Intrinsic Motivations Drive Learning of Eye Movements: An Experiment with Human Adults

Intrinsic motivations drive the acquisition of knowledge and skills on the basis of novel or surprising stimuli or the pleasure to learn new skills. In so doing, they are different from extrinsic motivations that are mainly linked to drives that promote survival and reproduction. Intrinsic motivations have been implicitly exploited in several psychological experiments but, due to the lack of proper paradigms, they are rarely a direct subject of investigation. This article investigates how different intrinsic motivation mechanisms can support the learning of visual skills, such as “foveate a particular object in space”, using a gaze contingency paradigm. In the experiment participants could freely foveate objects shown in a computer screen. Foveating each of two “button” pictures caused different effects: one caused the appearance of a simple image (blue rectangle) in unexpected positions, while the other evoked the appearance of an always-novel picture (objects or animals). The experiment studied how two possible intrinsic motivation mechanisms might guide learning to foveate one or the other button picture. One mechanism is based on the sudden, surprising appearance of a familiar image at unpredicted locations, and a second one is based on the content novelty of the images. The results show the comparative effectiveness of the mechanism based on image novelty, whereas they do not support the operation of the mechanism based on the surprising location of the image appearance. Interestingly, these results were also obtained with participants that, according to a post experiment questionnaire, had not understood the functions of the different buttons suggesting that novelty-based intrinsic motivation mechanisms might operate even at an unconscious level.     

Superoxide dismutase is upregulated in <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> following protoporphyrin-mediated photodynamic inactivation and does not directly influence the response to photodynamic treatment

Background  

Staphylococcus aureus, a major human pathogen causes a wide range of disease syndromes. The most dangerous are methicillin-resistant S. aureus (MRSA) strains, resistant not only to all β-lactam antibiotics but also to other antimicrobials. An alarming increase in antibiotic resistance spreading among pathogenic bacteria inclines to search for alternative therapeutic options, for which resistance can not be developed easily. Among others, photodynamic inactivation (PDI) of S. aureus is a promising option. Photodynamic inactivation is based on a concept that a non toxic chemical, called a photosensitizer upon excitation with light of an appropriate wavelength is activated. As a consequence singlet oxygen and other reactive oxygen species (e.g. superoxide anion) are produced, which are responsible for the cytotoxic effect towards bacterial cells. As strain-dependence in photodynamic inactivation of S. aureus was observed, determination of the molecular marker(s) underlying the mechanism of the bacterial response to PDI treatment would be of great clinical importance. We examined the role of superoxide dismutases (Sod) in photodynamic inactivation of S. aureus as enzymes responsible for oxidative stress resistance.     

Identification of Novel Loci Associated with Gastrointestinal Parasite Resistance in a Red Maasai x Dorper Backcross Population

Gastrointestinal (GI) parasitic infection is the main health constraint for small ruminant production, causing loss of weight and/or death. Red Maasai sheep have adapted to a tropical environment where extreme parasite exposure is a constant, especially with highly pathogenic Haemonchus contortus. This breed has been reported to be resistant to gastrointestinal parasite infection, hence it is considered an invaluable resource to study associations between host genetics and resistance. The aim of this study was to identify polymorphisms strongly associated with host resistance in a double backcross population derived from Red Maasai and Dorper sheep using a SNP-based GWAS analysis. The animals that were genotyped represented the most resistant and susceptible individuals based on the tails of phenotypic distribution (10% each) for average faecal egg counts (AVFEC). AVFEC, packed cell volume (AVPCV), and live weight (AVLWT) were adjusted for fixed effects and co-variables, and an association analysis was run using EMMAX. Revised significance levels were calculated using 100,000 permutation tests. The top five significant SNP markers with - log10 p-values >3.794 were observed on five different chromosomes for AVFEC, and BLUPPf90/PostGSf90 results confirmed EMMAX significant regions for this trait. One of these regions included a cluster of significant SNP on chromosome (Chr) 6 not in linkage disequilibrium to each other. This genomic location contains annotated genes involved in cytokine signalling, haemostasis and mucus biosynthesis. Only one association detected on Chr 7 was significant for both AVPCV and AVLWT. The results generated here reveal candidate immune variants for genes involved in differential response to infection and provide additional SNP marker information that has potential to aid selection of resistance to gastrointestinal parasites in sheep of a similar genetic background to the double backcross population.     

Visualization of HIV-1 Interactions with Penile and Foreskin Epithelia: Clues for Female-to-Male HIV Transmission

To gain insight into female-to-male HIV sexual transmission and how male circumcision protects against this mode of transmission, we visualized HIV-1 interactions with foreskin and penile tissues in ex vivo tissue culture and in vivo rhesus macaque models utilizing epifluorescent microscopy. 12 foreskin and 14 cadaveric penile specimens were cultured with R5-tropic photoactivatable (PA)-GFP HIV-1 for 4 or 24 hours. Tissue cryosections were immunofluorescently imaged for epithelial and immune cell markers. Images were analyzed for total virions, proportion of penetrators, depth of virion penetration, as well as immune cell counts and depths in the tissue. We visualized individual PA virions breaching penile epithelial surfaces in the explant and macaque model. Using kernel density estimated probabilities of localizing a virion or immune cell at certain tissue depths revealed that interactions between virions and cells were more likely to occur in the inner foreskin or glans penis (from local or cadaveric donors, respectively). Using statistical models to account for repeated measures and zero-inflated datasets, we found no difference in total virions visualized at 4 hours between inner and outer foreskins from local donors. At 24 hours, there were more virions in inner as compared to outer foreskin (0.0495 +/− 0.0154 and 0.0171 +/− 0.0038 virions/image, p = 0.001). In the cadaveric specimens, we observed more virions in inner foreskin (0.0507 +/− 0.0079 virions/image) than glans tissue (0.0167 +/− 0.0033 virions/image, p<0.001), but a greater proportion was seen penetrating uncircumcised glans tissue (0.0458 +/− 0.0188 vs. 0.0151 +/− 0.0100 virions/image, p = 0.099) and to significantly greater mean depths (29.162 +/− 3.908 vs. 12.466 +/− 2.985 μm). Our in vivo macaque model confirmed that virions can breach penile squamous epithelia in a living model. In summary, these results suggest that the inner foreskin and glans epithelia may be important sites for HIV transmission in uncircumcised men.     

Psychometric Properties of the Multidimensional Health Locus of Control Scale Form C in a Non-Western Culture

Form C of the Multidimensional Health Locus of Control Scales (MHLC-C) was designed to investigate health-related control beliefs of persons with an existing medical condition. The aim of the present study was to examine the psychometric properties of this instrument in a culture characterized by external control beliefs and learned helplessness—contrary to the societal context of original test development. Altogether, 374 Hungarian patients with cancer, irritable bowel syndrome, diabetes, and cardiovascular and musculoskeletal disorders were enrolled in the study. Besides the MHLC-C, instruments measuring general control beliefs, anxiety, depression, self-efficacy, and health behaviors were also administered to evaluate the validity of the scale. Both exploratory and confirmatory factor analytic techniques were used to investigate the factor structure of the scale. Our results showed that the Hungarian adaptation of the instrument had a slightly different structure than the one originally hypothesized: in the present sample, a three-factor structure emerged where the items of the Doctors and the Others subscales loaded onto a single common component. Internal reliability of all three subscales was adequate (alphas between .71 and .79). Data concerning the instrument''s validity were comparable with previous results from Western countries. These findings may suggest that health locus of control can be construed very similarly to Western countries even in a post-communist society—regardless of the potential differences in general control beliefs.     

The measurement of reactive oxygen species in human neat semen and in suspended spermatozoa: a comparison

Background  

It is generally accepted that oxidative stress is an important factor in male infertility because it may impair the physiological function of spermatozoa at the molecular level. Nevertheless, although several approaches have been reported, the imbalance between production of reactive oxygen species (ROS) and activity of the antioxidant defense system in semen is difficult to investigate and remains poorly understood.     

Silver(I) poly(1,2,3-benzotriazolyl)borate complexes containing mono- and bidentate phosphine coligands

New silver(I) derivatives [Ag{H_nB(btz)_4 − n}(PR₃)_x] (n = 1 or 2, x ranging from 1 to 3), containing monodentate tertiary phosphines and anionic poly(benzotriazol-1-yl)borates, have been prepared from the reaction of AgNO₃ with PR₃ (R = Ph, o-tolyl, m-tolyl, p-tolyl, Bns) and K[H₂B(btz)₂], or K[HB(btz)₃] (Hbtz = 1,2,3-benzotriazole). When the reaction between K[H₂B(btz)₂] and AgNO₃ was carried out in the presence of dppe (1,2-bis(diphenylphosphino)ethane), or dppf (1,1′-bis(diphenylphosphino)ferrocene), compounds [Ag{H₂B(btz)₂}]₂(L) (L = dppe or dppf) formed, the diphosphine acting as a bidentate bridging P₂-donor. Solid state and solution properties of all complexes have been investigated through analytical and spectroscopic measurements (IR, ¹H, ³¹P NMR), the ¹H and ³¹P NMR spectra being interpreted in terms of equilibria that involve mono- and di-nuclear complexes. Adducts [Ag{HB(btz)₃}(PPh₃)₃] · (1/2H₂O) and [Ag{H₂B(btz)₂}]₂ (dppf) have been characterised by single crystal X-ray studies. In the former, the HB(btz)₃ is unidentate in an NAgP₃ coordination environment; the latter is a dimer, the dppf bridging the two silver atoms, while the H₂B(btz)₂ ligand, which chelates one silver, bridges to the second also, the array having 2-symmetry.     

Silver (I) poly(1,2,4-triazolyl)borate complexes containing monodentate phosphane ligands

New silver (I) derivatives containing monodentate tertiary phosphanes and anionic poly(triazol-1-yl)borate ligands have been prepared from the reaction of AgNO₃ and PR₃ (R = Ph, Bn, o-tolyl, m-tolyl, p-tolyl) and potassium dihydrobis(1,2,4-triazolyl)borate, K[H₂B(tz)₂], or potassium hydrotris(1,2,4-triazolyl)borate, K[HB(tz)₃]; their solid state and solution properties have been investigated through analytical and spectroscopic measurements (IR, ¹H-, and ³¹P NMR). The ¹H- and ³¹P NMR solution spectra in some cases can be interpreted on the basis of a dissociation of [{H₂B(tz)₂}Ag(PR₃)₂] into [{H₂B(tz)₂}Ag(PR₃)] and PR₃. All the compounds are soluble in chlorinated solvents and are non-electrolytes in CH₂Cl₂ and acetone solutions. [{H₂B(tz)₂}Ag(PPh₃)₂] and [{H₂B(tz)₂}Ag{P(m-tolyl)₃}₂] are simple mononuclear arrays, the silver atoms lying in four-coordinate N₂AgP₂ environments. Owing to the presence of the methyl substituents on the phosphane ligand, the complex [{HB(tz)₃}Ag{P(o-tolyl)₃}], as expected, is mononuclear. In [{H₂B(tz)₂}Ag{P(p-tolyl)₃}], the silver environment is still four-coordinate but PAgN₃, utilizing the coordinating capability of one of the additional (‘exo’-) ring nitrogens not only to complete the four-coordinate array about the silver but, necessarily, to link successive asymmetric units into a single-stranded polymer.