Sex & vision I: Spatio-temporal resolution

The quantification of zebrafish ocular-associated proteins provides hints for sex-biased visual impairments and perception

Biochemical differences between sexes can also be seen in non-sexual organs and may affect organ functions and susceptibility to diseases. It has been shown that there are sex-biased visual perceptions and impairments. Abundance differences of eye proteins could provide explanations for some of these. Exploration of the ocular proteome was performed to find sex-based protein abundance differences in zebrafish Danio rerio. A label-free protein quantification workflow using high-resolution mass spectrometry was employed to find proteins with significant differences between the sexes. In total, 3740 unique master proteins were identified and quantified, and 49 proteins showed significant abundance differences between the eyes of male and female zebrafish. Those proteins belong to lipoproteins, immune system, blood coagulation, antioxidants, iron and heme-binding proteins, ion channels, pumps and exchangers, neuronal and photoreceptor proteins, and the cytoskeleton. An extensive literature review provided clues for the possible links between the sex-biased level of proteins and visual perception and impairments. In conclusion, sexual dimorphism at the protein level was discovered for the first time in the eye of zebrafish and should be accounted for in ophthalmological studies. Data are available via ProteomeXchange with identifier PXD033338.

Adopting the International Consensus on ANA Patterns (ICAP) classification for reporting: the experience of Italian clinical laboratories

The indirect immunofluorescence assay on HEp-2 cells (HEp-2 IFA) is still considered the reference method to detect anti-nuclear antibodies (ANA) because of its high sensitivity and represents a relevant tool for the diagnosis of autoimmune rheumatic diseases. During the last decade, the International Consensus on ANA Patterns (ICAP) initiative promoted harmonization and understanding of HEp-2 IFA staining pattern nomenclature, as well as promoting their use in patient care by providing interpretation for HEp-2 IFA test results. In conjunction with a nationwide survey on the evolution of autoantibody diagnostics in autoimmune rheumatic diseases, we focused on the adherence of the Italian laboratories to the ICAP nomenclature analyzing its lights and shadows. The recent ICAP-oriented report, largely used today among Italian laboratories, also represents a further step in harmonizing and improving communication with the clinicians, adding value to laboratory findings and helping with critical clinical decisions.

Cortical thickness reveals sex differences in verbal and visuospatial memory

Although previous studies have reported the sex differences in behavior/cognition and the brain, the sex difference in the relationship between memory abilities and the underlying neural basis in the aging process remains unclear. In this study, we used a machine learning model to estimate the association between cortical thickness and verbal/visuospatial memory in females and males and then explored the sex difference of these associations based on a community-elderly cohort (n = 1153, age ranged from 50.42 to 86.67 years). We validated that females outperformed males in verbal memory, while males outperformed females in visuospatial memory. The key regions related to verbal memory in females include the medial temporal cortex, orbitofrontal cortex, and some regions around the insula. Further, those regions are more located in limbic, dorsal attention, and default-model networks, and are associated with face recognition and perception. The key regions related to visuospatial memory include the lateral prefrontal cortex, anterior cingulate gyrus, and some occipital regions. They overlapped more with dorsal attention, frontoparietal and visual networks, and were associated with object recognition. These findings imply the memory performance advantage of females and males might be related to the different memory processing tendencies and their associated network.

On the utility of Colour in shape analysis: An introduction to Colour science via palaeographical case studies

In this article, we explore the use of colour for the analysis of shapes in digital images. We argue that colour can provide unique information that is not available from shape alone, and that familiarity with the interdisciplinary field of colour science is essential for unlocking the potential of colour. Within this perspective, we offer an illustrated overview of the colour-related aspects of image management and processing, perceptual psychology, and cultural studies, using for exemplary purposes case studies focused on computational palaeography. We also discuss the changing roles of colour in society and the sciences, and provide technical solutions for using digital colour effectively, highlighting the impact of human factors. The article concludes with an annotated bibliography. This work is a primer, and its intended readership are scholars and computer scientists unfamiliar with colour science.

Screen Time at 6 Years Old and Visual Function in Early Adolescence

Excessive screen time has been linked to adverse health outcomes in children, including vision-related problems such as myopia. However, very few studies have evaluated the effect of moderate screen exposure on the development of visual functions. This study aimed to examine the association between screen time during middle childhood and color discrimination, contrast sensitivity, and short-range visual acuity in 12-year-old children (n = 305) from the mother-child PELAGIE cohort (France) for the whole sample and for boys and girls separately. Visual functions were assessed using the Freiburg Acuity and Contrast Test and an adapted version of the Cambridge Color Test. Screen exposure was documented using a parent self-report questionnaire. Regression models showed that screen exposure at 6 years of age was significantly associated with higher contrast sensitivity across the entire sample at 12 years of age. However, when controlling for covariates, this association remained statistically significant in girls only. Sex-stratified analyses also showed that moderate screen exposure was linked to improved tritan-axis color vision in boys only. These findings suggest that moderate screen exposure in middle childhood is not harmful to visual function development and as such, provide new insights into the impact of digital technology on children's visual health and development.

The spatial contrast sensitivity function and its neurophysiological bases

Contrast processing is a fundamental function of the visual system, and contrast sensitivity as a function of spatial frequency (CSF) provides critical information about the integrity of the system. Here, we used a novel iPad-based instrument to collect CSFs and fitted the data with a difference of Gaussians model to investigate the neurophysiological bases of the spatial CSF. The reliability of repeat testing within and across sessions was evaluated in a sample of 22 adults for five spatial frequencies (0.41-13 cycles/degree) and two temporal durations (33 and 500 ms). Results demonstrate that the shape of the CSF, lowpass versus bandpass, depends on the temporal stimulus condition. Comparisons with previous psychophysical studies and with single-cell data from macaques and humans indicate that the major portion of the CSF, spatial frequencies >1.5 cycles/degree regardless of temporal condition, is determined by a 'sustained' mechanism (presumably parvocellular input to primary visual cortex [V1]). Contrast sensitivity to the lowest spatial frequency tested appears to be generated by a 'transient' mechanism (presumably magnocellular input to V1). The model fits support the hypothesis that the high spatial frequency limb of the CSF reflects the receptive field profile of the center mechanism of the smallest cells in the parvocellular pathway. These findings enhance the value of contrast sensitivity testing in general and increase the accessibility of this technique for use by clinicians through implementation on a commercially-available device.

Visual motion discrimination experiments reveal small differences between males and females

Recent results have shown that males have lower duration thresholds for motion direction discrimination than females. Measuring contrast thresholds, a previous study has shown that males have a greater sensitivity to fine details and fast flickering stimuli than females, and that females have a higher sensitivity to low spatial frequencies modulated at low temporal frequencies. Here, we present the data of a contrast-detection motion discrimination experiment and a reanalysis of four different motion discrimination experiments where we compare duration thresholds for males and females using different spatial frequencies, stimulus sizes, contrasts, and temporal frequencies (in two experiments, motion surround suppression was measured). Results from the main experiment and the reanalysis show that, in general, the association between sex and contrast and duration thresholds for motion discrimination is not significant, with males and females showing similar data patterns. Only the reanalysis of one out of four studies revealed different duration thresholds between males and females paired with a strong effect size supporting previous results in the literature, although motion surround suppression was identical between groups. Importantly, most of our results do not show significant differences between males and females in contrast and duration thresholds, suggesting that the sex variable may not be as relevant as previously claimed when testing visual motion discrimination.

Sex and estrous cycle affect experience-dependent plasticity in mouse primary visual cortex

Sex hormones can affect cellular physiology and modulate synaptic plasticity, but it is not always clear whether or how sex-dependent differences identified in vitro express themselves as functional dimorphisms in the brain. Historically, most experimental neuroscience has been conducted using only male animals and the literature is largely mute about whether including female mice in will introduce variability due to inherent sex differences or endogenous estrous cycles. Though this is beginning to change following an NIH directive that sex should be included as a factor in vertebrate research, the lack of information raises practical issues around how to design experimental controls and apply existing knowledge to more heterogeneous populations. Various lines of research suggest that visual processing can be affected by sex and estrous cycle stage. For these reasons, we performed a series of in vivo electrophysiological experiments to characterize baseline visual function and experience-dependent plasticity in the primary visual cortex (V1) of male and female mice. We find that sex and estrous stage have no statistically significant effect on baseline acuity measurements, but that both sex and estrous stage have can modulate two mechanistically distinct forms of experience dependent cortical plasticity. We also demonstrate that resulting variability can be largely controlled with appropriate normalizations. These findings suggest that V1 plasticity can be used for mechanistic studies focusing on how sex hormones effect experience dependent plasticity in the mammalian cortex.

Tissue-Specific Sex Difference in Mouse Eye and Brain Metabolome Under Fed and Fasted States

Purpose

Visual physiology and various ocular diseases demonstrate sexual dimorphisms; however, how sex influences metabolism in different eye tissues remains undetermined. This study aims to address common and tissue-specific sex differences in metabolism in the retina, RPE, lens, and brain under fed and fasted conditions.

Methods

After ad libitum fed or being deprived of food for 18 hours, mouse eye tissues (retina, RPE/choroid, and lens), brain, and plasma were harvested for targeted metabolomics. The data were analyzed with both partial least squares-discriminant analysis and volcano plot analysis.

Results

Among 133 metabolites that cover major metabolic pathways, we found 9 to 45 metabolites that are sex different in different tissues under the fed state and 6 to 18 metabolites under the fasted state. Among these sex-different metabolites, 33 were changed in 2 or more tissues, and 64 were tissue specific. Pantothenic acid, hypotaurine, and 4-hydroxyproline were the top commonly changed metabolites. The lens and the retina had the most tissue-specific, sex-different metabolites enriched in the metabolism of amino acid, nucleotide, lipids, and tricarboxylic acid cycle. The lens and the brain had more similar sex-different metabolites than other ocular tissues. The female RPE and female brain were more sensitive to fasting with more decreased metabolites in amino acid metabolism, tricarboxylic acid cycles, and glycolysis. The plasma had the fewest sex-different metabolites, with very few overlapping changes with tissues.

Conclusions

Sex has a strong influence on eye and brain metabolism in tissue-specific and metabolic state-specific manners. Our findings may implicate the sexual dimorphisms in eye physiology and susceptibility to ocular diseases.

Normative database for Spaeth Richman contrast sensitivity test for Indian eyes

Purpose

To ascertain normative database of contrast sensitivity (CS) using Spaeth/Richman CS test (SPARCS) in the Indian population.

Methods

This cross-sectional study enrolled 200 healthy individuals, and CS was tested in both eyes of each participant using SPARCS. A detailed ocular examination was done before enrollment to rule out pathologies that may affect CS. A practice test was performed in the right eye (OD), followed by uniocular testing in each eye and a final binocular test.

Results

Data of 400 eyes of 200 subjects who fulfilled the inclusion criteria was evaluated. The average age of subjects was 46.57 ± 16.77 years (range 21-79 years), with a slight female preponderance (53%, n = 106). A statistically significant decline in average SPARCS scores was noted with increasing age (P < 0.05), ranging from 86.68 (20-29 years age group) to 67.44 (70-79 years age group). Higher scores were noted in binocular testing than uniocular testing (Interclass correlation coefficient [ICC] = 0.83; P < 0.001). Females achieved statistically significant higher total scores in uniocular SPARCS testing (both OD and OS), but there was no significant difference noted between the two genders in binocular testing. Correlation between practice and main tests was statistically Significant with an interclass correlation coefficient of 0.54 (P < 0.001).

Conclusion

Normative database for SPARCS was established for Indian eyes, with a decreasing trend noted in peripheral as well as central CS scores with increasing age.

Gender benefit in laparoscopic surgical performance using a 3D-display system: data from a randomized cross-over trial

BACKGROUND

The use of 3D technique compared to high-resolution 2D-4K-display technique has been shown to optimize spatial orientation and surgical performance in laparoscopic surgery. Since women make up an increasing amount of medical students and surgeons, this study was designed to investigate whether one gender has a greater benefit from using a 3D compared to a 4K-display system.

METHODS

In a randomized cross-over trial, the surgical performance of male and female medical students (MS), non-board certified surgeons (NBCS), and board certified surgeons (BCS) was compared using 3D- vs. 4K-display technique at a minimally invasive training parkour with multiple surgical tasks and repetitions.

RESULTS

128 participants (56 women, 72 men) were included. Overall parkour time in seconds was 3D vs. 4K for all women 770.7 ± 31.9 vs. 1068.1 ± 50.0 (p < 0.001) and all men 664.5 ± 19.9 vs. 889.7 ± 31.2 (p < 0.001). Regarding overall mistakes, participants tend to commit less mistakes while using the 3D-vision system, showing 10.2 ± 1.1 vs. 13.3 ± 1.3 (p = 0.005) for all women and 9.6 ± 0.7 vs. 12.2 ± 1.0 (p = 0.001) for all men. The benefit of using a 3D system, measured by the difference in seconds, was for women 297.3 ± 41.8 (27.84%) vs. 225.2 ± 23.3 (25.31%) for men (p = 0.005). This can be confirmed in the MS group with 327.6 ± 65.5 (35.82%) vs. 249.8 ± 33.7 (32.12%), p = 0.041 and in the NBCS group 359 ± 52.4 (28.25%) vs. 198.2 ± 54.2 (18.62%), p = 0.003. There was no significant difference in the BCS group.

CONCLUSION

3D laparoscopic display technique optimizes surgical performance compared to the 2D-4K technique for both women and men. The greatest 3D benefit was found for women with less surgical experience. As a possible result of surgical education, this gender specific difference disappears with higher grade of experience. Using a 3D-vision system could facilitate surgical apprenticeship, especially for women.

Behavioural Adaptation to Hereditary Macular Dystrophy: A Systematic Review on the Effect of Early Onset Central Field Loss on Peripheral Visual Abilities

Purpose:

Hereditary macular dystrophies (HMD) result in early onset central field loss. Evidence for cortical plasticity has been found in HMD, which may enhance peripheral visual abilities to meet the increased demands and reliance on the peripheral field, as has been found in congenitally deaf adults and habitual action video-game players. This is a qualitative synthesis of the literature on the effect of early onset central field loss on peripheral visual abilities. The knowledge gained may help in developing rehabilitative strategies that enable optimisation of remaining peripheral vision.

Methods:

A systematic search performed on the Web of Science and PubMED databases yielded 728 records published between 1809 to 2020, of which seven case-control studies were eligible for qualitative synthesis.

Results:

The search highlighted an overall paucity of literature, which lacked validity due to small heterogeneous samples and deficiencies in reporting of methods and population characteristics. A range of peripheral visual abilities at different eccentricities were studied. Superior performance of HMD observers in the peripheral field or similarities between the preferred retinal loci (PRL) and normal fovea were observed in four of seven studies. Findings were often based on studies including a single observer. Further larger rigorous studies are required in this area.

Conclusions:

Spontaneous perceptual learning through reliance on and repeated use of the peripheral field and PRL may result in some specific superior peripheral visual abilities. However, worse performance in some tasks could reflect unexpected rod disease, lack of intensive training, or persistent limitations due to the need for cones for specific tasks. Perceptual learning through training regimes could enable patients to optimise use of the PRL and remaining peripheral vision. However, further studies are needed to design optimal training regimes.

Diverse patterns of vulnerability to visual illusions in children with neurodevelopmental disorders

Research on how children with neurodevelopmental disorders perceive, process, and interpret visual illusions (VIs) has been extensively focused on children with autism spectrum disorder providing controversial findings. In this study, we investigated the patterns of vulnerability to a wide set of VIs comprising 23 standard text book VIs and their variations in a clinical sample of children with neurodevelopmental disorders compared to typically developing children (TD). A total of 176 children, aged between 4.6 and 13.8 years old, were distributed into four groups: high-functioning autism (HFA; N = 23), attention-deficit/hyperactivity disorder (ADHD; N = 42), specific learning disorder (SLD; N = 70), and TD (N = 41). Regression models, adjusted for sex, age, and non-verbal IQ, showed that HFA was associated with greater responses accuracy than TD children to the full battery of VIs, to the cognitive illusions, to the distortions, and to both geometrical illusions of size/shape (cognitive distortions) and lightness contrast effects (physical distortions). The susceptibility of ADHD children was found attenuated for illusory contours and greater for paradoxical illusions in comparison with TD children. No significant differences were shown between the SLD group and the TD children. Our findings, which were adjusted for the same duration of visual working memory across groups, showed that there is a potential specific tendency of HFA children to failure of processing visual information in context. Contrarily, children with ADHD showed in general normal global processing such as children diagnosed with SLD.

Auditory Processing Differences Correlate With Autistic Traits in Males

Autism spectrum disorder (ASD) has high prevalence among males compared to females but mechanisms underlying the differences between sexes are poorly investigated. Moreover, autistic symptoms show a continuity in the general population and are referred to as autistic traits in people without an ASD diagnosis. One of the symptoms of ASD is sensory processing differences both in sensitivity and perception. To investigate sensory processing differences in autistic traits, we examined auditory and visual processing in a healthy population. We recruited 75 individuals (39 females and 36 males, mean age = 23.01 years, SD = 3.23 years) and assessed autistic traits using the Autism Spectrum Quotient, and sensory sensitivity using the Sensory Sensitivity Scales. Sensory processing in the visual domain was examined with the radial motion stimulus and the auditory domain was assessed with the 1,000 Hz pure tone stimulus with electroencephalography-evoked potentials. The results showed that the auditory sensitivity scores of the males (r_aud (34) = 0.396, p_aud = 0.017) and the visual sensitivity scores of females were correlated with autistic traits (r_vis (37) = 0.420, p_vis = 0.008). Moreover, the P2 latency for the auditory stimulus was prolonged in the participants with a higher level of autistic traits (r_s (61) = 0.411, p = 0.008), and this correlation was only observed in males (r_s (31) = 0.542, p = 0.001). We propose that auditory processing differences are related to autistic traits in neurotypicals, particularly in males. Our findings emphasize the importance of considering sex differences in autistic traits and ASD.

Gender-dependent variations in optical illusions: evidence from N400 waveforms

OBJECTIVE

The cognitive mechanisms (especially the gender-related ones) underlying optical illusion processing remain elusive. Since the N400 component of event-related potentials (ERPs) is an index of the semantic integration of information processing tasks, the present study focuses on gender-related differences in N400 waveforms elicited during the reasoning process applied to reach a valid conclusion of optical illusions engaging working memory (WM).

APPROACH

Fifty-one healthy participants (28 males, age = 34.25 years ± 10.25, years of education = 16.00 years ± 1.78; and 23 females, age = 33.43 ± 7.93, years of education = 15.56 ± 1.82) were measured. The N400 ERP component was evoked by 39 optical illusions adjusted to induce WM. We compared brain activation patterns while participants maintained conclusions of the optical illusions in WM. The N400 of ERPs was recorded during the WM phase, during which participants were required to draw a logical conclusion regarding the correctness of the optical illusions.

MAIN RESULTS

Analysis revealed that females compared to males exhibited significantly increased N400 amplitudes located at parietal and occipital sites, whereas males exhibited significantly higher N400 amplitudes located at frontal areas. Furthermore, females compared to males demonstrated significantly prolonged latencies of the N400 component located at right frontotemporal abductions.

SIGNIFICANCE

These results suggest that coupling of optical illusions with WM engages distinct gender-related variations of brain semantic processing as reflected by the N400 ERP component. Based on the dual process account, our study gives support to the notion that women tend to employ a more deliberate and slower semantic reasoning than the men who tend to employ an automatic and fast one. Topographically, within the network sub-serving the semantic operation, the posterior brain areas responsible for sensorimotor integration-related processes elicit a greater brain activation among females while the anterior brain areas responsible for control and storage/retrieval operation elicit a greater brain activation among males.

Atypical visual processing in a mouse model of autism

Human social cognition relies heavily on the processing of various visual cues, such as eye contact and facial expressions. Atypical visual perception and integration have been recognized as key phenotypes in individuals diagnosed with autism spectrum disorder (ASD), and may potentially contribute to impediments in normal social development, a hallmark of ASD. Meanwhile, increasing studies on visual function in ASD have pointed to detail-oriented perception, which has been hypothesized to result from heightened response to information of high spatial frequency. However, mixed results of human studies have led to much debate, and investigations using animal models have been limited. Here, using BTBR mice as a model of idiopathic ASD, we assessed retinal stimulus processing by full-field electroretinogram and found impaired photoreceptor function and retina-based alterations mostly in the cone pathway. Using the optokinetic reflex to evaluate visual function, we observed robustly enhanced visual response to finer spatial details and more subtle contrasts at only higher spatial frequencies in the BTBR mice, under both photopic and scotopic conditions. These behavioral results, which are similar to findings in a subset of ASD patients, indicate a bias toward processing information of high spatial frequencies. Together, these findings also suggest that, while enhancement of visual behaviors under both photopic and scotopic conditions might be due to alterations in visual processing common to both rod and cone pathways, these mechanisms are probably downstream of photoreceptor function.

A GICA-TVGL framework to study sex differences in resting state fMRI dynamic connectivity

BACKGROUND

Functional magnetic resonance imaging (fMRI) has been implemented widely to study brain connectivity. In particular, time-varying connectivity analysis has emerged as an important measure to uncover essential knowledge within the network. On the other hand, independent component analysis (ICA) has served as a powerful tool to preprocess fMRI data before performing network analysis. Together, they may lead to novel findings.

METHODS

We propose a new framework (GICA-TVGL) that combines group ICA (GICA) with time-varying graphical LASSO (TVGL) to improve the power of analyzing functional connectivity (FNC) changes, which is then applied for neuro-developmental study. To investigate the performance of our proposed approach, we apply it to capture dynamic FNC using both the Philadelphia Neurodevelopmental Cohort (PNC) and the Pediatric Imaging, Neurocognition, and Genetics (PING) datasets.

RESULTS

Our results indicate that females and males in young adult group possess substantial difference related to visual network. In addition, some other consistent conclusions have been reached by using these two datasets. Furthermore, the GICA-TVGL model indicated that females had a higher probability to stay in a stable state. Males had a higher tendency to remain in a globally disconnected mode.

COMPARISON WITH EXISTING METHOD

The performance of sliding window approach is largely affected by the window size selection. In addition, it also assumes temporal locality hypothesis.

CONCLUSION

Our proposed framework provides a feasible method to investigate brain dynamics and has the potential to become a widely used tool in neuroimaging studies.

Older Adults' Preference for Landscape Features Along Urban Park Walkways in Nanjing, China

Evidence shows that walking in urban parks has multiple health benefits for older adults, but little research is available on their preference for specific walkway features. This study explored a range of common landscape and hardscape features to learn which were preferred by park users over age 60. This photo comparison study hypothesized that older adults would prefer certain features of urban park walkways, with each feature represented by four different paired images (28 pairs in all). Within each pair of photos, both were identical except for the specific feature being tested in that comparison, where the image was digitally modified to depict the hypothesized feature. A total of 283 older adults (mean age 71 years) completed the survey by selecting the images they preferred. In this Chinese sample, older park users significantly favored all seven hypothesized walkway features, providing empirical support for the existing research and design-based literature on green space for older adults. This study found minor gender differences in visual preferences for walkway features and increasing preference for access to seating with advancing age. By helping to confirm which walkway features are preferred by older adults, these findings can be used to improve the future design and management of urban parks in China, which are an important source of exercise and recreation for nearby elderly residents.

Strategy Shift Toward Lower Spatial Frequencies in the Recognition of Dynamic Facial Expressions of Basic Emotions: When It Moves It Is Different

Facial expressions of emotion play a key role in social interactions. While in everyday life, their dynamic and transient nature calls for a fast processing of the visual information they contain, a majority of studies investigating the visual processes underlying their recognition have focused on their static display. The present study aimed to gain a better understanding of these processes while using more ecological dynamic facial expressions. In two experiments, we directly compared the spatial frequency (SF) tuning during the recognition of static and dynamic facial expressions. Experiment 1 revealed a shift toward lower SFs for dynamic expressions in comparison to static ones. Experiment 2 was designed to verify if changes in SF tuning curves were specific to the presence of emotional information in motion by comparing the SF tuning profiles for static, dynamic, and shuffled dynamic expressions. Results showed a similar shift toward lower SFs for shuffled expressions, suggesting that the difference found between dynamic and static expressions might not be linked to informative motion per se but to the presence of motion regardless its nature.

Gender-Based Occupational Segregation and Sex Differences in Sensory, Motor, and Spatial Aptitudes

Research on sex differences in humans documents gender differences in sensory, motor, and spatial aptitudes. These aptitudes, as captured by Dictionary of Occupational Titles (DOT) codes, predict the occupational choices of men and women in the directions indicated by this research. We simulate that eliminating selection on these skills reduces the Duncan index of gender-based occupational segregation by 20 % to 23 % in 1970 and 2012, respectively. Eliminating selection on DOT variables capturing other accounts of this segregation has a smaller impact.

Sex and age modulate the visual perception of distance

An experiment was conducted to evaluate the ability of 28 younger and older adults to visually bisect distances in depth both indoors and outdoors; half of the observers were male and half were female. Observers viewed 15-m and 30-m distance extents in four different environmental settings (two outdoor grassy fields and an indoor hallway and atrium) and were required to adjust the position of a marker to place it at the midpoint of each stimulus distance interval. Overall, the observers' judgments were more accurate indoors than outdoors. In outdoor environments, many individual observers exhibited perceptual compression of farther distances (e.g., these observers placed the marker closer than the actual physical midpoints of the stimulus distance intervals). There were significant modulatory effects of both age and sex upon the accuracy and precision of the observers' judgments. The judgments of the male observers were more accurate than those of the female observers and they were less influenced by environmental context. In addition, the accuracies of the younger observers' judgments were less influenced by context than those of the older observers. With regard to the precision of the observers' judgments, the older females exhibited much more variability across repeated judgments than the other groups of observers (younger males, younger females, and older males). The results of our study demonstrate that age and sex are important variables that significantly affect the visual perception of distance.

Sex-related differences in vision are heterogeneous

Despite well-established sex differences for cognition, audition, and somatosensation, few studies have investigated whether there are also sex differences in visual perception. We report the results of fifteen perceptual measures (such as visual acuity, visual backward masking, contrast detection threshold or motion detection) for a cohort of over 800 participants. On six of the fifteen tests, males significantly outperformed females. On no test did females significantly outperform males. Given this heterogeneity of the sex effects, it is unlikely that the sex differences are due to any single mechanism. A practical consequence of the results is that it is important to control for sex in vision research, and that findings of sex differences for cognitive measures using visually based tasks should confirm that their results cannot be explained by baseline sex differences in visual perception.

Foveal light and dark adaptation in patients with glaucoma and healthy subjects: A case-control study

INTRODUCTION

To determine whether foveal light and dark adaptation are affected in glaucoma.

METHODS

Case-control study with 23 glaucoma patients and 51 controls. Light and dark adaptation were measured twice. After 10 minutes pre-adaptation to 0.0032 cd/m2, the background luminance increased stepwise to 320 (5 log unit step) or 10,000 cd/m2 (6.5 log unit step) for 10 minutes, then it decreased back to 0.0032 cd/m2 for 30 minutes. Foveal contrast sensitivity [CS]) as a function of time was determined using a 1.15 degree increment. Time resolution of the experiments was 30 seconds. Multiple linear regression was used to analyse the effect of glaucoma on the CS plateau and adaptation time (time to reach the plateau minus 3 dB); analyses were adjusted for age and gender.

RESULTS

After light adaptation to 320 and 10,000 cd/m2, glaucoma patients had a 0.22 (P<0.001) and 0.13 (P = 0.010) log unit lower CS plateau than controls, respectively. After dark adaptation, this difference was 0.21 (P = 0.018) and 0.30 (P<0.001) log unit, respectively. Light adaptation occurred too fast to determine an accurate light adaptation time. Dark adaptation times of glaucoma patients and controls were similar, for both the 5 (7.2 versus 5.5 minutes; P = 0.10) and the 6.5 (18.2 versus 16.6 minutes; P = 0.14) log unit step.

CONCLUSION

After a sudden increase or decrease in luminance, the logCS adaptation curves of glaucoma patients are shifted downwards compared to the curves of healthy subjects. Glaucoma patients have a lower CS plateau than healthy subjects, for both light and dark adaptation; dark adaptation times are similar.

Chronic Organic Solvent Exposure Changes Visual Tracking in Men and Women

Organic solvents can change CNS sensory and motor function. Eye-movement analyses can be important tools when investigating the neurotoxic changes that result from chronic organic solvent exposure. The current research measured the eye-movement patterns of men and women with and without histories of chronic organic solvent exposure. A total of 44 volunteers between 18 and 41 years old participated in this study; 22 were men (11 exposed and 11 controls), and 22 were women (11 exposed and 11 controls). Eye movement was evaluated using a 250-Hz High-Speed Video Eye Tracker Toolbox (Cambridge Research Systems) via an image of a maze. Specific body indices of exposed and non-exposed men and women were measured with an Inbody 720 to determine whether the differences in eye-movement patterns were associated with body composition. The data were analyzed using IBM SPSS Statistics version 20.0.0. The results indicated that exposed adults showed significantly more fixations (t = 3.82; p = 0.001; r = 0.51) and longer fixations (t = 4.27; p = 0.001, r = 0.54) than their non-exposed counterparts. Comparisons within men (e.g., exposed and non-exposed) showed significant differences in the number of fixations (t = 2.21; p = 0.04; r = 0.20) and duration of fixations (t = 3.29; p = 0.001; r = 0.35). The same was true for exposed vs. non-exposed women, who showed significant differences in the number of fixations (t = 3.10; p = 0.001; r = 0.32) and fixation durations (t = 2.76; p = 0.01; r = 0.28). However, the results did not show significant differences between exposed women and men in the number and duration of fixations. No correlations were found between eye-movement pattern and body composition measures (p > 0.05). These results suggest that chronic organic solvent exposure affects eye movements, regardless of sex and body composition, and that eye tracking contributes to the investigation of the visual information processing disorders acquired by workers exposed to organic solvents.

Sex differences in the human visual system

This Mini-Review summarizes a wide range of sex differences in the human visual system, with a primary focus on sex differences in visual perception and its neural basis. We highlight sex differences in both basic and high-level visual processing, with evidence from behavioral, neurophysiological, and neuroimaging studies. We argue that sex differences in human visual processing, no matter how small or subtle, support the view that females and males truly see the world differently. We acknowledge some of the controversy regarding sex differences in human vision and propose that such controversy should be interpreted as a source of motivation for continued efforts to assess the validity and reliability of published sex differences and for continued research on sex differences in human vision and the nervous system in general. © 2016 Wiley Periodicals, Inc.

Transient sex differences during adolescence on auditory perceptual tasks

Many perceptual abilities differ between the sexes. Because these sex differences have been documented almost exclusively in adults, they have been attributed to sex-specific neural circuitry that emerges during development and is maintained in the mature perceptual system. To investigate whether behavioral sex differences in perception can also have other origins, we compared performance between males and females ranging in age from 8 to 30 years on auditory temporal-interval discrimination and tone-in-noise detection tasks on which there are no sex differences in adults. If sex differences in perception arise only from the establishment and subsequent maintenance of sex-specific neural circuitry, there should be no sex differences during development on these tasks. In contrast, sex differences emerged in adolescence but resolved by adulthood on two of the six conditions, with signs of a similar pattern on a third condition. In each case, males reached mature performance earlier than females, resulting in a sex difference in the interim. These results suggest that sex differences in perception may arise from differences in the maturational timing of common circuitry used by both sexes. They also imply that sex differences in perceptual abilities may be more prevalent than previously thought based on adult data alone.

Gender differences in the structural connectome of the teenage brain revealed by generalized q-sampling MRI

The question of whether there are biological differences between male and female brains is a fraught one, and political positions and prior expectations seem to have a strong influence on the interpretation of scientific data in this field. This question is relevant to issues of gender differences in the prevalence of psychiatric conditions, including autism, attention deficit hyperactivity disorder (ADHD), Tourette's syndrome, schizophrenia, dyslexia, depression, and eating disorders. Understanding how gender influences vulnerability to these conditions is significant. Diffusion magnetic resonance imaging (dMRI) provides a non-invasive method to investigate brain microstructure and the integrity of anatomical connectivity. Generalized q-sampling imaging (GQI) has been proposed to characterize complicated fiber patterns and distinguish fiber orientations, providing an opportunity for more accurate, higher-order descriptions through the water diffusion process. Therefore, we aimed to investigate differences in the brain's structural network between teenage males and females using GQI. This study included 59 (i.e., 33 males and 26 females) age- and education-matched subjects (age range: 13 to 14 years). The structural connectome was obtained by graph theoretical and network-based statistical (NBS) analyses. Our findings show that teenage male brains exhibit better intrahemispheric communication, and teenage female brains exhibit better interhemispheric communication. Our results also suggest that the network organization of teenage male brains is more local, more segregated, and more similar to small-world networks than teenage female brains. We conclude that the use of an MRI study with a GQI-based structural connectomic approach like ours presents novel insights into network-based systems of the brain and provides a new piece of the puzzle regarding gender differences.

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The GQI-based structural connectomic study provides a new piece of the puzzle regarding gender differences.

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Male brains exhibit better intrahemispheric communication, and female exhibit better interhemispheric communication.

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The network organization of teenage male brains is more local and more segregated than teenage female brains.

Effects of sex and gender on adaptation to space: neurosensory systems

Sex and gender differences have long been a research topic of interest, yet few studies have explored the specific differences in neurological responses between men and women during and after spaceflight. Knowledge in this field is limited due to the significant disproportion of sexes enrolled in the astronaut corps. Research indicates that general neurological and sensory differences exist between the sexes, such as those in laterality of amygdala activity, sensitivity and discrimination in vision processing, and neuronal cell death (apoptosis) pathways. In spaceflight, sex differences may include a higher incidence of entry and space motion sickness and of post-flight vestibular instability in female as opposed to male astronauts who flew on both short- and long-duration missions. Hearing and auditory function in crewmembers shows the expected hearing threshold differences between men and women, in which female astronauts exhibit better hearing thresholds. Longitudinal observations of hearing thresholds for crewmembers yield normal age-related decrements; however, no evidence of sex-related differences from spaceflight has been observed. The impact of sex and gender differences should be studied by making spaceflight accessible and flying more women into space. Only in this way will we know if increasingly longer-duration missions cause significantly different neurophysiological responses in men and women.

The impact of sex and gender on adaptation to space: executive summary

This review article is a compendium of six individual manuscripts, a Commentary, and an Executive Summary. This body of work is entitled "The Impact of Sex and Gender on Adaptation to Space" and was developed in response to a recommendation from the 2011 National Academy of Sciences Decadal Survey, "Recapturing a Future for Space Exploration: Life and Physical Sciences for a New Era," which emphasized the need to fully understand sex and gender differences in space. To ensure the health and safety of male and female astronauts during long-duration space missions, it is imperative to examine and understand the influences that sex and gender have on physiological and psychological changes that occur during spaceflight. In this collection of manuscripts, six workgroups investigated and summarized the current body of published and unpublished human and animal research performed to date related to sex- and gender-based differences in the areas of cardiovascular, immunological, sensorimotor, musculoskeletal, reproductive, and behavioral adaptations to human spaceflight. Each workgroup consisted of scientists and clinicians from academia, the National Aeronautics and Space Administration (NASA), and other federal agencies and was co-chaired by one representative from NASA and one from the external scientific community. The workgroups met via telephone and e-mail over 6 months to review literature and data from space- and ground-based studies to identify sex and gender factors affecting crew health. In particular, the Life Sciences Data Archive and the Lifetime Surveillance of Astronaut Health were extensively mined. The groups identified certain sex-related differences that impact the risks and the optimal medical care required by space-faring women and men. It represents innovative research in sex and gender-based biology that impacts those individuals that are at the forefront of space exploration.

Sex differences in interactions between nucleus accumbens and visual cortex by explicit visual erotic stimuli: an fMRI study

Men tend to have greater positive responses than women to explicit visual erotic stimuli (EVES). However, it remains unclear, which brain network makes men more sensitive to EVES and which factors contribute to the brain network activity. In this study, we aimed to assess the effect of sex difference on brain connectivity patterns by EVES. We also investigated the association of testosterone with brain connection that showed the effects of sex difference. During functional magnetic resonance imaging scans, 14 males and 14 females were asked to see alternating blocks of pictures that were either erotic or non-erotic. Psychophysiological interaction analysis was performed to investigate the functional connectivity of the nucleus accumbens (NA) as it related to EVES. Men showed significantly greater EVES-specific functional connection between the right NA and the right lateral occipital cortex (LOC). In addition, the right NA and the right LOC network activity was positively correlated with the plasma testosterone level in men. Our results suggest that the reason men are sensitive to EVES is the increased interaction in the visual reward networks, which is modulated by their plasma testosterone level.

A population study of binocular function

As part of a genome-wide association study (GWAS) of perceptual traits in healthy adults, we measured stereo acuity, the duration of alternative percepts in binocular rivalry and the extent of dichoptic masking in 1060 participants. We present the distributions of the measures, the correlations between measures, and their relationships to other psychophysical traits. We report sex differences, and correlations with age, interpupillary distance, eye dominance, phorias, visual acuity and personality. The GWAS, using data from 988 participants, yielded one genetic association that passed a permutation test for significance: The variant rs1022907 in the gene VTI1A was associated with self-reported ability to see autostereograms. We list a number of other suggestive genetic associations (p<10(-5)).

A parietal biomarker for ADHD liability: as predicted by the distributed effects perspective model of ADHD

BACKGROUND

We previously hypothesized that poor task-directed sensory information processing should be indexed by increased weighting of right hemisphere (RH) biased attention and visuo-perceptual brain functions during task operations and have demonstrated this phenotype in ADHD across multiple studies, using multiple methodologies. However, in our recent distributed effects model of ADHD, we surmised that this phenotype is not ADHD specific, but rather more broadly reflective of any circumstance that disrupts the induction and maintenance of an emergent task-directed neural architecture. Under this view, increased weighting of RH-biased attention and visuo-perceptual brain functions is expected to generally index neurocognitive sets that are not optimized for task-directed thought and action, and when durable expressed, liability for ADHD.

METHOD

The current study tested this view by examining whether previously identified rightward parietal EEG asymmetry in ADHD was associated with common ADHD characteristics and comorbidities [i.e., ADHD risk factors (RFs)].

RESULTS

Barring one exception (non-right handedness), we found that it was. Rightward parietal asymmetry (RPA) was associated with carrying the DRD4-7R risk allele, being male, having mood disorder, and having anxiety disorder. However, differences in the specific expression of RPA were observed, which are discussed in relation to possible unique mechanisms underlying ADHD liability in different ADHD RFs.

CONCLUSION

Rightward parietal asymmetry appears to be a durable feature of ADHD liability, as predicted by the Distributed Effects Perspective Model of ADHD. Moreover, variability in the expression of this phenotype may shed light on different sources of ADHD liability.

Neural correlates of four broad temperament dimensions: testing predictions for a novel construct of personality

Four suites of behavioral traits have been associated with four broad neural systems: the 1) dopamine and related norepinephrine system; 2) serotonin; 3) testosterone; 4) and estrogen and oxytocin system. A 56-item questionnaire, the Fisher Temperament Inventory (FTI), was developed to define four temperament dimensions associated with these behavioral traits and neural systems. The questionnaire has been used to suggest romantic partner compatibility. The dimensions were named: Curious/Energetic; Cautious/Social Norm Compliant; Analytical/Tough-minded; and Prosocial/Empathetic. For the present study, the FTI was administered to participants in two functional magnetic resonance imaging studies that elicited feelings of love and attachment, near-universal human experiences. Scores for the Curious/Energetic dimension co-varied with activation in a region of the substantia nigra, consistent with the prediction that this dimension reflects activity in the dopamine system. Scores for the Cautious/Social Norm Compliant dimension correlated with activation in the ventrolateral prefrontal cortex in regions associated with social norm compliance, a trait linked with the serotonin system. Scores on the Analytical/Tough-minded scale co-varied with activity in regions of the occipital and parietal cortices associated with visual acuity and mathematical thinking, traits linked with testosterone. Also, testosterone contributes to brain architecture in these areas. Scores on the Prosocial/Empathetic scale correlated with activity in regions of the inferior frontal gyrus, anterior insula and fusiform gyrus. These are regions associated with mirror neurons or empathy, a trait linked with the estrogen/oxytocin system, and where estrogen contributes to brain architecture. These findings, replicated across two studies, suggest that the FTI measures influences of four broad neural systems, and that these temperament dimensions and neural systems could constitute foundational mechanisms in personality structure and play a role in romantic partnerships.

Sex-dependent neurochemical effects of environmental enrichment in the visual system

Sex differences in the visual system have been reported in aspects of human vision, such as color perception, peripheral vision and even in the activation of the primary visual cortex. Similarly sex differences have been identified in the visual system of laboratory animals such as monkeys and rats. On the other hand, environmental enrichment (EE) has long been known to affect visual tissues. Taking into consideration the variation in the experimental approaches concerning EE and the sex differences in the visual system, we investigated in male and female rats the serotonergic and dopaminergic effects of EE in the retina and the visual cortex at different time points (i.e. P0-25, P0-P90 and P90-P150). Early EE in adulthood increased the serotonergic activity of the male visual cortex and the female retina (P0-P90). In addition early enrichment (P0-P90) increased dopaminergic activity in the female retina and in the visual cortex of both sexes. Late enrichment increased the serotonergic activity in the retina and visual cortex of both sexes (P90-P150), but increased the dopaminergic activity in the visual cortex only in male animals. In the present study we expose marked sex differences in the neurochemistry of visual tissues and we demonstrate for the first time that EE can in fact modify the serotonergic and dopaminergic neurotransmission in the retina and visual cortex. Overall, the present study underpins the sex-dependent neurochemical status of the visual system and provides insights into the different mechanisms underlying visual processing in the two sexes.

Neural correlates of sexual arousal in heterosexual and homosexual women and men

Most men have a category-specific pattern of genital and subjective sexual arousal, responding much more strongly to erotic stimuli depicting their preferred sex than to erotic stimuli depicting their nonpreferred sex. In contrast, women tend to have a less specific arousal pattern. To better understand this sex difference, we used neuroimaging to explore its neural correlates. Heterosexual and homosexual women viewed erotic photographs of either men or women. Evoked neural activity was monitored via fMRI and compared with responses to the same stimuli in heterosexual and homosexual men. Overall, a network of limbic (as well as the anterior cingulate) and visual processing regions showed significantly less category-specific activity in women than men. This was primarily driven by weaker overall activations to preferred-sex stimuli in women, though there was also some evidence of stronger limbic activations to nonpreferred-sex stimuli in women. Primary results were similar for heterosexual and homosexual participants. Women did show some evidence of category-specific responses in the visual processing regions, although even in these regions they exhibited less differential activity than men. In the anterior cingulate, a region with high concentrations of sex-hormone receptors, subjective and neural category specificity measures correlated positively for women but negatively for men, suggesting a possible sex difference in the role of the anterior cingulate. Overall, results suggest that men tend to show more differentiated neural responses than do women to erotic photographs of one sex compared to the other sex, though women may not be entirely indifferent to which sex is depicted.

Sex differences in thickness, and folding developments throughout the cortex

While significant differences in male and female brain structures have commonly been reported, only a few studies have focused on the sex differences in the way the cortex matures over time. Here, we investigated cortical thickness maturation between the age of 6 to 30 years, using 209 longitudinally-acquired brain MRI scans. Significant sex differences in the trajectories of cortical thickness change with age were evidenced using non-linear mixed effects models. Similar statistical analyses were computed to quantify the differences between cortical gyrification changes with age in males and females. During adolescence, we observed a statistically significant higher rate of cortical thinning in females compared to males in the right temporal regions, the left temporoparietal junction and the left orbitofrontal cortex. This finding is interpreted as a faster maturation of the social brain areas in females. Concomitantly, statistically significant sex differences in cortical folding changes with age were observed only in one cluster of the right prefrontal regions, suggesting that the mechanisms underlying cortical thickness and gyrification changes with age are quite distinct. Sexual dimorphism in the developmental course of the cortical maturation may be associated with the different age of onset and clinical presentation of many psychiatric disorders between males and females.

Gender recognition depends on type of movement and motor skill. Analyzing and perceiving biological motion in musical and nonmusical tasks

Gender recognition in point-light displays was investigated with regard to body morphology cues and motion cues of human motion performed with different levels of technical skill. Gestures of male and female orchestral conductors were recorded with a motion capture system while they conducted excerpts from a Mendelssohn string symphony to musicians. Point-light displays of conductors were presented to observers under the following conditions: visual-only, auditory-only, audiovisual, and two non-conducting conditions (walking and static images). Observers distinguished between male and female conductors in gait and static images, but not in visual-only and auditory-only conducting conditions. Across all conductors, gender recognition for audiovisual stimuli was better than chance, yet significantly less reliable than for gait. Separate analyses for two groups of conductors indicated an expertise effect in that novice conductors' gender was perceived above chance level for visual-only and audiovisual conducting, while skilled conducting gestures of experts did not afford gender-specific cues. In these conditions, participants may have ignored the body morphology cues that led to correct judgments for static images. Results point to a response bias such that conductors were more often judged to be male. Thus judgment accuracy depended both on the conductors' level of expertise as well as on the observers' concepts, suggesting that perceivable differences between men and women may diminish for highly trained movements of experienced individuals.