Hemispheric Specialization in Dogs for Processing Different Acoustic Stimuli

Considerable experimental evidence shows that functional cerebral asymmetries are widespread in animals. Activity of the right cerebral hemisphere has been associated with responses to novel stimuli and the expression of intense emotions, such as aggression, escape behaviour and fear. The left hemisphere uses learned patterns and responds to familiar stimuli. Although such lateralization has been studied mainly for visual responses, there is evidence in primates that auditory perception is lateralized and that vocal communication depends on differential processing by the hemispheres. The aim of the present work was to investigate whether dogs use different hemispheres to process different acoustic stimuli by presenting them with playbacks of a thunderstorm and their species-typical vocalizations. The results revealed that dogs usually process their species-typical vocalizations using the left hemisphere and the thunderstorm sounds using the right hemisphere. Nevertheless, conspecific vocalizations are not always processed by the left hemisphere, since the right hemisphere is used for processing vocalizations when they elicit intense emotion, including fear. These findings suggest that the specialisation of the left hemisphere for intraspecific communication is more ancient that previously thought, and so is specialisation of the right hemisphere for intense emotions

Social use of facial expressions in hylobatids

Non-human primates use various communicative means in interactions with others. While primate gestures are commonly considered to be intentionally and flexibly used signals, facial expressions are often referred to as inflexible, automatic expressions of affective internal states. To explore whether and how non-human primates use facial expressions in specific communicative interactions, we studied five species of small apes (gibbons) by employing a newly established Facial Action Coding System for hylobatid species (GibbonFACS). We found that, despite individuals often being in close proximity to each other, in social (as opposed to non-social contexts) the duration of facial expressions was significantly longer when gibbons were facing another individual compared to non-facing situations. Social contexts included grooming, agonistic interactions and play, whereas non-social contexts included resting and self-grooming. Additionally, gibbons used facial expressions while facing another individual more often in social contexts than non-social contexts where facial expressions were produced regardless of the attentional state of the partner. Also, facial expressions were more likely ‘responded to’ by the partner’s facial expressions when facing another individual than non-facing. Taken together, our results indicate that gibbons use their facial expressions differentially depending on the social context and are able to use them in a directed way in communicative interactions with other conspecifics

Visual laterality in dolphins: importance of the familiarity of stimuli

<p>Abstract</p> <p>Background</p> <p>Many studies of cerebral asymmetries in different species lead, on the one hand, to a better understanding of the functions of each cerebral hemisphere and, on the other hand, to develop an evolutionary history of hemispheric laterality. Our animal model is particularly interesting because of its original evolutionary path, i.e. return to aquatic life after a terrestrial phase. The rare reports concerning visual laterality of marine mammals investigated mainly discrimination processes. As dolphins are migrant species they are confronted to a changing environment. Being able to categorize new versus familiar objects would allow dolphins a rapid adaptation to novel environments. Visual laterality could be a prerequisite to this adaptability. To date, no study, to our knowledge, has analyzed the environmental factors that could influence their visual laterality.</p> <p>Results</p> <p>We investigated visual laterality expressed spontaneously at the water surface by a group of five common bottlenose dolphins (<it>Tursiops truncatus</it>) in response to various stimuli. The stimuli presented ranged from very familiar objects (known and manipulated previously) to familiar objects (known but never manipulated) to unfamiliar objects (unknown, never seen previously). At the group level, dolphins used their left eye to observe very familiar objects and their right eye to observe unfamiliar objects. However, eyes are used indifferently to observe familiar objects with intermediate valence.</p> <p>Conclusion</p> <p>Our results suggest different visual cerebral processes based either on the global shape of well-known objects or on local details of unknown objects. Moreover, the manipulation of an object appears necessary for these dolphins to construct a global representation of an object enabling its immediate categorization for subsequent use. Our experimental results pointed out some cognitive capacities of dolphins which might be crucial for their wild life given their fission-fusion social system and migratory behaviour.</p

Left Hemisphere Specialization for Oro-Facial Movements of Learned Vocal Signals by Captive Chimpanzees

The left hemisphere of the human brain is dominant in the production of speech and signed language. Whether similar lateralization of function for communicative signal production is present in other primates remains a topic of considerable debate. In the current study, we examined whether oro-facial movements associated with the production of learned attention-getting sounds are differentially lateralized compared to facial expressions associated with the production of species-typical emotional vocalizations in chimpanzees.Still images captured from digital video were used to quantify oro-facial asymmetries in the production of two attention-getting sounds and two species-typical vocalizations in a sample of captive chimpanzees. Comparisons of mouth asymmetries during production of these sounds revealed significant rightward biased asymmetries for the attention-getting sounds and significant leftward biased asymmetries for the species-typical sounds.These results suggest that the motor control of oro-facial movements associated with the production of learned sounds is lateralized to the left hemisphere in chimpanzees. Furthermore, the findings suggest that the antecedents for lateralization of human speech may have been present in the common ancestor of chimpanzees and humans approximately 5 mya and are not unique to the human lineage

Molecular basis of structure and function of the microvillus membrane of intestinal epithelial cells

Correlation of molecular structure with biochemical functions of the plasma membrane of the microvilli of intestinal epithelial cells has been investigated by biochemical and electron microscopic procedures. Repeating particles, measuring approximately 60 &#197;in diameter, were found on the surface of the microvilli membrane which had been isolated or purified from rabbit intestinal epithelial cells and negatively stained with phosphotungstic acid. These particles were proved to be inherent components of the microvillus membrane, attached to the outer surface of its trilaminar structure, and were designated as the elementary particles of the microvilli of intestinal epithelial cells. Biochemical and electron microscopic identification of these elementary particles has been carried out by isolation of the elementary particles with papain from the isolated microvillus membrane, followed by purification of the particles by chromatographies on DEAE-cellulose and Sephadex columns. The partially purified particles containing invertase and leucine aminopeptidase are similar in size and structure to those of the elementary particles in the microvillus membrane. Evidence indicates that each of the elementary particles coincide with or include an enzyme molecule such as disaccharidase or peptidase, which carry out the terminal hydrolytic digestion of carbohydrates and proteins, respectively, on the surface of the microvillus membrane. Magnesium ionactivated adenosine triphosphatase and alkaline phosphatase cannot be solubilized with papain but remains in the smooth-surface membrane after the elementary particles have been removed. Cytochemical electron microscopic observation revealed that the active site of magnesium ion-activated adenosine triphosphatase is localized predominantly in the inner surface of the trilaminar structure of the microvillus membrane.</p

Hand Preferences in New World Primates

Studies of hand preference s in the platyrrhine species are reviewed. Hand preferences of the New World species have been recorded during feeding&nbsp;activities, visuospatial reaching, haptic discrimination, tool use and in a variety of routine tasks using the hands. Of the New World species tested so far, the common marmoset (Callithrix jacchiis) and squirrel monkeys {Saimiri sciureus), appear to be the only species that do not display handedness in feeding activities: at the population level both species display a symmetrical distribution of hand preferences. It appears that only one New World primate species, the spider monkey (Ateles geoffroyi), displays left handedness during feeding while the other species are right handed or have no handedness. Thus,tlie findings for hand use in feeding do&nbsp;not support the Postural Origins hypothesis of MacNeilage et al. (1987) as it predicts left handedness rather than right in the arboreal platyrrhine species. Overall, tlie reports of handedness for tasks requiring complex visuospatial or tactile processing in the New World primates&nbsp;concur with those reported for humans, who have left handedness in haptic discrimination and complex visuospatial tasks and right handedness for manipulative tasks. Squirrel monkeys are left handed when reaching for moving objects and capuchins display left&nbsp;handedness in haptic discrimination tasks, and right handedness during sponging tasks.&nbsp;There is strong evidence of an effect of posture on the strength of hand preferences, and&nbsp;some affects of age and gender on hand use have also been reported. However, these&nbsp;variables do not influence hand preferences consistently across species or across&nbsp;tasks&nbsp;conducted with the same species.&nbsp

Hand Preferences in New World Primates

Studies ofhand preference s in the platyrrhine species are reviewed. Hand preferences of the New World species have been recorded during feeding activities, visuospatial reaching, haptic discrimination, tool use and in a variety of routine tasks using the hands. Of the New World species tested so far, the common marmoset (Callithrix jacchiis) and squirrel monkeys {Saimiri sciureus), appear to be the only species that do not display handedness in feeding activities: at the population level both species display a symmetrical distribution of hand preferences. It appears that only one New World primate species, the spider monkey (Ateles geoffroyi), displays left handedness during feeding while the other species are right handed or have no handedness. Thus,tlie findings for hand use in feeding do not support the Postural Origins hypothesis of MacNeilage et al. (1987) as it predicts left handedness rather than right in the arboreal platyrrhine species. Overall, tlie reports of handedness for tasks requiring complex visuospatial or tactile processing in the New World primates concur with those reported for humans, who have left handedness in haptic discrimination and complex visuospatial tasks and right handedness for manipulative tasks. Squirrel monkeys are left handed when reaching for moving objects and capuchins display left handedness in haptic discrimination tasks, and right handedness during sponging tasks. There is strong evidence of an effect of posture on the strength of hand preferences, and some affects of age and gender on hand use have also been reported. However, these variables do not influence hand preferences consistently across species or across tasks conducted with the same species.