Gender differences in event-related potentials during visual-spatial attention

Hierarchical Classification of Event-Related Potentials for the Recognition of Gender Differences in the Attention Task

Research on the functioning of human cognition has been a crucial problem studied for years. Electroencephalography (EEG) classification methods may serve as a precious tool for understanding the temporal dynamics of human brain activity, and the purpose of such an approach is to increase the statistical power of the differences between conditions that are too weak to be detected using standard EEG methods. Following that line of research, in this paper, we focus on recognizing gender differences in the functioning of the human brain in the attention task. For that purpose, we gathered, analyzed, and finally classified event-related potentials (ERPs). We propose a hierarchical approach, in which the electrophysiological signal preprocessing is combined with the classification method, enriched with a segmentation step, which creates a full line of electrophysiological signal classification during an attention task. This approach allowed us to detect differences between men and women in the P3 waveform, an ERP component related to attention, which were not observed using standard ERP analysis. The results provide evidence for the high effectiveness of the proposed method, which outperformed a traditional statistical analysis approach. This is a step towards understanding neuronal differences between men's and women's brains during cognition, aiming to reduce the misdiagnosis and adverse side effects in underrepresented women groups in health and biomedical research.

Sex Differences in Anatomical Rich-Club and Structural-Functional Coupling in the Human Brain Network

Structural and functional differences between the brains of female and male adults have been well documented. However, potential sex differences in the patterns of rich-club organization and the coupling between their structural connectivity (SC) and functional connectivity (FC) remain to be determined. In this study, functional magnetic resonance imaging and diffusion tensor imaging techniques were combined to examine sex differences in rich-club organization. Females had a stronger SC-FC coupling than males. Moreover, stronger SC-FC coupling in the females was primarily located in feeder connections and non-rich-club nodes of the left inferior frontal gyrus and inferior parietal lobe and the right superior frontal gyrus and superior parietal gyrus, whereas higher coupling strength in males was primarily located in rich-club connections and rich-club node of the right insula, and non-rich-club nodes of the left hippocampus and the right parahippocampal gyrus. Sex-specific patterns in correlations were also shown between SC-FC coupling and cognitive function, including working memory and reasoning ability. The topological changes in rich-club organization provide novel insight into sex-specific effects on white matter connections that underlie a potential network mechanism of sex-based differences in cognitive function.

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.

Interindividual differences in brain dynamics of early visual processes: Impact on score accuracy in the mental rotation task

Interindividual variations in the ability to perform visuospatial mental transformations have been investigated extensively, in particular through mental rotation tasks. However, the impact of early visual processes on performance has been largely ignored. To clarify this issue, we explored the time-course of early visual processing (from 0 to 450 ms poststimulus) using event-related potentials topographic analyses. The main findings demonstrated a significant link between early attentional processes and accuracy scores occurring more than five seconds later, as well as a strong association between spatial covariance and microstate topographies exhibiting substantial gender differences. More specifically, the results indicated that, in a classical mental rotation task, the male brain expends more time processing visual-spatial information resulting in a longer bilateral positive potential at posterior-occipital sites. In comparison, the female brain initiates earlier processing of non-spatial information resulting in a faster transition from a bilateral positive potential of posterior-occipital sites to a negative potential at central-frontal sites. These findings illustrate how a more complete utilization of the spatiotemporal information contained in EEG recordings can provide important insights about the impact of early visual processes on interindividual differences, particularly across gender, and thus shed new light on alternate cognitive strategies.

Children, Young Adults, and Older Adults Choose Different Fast Learning Strategies

The aim of the study was to establish whether there were differences in speed–accuracy movement learning strategies between children, young adults, and older adults. A total of 30 boys, 30 young adult men, and 30 older men were seated in a special chair at a table with a Dynamic Parameter Analyzer 1. Participants had to perform a speed–accuracy task with the right-dominant hand. It may be assumed that the motor variables of children are more prone to change during the fast learning process than those of young adults and older adults and that the development of internal models is more changeable in children than in young adults and the older adults during the fast adaptation-based learning process.

Power-Law Distribution of Natural Visibility Graphs from Reaction Times Series

In this study, we analyze the response times of students to yes/no decision tasks from the perspective of network science. We analyze the properties of the natural visibility graphs (NVG) associated with their reaction time series. We observe that the degree distribution of these graphs usually fits a power-law distribution px = x-α. We study the range in which parameter α occurs and the changes of this exponent with respect to the age and gender of the students. In addition to this, we also study the links between the parameter α and the parameters of the ex-Gaussian distribution that best fit the response times for each subject.

Gender effect in human brain responses to bottom-up and top-down attention using the EEG 3D-Vector Field Tomography

The effect of gender in rapidly allocating attention to objects, features or locations, as reflected in brain activity, is examined in this study. A visual-attention task, consisting of bottom-up (visual pop-out) and top-down (visual search) conditions during stimuli of four triangles, i.e., a target and three distractors, was engaged. In pop-out condition, both color and orientation of the distractors differed from target, while in search condition they differed only in orientation. During the task, high-density EEG (256 channels) data were recorded and analyzed by means of behavioral, event-related potentials, i.e., the P300 component and brain source localization analysis using 3D-Vector Field Tomography (3D-VFT). Twenty subjects (half female; 32±4.7 years old) participated in the experiments, performing 60 trials for each condition. Behavioral analysis revealed that both female and male outperformed in the pop-out condition compared to the search one, with respect to accuracy and reaction time, whereas no gender-related statistical significant differences were found. Nevertheless, in the search condition, higher P300 amplitudes were detected for females compared to males (p <; 7 · 10(-3)). Moreover, the findings suggested that the maximum activation in females was located mainly in the left inferior frontal and superior temporal gyri, whereas in males it was found in the right inferior frontal and superior temporal gyri. Overall, the experimental results show that visual attention depends on contributions from different brain lateralization linked to gender, posing important implications in studying developmental disorders, characterized by gender differences.

A sex comparison of reactive knee stiffness regulation strategies under cognitive loads

BACKGROUND

Sex differences may exist in cognitive faculties and neuromuscular strategies for maintaining joint stability. The purpose of this study was to assess whether preparatory and reactive knee stiffening strategies are affected differently in males and females exposed to sex-biased cognitive loads.

METHODS

20 male and 20 female volunteers were tested for knee joint stiffness and quadriceps and hamstring muscle activation patterns throughout a rapid eccentric knee extension perturbation. Participants were tested under 3 cognitive loads (Benton's Judgment of Line Orientation; Symbol Digit modalities Test; and Serial 7's) and a control condition. Apparent knee joint stiffness and muscle activation amplitude and timing were quantified throughout the perturbation across the 4 conditions.

FINDINGS

Reactive knee stiffness values were significantly less during the cognitive tasks compared to the control condition (Judgment of Line Orientation=0.034Nm/deg/kg, Symbol Digit Modalities Test=0.037Nm/deg/kg, Serial 7's=0.037Nm/deg/kg, control=0.048Nm/deg/kg). Females had greater normalized total apparent stiffness than males. The quadriceps muscles had faster and greater activation than the hamstring muscles; however, no group differences were observed. No overall differences in muscle activation (magnitude and timing) were found between the cognitive loading tasks.

INTERPRETATION

Cognitive loading may decrease the ability of healthy individuals to reactively stiffen their knee joint and appears to interfere with the normal stiffness regulation strategies. This may elucidate an extrinsic risk factor for non-contact knee ligament injury.

Spatiotemporal mapping of sex differences during attentional processing

Functional neuroimaging studies have increasingly aimed at approximating neural substrates of human cognitive sex differences elicited by visuospatial challenge. It has been suggested that females and males use different behaviorally relevant neurocognitive strategies. In females, greater right prefrontal cortex activation has been found in several studies. The spatiotemporal dynamics of neural events associated with these sex differences is still unclear. We studied 22 female and 22 male participants matched for age, education, and nicotine with 29-channel-electroencephalogram recorded under a visual selective attention paradigm, the Attention Network Test. Visual event-related potentials (ERP) were topographically analyzed and neuroelectric sources were estimated. In absence of behavioral differences, ERP analysis revealed a novel frontal-occipital second peak of visual N100 that was significantly increased in females relative to males. Further, in females exclusively, a corresponding central ERP component at around 220 ms was found; here, a strong correlation between stimulus salience and sex difference of the central ERP component amplitude was observed. Subsequent source analysis revealed increased cortical current densities in right rostral prefrontal (BA 10) and occipital cortex (BA 19) in female subjects. This is the first study to report on a tripartite association between sex differences in ERPs, visual stimulus salience, and right prefrontal cortex activation during attentional processing.

Gender related differences in visual and auditory processing of verbal and figural tasks

The aim of the present study was to investigate gender related differences in brain activity for tasks of verbal and figural content presented in the visual and auditory modality. Thirty male and 30 female respondents solved four tasks while their electroencephalogram (EEG) was recorded. Also recorded was the percentage of oxygen saturation of hemoglobin (%StO(2)) in the respondents' frontal brain areas with near-infrared spectroscopy (NIRS). The main findings of the study can be summarized as follows. (1) Most pronounced differences between males and females were observed for the factor modality-visual/auditory. (2) Gender related differences in neuroelectric brain responses could be observed during the solution of auditory and visual tasks; however, on the behavioral level only for the visual tasks did females display shorter reaction times than males. The ERP amplitudes of the early evoked gamma response, P1, and P3 were higher in females than males, whereas the N4 amplitude was higher in males than females. The differences were more noticeable in the visual modality. The NIRS showed a more bilateral involvement of the frontal brain areas in females as compared with a more left hemispheric frontal activity in males. In the task conditions an increase in right hemispheric activity in females was observed; however, this increase was less pronounced in the visual than the auditory domain, indicating a more lateralized processing of visual stimuli in females. Taken all together the results suggest that the females' visual event-categorization process is more efficient than in males.

Sex differences in auditory processing in peripersonal space: an event-related potential study

Further processing of auditory stimuli in the free field is attenuated when participants are in contact with speakers versus not touching them. Studies in the visual domain have found that men and women use different strategies for processing spatial information. In this study, we examined sex-related differences in event-related potentials while men and women performed an auditory discrimination task in peripersonal space when either holding speakers or resting their hands in their laps. We found that men responded more accurately than women to targets in attended locations, and that the sexes exhibited different event-related potential patterns during task performance. These differences are consistent with existing predictions of female top-down and male bottom-up strategies in spatial processing.

Sex-related lateralized effect of emotional content on declarative memory: an event related potential study

Several studies suggest that emotional arousal can promote memory storage. In this study, we evaluated the effects of emotional content on declarative memory, utilizing an adaptation of two versions of the same story, with different arousing properties (neutral or emotional), which have been already employed in experiments involving the enhancing effects of emotions on memory retention. We used event related potentials (ERP) to evaluate whether there is a sex-related hemispheric lateralization of electrical potentials elicited by the emotional content of a story. We compared left and right hemisphere P300 waves, recorded in P3 and P4 electrode sites, in response to emotional or neutral stimuli in men and women. In the left hemisphere, emotional stimuli elicited a stronger P300 in women, compared to men, as indexed by both amplitude and latency measures; moreover, the emotional content of the story elicited a stronger P300 in the right hemisphere in men than in women. The better memory for the arousal material may be related to the differential P300 at encoding. These data indicate that both sex and cerebral hemisphere constitute important, interacting influences on neural correlates of emotion, and of emotionally influenced memory.