Lateralization in accuracy, reaction time and behavioral processes in a visual discrimination task in an Indo-Pacific bottlenose dolphin (Tursiops aduncus)

Left or right, that is the question: use of egocentric frame of reference and the right-eye advantage for understanding gestural signs in bottlenose dolphins (Tursiops truncatus)

How do bottlenose dolphins visually perceive the space around them? In particular, what cues do they use as a frame of reference for left-right perception? To address this question, we examined the dolphin's responses to various manipulations of the spatial relationship between the dolphin and the trainer by using gestural signs for actions given by the trainer, which have different meanings in the left and right hands. When the dolphins were tested with their backs to the trainer (Experiment 1) or in an inverted position underwater (Experiments 2 and 3), correct responses from the trainer's perspective were maintained for signs related to movement direction instructions. In contrast, reversed responses were frequently observed for signs that required different sounds for the left and right hands. When the movement direction instructions were presented with symmetrical graphic signs such as " × " and "●", accuracy decreased in the inverted posture (Experiment 3). Furthermore, when the signs for sounds were presented from either the left or right side of the dolphin's body, performance was better when the side of the sign movement coincided with the body side on which it was presented than when it was mismatched (Experiment 4). In the final experiment, when one eye was covered with an eyecup, the results showed that, as in the case of body-side presentation, performance was better when the open eye coincided with the side on which the sign movement was presented. These results indicate that dolphins used the egocentric frame for visuospatial cognition. In addition, they showed better performances when the gestural signs were presented to the right eye, suggesting the possibility of a left-hemispheric advantage in the dolphin's visuospatial cognition.

The Role of Preventative Medicine Programs in Animal Welfare and Wellbeing in Zoological Institutions

The overarching goal of a preventative medicine program is to minimize the chances of health problems developing and to maximize the chances of detecting health problems early, in a manner that best benefits the animals and the organization. The traditional paradigms of animal welfare, stemming from the five freedoms and being progressively fleshed out to five domains, the 24/7 approach and so forth do not apply perfectly to zoological collections and less so to animals undergoing veterinary treatments. The physiology and behaviour of animals undergoing veterinary treatments, including therapeutic, quarantine and preventative medicine, are derailed from their normal states and their choices and comfort are de facto limited. A paradigm separating animal wellbeing from animal welfare is necessary to instil clarity of thought and to guide actions in regard to the welfare of animals under human care. Using such a model, preventative medicine programs emerge as a cornerstone of zoo and aquarium animal welfare, all the more if it incorporates modern veterinary and husbandry techniques, including operant conditioning.

Show me your best side: Lateralization of social and resting behaviors in feral horses

Growing evidence shows a variety of sensorial and motor asymmetries in social and non-social interactions in various species, indicating a lateralized processing of information by the brain. Using digital video cameras on tripods and drones, this study investigated lateralization in frequency and duration of social behavior patterns, in affiliative, agonistic, and resting contexts, in a feral population of horses (Equus ferus caballus) in Northern Portugal, consisting of 37 individuals organized in eight harem groups. Affiliative interactions (including grooming) were more often performed, and lasted longer, when recipients were positioned to the right side. In recumbent resting (animals lying down) episodes on the left side lasted longer. Our results of an affiliative behavior having a right side tendency, provide partial support to the valence-specific hypothesis of Ahern and Schwartz (1979) - left hemisphere dominance for positive affect, affiliative behaviors. Longer recumbent resting episodes on the left side may be due to synchronization. However, in both instances it is discussed how lateralization may be context dependent. Investigating the position asymmetries of social behaviors in feral equids will contribute to a better understanding of differential lateralization and hemispheric specialization from the ecological and evolutionary perspectives.

Behavioural responses of threespine stickleback with lateral line asymmetries to experimental mechanosensory stimuli

Behavioural asymmetry, typically referred to as laterality, is widespread among bilaterians and is often associated with asymmetry in brain structure. However, the influence of sensory receptor asymmetry on laterality has undergone limited investigation. Here we use threespine stickleback (Gasterosteus aculeatus) to investigate the influence of lateral line asymmetry on laterality during lab simulations of three mechanosensation-dependent behaviours: predator evasion, prey localization and rheotaxis. We recorded the response of stickleback to impacts at the water surface and water flow in photic conditions and low-frequency oscillations in the dark, across four repeat trials. We then compared individuals' laterality to asymmetry in the number of neuromasts on either side of their body. Stickleback hovered with their right side against the arena wall 57% of the time (P<0.001) in illuminated surface impact trials and 56% of the time in (P=0.085) dark low-frequency stimulation trials. Light regime modulated the effect of neuromast count on laterality, as fish with more neuromasts were more likely to hover with the wall on their right during illumination (P=0.007) but were less likely to do so in darkness (P=0.025). Population level laterality diminished in later trials across multiple behaviours and individuals did not show a consistent side bias in any behaviours. Our results demonstrate a complex relationship between sensory structure asymmetry and laterality, suggesting that laterality is modulated multiple sensory modalities and temporally dynamic.