craniotopic updating of visual space across saccadic eye movements are poorly understood. Previous single-unit recording studies in primates and clinical studies in brain-damaged patients have shown that the posterior parietal cortex (PPC) has a key role in this process. In the present study, we used single-pulse transcranial magnetic stimulation (TMS) to disrupt the processing within the PPC during a task that requires craniotopic updating: double saccades. In this task, two targets are presented in quick succession and the subject is required to make a saccade to each location as accurately as possible. We show here that TMS delivered to the PPC just prior to the second saccade effectively disrupts the craniotopic coding normally observed in this task. This causes subjects to revert to saccades more consistent with a representation of the targets based on their positions relative to one another. By contrast, stimulation at earlier times between the two saccades did not disrupt performance. These results suggest that extraretinal information generated during the first perisaccadic period is not put into functional use until just prior to the second saccade.     

Pull or Push? Octopuses Solve a Puzzle Problem

Octopuses have large brains and exhibit complex behaviors, but relatively little is known about their cognitive abilities. Here we present data from a five-level learning and problem-solving experiment. Seven octopuses (Octopus vulgaris) were first trained to open an L shaped container to retrieve food (level 0). After learning the initial task all animals followed the same experimental protocol, first they had to retrieve this L shaped container, presented at the same orientation, through a tight fitting hole in a clear Perspex partition (level 1). This required the octopuses to perform both pull and release or push actions. After reaching criterion the animals advanced to the next stage of the test, which would be a different consistent orientation of the object (level 2) at the start of the trial, an opaque barrier (level 3) or a random orientation of the object (level 4). All octopuses were successful in reaching criterion in all levels of the task. At the onset of each new level the performance of the animals dropped, shown as an increase in working times. However, they adapted quickly so that overall working times were not significantly different between levels. Our findings indicate that octopuses show behavioral flexibility by quickly adapting to a change in a task. This can be compared to tests in other species where subjects had to conduct actions comprised of a set of motor actions that cannot be understood by a simple learning rule alone.     

Methodological issues with the interpolated twitch technique.

A number of methodological issues in the use of the interpolated twitch technique were investigated for their effect on true maximum force (TMF) and activation (ACT): timing of control (pre- vs post-contraction) and superimposed twitches (first vs second); type of twitch stimulus (primarily magnitude); and the type of extrapolation utilised. On three occasions subjects performed a series of maximal and sub-maximal contractions of the knee extensors, with electrically evoked twitches delivered before, during and after each contraction. The twitch-voluntary force relationship was concave for all types of twitch stimuli, and extrapolation using this relationship typically calculated TMF 39N (7%) higher, and ACT 7% lower than linear extrapolation. The timing of the control (2-4%) and superimposed twitches (approximately 4%) both influenced TMF and ACT. Despite the different twitch stimuli being a range of magnitudes (13-32% maximum voluntary force) they did not affect TMF and ACT. A novel finding was that prior potentiation changed the shape of the twitch-voluntary force relationship. For precise measurement of TMF and ACT it is recommended that: extrapolation is based on the twitch-voluntary force relationship of the experimental model; and post-contraction potentiated twitches be used, as the superimposed twitch on a high level contraction appears to be potentiated.     

Role of the neocortical and subcortical commissures in the interhemispheric transfer of visual information to the hippocampus

The light flash evoked potentials were recorded in the hippocamp of cats with transected left optic tract and cerebral commissures. The data obtained show a significant reduction in the response amplitude (by 1.5-2 times) in both hemispheres after unilateral transection of the optic tract. The minimal response amplitude (10-15 times less than normal) was recorded in the left hippocamp of cats with additional transection of the commissures of the endbrain, mesencephalon and diencephalon. In contrast, the latent period of the first and second components of the evoked potential was similar to that in the control group animals. It is suggested that the neocortical commissural visual inputs play the most important role in interhemispheric transmission of visual information to the hippocamp.     

Temporal organization of multi-whisker contact in rats

Previous work has established that during exploration and discrimination, rats move their whiskers at frequencies between 6 and 12 Hz and that whisking frequency changes during contact. One critical component of any tactile system is contact. In the rat whisker system, such contacts may involve one or more vibrissa in the whisker array and contact duration of each whisker may vary over a considerable range, depending upon the behavioral context. However, little is known about the variables controlling contact duration or about the temporal relationships among contacts by adjacent whiskers. To address these issues head fixed rats were trained to touch a piezo-contact-sensor with the shaft of their whiskers (Bermejo and Zeigler, Somatosens Mot Res 17: 373-377, 2000). During the task, whisker movements and contacts were monitored with a high-speed camera at 500 frames/s and stored on videotape. To facilitate analysis, animals had their whiskers selectively trimmed. Data are reported from animals with C1 & C2, D1 & D2, or Arc2 (E2, D2, C2, B2) whiskers intact. For both row and arc animals, when just a single whisker touched the sensor the duration of contact was significantly shorter than when multiple whiskers made contact. When multiple whiskers made contact, onset was rarely simultaneous. Furthermore, in row-intact animals, contact progressed in an orderly fashion such that the rostral whisker in a row made contact first followed 24 ms (SE = 1.9 ms) later by the caudal whisker. When contact reversed the caudal whisker lifted off first, followed by the rostral whisker. Thus, the order in which whiskers touch an object regulates contact duration: the first whisker to touch the sensor stays in contact longer than any other whisker. The temporal discharge properties of neurons in the trigeminal system are expected to reflect position of whiskers on the nose.     

Temporal organization of multi-whisker contact in rats

Previous work has established that during exploration and discrimination, rats move their whiskers at frequencies between 6 and 12 Hz and that whisking frequency changes during contact. One critical component of any tactile system is contact. In the rat whisker system, such contacts may involve one or more vibrissa in the whisker array and contact duration of each whisker may vary over a considerable range, depending upon the behavioral context. However, little is known about the variables controlling contact duration or about the temporal relationships among contacts by adjacent whiskers. To address these issues head fixed rats were trained to touch a piezo-contact-sensor with the shaft of their whiskers (Bermejo and Zeigler, Somatosens Mot Res 17: 373-377, 2000 ). During the task, whisker movements and contacts were monitored with a high-speed camera at 500 frames/s and stored on videotape. To facilitate analysis, animals had their whiskers selectively trimmed. Data are reported from animals with C1 & C2, D1 & D2, or Arc2 (E2, D2, C2, B2) whiskers intact. For both row and arc animals, when just a single whisker touched the sensor the duration of contact was significantly shorter than when multiple whiskers made contact. When multiple whiskers made contact, onset was rarely simultaneous. Furthermore, in row-intact animals, contact progressed in an orderly fashion such that the rostral whisker in a row made contact first followed 24 ms (SE = 1.9 ms) later by the caudal whisker. When contact reversed the caudal whisker lifted off first, followed by the rostral whisker. Thus, the order in which whiskers touch an object regulates contact duration: the first whisker to touch the sensor stays in contact longer than any other whisker. The temporal discharge properties of neurons in the trigeminal system are expected to reflect position of whiskers on the nose.     

Inhibitory effects of selenium on the growth of DU-145 human prostate carcinoma cells in vitro

The growth of DU-145 human prostate carcinoma cells is reduced to 50% of control by 1 X 10(-6) M to 2 X 10(-6) M selenium and to 2% of control at 10(-4)M selenium. These cells show greater sensitivity to inhibition of growth or DNA synthesis by selenium than human W1-38 and HeLa cells and mouse mammary tumor cells. It has been shown that selenium inhibits carcinogenesis and reduces the incidence of chemical carcinogen and virus-induced tumors of a variety of organs in animals. Selenium may also inhibit the growth of certain tumor cells of non-human origin. To our knowledge, this is the first study on the effects of selenium on the growth of human tumor cells. From extrapolation, it is deduced that selenium serum levels in humans living in high selenium areas may be as high as 10(-6) M and could be effective in inhibiting the growth of tumor cells in vivo. These findings have implications in the prevention and intervention of prostate cancer in man.