Perceptual lateralization of vocal stimuli in goats

Functional asymmetries, for example, the preferential involvement of 1 brain hemisphere to process stimuli, may increase brain efficiency and the capacity to carry out tasks simultaneously. We investigated which hemisphere was primarily invoIved in processing acoustic stimuli in goats using a headorienting paradigm. Three playbacks using goat vocalizations recorded in different contexts: food anticipation (positive), isolation (negative), food frustration (negative), as well as 1 playback involving dog barks (negative) were presented on the left and right sides of the test subjects simultaneously. The head-orienting response (left or right) and latency to resume feeding were recorded. The direction of the head-orienting response did not differ between the various playbacks. However, when the head-orienting response was tested against chanee level, goats showed a right bias regardless of the stimuli presented. Goats responded more to dog barks than to food frustration calls, whereas responses to food anticipation and isolation calls were intermediate. In addition, the latency to resume feeding, an indicator of fear reaction, was not affected by the kind of vocalization presented. These results provide evidence for asymmetries in goat vocal perceptio n of emotional-li nked con specific and heterospecific calls. They also suggest involvement of the left brain hemisphere for processing acoustic stimuli, which might have been perceived as familiar and non -threate ning.

Assessing animal individuality:links between personality and laterality in pigs

Animal individuality is challenging to explain because individual differences are regulated by multiple selective forces that lead to unique combinations of characteristics.For instance,the study of personality,a core aspect of individuality,may benefit from integrating other factors underlying individual differences,such as lateralized cerebral processing.Indeed,the approach-withdrawal hypothesis(the left hemisphere controls approach behavior,the right hemisphere controls withdrawal behavior),may account for differences in boldness or exploration between left and right hemispheric dominant individuals.To analyze the relationships between personality and laterality we tested 80 male piglets with established laterality patterns for 2 motor functions(tail curling direction and the side of the snout used for manipulation)and a combined classification integrating both motor functions using cluster analysis.We analyzed basal salivary testosterone and cortisol along with their behavior in standardized tests as pre-established indicators of different personality traits(Boldness,Exploration,Activity,Sociability,and Coping).We found that the direction of the single motor biases showed significant associations with few personality traits.However,the combined laterality classification showed more,and more robust,significant associations with different personality traits compared with the single motor biases.These results supported the approachwithdrawal hypothesis because right-biased pigs were bolder and more explorative in a context of novelty.Additionally,right-biased pigs were more sociable than left-biased pigs.Therefore,the present study indicates that personality is indeed related to lateralized cerebral processing and provides insight into the multifactorial nature of individuality.