Food preference experiments with captive ptarmigan

Summary

Athyrium distentifolium is found in scattered sites in the Central and Northern Highlands of Scotland. In a few localities in the Central Highlands there is also an endemic variety: A. distentifolium var. flexile. Both types are found together in polymorphic populations with the two distinct forms. A. distentifolium can only grow well with moderate nutrients and in the polymorphic populations A. distentifolium is smaller than elsewhere and frequently infertile. A. distentifolium var. flexile is a smaller plant which is more frequently fertile than A. distentifolium in polymorphic populations and appears particularly well adapted to grow in stressful environments with low nutrient status.     

Evaluation of hand asymmetry in relation to hand preference

We evaluated the asymmetric hand measurements in right- and left-handed individuals. 343 men and 290 women aged 18-42 years (22.11 +/- 2.07) participated in the study. There were no statistically significant differences when right-left differences in hand length, third finger length, palmar length, and the digit index value were evaluated according to hand preference and sex. Statistically significant differences were found for right-left differences in hand width, hand-shape index, and the palmar length/width according to hand preference. The strong left-handers, weak left-handers, and ambidextrous individuals in the study group all exhibited asymmetry favoring the left and were considered together. Similarly, the strong and weak right-handers exhibited asymmetry favoring the right hand and were considered together. The difference between these two groups was significant. When the data were evaluated according to sex, significant differences were found between the subgroups. In particular, right-left differences in the hand-shape index and palmar length/width values of the strong left-handers, weak left-handers, and ambidextrous individuals were found to be statistically significant according to sex; in contrast, the strong and weak right-handers showed no significant differences according to sex. These results suggest a relation of hand asymmetry to hand preference in a Turkish population.     

Influence of the task on hand preference: individual differences among gorillas (Gorilla gorilla gorilla)

The degree of task complexity and bimanual complementarity have been proposed as factors affecting lateralization strength in humans. However, a large number of studies have demonstrated group-level lateral hand bias for different manual activities in numerous non-human primate species. However, no study has tested the effects that a variety of tasks may have in inducing differences in hand preference. Here, we aim to test if 3 adult gorillas exhibited a greater hand preference bias performing 4 tasks of varying complexity: grasping small versus large foods, proto-tool use task and tool use task involving greater visuospatial requirements. We found that (1) the complexity of the task does not necessarily induce a right-handed bias and (2) a subject can be right-handed for a complex task and left-handed for another one. These results, complemented by many publications on hand preference in non-human primates, reveal a great variability in hand preference, which makes it very difficult to deduce any details of hominin handedness with artefacts.     

Hand preference behaviors shared by two groups of captive bonobos

Fourteen bonobos (Pan paniscus) from the San Diego Zoo and the San Diego Wild Animal Park were focally observed at different times of day for all right, left, and bi-manual behaviors which occurred naturally in the two settings. A total of 36,288 behaviors were recorded. There were 17,762 (49%) right-handed behaviors, 14,080 (39%) left-handed behaviors, and 4,446 (12%) bilateral behaviors. Based onz-scores (p<.05), 11 individuals were significantly right-biased, 2 individuals were significantly left-biased, and 1 was right biased, but not significantly. Age, sex, and environmental factors are discussed.     

Hand preference in a captive island group of chimpanzees (Pan troglodytes)

Morphological cerebral asymmetries in chimpanzee brains, similar to those found in humans, in whom they are associated with speech and handedness, suggest the possibility of functional lateralization in the chimpanzee. This possibility was investigated by examining hand preferences in an island group of five chimpanzees on a series of unimanual and bimanual tasks that are diagnostic of human hand and cerebral dominance. Each subject was tested in a double compartment cage on three unimanual nonsequential, three unimanual sequential, and three bimanual coordination tasks. One of the three unimanual sequential tasks was a bar-press task that is analogous to the commonly used human finger-tapping task. For the unimanual tasks, exclusive of the bar-press, the chimpanzees showed a highly individualistic pattern of hand preference that did not change as a function of task complexity. On the bar-press task, four of five subjects produced higher rates with one hand compared to the other; however, relative hand performance on this task was unrelated to hand preference on the other unimanual tasks. For the group of subjects, performance rates did not differ between the left and right hands; however, a practice effect was observed for the right hand in all subjects. The bimanual tasks also revealed a complex pattern of individual handedness, with no trends apparent for the group as a whole. Consistent with previous findings, the results from these tests on this group of five chimpanzees suggest that cerebral morphological asymmetries in the chimpanzee are not associated with motor dominance as reflected in handedness.     

Preliminary study on hand preference in captive northern white-cheeked gibbons (<Emphasis Type="Italic">Nomascus leucogenys</Emphasis>)

The postural origin hypothesis and the task complexity hypothesis propose that hand preference in non-human primates evolved in association with body posture and task complexity, respectively. The results of previous studies testing these two hypotheses, however, vary greatly with the different primate species and methods used. To investigate the effect of body posture and task complexity on hand preference, we recorded bouts of hand usage in nine captive northern white-cheeked gibbons (Nomascus leucogenys) housed at Beijing Zoo as they reached for food items in a ground-reaching task, a box task, and a tube task. The results showed that four to seven of the nine gibbons displayed a hand preference at the individual level in different tasks, and that hand preference in individuals was task-specific; there was no group-level hand preference in any task. The box task seemed to elicit a greater strength of hand preference than the ground-reaching task at the individual level. Although the small sample size rules out drawing any strong conclusions concerning hand preference at the group level, our results suggest that the suspensory reaching posture might increase the expression of hand preference at the individual level. This study provides preliminary information on hand preference in captive northern white-cheeked gibbons, and will be helpful for future studies addressing the origin and evolution of hand preference in small apes.     

Black lemur (Lemur macaco) hand preference in food reaching

The present study assessed the hand preferences exhibited by 33 black lemurs during routine feeding. Individual animals displayed hand preferences that were consistent across observations separated by as much as seven months. Within this population, 20 were left hand preferent, 12 right preferent, and 1 was ambidextrous. Correlational analysis of age and percentage left hand use indicated an inverse relationship in which younger animals tended towards the preferential use of the left hand and older animals the preferential use of the right hand. Similar analysis found no relationship between either sex and hand preference or familial relationship and hand preference. The skewed distribution of age in this sample renders tentative conclusions regarding age-related variations in hand preference. It is suggested that if the hand preferences of the black lemur are not age-related, then this species may be characterized as having a bias towards the preferential use of the left hand for food reaching.     

Rat behavior in a light/dark chamber: place preference task

After a 6-week social isolation (from 22nd to 70th day from birth) male Wistar rats (a sibship, 10 animals), were tested for 20 min in a light/dark box in order to reveal behavioral features of choice of their spatial localization in unknown conditions. Socially deprived rats significantly differed from control animals in longer time of the room choice, higher number of entries of the light section, and higher number of rearings, which was probably explained by their higher anxiety and lack of experience to estimate unexpected stimuli and select a response. The mean level of behavioral activity during exploration of the box defined by the number of elementary operations per minute remained constant and was significantly higher in the socially deprived rats than in the control animals.     

Skeletal asymmetry and hand preference during termite fishing by gombe chimpanzees

Skeletons of chimpanzees with recorded life stories allow assessment of the potential relationships among hard tissue features and expressed behaviors. We analyze bone size, weight, and mineralization to assess osteological characters for identification of laterality of expressed behaviors involving the upper body. Results show that associations are not yet clearly defined.     

Decoding hand movement velocity from electroencephalogram signals during a drawing task

Background  

Decoding neural activities associated with limb movements is the key of motor prosthesis control. So far, most of these studies have been based on invasive approaches. Nevertheless, a few researchers have decoded kinematic parameters of single hand in non-invasive ways such as magnetoencephalogram (MEG) and electroencephalogram (EEG). Regarding these EEG studies, center-out reaching tasks have been employed. Yet whether hand velocity can be decoded using EEG recorded during a self-routed drawing task is unclear.     

Influence of nerve supply on hand electromyography coherence during a three-digit task

Intermuscular coupling has been investigated to understand neural inputs to coordinate muscles in a motor performance. However, little is known on the role of nerve innervation on intermuscular coupling. The purpose of this study was to investigate how the anatomy of nerve distribution affected intermuscular coupling in the hand during static grip. Electromyographic (EMG) signals were recorded from intrinsic and extrinsic muscles while subjects performed a static grip. Coherence was computed for muscle pairs innervated by either the same or different nerves. The results did not support the hypothesis that muscles sharing the same nerve exhibit greater coupling than muscles innervated by different nerves. In general, extrinsic muscle pairs displayed higher coherence than intrinsic pairs. The results suggest that intermuscular coupling in a voluntary motor task is likely modulated in a functional manner and that different nerves might transport common neural inputs to functionally coupled muscles.     

Sex-specific asymmetries in communication sound perception are not related to hand preference in an early primate

Background  

Left hemispheric dominance of language processing and handedness, previously thought to be unique to humans, is currently under debate. To gain an insight into the origin of lateralization in primates, we have studied gray mouse lemurs, suggested to represent the most ancestral primate condition. We explored potential functional asymmetries on the behavioral level by applying a combined handedness and auditory perception task. For testing handedness, we used a forced food-grasping task. For testing auditory perception, we adapted the head turn paradigm, originally established for exploring hemispheric specializations in conspecific sound processing in Old World monkeys, and exposed 38 subjects to control sounds and conspecific communication sounds of positive and negative emotional valence.     

Genetic basis in motor skill and hand preference for tool use in chimpanzees (Pan troglodytes)

Chimpanzees are well known for their tool using abilities. Numerous studies have documented variability in tool use among chimpanzees and the role that social learning and other factors play in their development. There are also findings on hand use in both captive and wild chimpanzees; however, less understood are the potential roles of genetic and non-genetic mechanisms in determining individual differences in tool use skill and laterality. Here, we examined heritability in tool use skill and handedness for a probing task in a sample of 243 captive chimpanzees. Quantitative genetic analysis, based on the extant pedigrees, showed that overall both tool use skill and handedness were significantly heritable. Significant heritability in motor skill was evident in two genetically distinct populations of apes, and between two cohorts that received different early social rearing experiences. We further found that motor skill decreased with age and that males were more commonly left-handed than females. Collectively, these data suggest that though non-genetic factors do influence tool use performance and handedness in chimpanzees, genetic factors also play a significant role, as has been reported in humans.     

Brief communication: Hand preference for bimanual and unimanual feeding in captive gorillas: extension in a second colony of apes

Right-hand dominance is widely considered to be a uniquely human trait. Whether nonhuman primates exhibit similar population-level hand preferences remains a topic of considerable debate. Despite extensive research focusing on laterality in nonhuman primates, our interpretation of these studies is limited due to methodological issues including the lack of a common measure of hand preference and the use of tasks that may not be reliable indicators of handedness. The use of consistent methods between studies is necessary to enable comparisons within and between species and allow for more general conclusions to be drawn from these results. The present study replicates methods used in recent research reporting population-level right-handedness in captive gorillas (Meguerditchian et al.,2010). Observational data were collected on hand preference for unimanual and bimanual feeding in 14 captive western lowland gorillas (Gorilla gorilla gorilla). Individual-level preferences were found, primarily for bimanual feeding; however, the data reveal no group-level directional bias (contra Meguerditchian et al.). Like the study by Meguerditchian et al. (2010), though, bimanual feeding revealed significantly stronger hand preferences than unimanual reaching, and age, sex, group membership, or rearing history had no effect on hand preference. Finally, variations in diet and corresponding grip type between studies suggest that hand preferences may vary across bimanual tasks depending on grip morphology. This study aims to contribute to our existing knowledge of primate laterality by increasing the number of individuals investigated using methods that allow for comparisons with similar research.     

Hand preference in unimanual and bimanual tasks and postural effect on manual laterality in captive red-capped mangabeys (Cercocebus torquatus torquatus)

Hand preference in 11 captive red-capped mangabeys (Cercocebus torquatus torquatus) was examined under different conditions: a free situation during spontaneous food processing, three different postural conditions (brachiating, and bipedal and tripedal standing), and a situation involving bimanual processing. Generally, individual laterality was found regardless of the task and behavior involved. However, the number of monkeys with hand preferences and the strength of the preference increased with the complexity of the tasks. The monkeys exhibited a significantly higher and positive mean manual preference index (HI) when they were hanging than when they were quadrupedal or sitting. The strength of manual preference (ABS-HI) was in turn higher when the monkeys were hanging or bipedal than when they were quadrupedal. The strength of manual preference was higher for both the bimanual and experimental tasks than for unimanual tasks and spontaneous activities. Although our sample was too small to allow us to make any generalizations concerning lateral preferences in red-capped mangabeys, we propose some hypotheses about the influence of posture stability and task complexity.