Does an altruist-detection cognitive mechanism function independently of a cheater-detection cognitive mechanism? Studies using Wason selection tasks

Subjects performed four deontic Wason selection tasks in three experiments to investigate possible commonalities in people's performance in making logical inferences in social contexts. These tasks tested sensitivity to another party being an altruist, cheater or willing to share a resource and following a precaution rule in the context of danger. The results indicated no significant association between performance on the altruist detection and the cheater detection tasks. This result suggests that whatever the nature of the altruist-detection algorithm, it functions independently of the cheater-detection algorithm. The results also indicated significant associations between the cheater-detection task and the resource-sharing task. Possible mechanisms and functions of social intelligence suggested by these results are discussed.     

Toxic triplets provide clues to neurodegeneration

Cleavage, aggregation and toxicity of the expanded androgen receptor in spinal and bulbar muscular atrophyMerry, D.E. et al. (1998)Hum. Mol. Genet. 7, 693–701Truncated N-terminal fragments of huntingtin with expanded glutamine repeats form nuclear and cytoplasmic aggregates in cell cultureCooper, J.K. et al. (1998)Hum. Mol. Genet. 7, 783–790Aggregation of N-terminal huntingtin is dependent on the length of its glutamine repeatsLi, S.H. and Li, X.J. (1998)Hum. Mol. Genet. 7, 777–782     

Is prospective altruist-detection an evolved solution to the adaptive problem of subtle cheating in cooperative ventures? Supportive evidence using the Wason selection task

Reciprocal altruism in humans may be made possible in part by the existence of information processing mechanisms for the detection of overt cheating. However, cheating may not always be readily detectable due to the division of labor. Subtle cheating poses a serious problem for the evolution of altruism. This article argues that subtle cheating may have exerted selective pressures on early hominids to be sensitive to information regarding the genuineness of an altruistic act. In two experiments, subjects were required to complete Wason selection tasks designed to allow for the detection of altruism. Performance on the altruist-detection tasks was compared to performance on control Wason selection tasks (Experiment 1) and to performance on control and cheater detection tasks (Experiment 2). Participants were significantly better at solving cheater-detection and altruist-detection versions compared to control versions of the problems, and there was no significant difference between altruist-detection and cheater-detection. Results are discussed in relation to recent conceptual models for the evolution of altruism. Specifically, it is argued that non-kin altruism may be an evolutionarily stable strategy if altruists can detect one another and form mutually beneficial social support networks.     

Stretching the boundaries of elastin function

Elastin is an essential determinant of arterial morphogenesisLi, D.Y. et al. (1998)Nature 393, 276–280An elastin gene mutation producing abnormal tropoelastin and abnormal elastic fibres in a patient with autosomal dominant cutis laxaTassabehji, M. et al. (1998)Hum. Mol. Genet. 7, 1021–1028     

Making an impression on X-linked mental retardation

Oligophrenin-1 encodes a rhoGAP protein involved in X-linked mental retardationBilluart, P. (1998)Nature 392, 923–926PAK3 mutation in nonsyndromic X-linked mental retardationAllen, K.M. et al. (1998)Nat. Genet. 20, 25–30Mutations in GDI1 are responsible for X-linked non-specific mental retardationD'Adamo, P. et al. (1998)Nat. Genet. 19, 134–139Non-specific X-linked semidominant mental retardation by mutations in a Rab GDP-dissociation inhibitorBienvenu, T. et al. (1998)Hum. Mol. Genet. 7, 1311–1315     

The synaptonemal complex and meiotic recombination in humans: new approaches to old questions

Meiotic prophase serves as an arena for the interplay of two important cellular activities, meiotic recombination and synapsis of homologous chromosomes. Synapsis is mediated by the synaptonemal complex (SC), originally characterized as a structure linked to pairing of meiotic chromosomes (Moses (1958) J Biophys Biochem Cytol 4:633–638). In 1975, the first electron micrographs of human pachytene stage SCs were presented (Moses et al. (1975) Science 187:363–365) and over the next 15 years the importance of the SC to normal meiotic progression in human males and females was established (Jhanwar and Chaganti (1980) Hum Genet 54:405–408; Pathak and Elder (1980) Hum Genet 54:171–175; Solari (1980) Chromosoma 81:315–337; Speed (1984) Hum Genet 66:176–180; Wallace and Hulten (1985) Ann Hum Genet 49(Pt 3):215–226). Further, these studies made it clear that abnormalities in the assembly or maintenance of the SC were an important contributor to human infertility (Chaganti et al. (1980) Am J Hum Genet 32:833–848; Vidal et al. (1982) Hum Genet 60:301–304; Bojko (1983) Carlsberg Res Commun 48:285–305; Bojko (1985) Carlsberg Res Commun 50:43–72; Templado et al. (1984) Hum Genet 67:162–165; Navarro et al. (1986) Hum Reprod 1:523–527; Garcia et al. (1989) Hum Genet 2:147–53). However, the utility of these early studies was limited by lack of information on the structural composition of the SC and the identity of other SC-associated proteins. Fortunately, studies of the past 15 years have gone a long way toward remedying this problem. In this minireview, we highlight the most important of these advances as they pertain to human meiosis, focusing on temporal aspects of SC assembly, the relationship between the SC and meiotic recombination, and the contribution of SC abnormalities to human infertility.The synaptonemal complex–50 years     

The ontogeny of nasal floor shape variation in extant humans

Variation in nasal floor topography has generated both neontological and paleontological interest. Three categories of nasal floor shape (Franciscus: J Hum Evol 44 (2003) 699–727) have been used when analyzing this trait in extant humans and fossil Homo: flat, sloped, and depressed (or “bi‐level”). Variation in the frequency of these configurations within and among extant and fossil humans has been well‐documented (Franciscus: J Hum Evol 44 (2003) 699–727; Wu et al.: Anthropol Sci 120 (2012) 217–226). However, variation in this trait in Homo has been observed primarily in adults, with comparatively small subadult sample sizes and/or large age gradients that may not sufficiently track key ontogenetic changes. In this study, we investigate the ontogeny of nasal floor shape in a relatively large cross‐sectional age sample of extant humans (n = 382) ranging from 4.0 months fetal to 21 years post‐natal. Results indicate that no fetal or young infant individuals possess a depressed nasal floor, and that a depressed nasal floor, when present (ca. 21% of the sample), does not occur until 3.0 years postnatal. A canonical variates analysis of maxillary shape revealed that individuals with depressed nasal floors were also characterized by relatively taller anterior alveolar regions. This suggests that palate remodeling at about 3.0–3.5 years after birth, under the influence of tooth development, strongly influences nasal floor variation, and that various aspects of dental development, including larger crown/root size, may contribute to the development of a depressed nasal floor. These results in extant humans may help explain the high frequency of this trait found in Neandertal and other archaic Homo maxillae. Am J Phys Anthropol 155:369–378, 2014. © 2014 Wiley Periodicals, Inc.     

Rethinking relevance: Repetition priming reveals the psychological reality of adaptive specializations for reasoning

Theories advanced to explain conditional reasoning range from those that invoke inference systems that evolved for specific domains (such as social exchange, precautions, or deontic regulations) to relevance theory, a relatively domain-general account that invokes conversational pragmatics. The present research utilized a novel extension of repetition priming, in conjunction with the Wason selection task (a widely known and used task to test people's conditional reasoning), to evaluate alternative theories of human reasoning. Across five experiments, testing over 600 participants, consistent priming across selection tasks was demonstrated. The pattern of priming effects supports models of human reasoning based on specific evolved reasoning abilities, and was inconsistent with general conditional reasoning models such as relevance theory. These results also converge with neurological and clinical evidence of divided psychological processes for reasoning about relatively specific domains, based on functionally distinct inference systems.     

New body mass estimates for Omomys carteri,a middle Eocene primate from North America

We report new body mass estimates for the North American Eocene primate Omomys carteri. These estimates are based on postcranial measurements and a variety of analytical methods, including bivariate regression, multiple regression, and principal components analysis (PCA). All body mass estimation equations show high coefficients of determination (R²), and some equations exhibit low prediction errors in accuracy tests involving extant species of body size similar to O. carteri. Equations derived from PCA-summarized data and multiple regression generally perform better than those based on single variables. The consensus of estimates and their statistics suggests a body mass range of 170–290 g. This range is similar to previous estimates for this species based on first molar area (Gingerich, J Hum Evol 10:345–374, 1981; Conroy, Int J Primatol 8:115–137, 1987). Am J Phys Anthropol 109:41–52, 1999. © 1999 Wiley-Liss, Inc.     

A new type of tumour suppressor gene: a serine/threonine kinase joins the list

Peutz–Jeghers syndrome is caused by mutations in a novel serine threonine kinaseJenne, D.E. et al. (1998)Nat. Genet. 18, 38–43A serine/threonine kinase gene defective in Peutz–Jeghers syndromeHemminki, A. et al. (1998)Nature 391, 184–187     

Non-viral gene transfer: liposomes and nanospheres promise to deliver the goods

Effective treatment of early endobronchial cancer with regional administration of liposome–p53 complexesZou, Y. et al. (1998)J. Natl. Cancer Inst. 90, 1130–1137Controlled gene delivery by DNA–gelatin nanospheresTruong-Le, V.L. et al. (1998)Hum. Gene Ther. 9, 1709–1717     

Two degrees of freedom quasi-static EMG-force at the wrist using a minimum number of electrodes

Surface electromyogram-controlled powered hand/wrist prostheses return partial upper-limb function to limb-absent persons. Typically, one degree of freedom (DoF) is controlled at a time, with mode switching between DoFs. Recent research has explored using large-channel EMG systems to provide simultaneous, independent and proportional (SIP) control of two joints—but such systems are not practical in current commercial prostheses. Thus, we investigated site selection of a minimum number of conventional EMG electrodes in an EMG-force task, targeting four sites for a two DoF controller. In a laboratory experiment with 10 able-bodied subjects and three limb-absent subjects, 16 electrodes were placed about the proximal forearm. Subjects produced 1-DoF and 2-DoF slowly force-varying contractions up to 30% maximum voluntary contraction (MVC). EMG standard deviation was related to forces via regularized regression. Backward stepwise selection was used to retain those progressively fewer electrodes that exhibited minimum error. For 1-DoF models using two retained electrodes (which mimics the current state of the art), subjects had average RMS errors of (depending on the DoF): 7.1–9.5% MVC for able-bodied and 13.7–17.1% MVC for limb-absent subjects. For 2-DoF models, subjects using four electrodes had errors on 1-DoF trials of 6.7–8.5% MVC for able-bodied and 11.9–14.0% MVC for limb-absent; and errors on 2-DoF trials of 9.9–11.2% MVC for able-bodied and 15.8–16.7% MVC for limb-absent subjects. For each model, retaining more electrodes did not statistically improve performance. The able-bodied results suggest that backward selection is a viable method for minimum error selection of as few as four electrode sites for these EMG-force tasks. Performance evaluation in a prosthesis control task is a necessary and logical next step for this site selection method.     

Unexpected Dual Task Benefits on Cycling in Parkinson Disease and Healthy Adults: A Neuro-Behavioral Model

BackgroundWhen performing two tasks at once, a dual task, performance on one or both tasks typically suffers. People with Parkinson’s disease (PD) usually experience larger dual task decrements on motor tasks than healthy older adults (HOA). Our objective was to investigate the decrements in cycling caused by performing cognitive tasks with a range of difficulty in people with PD and HOAs.MethodsTwenty-eight participants with Parkinson’s disease and 20 healthy older adults completed a baseline cycling task with no secondary tasks and then completed dual task cycling while performing 12 tasks from six cognitive domains representing a wide range of difficulty.ResultsCycling was faster during dual task conditions than at baseline, and was significantly faster for six tasks (all p<.02) across both groups. Cycling speed improved the most during the easiest cognitive tasks, and cognitive performance was largely unaffected. Cycling improvement was predicted by task difficulty (p<.001). People with Parkinson’s disease cycled slower (p<.03) and showed reduced dual task benefits (p<.01) than healthy older adults.ConclusionsUnexpectedly, participants’ motor performance improved during cognitive dual tasks, which cannot be explained in current models of dual task performance. To account for these findings, we propose a model integrating dual task and acute exercise approaches which posits that cognitive arousal during dual tasks increases resources to facilitate motor and cognitive performance, which is subsequently modulated by motor and cognitive task difficulty. This model can explain both the improvement observed on dual tasks in the current study and more typical dual task findings in other studies.     

Unusual imprinting defects with low recurrence risks

Sporadic imprinting defects in Prader–Willi syndrome and Angelman syndrome: implications for imprint-switch models, genetic counselling, and prenatal diagnosisBuiting, K. et al. (1998)Am. J. Hum. Genet. 63, 170–180     

Impulsive Action but Not Impulsive Choice Determines Problem Gambling Severity

Background

Impulsivity is a hallmark of problem gambling. However, impulsivity is not a unitary construct and this study investigated the relationship between problem gambling severity and two facets of impulsivity: impulsive action (impaired ability to withhold a motor response) and impulsive choice (abnormal aversion for the delay of reward).

Methods

The recruitment includes 65 problem gamblers and 35 normal control participants. On the basis of DSM-IV-TR criteria, two groups of gamblers were distinguished: problem gamblers (n = 38) and pathological gamblers (n = 27) with similar durations of gambling practice. Impulsive action was assessed using a response inhibition task (the stop-signal task). Impulsive choice was estimated with the delay-discounting task. Possible confounds (e.g., IQ, mood, ADHD symptoms) were recorded.

Results

Both problem and pathological gamblers discounted reward at a higher rate than their controls, but only pathological gamblers showed abnormally low performance on the most demanding condition of the stop-signal task. None of the potential confounds covaried with these results.

Conclusions

These results suggest that, whereas abnormal impulsive choice characterizes all problem gamblers, pathological gamblers'' impairments in impulsive action may represent an important developmental pathway of pathological gambling.     

Sex differences in prefrontal hemodynamic response to mental arithmetic as assessed by near-infrared spectroscopy

Background: Sex differences in cognitive tasks have been widely investigated. With brain-imaging techniques, the functions of the brain during the performance of tasks can be examined.Objective: Mental arithmetic and near-infrared spectroscopy (NIRS) were used to assess sex differences in prefrontal area activation in a functional brain study.Methods: Healthy college students were recruited to perform 2 mental arithmetic tasks. In the first (easy) task, students had to subtract a 1-digit number from a 3-digit number. In the second (difficult) task, they had to subtract a 2-digit number from a 3-digit number. Changes in the concentration of oxygenated hemoglobin (oxy-Hgb) in the prefrontal area during the tasks were measured with NIRS.Results: Thirty students (15 men, 15 women; mean [SD] age: 24.9 [2.2] and 24.3 [2.6] years, respectively) were recruited from Southeast University, Nanjing, China, to participate in the study. The concentration of oxy-Hgb increased during both mental arithmetic tasks (difficult task vs easy task, mean [SD] % arbitrary units: 4.36 [4.38] vs 2.26 [2.82]; F_1,28 = 222.80; P < 0.01). Significant interactions of task x sex (F_1,28 = 82.95), time × sex (F_1,28 = 34.48), task × time (F_1,28 = 222.57), and task × time × sex (F_1,28 = 83.09) were obtained (all, P < 0.01). However, for the 2 tasks, no significant differences between men and women were observed in the mean (SD) response time (men vs women, sec: 3.60 [0.74] vs 3.56 [0.49] for the easy task, 6.55 [0.77] vs 6.44 [0.75] for the difficult task; F_1,28 = 0.67; P = NS) or accuracy rate (men vs women, %: 95.33 [7.40] vs 92.77 [8.80] for the easy task, 62.67 [28.56] vs 54.67 [18.75] for the difficult task; F_1,28 = 0.54; P = NS). Male students showed neural efficiency (less prefrontal activation in subjects with better performance) during the difficult task.Conclusions: In these subjects, sex differences in prefrontal response when performing mental arithmetic were associated with the intensity of the task. Compared with men, women had greater efficiency in task performance (ie, less activation or oxygen consumption for equal performance).     

Therapy for CAG-repeat diseases?

Suppression of aggregate formation and apoptosis by transglutaminase inhibitors in cells expressing truncated DRPLA protein with an expanded polyglutamine stretchIgarashi, S. et al. (1998)Nat. Genet. 18, 111–117     

Selfing for the design of genomic selection experiments in biparental plant populations

Self-fertilization (selfing) is commonly used for population development in plant breeding, and it is well established that selfing increases genetic variance between lines, thus increasing response to phenotypic selection. Furthermore, numerous studies have explored how selfing can be deployed to maximal benefit in the context of traditional plant breeding programs (Cornish in Heredity 65:201–211,1990a, Heredity 65:213–220,1990b; Liu et al. in Theor Appl Genet 109:370–376, 2004; Pooni and Jinks in Heredity 54:255–260, 1985). However, the impact of selfing on response to genomic selection has not been explored. In the current study we examined how selfing impacts the two key aspects of genomic selection—GEBV prediction (training) and selection response. We reach the following conclusions: (1) On average, selfing increases genomic selection gains by more than 70 %. (2) The gains in genomic selection response attributable to selfing hold over a wide range population sizes (100–500), heritabilities (0.2–0.8), and selection intensities (0.01–0.1). However, the benefits of selfing are dramatically reduced as the number of QTLs drops below 20. (3) The major cause of the improved response to genomic selection with selfing is through an increase in the occurrence of superior genotypes and not through improved GEBV predictions. While performance of the training population improves with selfing (especially with low heritability and small population sizes), the magnitude of these improvements is relatively small compared with improvements observed in the selection population. To illustrate the value of these insights, we propose a practical genomic selection scheme that substantially shortens the number of generations required to fully capture the benefits of selfing. Specifically, we provide simulation evidence that indicates the proposed scheme matches or exceeds the selection gains observed in advanced populations (i.e. F ₈ and doubled haploid) across a broad range of heritability and QTL models. Without sacrificing selection gains, we also predict that fully inbred candidates for potential commercialization can be identified as early as the F ₄ generation.     

Genetic and phenotypic characterization of a Japanese wild-derived DOB/Oda rat strain

Wild-derived rat strains can provide novel genome resources that are not available in standard laboratory strains. Genetic backgrounds of wild-derived strains can facilitate effective genetic linkage analyses and often modulate the expression of mutant phenotypes. Here we describe the development and characterization of a new inbred rat strain, DOB/Oda, from wild rats (Rattus norvegicus) captured in Shitara, Aichi, Japan. Phenotype analysis of 109 parameters revealed that the DOB/Oda rats had small body weight, preference for darkness, and high locomotor activity compared with the rat strains in the National BioResource Project for the Rat (NBRP-Rat) database. Genome analysis with 357 SSLP markers identified DOB/Oda-specific alleles in 70 markers. The percentage of SSLP markers that showed polymorphism between the DOB/Oda strain and any of 132 laboratory strains from NBRP-Rat varied from 89 to 95 %. The polymorphic rate (average of the values of the percentage) for the DOB/Oda strain was 91.6 %, much higher than the rates for available wild-derived strains such as the Brown Norway rat. A phylogenic tree constructed with DOB/Oda and all the strains in NBRP-Rat showed that the DOB/Oda strain localized within the wild rat groups, apparently separate from the laboratory strains. Together, these findings indicated that the DOB/Oda rat has a unique genome that is not available in the laboratory strains. Therefore, the new DOB/Oda strain will provide an important genome resource that will be useful for designing genetic experiments and for the discovery of genes that modulate mutant phenotypes.     

Oxytocin and vasopressin hormone genes in children's externalizing problems: A cognitive endophenotype approach

Externalizing problems are among the most common mental health problems of children. Research suggests that these problems are heritable, yet little is known about the specific genes involved in their pathophysiology. The current study examined a genotype-endophenotype-phenotype model of externalizing problems in 320 preschool-aged children. Markers of the oxytocin (OXT) and arginine vasopressin (AVP) hormone genes were selected as candidates owing to their known association with psychopathology in other domains. We tested whether OXT and AVP variants were related to children's externalizing problems, as well as two cognitive endophenotypes presumed to underlie these problems: theory of mind (ToM) and executive functioning (EF). Externalizing problems were assessed at age 4.5 using a previously-validated rating scale. ToM and EF were measured with age-appropriate tasks. Using a family-based association design and controlling for non-genomic confounds, support was found for an association between a two-marker OXT haplotype (rs2740210–rs2770378) and a two-marker AVP haplotype (rs1887854–rs3761249) and externalizing problems. Specific associations of these haplotypes with ToM and EF were also observed. Further, ToM and EF were shown to independently and jointly predict externalizing problems, and to partially mediate the effects of OXT and AVP on externalizing problems. This study provides the first evidence that genetic variation in OXT and AVP may contribute to individual differences in childhood externalizing problems, and that these effects may operate through emerging neurocognitive abilities in the preschool period.