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Rats are social animals that use ultrasonic vocalizations (USV) to communicate. USV are usually divided into 50 kHz calls which accompany appetitive states, and 22 kHz vocalizations which are usually associated with aversive states. Both kinds of states are known to affect animals’ heart rate (HR). Also, the polyvagal theory claims that both cardiovascular parameters and USV emission is affected by the autonomous system, as they share a common signaling pathway. The aim of the study was to evaluate the changes in behavior, HR, and USV emission after playback of ultrasounds. Male Wistar rats were housed in pairs or separately for 4 weeks, and some of the animals underwent fear conditioning. Animals were implanted with DSI telemetry transmitters for acquisition of cardiovascular parameters. After recovery, rats were subjected to ultrasounds playback consisting of initial 10 min of static silence and five sets of 10 s sounds (50 or 22 kHz), either natural, collected from animals, or artificial tones, separated by 5 min silence intervals. Video, audio, and cardiovascular parameters were collected. Surprisingly, presentation of both 50 and 22 kHz sounds induced approach behavior. Both single- and pair-housed animals responded with a larger number of USV to both natural and artificial 50 kHz sounds playback rather than to 22 kHz sounds. The emitted USV were, almost exclusively, within the 50 kHz range. Animal HR levels decreased gradually during the experimental session. Single‑housed animals had, in general, higher HR than paired rats. There was an impact of every kind of ultrasonic presentation on HR levels; in general, 50 kHz ultrasonic playback caused a sudden increase in HR, whereas 22 kHz presentations evoked a HR drop. Surprisingly, USV and artificial tones had similar effects on HR and USV responses. Social context did not appear to alter rats’ USV emission. The results following fear conditioning are being analyzed. Also, in a separate set of experiments, rats ultrasonic responses were analyzed following presentation of a defined number of pre‑recorded USV.
Our study investigated the behavioural responses of medicinal leech and rainbow trout at different ontogenetic levels under the effect of crude oil (CO) and heavy fuel oil (HFO), performed comparative analysis of the sensitivity of animal responses, evaluated the specificity of these responses, and determined “safe“ toxicant concentrations. Comparison of sensitivity of behavioural responses of leech and fish revealed that the most sensitive response to long-term exposure to CO was leech locomotor activity, while the most sensitive parameter to HFO was the coughing rate in juvenile fish. Our study showed that the sensitivity and specificity of behavioural responses of aquatic animals at different phylogenetic and ontogenetic levels can be successfully used to evaluate the toxicity of ambient water polluted with oil hydrocarbons.
The neurocognitive consequences of correct or incorrect spatial prediction in a sequential S1-S2 paradigm were assessed. Sequential dependence on previous trial outcome (valid or invalid) was assessed by late Event-Related Potentials (ERPs) and behavioural responses. Two different experiments were performed, situating the target in the vertical (Experiment 1) or in the horizontal (Experiment 2) meridian. RTs and late positivities (P3a and P3b) were recorded. ERPs showed that posterior positivity (probably a P3b) was greater in invalid-valid trials than in valid-valid trials but lower than in valid- invalid trials. However, at the frontal electrodes, late positivity (probably a P3a) only appeared in valid-invalid trials, indicating that invalid trials are analyzed as novel-like stimuli. The P3b results suggest trial-by-trial learning of the predictive value of the cue, which needs to be updated as indicated by the pattern of P3b amplitudes: valid-invalid > invalid-valid > valid-valid.
Experiments were conducted to document behavioural responses of koi carp, Cyprinus carpio L., and goldfish, Carassius auratus (L.) to monoculture and polyculture conditions in aquaria. Two parallel experiments, otherwise involving similar experimental protocols, were carried out with two batches of fish, fed with live tubifex worm (first batch) and live zooplankton (second batch). Each of the trials, randomized with respect to treatment, yielded data on aggressive encounters (chases, nips), both in presence and absence of food. The two species exhibited considerable variation in the extent and type of aggression displayed, koi carp being the more aggressive species. Frequency of attack increased in the presence of food. The impact of aggressive behaviour of koi carp was conspicuous by the increased level of attack on goldfish in polyculture trials in both experimental batches.
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