Experience-dependent learning of behavioral laterality in the scale-eating cichlid Perissodus microlepis occurs during the early developmental stage

Behavioral laterality—typically represented by human handedness—is widely observed among animals. However, how laterality is acquired during development remains largely unknown. Here, we examined the effect of behavioral experience on the acquisition of lateralized predation at different developmental stages of the scale-eating cichlid fish Perissodus microlepis. Naïve juvenile fish without previous scale-eating experience showed motivated attacks on prey goldfish and an innate attack side preference. Following short-term predation experience, naïve juveniles learned a pronounced lateralized attack using their slightly skewed mouth morphology, and improved the velocity and amplitude of body flexion to succeed in foraging scales during dominant-side attack. Naïve young fish, however, did not improve the dynamics of flexion movement, but progressively developed attack side preference and speed to approach the prey through predation experience. Thus, the cichlid learns different aspects of predation behavior at different developmental stages. In contrast, naïve adults lost the inherent laterality, and they neither developed the lateralized motions nor increased their success rate of predation, indicating that they missed appropriate learning opportunities for scale-eating skills. Therefore, we conclude that behavioral laterality of the cichlid fish requires the integration of genetic basis and behavioral experiences during early developmental stages, immediately after they start scale-eating.

Is There a “Right” Side of Communicating Friendship? Lateralization of Social Interactions in Zoo Barbary macaques (Macaca sylvanus)

Social laterality in non-human primates has started to attract attention in recent years. The positioning of individuals during social interactions could possibly suggest the nature of a relationship and the social ranking of the subjects involved. The subjects of the present study were 12 adult Barbary macaques (Macaca sylvanus) housed in a zoological garden. We carried out fourteen 210-min video-recorded sessions and we used a focal animal sampling method to collect the position of the subjects during different social interactions. Data on the position of each macaque during three types of social interactions were collected (approach, proximity and affiliative contacts). Moreover, we focused on the outcomes of dyadic agonistic encounters to build the hierarchy of the colony. For each social interaction, two conditions were considered: the side preference (being kept on the left or on the right) and the sagittal preference (being kept in front or on the rear). Bouts of preference of different positions were collected for different social interactions (approach, proximity and contacts). No group-level side preferences were found for any social interaction, suggesting that both hemispheres might be complemental and balance each other during intraspecific communication. For the sagittal preference, we found a group-level bias for proximity, with macaques being kept in front rather than on the rear by close conspecifics. This might be due to the need to detect emotions and intentions of conspecifics. Moreover, high-ranking individuals are kept more frontally than on the rear when in proximity with other macaques. More studies are needed to better investigate social laterality, possibly distinguishing more categories of social interaction, and detecting other variables that might influence the positioning preferences.

361 Methods for Identification and Classification of Phenylthiocarbamide Sensitivity in Mature Rams

Rams exhibit varying levels of sensitivity to phenylthiocarbamide (PTC), which has been correlated with the ability to perceive bitter-tasting foods. Previously, the only procedure for measuring PTC-sensitivity in rams involved a 9-d test phase with 5 PTC concentrations. The objective of this experiment was to develop a more streamlined approach for identifying and classifying rams on extreme ends of the bitter-tasting spectrum. Mature Targhee, Rambouillet, Polypay, and Composite-breed rams (n = 44), housed in three separate barns, and subjected to 4-d acclimation, 2-d sham, and 2-d testing phases. The 2-d sham phase was conducted to determine if ethanol-spiked water (delivery vehicle for PTC) influenced voluntary fluid intake; no effect (P = 0.16) was observed. The 2-d test phase was a side-by-side preference study between water (control; 3.0 kg) and 1 of 2 concentrations (0.2 and 2.0 mM) of PTC solution (3.0 kg) delivered on alternate days. Average consumption of PTC as a percentage of total test fluid intake was used determine taster status. No PTC-treatment effect (P ≥ 0.23) was observed, but within each treatment level, PTC intake was less (P < 0.001) than water intake. Classification levels of PTC consumption were determined by ± 1.0 standard deviation of the mean and used to classify rams into non- (n = 9; 61.5 ± 3.9%), intermediate- (n = 29; 40.7 ± 1.8%), or super- (n = 6; 15.6 ± 3.3%) PTC tasting groups, which were different (P < 0.001) from each other. Likewise, water consumption intakes were different (P< 0.001) between the non- (38.5 ± 3.9%), intermediate- (59.3 ± 1.8%), and super- (84.4 ± 3.3%) PTC tasting groups. The methods outlined in this study will facilitate further research focused on the influence of bitter tasting sensitivities on the dietary preferences of sheep.

Cone-beam computed tomographic assessment of the inclination of the articular eminence in patients with temporomandibular disorders and chewing side preference

Background Chewing side preference (CSP) has been proposed as one etiology of temporomandibular disorders (TMDs) as it can induce the structural changes of the temporomandibular joint. But its association with the inclination of the articular eminence (IAE) is unknown. This study aimed to compare IAE between patients with CSP and without CSP. Methods Cone-beam computed tomography images of 90 patients with TMD (mean age of 45.6 years, 69 with CSP, 21 without CSP) and 20 participants without TMD and CSP (mean age of 41.3 years) were measured to compare IAE and depth of the glenoid fossa (DGF) Results IAE and DGF showed a positive correlation among all the participants. Compared with the participants without TMD and CSP, the TMD patients without CSP presented a similar IAE but with a significantly higher value of DGF (p < 0.05); in contrast, the TMD patients with CSP presented a significantly greater IAE and DGF (p < 0.05). No bilateral differences in IAE and DGF were observed in all the participants. Except the male patients with CSP had a deeper fossa than did the female, no differences in IAE and DGF according to gender were observed. Conclusions TMD patients with CSP seem to have a deep glenoid fossa with steep eminence which might be considered one characteristic imaging feature.

Selection and analysis of input parameters influencing pedestrian micro-simulated crossing time

Pedestrian unrestrained behaviour, sudden movements and vulnerability are elements, which can highly affect road safety, especially when interacting with motorized vehicles. Therefore, it is important to have a deep insight in pedestrian behaviour. A way to tackle this issue is micro-simulation. Modern micro-simulation tools, indeed, allow, thanks to the implemented mathematical formulation of the problem, to model and repeat a real situation in a virtual environment. Nevertheless, they need to well-fit the real observed behaviour: the calibration step allows to make the model reliable, by adapting selected, influential model input parameters. By dealing with pedestrian issues, software Vissim/Viswalk has been selected for micro-simulation, which implements Helbing's Social Force model. This model is based on several parameters, like relaxation time, side preference, strength and range of pedestrian interactions, amount of anisotropy, parameters governing the forces among pedestrians, noise, number of reacting pedestrians, queue order and straightness, which need to be set by the user when creating the model, but they can be hardly measured. This paper presents a selection of the recalled input parameters, on which statistical tests are carried out to understand their influence on the behavioural output – crossing time - that is supposed to describe pedestrian crossing behaviour. This is the first step towards the development of a new calibration methodology, which will keep advantage of artificial intelligence tools to fine-tune micro-simulation input parameters.

Side preference of dairy cows in the milking parlour and its impact on daily milk yield

Monitoring of the side preference of dairy cows in the milking parlour was performed in a group of 40 dairy cows (Czech spotted cattle). Twenty milking sessions were evaluated for each cow, and the composition of the monitored group of cows was kept constant. A significant side preference was found in 26 (65%) cows. The results show that in the dairy herd, a significant percentage of cows prefer one side of the milking parlour. Furthermore, in dairy cows with a significant side preference, their milk yield on the preferred and non-preferred side of milking parlour was compared and a statistically significant difference was found. When the dairy cows were milked on their preferred side of the milking parlour, higher milk yield was achieved (12.21 vs. 10.38 kg).