Differences In Behavioral Variables Research Articles

Effect of binocular visual cue availability on fruit and insect grasping performance in two cheirogaleids: Implications for primate origins hypotheses

Forward-facing eyes with parallel optic axes, which provide a wide field of binocular vision and precise depth perception, are among the diagnostic features of crown primates; however, the adaptive significance of this feature remains contentious. Two of the most prominent primate-origins hypotheses propose that either foraging for fruit or nocturnal predation on insects created selective pressures that led to the evolution of diagnostic primate traits, including a wide binocular field. To determine whether either of these hypotheses provides a viable explanation for the evolution of primates' derived eye orientation, the importance of binocular depth cues for the two tasks invoked by these hypotheses was evaluated experimentally in Microcebus murinus and Cheirogaleus medius, cheirogaleids' considered reasonable living analogs of the earliest euprimates. Performance in grasping insects and fruit was evaluated when the animals made use of their full binocular visual field and when their binocular visual field was restricted using a helmet-mounted blinder. Restriction of the binocular field had no effect on fruit grasping performance; however, restriction of the binocular field resulted in a significant deficit in insect predation performance. Differences in behavioral variables also suggest that insect predation is a more visually demanding task than fruit foraging. These results support the role of insect predation, but not fruit foraging, in contributing to the selective pressures that led to the evolution of parallel optic axes and a wide binocular field in crown primates.

Reward-dependent Graded Suppression of Sensorimotor Beta-band Local Field Potentials During an Arm Reaching Task in NHP.

A better understanding of reward signaling in the sensorimotor cortices can aid in developing Reinforcement Learning-based Brain-Computer Interfaces (RLBCI) for restoration of movement functions with fewer implants. Brain-computer interfaces (BCIs) using local field potentials (LFPs) have recently achieved performance comparable to spike-BCIs [1]. With superior stability over time, LFPs may be the preferred signal for BCIs. We show that sensorimotor LFPs can provide reward level information (R1 - R3) like spikes[2]. We used a cued reward-level reaching task in which reward information was temporally dissociated from movement information. This allowed the study of reward- and movement-related modulations in LFPs. We recorded simultaneously from contralateral primary -somatosensory (S1), -motor (M1), and the dorsal premotor (PMd) cortices in a female Macaca Mulatta. We found that all three cortices' average beta band (14-30 Hz) amplitude showed robust modulation with reward levels during the cue presentation period. Such modulation was consistently observed after controlling for cue color, differences in behavioral variables, and electromyogram (EMG) activity. Statistical amplitude analysis showed that reward level could be extracted from the simple LFP feature of beta band amplitude, even before a reaching target appeared, and no specific reach plan could be developed. Clinical Relevance - The availability of reward-related signals in the sensorimotor cortical (S1, M1,and PMd) LFPs' prior to movement planning opens new avenues to build RLBCIs with fewer implants recording fewer sites among different cortices Reward and motivational representations derived from LFPs compared to spikes allow the development of long-term clinical applications given LFP's stability and ease of recording over long periods.

Characterization of swine behavior and production using measurements collected via indoor positioning system

Legislative and market initiatives are requiring that gestating sows move from individual housing to group settings. Little information is known about coping of individual sows in these more socially complex environments and thus the impact of different behaviors on sow reproductive success was investigated. The movements of 70 sows during periods of reintroduction into large pen gestational housing following insemination was measured using Smartbow indoor positioning technology (Smartbow, Smartbow GmbH, Weibern, Austria) that tracked animal location and accelerations. Principle component analysis (PCA) was used to establish composite variables characterizing each animal’s behavioral response to social reintroduction and revealed the presence of two new variables accounting for over 60 % of the variance in behaviors: one pertaining to total movement and the other pertaining to social dominance/rapid movements. Component scores of total movement predicted measures of reproductive success whereas social dominance/rapid movements predicted piglet birth weight. These findings suggest that differences in behavioral variables as measured by Smartbow’s automated, non-invasive, real time tracking system are correlated with productivity of sows housing in socially complex settings.

Forced monogamy in a multiply mating species does not impede colonisation success.

BackgroundThe guppy (Poecilia reticulata) is a successful invasive species. It is also a species that mates multiply; previous studies have demonstrated that this strategy carries fitness benefits. Guppies are routinely introduced to tanks and troughs in regions outside their native range for mosquito-control purposes, and often spread beyond these initial confines into natural water bodies with negative ecological consequences. Here, using a mesocosm set up that resembles the containers into which single guppies are typically introduced for mosquito control, we ask whether singly-mated females are at a disadvantage, relative to multiply-mated females, when it comes to founding a population. Treatments were monitored for one year.ResultsA key finding was that mating history did not predict establishment success, which was 88% in both treatments. Furthermore, analysis of behavioural traits revealed that the descendants of singly-mated females retained antipredator behaviours, and that adult males showed no decrease in courtship vigour. Also, we detected no differences in behavioural variability between treatments.ConclusionsThese results suggest that even when denied the option of multiple mating, singly-mated female guppies can produce viable populations, at least at the founder stage. This may prove to be a critical advantage in typical introduction scenarios where few individuals are released into enclosed water bodies before finding their way into natural ecosystems.

Comparing Dietary and Other Lifestyle Factors Among Immigrant Nigerian Men Living in the US and Indigenous Men from Nigeria: Potential Implications for Prostate Cancer Risk Reduction

Although African men may share a common genetic predisposition contributing to the higher incidence of prostate cancer (CaP), the etiology of the variability in risk observed even among African men living in varying environments and cultures, highlights the strong and evolving research regarding the contribution of behavioral factors that may modify these biological risk factors. Our aim was to recruit Nigerian men from West Africa who had migrated and currently living in the US and indigenous men living in Nigeria to evaluate and compare differences in behavioral variables that are implicated to in contribute to CaP mortality and morbidity. Using a cross-sectional study design, we recruited participants between age 35 and 70 during a CaP screening event in Abeokuta (Nigeria) and Houston (US). Data were collected using standard questionnaires and subject interviews on factors such as smoking, dietary intake, intake of traditional and non-traditional supplements, physical activity and alcohol consumption. Descriptive analyses were used to characterize the demographic characteristics of the study participants. Sample t-test analyses were then used to compare the behavioral variables of the migrant and indigenous men from Nigeria. Immigrant men from Nigeria had significantly higher fruit and whole grain intake, higher number of hours of purposeful physical activity and significantly lower tobacco use and intake of trans fats in their diet compared to their indigenous counterparts which may potentially contribute to decreased CaP risk in this cohort. However, greater intake of meats, oils, alcohol and reduction in fish intake may contribute to greater risk, although the proportion of risk reduction or risk increase is difficult to estimate in this sample size. Factors associated to acculturation, the relative accessibility and the affordability may contribute to the choices made by immigrant Nigerian men compared to their indigenous counterparts. Although these results are provocative and significant, future well powered studies controlling for variability in population sampling should validate these observations.

Behavioral habituation to spatial novelty: Interference and noninterference studies

Long-term behavioral habituation (LTH), that is activity decrement upon repeated exposures to spatial novelty, is a relatively simple and ubiquitous form of behavioral plasticity in the animal kingdom, that can be used as a model of nonassociative learning in the freely behaving organism. Several strategies can be followed to tackle upon it. (a) Interference studies pertain to manipulation of the between-exposure interval by a variety of agents of different nature, that are known to interfere with hypothesized “consolidation process(es)” in associative learning paradigms. This approach indicates that LTH is modulated by NMDA receptors, requires polysome aggregation and protein synthesis, a functioning neocortex and both slow wave and paradoxical sleep. Further, it is modulated by endogenously released or exogenously given vasopressin and is not affected by blockade of endogenous opioids, at least through the “mu” receptor type. Moreover, LTH is disrupted by bilateral, electrolytic lesion of the locus coeruleus, but it is only impaired by 6-OH-DA bilateral lesion of the dorsal noradrenergic bundle, and it is facilitated by electrolytic lesion of the medial septal nuclei. (b) Noninterference correlative studies: Individual differences in behavioral variables can be correlated to some components of the architecture of the hippocampus to reveal structure-function relationships. (c) Noninterference maturation studies pertain to the study of the maturation of LTH during postnatal development in a scaled-down Làt-maze in normally reared rats and in rats with deranged rate of body and brain growth by litter size technique, differential stimulation or by perinatal propylthiouracil-induced hypothyroidism. (d) Noninterference development studies pertain to the formation of LTH varying the between-exposure interval. It was studied in albino rats of a Sprague-Dawley, random-bred stock (NRB) and of the Naples High (NHE) and Low-Excitability (NLE) lines. The study was carried out during the light or the dark phase of a 12 : 12LD cycle, by retesting at different inter-exposure intervals. Multivariate analysis of variance showed significant effects of strain, inter-exposure interval and of postexposure sleep or wakefulness. Furthermore, analysis of the temporal pattern showed the formation of LTH to follow a non linear complex function. Further, behavioral habituation consists of emotional and cognitive components that can be separated across different approaches. In conclusion, long-term habituation to a novel environment is a useful model to study experience-induced nonassociative behavioral modifications.

The ontogeny of twilight migration patterns in grunts (Pisces: Haemulidae)

The development of dusk and dawn migratory behaviours was investigated in French and white grunts ( Haemulon flavolineatum and H. plumieri) at St. Croix, U.S. Virgin Islands. Four juvenile stages were recognized: small, medium, transitional, and large. Each stage differed in age, size, coloration, habitat preference, diel foraging patterns, and twilight migratory behaviour. Comparisons between medium (15 to 30 mm long, 30 to 50 days old) and large juveniles (40 to 120 mm, 80 to 700 days) were emphasized. Medium juveniles occurred in small, diurnally feeding groups near sea urchins in the sand halo around a reef. Group composition varied during the day. They migrated at 15 min after sunset, moving hesitantly from halo to grassbed. Migration routes remained constant over a month, but differed over two years. Large juveniles fed nocturnally, formed daytime resting schools over coral heads, and migrated at 25 min after sunset. Compared with medium fish, resting site constancy was greater during a day, migration activities were significantly less variable, and migration routes remained relatively constant for two years. Ontogenetic differences in constancy of daytime school locales and migration routes may result from learning, facilitated perhaps by greater overlap of age cohorts in large juveniles. Other differences in behavioural variability may result from ontogenetic development of the visual apparatus, plus stabilizing selection due to greater predation on smaller, behaviourally variable fish.

Unexpected Correlations and the Cross-Cultural Method

Cross-cultural studies, in which the cases are societies rather than individuals, may be subject to errors due to individual differences within societies, cultural differences in behavior variables, and the implicit theories of the observers. In addition, antecedent variables may correlate more highly with unexpected consequences than with dependent variables predicted from theory. Ratings provided by Whiting and Child (1953) were correlated and the resulting matrix of correlations between all antecedent and all dependent variables was examined. Off-diagonal correlations, e.g., that between oral socialization anxiety and anal explanations of illness, were often found to be as high as correlations predicted from psychoanalytic theory. It was concluded that the caution suggested by Campbell and Fiske (1959) for validity studies should be applied to crosscultural studies.