Search

Humans have long wondered about the function of mental imagery and its relationship to vision. Although visual representations are utilized during imagery, the computations they subserve are unclear. Building on a theory that treats vision as inference about the causes of sensory stimulation in an internal generative model, we propose that mental imagery is inference about the sensory consequences of predicted or remembered causes. The relation between these complementary inferences yields a relation between the brain activity patterns associated with imagery and vision. We show that this relation has the formal structure of an echo that makes encoding of imagined stimuli in low-level visual areas resemble the encoding of seen stimuli in higher areas. To test for evidence of this echo effect we developed imagery encoding models—a new tool for revealing how imagined stimuli are encoded in brain activity. We estimated imagery encoding models from brain activity measured with fMRI while human subjects imagined complex visual stimuli, and then compared these to visual encoding models estimated from a matched viewing experiment. Consistent with an echo effect, imagery encoding models in low-level visual areas exhibited decreased spatial frequency preference and larger, more foveal receptive fields, thus resembling visual encoding models in high-level visual areas where imagery and vision appeared to be almost interchangeable. Our findings support an interpretation of mental imagery as a predictive inference that is conditioned on activity in high-level visual cortex, and is related to vision through shared dependence on an internal model of the visual world.

Oocytes collected from prepubertal animals are known to be less developmentally competent than those from adult animals. There is evidence suggesting that acquisition of developmental competence in bovine oocytes may be linked to the expression profile of genes in the granulosa cells (GCs). Cumulus-oocyte complexes (COC) and GCs were collected from 12 Holstein heifers between 2 and 6 months of age (nine follicle-stimulating hormone [FSH] treated and three untreated) and eight FSH-treated cows. The COCs from prepubertal animals were matured, fertilized, and cultured in vitro to assess development to the blastocyst stage. The relative messenger RNA (mRNA) abundance of FSHR, StAR, CYP19A1, HSD3B1, CX43, FOXO1, and XIAP in GCs were quantified by real-time quantitative polymerase chain reaction. Results from this study revealed that GCs of prepubertal animals respond to FSH treatment by increasing mRNA levels of genes promoting estradiol synthesis and follicular growth ( FSHR and CYP19A1), and preventing cell apoptosis ( XIAP), and by decreasing mRNA levels of genes promoting progesterone production ( StAR and HSD3B1). This study also revealed that the relative mRNA abundance of FOXO1 in GCs is associated with oocyte competence to support embryo development to the blastocyst stage in prepubertal Holstein heifers.

We introduce the feature-weighted receptive field (fwRF), an encoding model designed to balance expressiveness, interpretability and scalability. The fwRF is organized around the notion of a feature map—a transformation of visual stimuli into visual features that preserves the topology of visual space (but not necessarily the native resolution of the stimulus). The key assumption of the fwRF model is that activity in each voxel encodes variation in a spatially localized region across multiple feature maps. This region is fixed for all feature maps; however, the contribution of each feature map to voxel activity is weighted. Thus, the model has two separable sets of parameters: “where” parameters that characterize the location and extent of pooling over visual features, and “what” parameters that characterize tuning to visual features. The “where” parameters are analogous to classical receptive fields, while “what” parameters are analogous to classical tuning functions. By treating these as separable parameters, the fwRF model complexity is independent of the resolution of the underlying feature maps. This makes it possible to estimate models with thousands of high-resolution feature maps from relatively small amounts of data. Once a fwRF model has been estimated from data, spatial pooling and feature tuning can be read-off directly with no (or very little) additional post-processing or in-silico experimentation.We describe an optimization algorithm for estimating fwRF models from data acquired during standard visual neuroimaging experiments. We then demonstrate the model’s application to two distinct sets of features: Gabor wavelets and features supplied by a deep convolutional neural network. We show that when Gabor feature maps are used, the fwRF model recovers receptive fields and spatial frequency tuning functions consistent with known organizational principles of the visual cortex. We also show that a fwRF model can be used to regress entire deep convolutional networks against brain activity. The ability to use whole networks in a single encoding model yields state-of-the-art prediction accuracy. Our results suggest a wide variety of uses for the feature-weighted receptive field model, from retinotopic mapping with natural scenes, to regressing the activities of whole deep neural networks onto measured brain activity.

International audience; Six coatings containing different ratios of polysaccharides and antimicrobials were prepared and tested in vitro against Listeria monocytogenes. Best coating mixtures were then applied on vegetables and submitted to a sensorial analysis. Finally, their effect on the quality, the color and the consistency of vegetables during a one-week storage was determined. All selected coatings showed a total in vitro inhibition of bacteria at concentrations of 8–10 mL L−1. One formulation containing the antimicrobials induced vegetables to have similar characteristics (smell, taste and texture) as compared to the non-treated vegetables. Treatments with this coating generated minor changes concerning the respiration rate and no differences were visually observed on cauliflowers. Finally, in situ analyses showed a good antimicrobial effect and allowed a complete inhibition of Listeria innocua after seven days of storage at 4 °C.

Entering pregnancy with overweight, obesity or gaining excessive gestational weight could increase the risk of gestational diabetes mellitus (GDM), which is associated with negative consequences for both the mother and the offspring. The objective of this article was to review scientific evidence regarding the association between obesity and GDM, and how weight management through nutritional prevention strategies could prove successful in reducing the risk for GDM. Studies published between January 1975 and January 2009 on the relationship between GDM, pre-pregnancy body mass index (BMI), gestational weight gain and nutritional prevention strategies were included in this review. Results from these reports suggest that maternal obesity assessed by pre-pregnancy BMI is associated with an increased risk of GDM. They also show an association between gestational weight gain and increased risk for GDM. Higher dietary fat and lower carbohydrate intakes during pregnancy appear to be associated with a higher risk for GDM, independent of pre-pregnancy BMI. Some studies showed that restricting energy and carbohydrates could minimize gestational weight gain. However, a firm conclusion on the most effective nutritional intervention for the control of gestational weight gain and glycaemic responses could not be reached based on available studies. In light of the studies reviewed, we conclude that weight management through nutritional prevention strategies could be successful in reducing the risk of GDM. Further studies are required to identify the most effective diet composition to prevent GDM and excessive gestational weight gain.

A specific assay based on the spectrophotometric determination of the release of p-nitrophenol from p-nitrophenol-alpha-D-glucopyranoside by maltase has been used to measure the activity of the enzyme in seminal plasma and in homogenates of accessory reproductive organs. Specific activity of seminal plasma maltase was 467 muU/mg of proteins in 68 fertile men, decreased significantly in varicocele (296 muU/mg), in azoospermia (246 muU/mg) and in vasectomized patients (62 muU/mg). Application of ion exchange chromatography on DEAE-Sephadex A-50 columns led to the demonstration that maltase activity of seminal plasma and of cytosols from normal reproductive organs was recovered in three different fractions. Maltase activity is thus frequently decreased in infertility.

The activity of mice from two selected lines, differing in degree of paw preference, was observed. Differences in the relative frequencies of certain categories of activity were found both between the two lines of mice and betwen the sexes; sex differences were in general more pronounced between mice from the strongly lateralized line. This finding is consistent with a theory which attempts to relate lateralization of function in the nervous system to developmental effects of differences in metabolism of gonadal steroids.

This study investigated the associations of Locus of Control (Children Nowicki-Strickland Internal-External Control Scale) with state and trait anxiety (State-Trait Anxiety Inventory for Children) in 302 children aged 9 to 12 yr. No significant differences were found between the groups. No significant correlations were found between the anxiety measures and externality for the 31 children from maritally disrupted families, but significant positive Pearson correlations were found for the 271 children of intact families. The results are discussed in terms of the possibility of under-reporting of marital disruption by children.

Summary.-This study investigates the relationship between burnout as measured by the Maslach Burnout Inventory and locus of control as measured by the Adult Nowicki-Strickland Internal-External Locus of Control (ANS-IE) for 82 dentists. Significant Pearson correlations between two Maslach subscales and locus of control show Personal Accomplishment to be negatively associated -.31 and Emotional Exhaustion to be positively correlated .21 to exrernality. Burnout is defined by Maslach (13) and Maslach and Jackson (14) as a syndrome of physical and emotional fatigue which results in a negative selfimage, negative attitudes toward work, and a drop in personal involvement with clients. Maslach and his colleagues have identified three components: emotional exhaustion, depersonalization, and low personal accomplishment. Numerous environmental factors contribute to burnout, and Pines, Aronson, and Kafry (19) have identified the nature of the work as an important situational factor. Several empirical studies have identified particular job-related stressors for dentists: difficulties with patients, problems with staff, schedule and time pressure, and finances (4, 6, lo), with pain (4, 10, 22), and with lack of personal achievement (4, 6, 20). However, not aII persons in the same occupational situation experience burnout; individual factors are also involved (14). Possible individual factors include personality variables such as locus of control. The relationship between locus of control and burnout has already been studied for certain populations. McIntyre (15) established significant positive correlations for a group of teachers between externality as measured by ANS-IE and the Emotional Exhaustion (EE) and Depersonahzation (DP) scales of the Maslach Burnout Inventory (MBI) and a negative correlation between externality and Personal Accomplishment (PA). For a group of chddcare workers Fuqua and Couture (9) used a regression model which yielded a significant relationship between a group of nine personal and situational factors including the locus of control and the three Maslach subscales. The only significant univariate relationship was between locus of control and Personal