55 research outputs found
Effects of isolation on activity, reactivity, excitability and aggressive behavior in two inbred strains of mice.
No full textIn order to investigate mechanisms of isolation-induced aggressive behaviour, inbred mice of the C57BL/6 and DBA/2 strains were individually housed over a period of 8 weeks. In the DBA/2 strain only, isolation was followed by a clear increase in activity (Animex), reactivity (reactions upon tactile body stimulation), excitability (duration of EEG desynchronization elicited by tactile stimulation of the thorax area under urethane anesthesia) and intermale aggression (biting and fighting responses). The use of inbred strains of mice proved to be a useful tool for the examination of the relationship between various parameters. It is concluded that there are no clear correlations between activity, reactivity and aggressive behavior and that the resulting aggressive responses in the DBA/2 strain are likely due to the increase of excitability
Variation in Environmental Parameters in Research and Aquaculture: effects on behaviour, physiology and cell Biology of Teleost fish
No full textOver the last few years the increasing use of fish as animal models in scientific research and the increased fish breeding for human consumption have stressed the need for more knowledge on the effect of variations in environmental parameters on fish biology and on the welfare of specimens used both in research and aquaculture contexts. Experimental evidence shows that environmental variations can affect fish biology at various levels, from the molecular to that of the population, sometimes in a different way depending on the species considered. In order to achieve reproducible results in experiments involving fish it is necessary to set and maintain all environmental parameters constant at the optimal value to guarantee the wellness of the animal. The effects of the variation in environmental parameters on the behaviour, physiology and cell biology of teleosts are here discussed in order to provide useful information for research based on fish models
Feeding Behaviour of Larval European Sea Bass (Dicentrarchus labrax L.) in Relation to Temperature and Prey Density
No full textThe feeding behaviour of larval European sea bass (Dicentrarchus labrax, L.) was analysed in relation to temperature and prey
density under controlled laboratory conditions with the aim to assess the ability of larval fish to change the feeding tactic as a
response to environmental changes. Larvae were acclimated for 20 days at three different temperatures (19, 22 and 26°C), and
their feeding behaviour was then video-recorded in experimental trials, at two prey densities, consisting of swarms of 400/l
and 1440/l Artemia nauplii. Results showed that there was a significant effect of the interaction between temperature and prey
density on the proportion of swimming activity that was reduced at the high temperature-high prey density combination. This
suggested a switching in the larval feeding behaviour from an active to an ambush tactic, when the temperature reached 26°C
and the prey density was 1440 /l Artemia nauplii. These results are consistent with the current literature on fish larval behaviour
in showing that the foraging tactic can be modulated by the interaction of different abiotic and biotic factors characterising the
rearing environment
Effetti dell’incremento termico sul comportamento antipredatorio di giovanili di spigola (Dicentrachus labrax L. )
No full textAnkle Prosthesis with an Active Control of the Pitch and the Release of the Energy
No full textThis paper describes a model of a prosthesis of ankle able to control the pitch and the release of energy recovered during the gait; moreover, the model is able to provide to the user more power than the one recovered during the gait, in order to ensure a natural gait. The development of the model has been articulated in 3 steps: the study of the gait of able body people; the design of a mechanical system able to adjust the pitch of the ankle and at the same time able to store the mechanical energy; the development of an active control of the foot and of the energy recovery system. The conceived model is made of a four-bar linkage with a further fifth element. Two of those elements can modify the length: one is an active shock absorber for damping and for the energy recovery; the other is a linear actuator for the pitch adjusting. The first is equipped with two control flow valves; the second is made of a screw nut mechanism. The control system is based on a central control unit that detects signals from three sensors to determine the gait phase, to control the shock absorber and to adapt the actuator to the correct position
Activation of 5-HT7 receptor by administration of its selective agonist, LP-211, modifies explorative-curiosity behavior in rats in two paradigms which differ in visuospatial parameters
No full textAims: The serotonin 7 receptor (5-HT7R) subtype, coded by Htr7 gene, is broadly expressed in the central nervous system (CNS) with clear involvement in behavioral functions such as learning/memory, regulation of mood, and circadian rhythms. In this study, we assessed effects of 5-HT7R stimulation by administration of its selective agonist, LP-211 (0.25 mg/kg i.p.), in adult Wistar-Han rats. Methods: We used two different explorative-curiosity tests. Drug was administered either before one side-chamber familiarization (CF/V group) or immediately after it, to act on consolidation of familiarization (V/CF group). Results: Exp. 1 for novelty seeking in black/white boxes (BWB), with door opening after 5 minutes in the familiar chamber, showed that (i) time spent in the novel environment (significantly higher than in familiar chamber for controls) is enhanced in V/CF group (potentiated recognition for a “visual” consolidation) and not different in CF/V group; (ii) activity and chamber transitions, made by CF/V rats, are significantly higher than for other groups (interference on recognition for a “spatial” acquisition). Exp. 2 for novelty preference in D- vs L-shaped chambers (D/L), with start from neutral center, gave different results: (i) time spent in the novel environment by CF/V group is significantly higher than other groups (potentiated “cognitive” acquisition); (ii) chamber transitions made by V/CF group are significantly higher than other groups (potentiated “emotional” consolidation). Conclusion: These apparently conflicting results may reflect LP-211 effects on visual vs spatial memory (D/L apparatus has more pronounced hippocampal components than BWB). However, further experiments are needed to analyze more in depth the mechanisms involved
Powered off-road wheelchair for the transportation of tetraplegics along mountain trails
No full textPurpose: For off-road mobility, some manual or power assisted devices were conceived to be self-driven by paraplegics while for tetraplegics non power-assisted devices were conceived. These devices require one or more conductors who are subjected to a high physical demand thus potentially creating: precarious safety condition for the user an elevated physical demand of conductors could reduce the care and the attention to give to the user; the time of the outdoor adventure experience of the user could be limited. Methods: To address these issues, an innovative user-centered power assisted off-road wheelchair for the transportation of tetraplegics along mountain trails was developed. The device, structured like a trike, is driven by two healthy conductors; the user is placed in the middle of the frame. A movable seat provides for the transfer from the standard to the off-road wheelchair. An electrical motor, powered by a battery pack, provides for the actuation. All the design and prototype aspects, the control system and experimental tests are detailed. Results: The prototype satisfies mechanical, safety and duration requirements. No physical demand while using the device and for the transfer of the user to the device was identified. Fun and engaging tests were carried out and all the participants were involved.Implications for RehabilitationThe device has the potential to enhance the quality of life of tetraplegics in terms of new life experiences.The device revealed the real possibility of a full recreational experience, an enhanced participation and a better social integration of tetraplegics
Effects of temperature on the antipredator behaviour and on the cholinergic expression in the European sea bass (Dicentrarchus labrax L.) juveniles.
No full textIn this paper, an experimental approach was used to test for the parallel effects of temperature (T) increase on the antipredator behaviour and the cholinergic expression in the juvenile European sea bass (Dicentrarchus labrax L.). The effects of three T treatments (18, 22 and 26°C) were tested on the main behavioural components of the antipredator response towards live aquatic predators and aerial simulated attacks, whereas brain cholinergic expression was evaluated by choline acetyltransferase (ChAT) immunoblotting (Western blot) at the extreme values of the thermal range (18 and 26°C). Antipredator responses towards a live fish were analysed over pre-exposure and exposure phases within a short temporal scale (20 s before and after the stimulus). The results suggest that T modulates several quantitative components of the antipredator behaviour. The mean shoaling index (shoal cohesiveness) was higher at 22°C than at 18 and 26°C during both the pre-stimulus and the exposure phase. Conversely, the mean distances from the predator and the tank bottom were, respectively, lower and higher at 26°C than in the other two treatments. In regard to the antipredator response on the aerial stimulus, comparisons across treatments revealed statistically significant differences between fish performing freezing or latency to recovery, suggesting that the fright reaction has a higher persistence at the coldest T (18°C) than at 22 and 26°C. Western blot analysis revealed a reduction in brain ChAT expression in fish acclimated to 26°C compared to those at 18°C. Results were discussed in the light of the relationships between behavioural traits, metabolism and their consequences on the population level, as a response to climate change in coastal habitats. © 2013 Blackwell Verlag GmbH
A METHODOLOGY FOR THE DEVELOPMENT OF ACTIVE ANKLE PROSTHESIS
No full textIn the present work a methodology for the functional design of ankle prostheses is
presented. This methodology is applied to the functional design of an innovative active
prosthesis for the lower limb able to guarantee the physiologically correct movement
of the ankle. This new prosthesis, described in this paper, is based on a mechanism
with two links: one replaces the tibia and the other, coupled together with a hinge at
the ankle level, replaces the foot. For the functionality of the device, an active shock
absorber is placed between the two links and acts for damping and for accumulating
potential elastic energy; furthermore, the anchoring point of the shock absorber on
the tibia is adjustable by means of a motor that acts on a rocker arm. The
methodology for the functional design of ankle prosthesis is based on 4 steps: 1) the
analysis of the gait of able-bodied men with the definition of a dimensionless model of
the lower limb in a numerical computing environment; 2) the analysis of the force
exchanged with a sensorized treadmill in a virtual ambient; 3) the functional design of
the prosthesis able to adjust the pitch of the ankle and at the same time able to store
and provide the mechanical energy; 4) the preliminary draft of the control system of
the actuators able to define the law of motion to reproduce the physiological gait
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