Ovarian hormones and sexual behavior in Macaca nemestrina.

Determined the concentrations of the ovarian steroids, estradiol and progesterone, in the systemic plasma of 8 female pigtailed macaques and the correlations with sexual behavior and measurements of perineal swelling during the intermenstrual period. Estradiol peaked the day before maximum swelling of the perineum at the end of the 20.7-day follicular phase. Maximum titers of progesterone were recorded during the middle of the 15.1-day luteal phase. None of the female sexual behaviors changed significantly during the ovarian cycle, although intromission rate and frequency of ejaculation by 7 males were higher during the follicular phase. The pattern of ovarian hormone secretion and copulation throughout the menstrual cycle was more like that reported for women than for other mammalian species. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parental handedness and relative hand skill: A test of the developmental instability hypothesis.

In previous studies (e.g, R. A. Yeo et al; see record 1993-40422-001), both left-handers and extreme right-handers showed evidence of increased developmental instability, as indexed by minor physical anomalies and by specific fluctuating anatomic asymmetries. Thus, developmental instability may be an important factor affecting handedness. In the present study, a specific prediction of the developmental instability model of handedness, one that distinguishes it from the single-gene models of M. Annett (1985) and I. C. McManus (see record 1986-21280-001), was tested among 225 undergraduates. The model suggests that the degree of deviation from modal handedness, rather than direction of handedness, is heritable. Thus, it was hypothesized that extreme right-handers as well as left-handers have an elevated proportion of left-handed parents. Results supported this hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Limb laterality and motor proficiency in children

This investigation examined the premise derived from recent reports, that children who are consistent right-handers are better coordinated than their left- and mixed-sided (inconsistent) peers. The observation of limb laterality was extended to include footedness. Two samples of children (N = 273) (foot laterality/hand laterality), matched for age and sex, were assessed for motor proficiency and compared according to limb preference (right, mixed, left). Overall, results indicated no significant group differences (ps > .05) in composite scores (upper-limb, lower-limb, combination) and total performance, within foot and hand laterality. In view of recent studies (noting differences between laterality groups) and these nonsupportive results, it appears that additional inquiry is warranted before any consensus regarding the association between limb laterality and motor coordination can be established. Suggestions for further inquiry are presented.     

Behavioral asymmetries of psychomotor performance in rhesus monkeys (Macaca mulatta): A dissociation between hand preference and skill.

Hand preferences were recorded for 35 rhesus monkeys as they manipulated a joystick in response to 2 computerized tasks. These preferences were then used to contrast 8 left- and 10 right-handed Ss on performance measures of hand skill. Individual hand preferences were found, but no significant population asymmetry was observed across the sample. However, the performance data reveal substantial benefits of right-handedness for joystick manipulation, as this group of monkeys mastered the 2 psychomotor tasks significantly faster than did their left-handed counterparts. The data support earlier reports of a right-hand advantage for joystick manipulation and also support the importance of distinguishing between hand preference and manual performance in research on functional asymmetries. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human leukocyte antigens and hand preference: Preliminary observations.

To date, no specific genetic markers have been associated with human hand preference. In this study, we examined relations between human leukocyte antigen (HLA) alleles and hand preference. Based on established associations between handedness and autoimmune diseases related to HLA alleles, we predicted that left-handers would be more likely to possess the A1, B8, and DR3 alleles. In a sample of 664 individuals who filled out the Annett Handedness Questionnaire, these predictions were generally supported. In addition, we found that left-handedness and the B8 allele were negatively related to number of offspring, after controlling for age. These results are discussed in light of the developmental instability model of the origins of handedness, as well as single major gene models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grip morphology and hand use in chimpanzees (Pan troglodytes): Evidence of a left hemisphere specialization in motor skill.

Three experiments on grip morphology and hand use were conducted in a sample of chimpanzees. In Experiment 1, grip morphology when grasping food items was recorded, and it was found that subjects who adopted a precision grip were more right-handed than chimpanzees using other grips. In Experiment 2, the effect of food type on grasping was assessed. Smaller food items elicited significantly more precision grips for the right hand. In Experiment 3, error rates in grasping foods were compared between the left and right hands. Significantly more errors were made for the left compared with the right hand. The cumulative results indicate that chimpanzees show a left-hemisphere asymmetry in motor skill that is associated with the use of precision grips. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Environmental influences in hand preference: an African point of view

In the analysis of survival data from clinical trials and other studies, the censoring generally precludes estimation of the mean survival time. To accommodate censoring, Irwin (1949) proposed, as an alternative, estimation of the mean lifetime restricted to a suitably chosen time T. In this article we consider the use of Irwin's restricted mean as an index for comparing survival in different groups, using as an example published data from a randomized clinical trial in patients with primary biliary cirrhosis. Irwin's method, originally based on the actuarial survival estimator, is extended to incorporate covariates into the analysis through the use of piecewise exponential models. For comparing two survival curves, the logrank test is known to be optimal under proportional hazards alternatives. However, comparison of restricted means may outperform the logrank test in situations involving nonproportional hazard rates. We examine the size and power of these two procedures under various proportional and nonproportional hazards alternatives, with and without covariate adjustment. For survival curves that separate early in time the censored data generalization of the Wilcoxon test is known to exhibit high power, and we examine how the comparison of restricted means performs relative to this procedure also.     

Footedness: Asymmetries in foot preference and skill and neuropsychological assessment of foot movement.

If footedness is defined in terms of a reliable role differentiation of the two feet and legs, right-handers show a right-foot bias for activities requiring fine manipulation and focused attention. In adult right-handers, the left leg tends to be the longer and heavier one, in keeping with the support role of that leg. In left-handers, anatomical asymmetries tend to be in the opposite direction, and functional preferences are somewhat less clearly expressed. Foot biases and their interaction with hand biases are of practical importance in the design of man-machine systems. The considerable sensitivity of foot and leg performance to neurological insult renders the assessment of foot and leg use very attractive for purposes of clinical neuropsychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of hand preference in Japan and Canada.

An analysis was performed on 47 items of a hand preference inventory administered to 1275 undergraduate students in Japan and Canada. Factor analysis indicated that items grouped into three factors, representing skilled activities, unskilled activities, and turning movements. Analysis of the factor scores revealed that neither skilled handedness nor unskilled handedness was significantly influenced by cultural group or sex. On the third factor, Japanese students were far more right-handed than were Canadian students. Although mean factor scores for skilled handedness did not differ between groups, the prevalence of left-handedness was significantly lower in Japan than in Canada. Cultural pressures have their primary effect on turning movements, and on specific skilled activities such as writing and eating. Although the data are consistent with the view that a right shift for skilled activities has been superimposed on an undifferentiated handedness, other considerations make such a theory less tenable. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective corticostriatal dysfunction in schizophrenia: Examination of motor and cognitive skill learning.

[Correction Notice: An erratum for this article was reported in Vol 22(3) of Neuropsychology (see record 2008-05020-015). Table 1 on page 102 should have included the BPRS Depression-Anxiety subscale score 9.00 (3.99) under the column heading Schiz pts. Table displays means with standard deviations in parentheses.] [Correction Notice: An erratum for this article was reported in Vol 22(2) of Neuropsychology (see record 2008-02526-002). The DOI for the supplemental materials was printed incorrectly. The correct DOI is as follows: http://dx.doi.org/10.1037/0894-4105.22.1.100.supp.] It has been suggested that patients with schizophrenia have corticostriatal circuit dysfunction (Carlsson & Carlsson, 1990). Skill learning is thought to rely on corticostriatal circuitry and different types of skill learning may be related to separable corticostriatal loops (Grafton, Hazeltine, & Ivry, 1995; Poldrack, Prabhakaran, Seger, & Gabrieli, 1999). The authors examined motor (Serial Reaction Time task, SRT) and cognitive (Probabilistic Classification task, PCT) skill learning in patients with schizophrenia and normal controls. Development of automaticity was examined, using a dual task paradigm, across three training sessions. Patients with schizophrenia were impaired at learning on the PCT compared to controls. Performance gains of controls occurred within the first session, whereas patients only improved gradually and never reached the performance level of controls. In contrast, patients were not impaired at learning on the SRT relative to controls, suggesting that patients with schizophrenia may have dysfunction in a specific corticostriatal subcircuit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bipedal posture and hand preference in humans and other primates.

Hand preference for quadrupedal and bipedal reaching in humans and rhesus macaques (Macaca mulatta) was examined, and the data were compared with postural reaching data that have been reported for 8 other primate species. Population-level biases were found toward use of the right hand for quadrupedal and bipedal reaching in humans and use of the left hand for quadrupedal reaching in rhesus macaques. Rhesus macaques showed a significant shift toward greater use of the right hand for bipedal vs. quadrupedal reaching. Comparisons with other species showed significant variance in the direction and strength of hand preference across reaching postures. The study noted right-hand biases for bipedal reaching in humans, great apes, and tufted capuchins and shifts toward greater use of the right hand for bipedal vs. quadrupedal reaching in great apes, tufted capuchins, and rhesus macaques. These results suggest that posture alters both the direction and strength of primate hand preference and that bipedalism may have facilitated species-typical right-handedness in humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The mixture distribution of left minus right hand skill in men and women

A series of two-dimensional images of proton distribution in a hardened concrete sample has been obtained during the thawing process (from -50 degrees C up to 11 degrees C). The SPRITE sequence is optimal for this study given the characteristic short relaxation times of water in this porous media (T2* < 200 micros and T1 < 3.6 ms). The relaxation parameters of the sample were determined in order to optimize the time efficiency of the sequence, permitting a 4-scan 64 x 64 acquisition in under 3 min. The image acquisition is fast on the time scale of the temperature evolution of the specimen. The frozen water distribution is quantified through a position based study of the image contrast. A multiple point acquisition method is presented and the signal sensitivity improvement is discussed.     

Configural response learning: The acquisition of a nonpredictive motor skill.

This study examined the representational nature of configural response learning using a task that required simultaneous keypresses with 2 or 3 fingers, similar to the production of chords on the piano. If the benefits of learning are related to the retrieval of individual stimulus-response mappings, performance should depend on the frequencies of the individual responses forming each chord. Alternatively, learning may involve the encoding of configural information concerning the relationship between the chord elements. In Experiment 1, training was restricted to a subset of the 120 possible 3-element chords. Probe blocks included the practiced chords, chords composed of novel configurations of practiced elements (reconfigured), and chords that contained a new element (new). Practiced chords were performed faster than reconfigured chords, indicating learning involves the encoding of configural information. Experiment 2 showed that learning was not restricted to configurations within each hand. Experiments 3 and 4 demonstrated that learning was largely response based. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Handedness and asymmetry of hand representation in human motor cortex

The cortical representation of five simple hand and finger movements in the human motor cortex was determined in left- and right-handed people with whole-head magnetoencephalography. Different movements were found to be represented by spatially segregated dipolar sources in primary motor cortex. The spatial arrangement of neuronal sources for digit and wrist movements was nonsomatotopic and varied greatly between subjects. As an estimator of hand area size in primary motor cortex, we determined the smallest cuboid volume enclosing the five dipole sources within the left and right hemisphere of each subject. Interhemispheric comparison revealed a significant increase of this volume in primary motor cortex opposite to the preferred hand. This asymmetry was due to a greater spatial segregation of neuronal dipole generators subserving different hand and finger actions in the dominant hemisphere. Mean Euclidean distances between dipole sources for different movements were 10.7 +/- 3.5 mm in the dominant and 9.4 +/- 3.5 mm in the nondominant hemisphere (mean +/- SD; P = 0. 01, two-tailed t-test). The expansion of hand representation in primary motor cortex could not simply be attributed to a greater number of pyramidal cells devoted to each particular movement as inferred from current source amplitudes. The degree of hemispheric asymmetry of hand area size in the primary motor cortex was correlated highly with the asymmetry of hand performance in a standardized handedness test (r = -0.76, P < 0.01). These results demonstrate for the first time a biological correlate of handedness in human motor cortex. The expansion of hand motor cortex in the dominant hemisphere may provide extra space for the cortical encoding of a greater motor skill repertoire of the preferred hand.     

Associations of postural knowledge and basic motor skill with dyspraxia in autism: Implication for abnormalities in distributed connectivity and motor learning.

Children with autism often have difficulty performing skilled movements. Praxis performance requires basic motor skill, knowledge of representations of the movement (mediated by parietal regions), and transcoding of these representations into movement plans (mediated by premotor circuits). The goals of this study were (a) to determine whether dyspraxia in autism is associated with impaired representational (“postural”) knowledge and (b) to examine the contributions of postural knowledge and basic motor skill to dyspraxia in autism. Thirty-seven children with autism spectrum disorder (ASD) and 50 typically developing (TD) children, ages 8–13, completed (a) an examination of basic motor skills, (b) a postural knowledge test assessing praxis discrimination, and (c) a praxis examination. Children with ASD showed worse basic motor skill and postural knowledge than did controls. The ASD group continued to show significantly poorer praxis than did controls after accounting for age, IQ, basic motor skill, and postural knowledge. Dyspraxia in autism appears to be associated with impaired formation of spatial representations, as well as transcoding and execution. Distributed abnormality across parietal, premotor, and motor circuitry, as well as anomalous connectivity, may be implicated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social transmission of food preference in mice: Methodology and application to galanin-overexpressing transgenic mice.

Social transmission of food preference (STFP) is a test of olfactory memory that can be used in mice. Confounds in STFP that can lead to misinterpretation of an STFP deficit as a memory impairment include changes in social interaction and olfaction. The issue of changes in social interaction was addressed by evaluating an observer-centric and a demonstrator-centric method for scoring the interaction phase of STFP in mice. The demonstrator-centric method was applied to a line of STFP-impaired, galanin-overexpressing transgenic (GAL-tg). GAL-tg mice were impaired in STFP without deficits in social interaction. In tests of olfactory ability, GAL-tg mice were unimpaired on buried-food and habituation-dishabituation tasks. The current studies describe an expanded method for using STFP in mice and confirm a deficit in olfactory memory in GAL-tg mice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pharmacokinetics of stavudine (2',3'-didehydro-3'-deoxythymidine) in the neonatal macaque (Macaca nemestrina)

Our objective was to determine whether age effects the pharmacokinetics of stavudine (2',3'-didehydro-3'-deoxythymidine) in the neonatal pig-tailed macaque (Macaca nemestrina). The drug (5 mg/kg of body weight) was administered serially as a single intravenous bolus to the same four macaques at the ages of < 1 week, 1 month, and 4 months. Plasma clearance at < 1 week of age was significantly lower (P < 0.05) than the corresponding values at 1 month and 4 months. Our data indicate that the pharmacokinetics of stavudine change significantly with age in M. nemestrina.