Novelty stress and reproductive state alters responsiveness to sensory stimuli and 5-HT neuromodulation in crayfish

Sensory stimuli can produce varied responses depending on the physiological state of an animal. Stressors and reproductive stage can result in altered biochemical status that changes the responsiveness of an animal to hormones and neuromodulators, which affects whole animal behavior in relation to sensory stimuli. Crayfish serve as a model for examining the effects of neuromodulators at the neuromuscular junctions (NMJs) and for alterations in stereotypic behaviors for particular stimuli. Thus, we used crayfish to examine the effect of novelty stressors in males and the effect of being gravid in female crayfish to exogenous application of serotonin (5-HT). The responsiveness of neuromuscular junctions to 5-HT revealed that stressed as well as gravid crayfish have a reduced response to 5-HT at NMJs. The stressed crayfish were not fatigued since the basal synaptic responses are large and still showed a pronounced response to 5-HT. Using intact animals to examine a tail flip behavior, we showed that the rate of habituation in tail flipping to a strong repetitive stimulus on the telson is reduced in stressed males. Gravid females show no tail flipping behavior upon telson stimulation.     

Heart rate measures in blind cave crayfish during environmental disturbances and social interactions

Most animals continually assess the environment in which they live and alter their behavior according to various stimuli. As an observer, one looks for changes in a behavior indicating that an animal responded to a particular event. When the animal does not make significant behavioral changes as measured by bodily movements, the animal may be characterized as unresponsive to a given stimulus. This study demonstrates that when behavioral body movements can not be observed an internal physiological measure of heart rate (HR) shows dramatic changes following presentation of defined stimuli. This study used the blind cave crayfish and examined their responsiveness to the following stimuli: light (infrared, dim red, and white), water-borne vibrations, removal of water, olfactory cues, and social interaction with partners. This study demonstrates that there is substantial individual variation of HR at basal levels and with the intensity of an social interaction. We find HR is a reasonable measure of the responsiveness of blind cave crayfish to given stimuli even in the absence of observable behavioral changes. This enables the observer to determine if an individual is responsive to and making an assessment of particular cues.     

Long-term Behavioral Tracking of Freely Swimming Weakly Electric Fish

Long-term behavioral tracking can capture and quantify natural animal behaviors, including those occurring infrequently. Behaviors such as exploration and social interactions can be best studied by observing unrestrained, freely behaving animals. Weakly electric fish (WEF) display readily observable exploratory and social behaviors by emitting electric organ discharge (EOD). Here, we describe three effective techniques to synchronously measure the EOD, body position, and posture of a free-swimming WEF for an extended period of time. First, we describe the construction of an experimental tank inside of an isolation chamber designed to block external sources of sensory stimuli such as light, sound, and vibration. The aquarium was partitioned to accommodate four test specimens, and automated gates remotely control the animals'' access to the central arena. Second, we describe a precise and reliable real-time EOD timing measurement method from freely swimming WEF. Signal distortions caused by the animal''s body movements are corrected by spatial averaging and temporal processing stages. Third, we describe an underwater near-infrared imaging setup to observe unperturbed nocturnal animal behaviors. Infrared light pulses were used to synchronize the timing between the video and the physiological signal over a long recording duration. Our automated tracking software measures the animal''s body position and posture reliably in an aquatic scene. In combination, these techniques enable long term observation of spontaneous behavior of freely swimming weakly electric fish in a reliable and precise manner. We believe our method can be similarly applied to the study of other aquatic animals by relating their physiological signals with exploratory or social behaviors.     

Behavioral study of chemoreception in the sea starMarthasterias glacialis: Structure-activity relationships of lactic acid,amino acids,and acetylcholine

Behavioral responses of Marthasterias glacialis to low molecular compounds were studied under laboratory conditions. Feeding postures, stomach eversions and locomotion of initially inactive animals can be released with very dilute solutions of lactic acid, neutral 2 and 3 carbon amino acids, L isomers of 4 to 6 carbon neutral amino acids, L-arginine, acetylcholine iodide, and several of their analogues. Hunger was induced by temporary withdrawal of food. Responsiveness to feeding stimuli was controlled with L-cysteine and L-leucine. The lowest behavioral thresholds for the most effective feeding stimuli were 3 X 10(-11) mol/l for both enantiomers of lactic acid, 10(-8) mol/l for L-proline and both enantiomers of cysteine and 10(-7) mol/l for acetylcholine iodide and some of the effective neutral amino acids. The behavioral threshold values for chemical stimuli differed by a factor between 30 and 100 in different sea stars. The test concentration was 3 X 10(-7) mol/l, the level at which L-cysteine elicited a complete feeding response from all the animals. Structure-activity comparison of substances less effective than the control stimulus was thus possible. The behavioral threshold of fully effective substances was determined later. The independence of receptor mechanisms for different substances can be inferred as: L-cysteine controlled responsiveness is not always accompanied by responsiveness to neutral amino acids. Autotomized marthasterias arms crawled after stimulation with lactic acid, cysteine, and acetylcholine iodide but did not respond to the feeding stimuli betaine and L-proline. An animal became inactive if electric shocks were paired with L-proline or L-cysteine emanating from an 'electric' food model.(ABSTRACT TRUNCATED AT 250 WORDS)     

Methods to Test Visual Attention Online

Online data collection methods have particular appeal to behavioral scientists because they offer the promise of much larger and much more representative data samples than can typically be collected on college campuses. However, before such methods can be widely adopted, a number of technological challenges must be overcome – in particular in experiments where tight control over stimulus properties is necessary. Here we present methods for collecting performance data on two tests of visual attention. Both tests require control over the visual angle of the stimuli (which in turn requires knowledge of the viewing distance, monitor size, screen resolution, etc.) and the timing of the stimuli (as the tests involve either briefly flashed stimuli or stimuli that move at specific rates). Data collected on these tests from over 1,700 online participants were consistent with data collected in laboratory-based versions of the exact same tests. These results suggest that with proper care, timing/stimulus size dependent tasks can be deployed in web-based settings.     

Effects of oestradiol-17 beta on peripheral plasma concentrations of LH and FSH in ovariectomized tammars (Macropus eugenii)

Two experiments, each using 8 animals, were conducted in the non-breeding and breeding seasons, respectively, and each animal was injected with 4 different doses of oestradiol benzoate over 4 trials. The resulting physiological concentrations of plasma oestradiol caused depression of both LH and FSH values. The highest dose elicited a biphasic response in LH with a pulse-like surge at 24 h after injection. There was no significant difference between the response of either hormone at the two times of the year and it is concluded that, in tammars, there is no seasonal difference in the responsiveness of the hypothalamus/pituitary to the negative feedback effect of oestradiol.     

Heart and ventilatory measures in crayfish during environmental disturbances and social interactions

Most animals assess the environment in which they live and alter their behavior according to various stimuli. When the animal does not make significant behavioral changes, as measured by bodily movements, the animal may be characterized as unresponsive to a given stimulus. This study demonstrates that when behavioral movements of crayfish cannot be observed, physiological measures of heart rate (HR) and ventilatory rate (VR) show dramatic changes in response to defined sensory stimuli. In the majority of cases, upon anticipation of a social interaction with another crayfish both HR and VR will increase. During an agonistic encounter between two crayfish, the level of HR and VR correlate with the intensity of the interaction. Such rapid responses in cardiac and respiratory systems to environmental disturbances and anticipation of a social interaction suggest an autonomic-like regulation associated with fear, flight or fight. Since behavioral observations do not allow an internal status to be readily assessed, we suggest that HR and VR may serve as a useful bioindex in crustaceans to their internal drive or possibly an awareness level to environmental cues.     

Peculiarities of Cardiac Activity in the Crayfish Astacus astacus in Different Functional States

Analyzed are changes of temporal and amplitude characteristics of the cycles in animals in different functional states, using a non-invasive method of recording of cardiac activity in the adult noble crayfish Astacus astacus L. under laboratory conditions. It has been shown that the state of excitation in the crayfish after action of an intense stimulus lasts for a long time (more than 1 h) and can have no manifestations in some observed behavioral responses. Based only on the cardiac response (the heart rate), the real physiological state of the animal could be evaluated. Characteristic of the excited animal is a short-term response to the stimulus. In a high excitement of the animal (a high heart rate), significant transformations of the heart activity in response to other current stimuli may be barely noticeable. For the quiet animal, the response to a stimulus is longer than for the excited animal at the same stimulus intensity; for a comparative search for significant readjustments of the animal state, based on the heart activity parameters, the cardiograms typical of the quiet animal should be used. In the quiet animals, the cardiogram parameters change to a greater extent than in the excited ones. The quiet animals have longer diastole duration (DD) than the systole duration (SD). The diastole amplitude (DA) is higher than the systole amplitude (SA), and DA changes more markedly than SA. The healthy animals are characterized by equal values of DD and SD, sometimes by longer SD than DD, but, on the background of a continuing action, their values and the values of DA and SA become equal. There were noted a negative correlation between the systolic and diastolic phases by temporal parameters for healthy animals and an increase of the correlation significance in transition of the animal into the excited state. Based on the cardiovascular system response, the chief features of a shift of the functional crayfish state to pathological direction seem to include a stable heart rate reduction, a decrease of the heart contraction amplitude, a more frequent predominance of SD over DD, an increase of the means and the standard deviations of the parameters, especially of the cycle amplitudes. Changes of the sign and significance of correlation relations between inotropic and chronotropic parameters of cardiac activity in sick animals appear to indicate a disturbed mechanism of central coordination of the cardiovascular system work with its autonomic mechanisms. The results are discussed on the basis of known mechanisms of the heart activity control in Decapoda. The records of cardiac activity, such as laser light cardiograms (LLC), in testaceous invertebrates may be useful and interesting in studies on mechanisms and processes of internal control and management of the cardiovascular system activity of the animals.     

Sensory representation abnormalities that parallel focal hand dystonia in a primate model

In our hypothesis of focal dystonia, attended repetitive behaviors generate aberrant sensory representations. Those aberrant representations interfere with motor control. Abnormal motor control strengthens sensory abnormalities. The positive feedback loop reinforces the dystonic condition. Previous studies of primates with focal hand dystonia have demonstrated multi-digit or hairy-glabrous responses at single sites in area 3b, receptive fields that average ten times larger than normal, and high receptive field overlap as a function of horizontal distance. In this study, we strengthen and elaborate these findings. One animal was implanted with an array of microelectrodes that spanned the border between the face and digits. After the animal developed hand dystonia, responses in the initial hand representation increasingly responded to low threshold stimulation of the face in a columnar substitution. The hand-face border that is normally sharp became patchy and smeared over 1 mm of cortex within 6 weeks. Two more trained animals developed a focal hand dystonia variable in severity across the hand. Receptive field size, presence of multi-digit or hairy-glabrous receptive fields, and columnar overlap covaried with the animal's ability to use specific digits. A fourth animal performed the same behaviors without developing dystonia. Many of its physiological measures were similar to the dystonic animals, but receptive field overlap functions were minimally abnormal, and no sites shared response properties that are normally segregated such as hairy-glabrous combined fields, or multi-digit fields. Thalamic mapping demonstrated proportionate levels of abnormality in thalamic representations as were found in cortical representations.     

Sensory representation abnormalities that parallel focal hand dystonia in a primate model

In our hypothesis of focal dystonia, attended repetitive behaviors generate aberrant sensory representations. Those aberrant representations interfere with motor control. Abnormal motor control strengthens sensory abnormalities. The positive feedback loop reinforces the dystonic condition. Previous studies of primates with focal hand dystonia have demonstrated multi-digit or hairy-glabrous responses at single sites in area 3b, receptive fields that average ten times larger than normal, and high receptive field overlap as a function of horizontal distance. In this study, we strengthen and elaborate these findings. One animal was implanted with an array of microelectrodes that spanned the border between the face and digits. After the animal developed hand dystonia, responses in the initial hand representation increasingly responded to low threshold stimulation of the face in a columnar substitution. The hand-face border that is normally sharp became patchy and smeared over 1 mm of cortex within 6 weeks. Two more trained animals developed a focal hand dystonia variable in severity across the hand. Receptive field size, presence of multi-digit or hairy-glabrous receptive fields, and columnar overlap covaried with the animal's ability to use specific digits. A fourth animal performed the same behaviors without developing dystonia. Many of its physiological measures were similar to the dystonic animals, but receptive field overlap functions were minimally abnormal, and no sites shared response properties that are normally segregated such as hairy-glabrous combined fields, or multi-digit fields. Thalamic mapping demonstrated proportionate levels of abnormality in thalamic representations as were found in cortical representations.     

Is there “pain” in Invertebrates?

In contrast to nociception, the perception of pain, or pain experience, remains a subjective notion applicable to humans, but untestable with animals. Yet, when defined operationally as a physiological response induced in an animal by stimuli painful to humans, and resulting in a protective stimulus avoidance response, pain is amenable to testing with non-human subjects. This paper considers a series of examples showing responses to stimuli that are both painful (nociceptive) and responsible for eliciting natural self-preserving behavior in Invertebrates. Consideration is also given to the evolution and possible mechanism underlying the “pain-system” in Invertebrates.     

Narcolepsy,orexins and respiratory regulation

Narcolepsy is a debilitating sleep disorder characterized by excessive daytime sleepiness, cataplexy and intrusive rapid–eye movement sleep. Deficits in endogenous orexins are a major pathogenic component of the disease. This disorder is also associated with the gene marker HLADQB1*0602. Orexins as hypothalamic neuropeptides have multiple physiological functions, and their primary functions are regulation of the sleep–wake cycle and feeding. Evidence from animal studies using orexin knockout mice and focal microdialysis of an orexin receptor antagonist at the retrotrapezoid nucleus and medullary raphe in rats demonstrated that orexins also contribute to respiratory regulation in a vigilance state–dependent manner, as animals with orexin dysregulation have attenuated hypercapnic ventilatory responses predominantly in wakefulness. These findings are consistent with the notion that the activity of orexinergic neurons is higher during wake than sleep periods. Orexin neurons seem to be a pivotal link between conscious and unconscious brain functions in animals. The human model of hypocretin deficiency is patients with narcolepsy–cataplexy. In contrast to the findings suggested by animal studies, we found significant decreases in hypoxic responsiveness, but not in hypercapnic responsiveness, in narcoleptics, and further analysis indicated that decreased ventilatory responses to hypoxia in human narcolepsy–cataplexy is in relation to HLA-DQB1*0602 status, not hypocretin deficiency. This is confirmed by the fact that the hypoxic responsiveness was lower in HLA positive versus negative controls. Unlike in mice, hypocretin-1 is not a major factor contributing to depressed hypoxic responses in humans. Species differences may exist.

     

What can we know from pituitary-adrenal hormones about the nature and consequences of exposure to emotional stressors?

Exposure to stress induces profound physiological and behavioral changes in the organisms and some of these changes may be important regarding stress-induced pathologies and animal models of psychiatric diseases. Consequences of stress are dependent on the duration of exposure to stressors (acute, chronic), but also of certain characteristics such as intensity, controllability, and predictability. If some biological variables were able to reflect these characteristics, they could be used to predict negative consequences of stress. Among the myriad of physiological changes caused by stress, only a restricted number of variables appears to reflect the intensity of the situation, mainly plasma levels of ACTH and adrenaline. Peripheral hypothalamic-pituitary-adrenal (HPA) hormones (ACTH and corticosterone) are also able to reflect fear conditioning. In contrast, the activation of the HPA axis is not consistently related to anxiety as evaluated by classical tests such as the elevated plus-maze. Similarly, there is no consistent evidence about the sensitivity of the HPA axis to psychological variables such as controllability and predictability, despite the fact that: (a) lack of control over aversive stimuli can induce behavioral alterations not seen in animals which exert control, and (b) animals showed clear preference for predictable versus unpredictable stressful situations. New studies are needed to re-evaluate the relationship between the HPA axis and psychological stress characteristics using ACTH instead of corticosterone and taking advantages of our current knowledge about the regulation of this important stress system.     

Effects of predictability on the welfare of captive animals

Variations in the predictability of a stressor have pronounced effects on the behavioural and physiological effects of stress in rats. It is reasonable to expect that variations in the predictability of husbandry routines thought to be aversive to animals might have similar effects on stress indices. Similarly, variations in the predictability of positive events, of which feeding is an obvious example, may affect welfare. This review examines the behavioural and physiological effects of the predictability of aversive and appetitive stimuli, and the application of experimental findings to animal husbandry in practice. It is argued here that two distinct but overlapping types of predictability exist. ‘Temporal’ predictability describes whether an event occurs at fixed or variable intervals, whereas ‘signalled’ predictability relates to the reliability of a signal preceding the event. This review examines the effects of each of these types of predictability in relation to positively and negatively perceived events, and examines the link between predictability and control. Recommendations are made for relatively simple and inexpensive modifications to husbandry routines that may be easy to incorporate into the schedules of busy staff yet could have a profound impact on the welfare of animals in their care.     

Attitudes toward Animals among Kindergarten Children: Species Preferences

ABSTRACT

Attitudes toward animals are influenced by both animal traits (e.g., similarity to humans, aesthetic quality, size) and individual human attributes (e.g., gender, age, educational level, cultural factors). Although the examination of children's interest in animals, and their preference for different species, may evidence specific trends and help explain the development of attitudes, the vast majority of research has not considered children younger than 6 years. The present study was aimed at assessing preferences for a variety of animal species in a sample of 3–6 year-old Italian children, using a forced-choice task and visual aids (images of the animals). Pictures of 48 animal species, ranging from mammals to invertebrates, were presented to the children. Two photographic stimuli were simultaneously displayed and participants were asked to indicate their preference. Results show that the children preferred higher-order species, and domestic over wild animals. Apart from a few exceptions, invertebrates were the most disliked group of species among the children. Girls showed more negative and fear-related attitudes than the boys. Results are discussed taking into account different factors that may affect children's preferences for various animal species, that is, similarity to humans and aesthetical appeal. Greater knowledge on early attitudes toward animals has implications for promoting interest in animals and for building educational interventions for kindergarten children. This is particularly important in light of the growing use of different animals in educational and therapeutic contexts, as well as from an animal welfare perspective.     

Changes in molluscan neurosecretory cells during reproductive cessation: cause or effect?

The pond snail Lymnaea stagnalis has a maximum life span of about 22 months. At the age of about 250 days animals start to decrease egg laying activity and at about 500 days most animals ceased egg laying activity. At the age of cessation of egg laying the neurosecretory caudodorsal cells (CDCs) which control egg laying in Lymnaea exhibit reduced branching patterns. At this stage the cells still exhibit their physiological properties. CDCs still contain biologically active peptides and in the isolated CNS they still exhibit an afterdischarge upon electrical stimulation. Probably in the intact animal cessation of egg laying occurs because the CDCs are not activated anymore by natural egg laying inducing stimuli. In very old animals CDCs exhibit signs of degeneration indicating that cell death occur. After an extended period of no egg laying of Lymnaea physiological changes occur in the CDCs. CDCs from animals after an extended period of no egg laying failed to exhibit an afterdischarge. In such CDCs chemical and electrical coupling among the CDCs are reduced. Morphologically reduced CDCs predominantly fail to exhibit an afterdischarge. However, there are minimally branched CDCs that still could give an afterdischarge. Probably morphological reduction is not the only factor that defines afterdischarge failure. At present we suggest the following sequence of changes. 1. Morphological reduction of CDC branching patterns. 2. Cessation of egg laying. 3. Physiological changes in the CDCs resulting in afterdischarge failure. 4. Further morphological and physiological deterioration of CDCs.     

Predator discrimination and 'personality' in captive Vancouver Island marmots (Marmota vancouverensis)

A major impediment to recovering declining populations successfully is the mortality of reintroduced or translocated animals. We generally assume that captive-born animals may lose their antipredator behaviour abilities in captivity, but studies rarely compare predator recognition abilities of captive-born and wild-captured animals to test this. To identify whether predator discrimination abilities of the critically endangered Vancouver Island marmots Marmota vancouverensis were lost in captivity, we presented wild-captured and captive-born marmots with taxidermic mounts of predators (a cougar Felis concolor and wolf Canis lupus ) together with control stimuli (marmot, domestic goat Capra aegagrus , the cart on which all stimuli were presented and a 'blank' no-stimulus control). Regardless of specific predator discrimination abilities, for some species overall 'personality' may be associated with response to predators and subsequent survival. Thus, to quantify overall reactivity in the presence of a predator, we also conducted a mirror-image stimulus (MIS) presentation experiment where marmots were video-recorded with or without the presence of a wolf. Marmots discriminated among these stimuli, responding the most to the wolf and cougar. The MIS results suggest that marmots varied along a continuum of reactivity. The amount of reactivity was unaffected by the presence of a wolf, and was correlated with our highest level of responsiveness (vigilance at the burrow and time within the burrow) to the wolf. Taken together, we conclude that marmots differentiate predators from non-predators and that this ability has not been lost under the conditions in which they have been reared.     

Octopamine effects mimick state-dependent changes in a proprioceptive feedback system

The modulatory actions of the biogenic amine octopamine on the femur tibia (FT) control loop in the stick insect Carausius morosus were examined. The response properties of the FT control loop were determined under open loop conditions. Mechanical stimulation of the femoral chordotonal organ (fCO) was the input and tibial movement and motoneuronal activity were measured as the output of the system. Following octopamine injection into the hemolymph of intact, inactive animals, two consecutive phases occurred at the behavioral level. Octopamine caused initially an activation of the animal. During this first phase (3.5–12 min duration) the response properties of the FT control loop were similar to those found in animals that were activated by tactile stimuli under normal conditions. Afterward, animals became inactive. During this second phase (15–20 min duration), the gain of the control loop was zero and no resistance reflex in the FT joint was generated in response to fCO stimulation. However, active movements of the tibia could still be elicited. As we could show in restrained animals, where dl-octopamine was applied topically onto the undesheated mesothoracic ganglion, the complete suppression of the resistance reflex on the motoneuronal level was dose dependent starting at concentrations of 5 ± 10^?3 M octopamine. We could show that octopamine specifically suppressed the pathways involved in the resistance reflex, while feedback loop responses to fCO stimuli typical for active animals could still be elicited. Our results indicate that an increase in the octopamine concentration mimicks activation of the animal: Properties being characteristic for the control of the FT joint in the inactive animal are inhibited by octopamine, while properties of the FT control loop typical for the active animal appear to be facilitated following octopamine injection. The results clearly demonstrate that different pathways in the neuronal network underlying the FT control loop are involved in the responses of the control loop to fCO stimuli in the inactive and active behavioral states of the stick insect. © 1993 John Wiley & Sons, Inc.     

Can video images imitate real stimuli in animal behaviour experiments?

The use of video images in place of natural stimuli in animal behaviour experiments is reviewed. Unlike most other artificial means of stimulus presentation, video stimuli can depict complex moving objects such as other animals, preserving the temporal and spatial patterns of movement precisely as well as colour and sounds for repeated playback. Computer editing can give flexibility and control over all elements of the stimulus. A variety of limitations of video image presentation are also considered. Televisions and video monitors are designed with human vision in mind, and some non-human animals that differ in aspects of visual processing such as their colour vision, critical flicker-fusion threshold, perception of depth and visual acuity, may perceive video images differently to ourselves. The failure of video stimuli to interact with subjects can be a drawback for some studies. For video to be useful, it is important to confirm that the subject animal responds to the image in a comparable way to the real stimulus, and the criteria used to assess this are discussed. Finally, the contribution made by video studies to date in the understanding of animal visual responses is considered, and recommendations as to the future uses of video are made.     

老年猫视皮层细胞对刺激反应的对比敏感度下降伴随皮层内抑制作用减弱(英文)

对人类和动物的心理学研究证实,老年个体的视觉对比敏感度相对青年个体显著下降。为揭示其可能的神经机制,采用在体细胞外单细胞记录技术研究青、老年猫(Felis catus)初级视皮层(primary visual cortex,V1)细胞对不同视觉刺激对比度的调谐反应。结果显示,老年猫V1细胞对视觉刺激反应的平均对比敏感度比青年猫显著下降,这与灵长类报道的研究结果相一致,表明衰老影响视皮层细胞对视觉刺激反应的对比敏感度是灵长类和非灵长类哺乳动物中普遍存在的现象,并可能是介导老年性视觉对比敏感度下降的神经基础。另外,与青年猫相比,老年猫初级视皮层细胞对视觉刺激的反应性显著增强,信噪比下降,感受野显著增大,表明衰老导致的初级视皮层细胞对视觉刺激反应的对比敏感度下降伴随着皮层内抑制性作用减弱。