Sex-related hemispheric lateralization of electrical potentials evoked by arousing negative stimuli

Executive functioning profiles and mathematical and reading achievement in Grades 2, 6, and 10

Using a person-centered approach, we aimed to identify different executive functioning profiles to assess heterogeneity across individuals within the same school grade through latent profile analysis. A sample of 150 Grade 2 (7-8 years old), 150 Grade 6 (11-12 years old), and 150 Grade 10 (15-16 years old) children and adolescents were assessed on 11 different executive tasks representative of the three main executive functioning subcomponents (i.e., inhibition, cognitive flexibility, and working memory), fluid intelligence, processing speed, problem-solving, and reading comprehension. Three different executive functioning profiles of different patterns of interactions based on inhibition, cognitive flexibility, and working memory within and between grades were identified. Moreover, these profiles were differentially related to reading comprehension and mathematical achievement. Second, as expected, we did not find these profiles to be associated with sociodemographic variables such as chronological age or sex. Still, fluid intelligence and processing speed were differentially related to the different profiles at each grade. We also found that the executive functioning profiles interacted with each cognitive skill (i.e., fluid intelligence and processing speed) in predicting reading comprehension and math achievement. These findings provide valuable insights for developing preventive and intervention strategies in education.

Functional lateralization in social-emotional processing: The influence of sexual orientation and gender identity on cradling preferences

The left-cradling bias (i.e., the motor asymmetry for cradling infants on the left side) has often been associated to the right-hemispheric social-emotional specialization, and it has often been reported to be stronger in females than in males. In this study we explored the effects of sexual orientation and gender identity on this lateral bias by means of a web-based investigation in a sample of adults (485 biological females and 196 biological males) recruited through LGBTQIA+ networks and general university forums. We exploited a cradling imagery task to assess participants' cradling-side preference, and standardized questionnaires to assess participants' homosexuality (Klein Sexual Orientation Grid) and gender nonconformity (Gender Identity/Gender Dysphoria Questionnaire for Adults and Adolescents). Results confirmed the expected left-cradling bias across all sexual orientation groups except for heterosexual males. Importantly, higher homosexuality scores were associated with higher proportions of left cradling in males. These results suggest that sexual orientation can influence cradling preference in males, indicating a complex interaction between biological and psychological factors in the laterality of social-emotional processing. Finally, the left-cradling bias seems to confirm its role as a behavioral proxy of social-emotional functional lateralization in humans.

Gender effect in affective processing: Alpha EEG source analysis on emotional slides and film-clips

Past research on gender-related brain asymmetries in emotions was limited and not univocal. The present study analyzed EEG alpha activity (indexing cortical de-activation) from 64 scalp sites in 20 women and 20 men during a counterbalanced block presentation of emotional slides and short video-clips. Stimuli consisted of 45 brief clips of 13 s, divided into 15 erotic (pleasant), 15 neutral and 15 fear (unpleasant) contents. Slides consisted in 45 photo shots (presented for 13 s each) extracted from the videos. As expected, women perceived fear stimuli as more arousing and more unpleasant compared to men. Alpha EEG source analysis revealed gender effects depending on stimulus. Emotional film-clips elicited in both groups a pattern of greater right than left occipital activation. Instead, emotional pictures activated opposite occipital regions, as women showed greater activation in the left, men in the right hemisphere. Men also showed greater activation to Erotic compared to Fear stimuli (i.e., pictures/clips) in the posterior parietal complex. Results point to the relevance of emotional stimulus type to reveal gender effects: clips are ecological, dynamic and engaging, and forced a unified pattern of emotional responses that reset individual differences. Emotional pictures, less engaging, allowed individual differences to emerge and interact with the stimulus category.

[Gender characteristics of depressive disorders: clinical, psychological, neurobiological and translational aspects]

Various studies have indicated that the prevalence of depression is almost twice as high among women as among men. A major factor associated with the development of depression and other affective disorders are adverse and psychologically traumatic life events that contribute to changes in the neuroendocrine system, altering the capacity to adapt to stress. These changes are involved in the pathogenesis of mental disorders, along with genetic and other factors, and are to a significant degree regulated by gender dependent mechanisms. While women have a high prevalence of depressive disorders, men show a higher rate of alcohol and substance abuse. These differences in the epidemiology are most likely explained by different predisposition to mental disorders in men and women and a diversity of biological consequences to adverse life events. Taking this into account, there is a need for a critical review of currently used approaches to modeling depressive disorders in preclinical studies, including the use of animals of both sexes. Adaptation of experimental models and protocols taking into account gender characteristics of neuroendocrine changes in response to stress, as well as structural-morphological, electrophysiological, molecular, genetic and epigenetic features, will significantly increase the translational validity of experimental work.

Impact of negative links on the structural balance of brain functional network during emotion processing

Activation of specific brain areas and synchrony between them has a major role in process of emotions. Nevertheless, impact of anti-synchrony (negative links) in this process still requires to be understood. In this study, we hypothesized that quantity and topology of negative links could influence a network stability by changing of quality of its triadic associations. Therefore, a group of healthy participants were exposed to pleasant and unpleasant images while their brain responses were recorded. Subsequently, functional connectivity networks were estimated and quantity of negative links, balanced and imbalanced triads, tendency to make negative hubs, and balance energy levels of two conditions were compared. The findings indicated that perception of pleasant stimuli was associated with higher amount of negative links with a lower tendency to make a hub in theta band; while the opposite scenario was observed in beta band. It was accompanied with smaller number of imbalanced triads and more stable network in theta band, and smaller number of balanced triads and less stable network in beta band. The findings highlighted that inter regional communications require less changes to receive new information from unpleasant stimuli, although by decrement in beta band stability prepares the network for the upcoming events.

Functional role of frontal electroencephalogram alpha asymmetry in the resting state in patients with depression: A review

Depression is a psychological disorder that affects the general public worldwide. It is particularly important to make an objective and accurate diagnosis of depression, and the measurement methods of brain activity have gradually received increasing attention. Resting electroencephalogram (EEG) alpha asymmetry in patients with depression shows changes in activation of the alpha frequency band of the left and right frontal cortices. In this paper, we review the findings of the relationship between frontal EEG alpha asymmetry in the resting state and depression. Based on worldwide studies, we found the following: (1) Compared with individuals without depression, those with depression showed greater right frontal EEG alpha asymmetry in the resting state. However, the pattern of frontal EEG alpha asymmetry in the resting state in depressive individuals seemed to disappear with age; (2) Compared with individuals without maternal depression, those with maternal depression showed greater right frontal EEG alpha asymmetry in the resting state, which indicated that genetic or experience-based influences have an impact on frontal EEG alpha asymmetry at rest; and (3) Frontal EEG alpha asymmetry in the resting state was stable, and little or no change occurred after antidepressant treatment. Finally, we concluded that the contrasting results may be due to differences in methodology, clinical characteristics, and participant characteristics.

Stability of associations between neuroticism and microstructural asymmetry of the cingulum during late childhood and adolescence: Insights from a longitudinal study with up to 11 waves

Adolescence is characterized by significant brain development and marks a period of the life span with an increased incidence of mood disorders, especially in females. The risk of developing mood disorders is also higher in individuals scoring high on neuroticism, a personality trait characterized by a tendency to experience negative and anxious emotions. We previously found in a cross-sectional study that neuroticism is associated with microstructural left-right asymmetry of the fronto-limbic white matter involved in emotional processing, with opposite effects in female and male adolescents. We now have extended this work collecting longitudinal data in 76 typically developing children and adolescents aged 7-18 years, including repeated MRI sampling up to 11 times. This enabled us, for the first time, to address the critical question, whether the association between neuroticism and frontal-limbic white matter asymmetry changes or remains stable across late childhood and adolescence. Neuroticism was assessed up to four times and showed good intraindividual stability and did not significantly change with age. Conforming our cross-sectional results, females scoring high on neuroticism displayed increased left-right cingulum fractional anisotropy (FA), while males showed decreased left-right cingulum FA asymmetry. Despite ongoing age-related increases in FA in cingulum, the association between neuroticism and cingulum FA asymmetry was already expressed in females in late childhood and remained stable across adolescence. In males, the association appeared to become more prominent during adolescence. Future longitudinal studies need to cover an earlier age span to elucidate the time point at which the relationship between neuroticism and cingulum FA asymmetry arises.

Gender dimorphic M1 excitability during emotional processing: a transcranial magnetic stimulation study

Background

It is widely held that emotions prime the body for action. However, the influence of gender on primary motor cortex (M1) excitability during emotional processing is not well explored.

Methods

Using single-pulse transcranial magnetic stimulation (TMS), we stimulated the right or left M1 at 150 ms and 300 ms after emotional stimulation onset (presentation of negative, neutral, and positive pictures to male and female subjects). Motor-evoked potentials (MEPs) ratio induced by single-pulse TMS was used to assess changes in corticospinal excitability.

Results

In response to right M1 stimulation, males demonstrated higher MEP ratios following presentation of negative pictures at 150 ms while MEP ratios in response to presentation of positive pictures were greater at 300 ms. Furthermore, male subjects showed larger MEP ratios in right M1 versus left M1 at 300 ms after initiation of positive pictures, indicating lateralization of motor excitability in male subjects.

Conclusions

The current study thus provides neurophysiological evidence to support gender differences and functional lateralization of motor excitability in response to emotional stimuli.

Auditory and cross-modal attentional bias toward positive natural sounds: Behavioral and ERP evidence

Recently, researchers have expanded the investigation into attentional biases toward positive stimuli; however, few studies have examined attentional biases toward positive auditory information. In three experiments, the present study employed an emotional spatial cueing task using emotional sounds as cues and auditory stimuli (Experiment 1) or visual stimuli (Experiment 2 and Experiment 3) as targets to explore whether auditory or visual spatial attention could be modulated by positive auditory cues. Experiment 3 also examined the temporal dynamics of cross-modal auditory bias toward positive natural sounds using event-related potentials (ERPs). The behavioral results of the three experiments consistently demonstrated that response times to targets were faster after positive auditory cues than they were after neutral auditory cues in the valid condition, indicating that healthy participants showed a selective auditory attentional bias (Experiment 1) and cross-modal attentional bias (Experiment 2 and Experiment 3) toward positive natural sounds. The results of Experiment 3 showed that N1 amplitudes were more negative after positive sounds than they were after neutral sounds, which further provided electrophysiological evidence that positive auditory information enhances attention at early stages in healthy adults. The results of the experiments performed in the present study suggest that humans exhibit an attentional bias toward positive natural sounds.

An event-related potential investigation of distanced self-talk: Replication and comparison to detached reappraisal

Emotion regulation is critical for managing stress, but many regulatory strategies consume high levels of cognitive resources to implement, which are depleted under stress. This raises a conundrum: the tools we have to feel better may be ineffective when they are most needed. Recent event-related potential (ERP) research indicates that distanced self-talk (i.e., reflecting on one's experiences using non-first-person singular pronouns and one's name) reduces negative emotional reactivity without overtaxing cognitive resources. Here, we report the first direct replication of this work and extend it by examining how distanced self-talk compares to detached reappraisal, one of the most frequently studied regulatory techniques. Sixty-seven participants were randomly assigned to an emotion regulation picture task and instructed to reflect on the feelings they experienced in response to viewing negative emotional images using distanced self-talk or detached reappraisal while ERPs were measured. Directly replicating past findings, distanced self-talk led to a reduction in an affective arousal ERP, the late positive potential (LPP), without increasing stimulus preceding negativity (SPN), an ERP that reflects anticipatory and preparatory processing. These results further bolster support for distanced self-talk as a relatively effortless emotion regulation strategy. On the other hand, detached reappraisal was neither associated with the modulation of the LPP nor the SPN. Due to the failed replication of the reappraisal effect, a direct comparison between emotion regulation strategies was not conducted. Methodological limitations that may have contributed to the reappraisal failure and future directions for comparisons between emotion regulation strategies comparison are discussed.

Electroencephalography Correlates of Well-Being Using a Low-Cost Wearable System

Electroencephalography (EEG) alpha asymmetry is thought to reflect crucial brain processes underlying executive control, motivation, and affect. It has been widely used in psychopathology and, more recently, in novel neuromodulation studies. However, inconsistencies remain in the field due to the lack of consensus in methodological approaches employed and the recurrent use of small samples. Wearable technologies ease the collection of large and diversified EEG datasets that better reflect the general population, allow longitudinal monitoring of individuals, and facilitate real-world experience sampling. We tested the feasibility of using a low-cost wearable headset to collect a relatively large EEG database (N = 230, 22-80 years old, 64.3% female), and an open-source automatic method to preprocess it. We then examined associations between well-being levels and the alpha center of gravity (CoG) as well as trait EEG asymmetries, in the frontal and temporoparietal (TP) areas. Robust linear regression models did not reveal an association between well-being and alpha (8-13 Hz) asymmetry in the frontal regions, nor with the CoG. However, well-being was associated with alpha asymmetry in the TP areas (i.e., corresponding to relatively less left than right TP cortical activity as well-being levels increased). This effect was driven by oscillatory activity in lower alpha frequencies (8-10.5 Hz), reinforcing the importance of dissociating sub-components of the alpha band when investigating alpha asymmetries. Age was correlated with both well-being and alpha asymmetry scores, but gender was not. Finally, EEG asymmetries in the other frequency bands were not associated with well-being, supporting the specific role of alpha asymmetries with the brain mechanisms underlying well-being levels. Interpretations, limitations, and recommendations for future studies are discussed. This paper presents novel methodological, experimental, and theoretical findings that help advance human neurophysiological monitoring techniques using wearable neurotechnologies and increase the feasibility of their implementation into real-world applications.

Electrophysiological and Behavioral Indices of the Role of Estrogens on Memory Processes for Emotional Faces in Healthy Young Women

It is well known that estrogens influence cognitive activities, such as memory, and emotional states. The objective of the present study was to investigate the role of estrogens in the short-term memory processing of basic emotional face expressions, by means of event-related potentials (ERPs) and a recognition memory (RM) behavioral task. Healthy young women were divided into a periovulatory (PO) group, characterized by high levels of estrogens and low levels of progesterone, and an early follicular (EF) group, characterized by low levels of both estrogens and progesterone. During the RM task, all subjects viewed images of faces expressing six basic emotions (happiness, anger, disgust, sadness, surprise, fear) and one neutral expression while their electrophysiological activity was recorded. We considered P300 components, amplitude, and latency in response to each stimulus. Soon after the presentation of each stimulus face, a target image was presented, consisting of two faces, one of which was the same, while the other was a chimerical face, obtained by mixing the upper or lower halves of the faces of the stimulus image with a different emotion. The subjects had to choose between the two alternatives, and the reaction time (RT) and accuracy of response (RM errors) were measured. The main findings of this study showed that P300 amplitudes are significantly higher in response to the expressions of happiness, but significantly lower for sadness, in PO compared to EF. The P300 data are consistent with performance in the RM task and with the measures of RT. The interest in the emotion of happiness, unlike sadness, during the PO phase may reflect the evolutionary significance of female sex hormones linked to mating behavior.

Examining the contribution of histone modification to sex differences in learning and memory

The epigenome serves as a signal integration platform that encodes information from experience and environment that adds tremendous complexity to the regulation of transcription required for memory, beyond the directions encoded in the genome. To date, our understanding of how epigenetic mechanisms integrate information to regulate gene expression required for memory is primarily obtained from male derived data despite sex-specific life experiences and sex differences in consolidation and retrieval of memory, and in the molecular mechanisms that mediate these processes. In this review, we examine the contribution of chromatin modification to learning and memory in both sexes. We provide examples of how exposure to a number of internal and external factors influence the epigenome in sex-similar and sex-specific ways that may ultimately impact transcription required for memory processes. We also pose a number of key open questions and identify areas requiring further investigation as we seek to understand how histone modifying mechanisms shape memory in females.

EVALUATION OF SIGNAL PROCESSING TECHNIQUES IN DISCRIMINATING ECG SIGNALS OF MEN AND WOMEN DURING REST CONDITION AND EMOTIONAL STATES

Great range of electrocardiogram (ECG) signal processing methods can be found in the literature. In addition, the importance of gender differences in physiological activities was also identified in various conditions. This article aims to provide a comprehensive evaluation of linear and nonlinear ECG parameters to indicate suitable signal processing approaches which can show significant differences between men and women. These differences were investigated in two conditions: (i) during rest condition, and (ii) during the affective image inducements. A wide range of parameters from time-, frequency-, wavelet-, and nonlinear-techniques were examined. Applying the Wilcoxon rank sum test, significant differences between two genders were inspected. The analysis was performed on 47 college students at rest condition and while subjects watching four types of affective pictures, including sadness, happiness, fear, and peacefulness. The impact of these emotions on the results was also investigated. The results indicated that 72.95% and 72.61% of all features were significantly different between male and female in rest condition and affective inducements, respectively. In addition, the highest percentage of the significant difference between ECG parameters of men and women was achieved using nonlinear characteristics. Considering all features together, the highest significant difference between two genders was achieved for negative emotions, including sadness and fear. In conclusion, the results of this study emphasized the importance of gender role in cardiac responses during rest condition and different emotional states. Since these gender differences are well manifested by nonlinear signal processing techniques, dynamical gender-specific ECG system may improve the automatic emotion recognition accuracies.

Hearing taboo words can result in early talker effects in word recognition for female listeners

Previous spoken word recognition research using the long-term repetition-priming paradigm found performance costs for stimuli mismatching in talker identity. That is, when words were repeated across the two blocks, and the identity of the talker changed reaction times (RTs) were slower than when the repeated words were spoken by the same talker. Such performance costs, or talker effects, followed a time course, occurring only when processing was relatively slow. More recent research suggests that increased explicit and implicit attention towards the talkers can result in talker effects even during relatively fast processing. The purpose of the current study was to examine whether word meaning would influence the pattern of talker effects in an easy lexical decision task and, if so, whether results would differ depending on whether the presentation of neutral and taboo words was mixed or blocked. Regardless of presentation, participants responded to taboo words faster than neutral words. Furthermore, talker effects for the female talker emerged when participants heard both taboo and neutral words (consistent with an attention-based hypothesis), but not for participants that heard only taboo or only neutral words (consistent with the time-course hypothesis). These findings have important implications for theoretical models of spoken word recognition.

Frontal EEG Asymmetry of Mood: A Mini-Review

The present mini-review was aimed at exploring the frontal EEG asymmetry of mood. With respect to emotion, interpreted as a discrete affective process, mood is more controllable, more nebulous, and more related to mind/cognition; in addition, causes are less well-defined than those eliciting emotion. Therefore, firstly, the rational for the distinction between emotion and mood was provided. Then, the main frontal EEG asymmetry models were presented, such as the motivational approach/withdrawal, valence/arousal, capability, and inhibition asymmetric models. Afterward, the frontal EEG asymmetry of mood was investigated following three research lines, that is considering studies involving different mood induction procedures, dispositional mood (positive and negative affect), and mood alterations in both healthy and clinical populations. In general, results were found to be contradictory, no model is unequivocally supported regardless the research line considered. Different methodological issues were raised, such as: the composition of samples used across studies, in particular, gender and age were found to be critical variables that should be better addressed in future studies; the importance of third variables that might mediate the relationship between frontal EEG asymmetries and mood, for example bodily states and hormonal responses; the role of cognition, namely the interplay between mood and executive functions. In light of these issues, future research directions were proposed. Amongst others, the need to explore the neural connectivity that underpins EEG asymmetries, and the need to include both positive and negative mood conditions in the experimental designs have been highlighted.

Gender Differences in Neural Responses to Perceptually Invisible Fearful Face-An ERP Study

Women tend to respond to emotional stimuli differently from men. This study aimed at investigating whether neural responses to perceptually “invisible” emotional stimuli differ between men and women by exploiting event-related potential (ERP). Forty healthy participants (21 women) were recruited for the main experiment. A control experiment was conducted by excluding nine (7 women) participants from the main experiment and replacing them with additional ten (6 women) participants (total 41 participants) where Beck's Anxiety Inventory (BAI) and Beck's Depression Inventory (BDI) scores were controlled. Using the visual backward masking paradigm, either a fearful or a neutral face stimulus was presented in varied durations (subthreshold, near-threshold, or suprathreshold) followed by a mask. Participants performed a two-alternative forced choice (2-AFC) emotion discrimination task on each face. Behavioral analysis showed that participants were unaware of masked stimuli of which duration was the shortest and, therefore, processed at subthreshold. Nevertheless, women showed significantly larger response in P100 amplitude to subthreshold fearful faces than men. This result remained consistent in the control experiment. Our findings indicate gender-differences in neural response to subthreshold emotional face, which is reflected in the early processing stage.

Diversity and representation: Key issues for psychophysiological science

This Special Issue is devoted to the illustration and discussion of three key demographic variables (sex/gender, race/ethnicity, and socioeconomic status) that have been shown to moderate associations between psychophysiological processes and behavior. The introduction to the issue discusses the role of phenotypic plasticity in the emergence of different neural processes that achieve the same behavioral outcome, with emphasis on how these relatively stable developmental contexts affect brain/behavior associations without necessarily resulting in difference in behavior. These findings have profound significance for the implications of generalization and call into question the presumption that diverse samples produce an average result that is appropriately reflective of the individuals themselves. Increasing diversity within psychophysiological research is critical in elucidating mechanisms by which the human brain can accomplish cognitive and affective behaviors. This article further examines the logistical and ethical challenges faced in achieving this goal.

GENDER DIFFERENCES IN RESPONSE TO AFFECTIVE AUDIO AND VISUAL INDUCTIONS: EXAMINATION OF NONLINEAR DYNAMICS OF AUTONOMIC SIGNALS

Physiological reflection of emotions can be tracked by autonomic signals. Several studies have been conducted using autonomic signal processing to examine men and women differences during the exposure of affective stimuli. Emotional pictures and music are two commonly used methods to induce affects in an experimental setup. The biological changes have been commonly monitored during a certain emotional inducement protocol, solely. This study was aimed to examine two induction paradigms involved auditory and visual cues using nonlinear dynamical approaches. To this end, various nonlinear parameters of galvanic skin response (GSR) and pulse signals of men and women were examined. The nonlinear analysis was performed using lagged Poincare parameters, detrended fluctuation indices (DFAs), Lyapunov exponents (LEs), some entropy measures, and recurrence quantification analysis (RQA). The Wilcoxon rank sum test was used to show significant differences between the groups. The results indicate that besides the type of affect induction, physiological differences of men and women are notable in negative emotions (sadness and fear). Regardless to the inducements, lagged Poincare parameters of the pulse signals and DFA indices of the GSR have shown significant differences in gender affective responses. However, applying pictorial stimuli, LEs are appropriate indicators for gender discrimination. It is also concluded that GSR dynamics are intensely affected by the kind of stimuli; while this is not validated for the pulse. These findings suggest that different emotional inductions evoked different autonomic responses in men and women, which can be appropriately monitored using nonlinear signal processing approaches.

Evidence of estrogen modulation on memory processes for emotional content in healthy young women

PURPOSE

It is well accepted that emotional content can affect memory, interacting with the encoding and consolidation processes. The aim of the present study was to verify the effects of estrogens in the interplay of cognition and emotion.

METHODS

Images from the International Affective Pictures System, based on valence (pleasant, unpleasant and neutral), maintaining arousal constant, were viewed passively by two groups of young women in different cycle phases: a periovulatory group (PO), characterized by high level of estrogens and low level of progesterone, and an early follicular group (EF), characterized by low levels of both estrogens and progesterone. The electrophysiological responses to images were measured, and P300 peak was considered. One week later, long-term memory was tested by means of free recall.

FINDINGS

Intra-group analysis displayed that PO woman had significantly better memory for positive images, while EF women showed significantly better memory for negative images. The comparison between groups revealed that women in the PO phase had better memory performance for positive pictures than women in the EF phase, while no significant differences were found for negative and neutral pictures. According to the free recall results, the subjects in the PO group showed greater P300 amplitude, and shorter latency, for pleasant images compared with women in the EF group.

CONCLUSION

Our results showed that the physiological hormonal fluctuation of estrogens during the menstrual cycle can influence memory, at the time of encoding, during the processing of emotional information.

Social cognition as an RDoC domain

While the bulk of research into neural substrates of behavior and psychopathology has focused on cognitive, memory and executive functions, there has been a recent surge of interest in emotion processing and social cognition, manifested in designating Social Cognition as a major RDoC domain. We describe the origins of this field's influence on cognitive neuroscience and highlight the most salient findings leading to the characterization of the "social brain" and the establishments of parameters that quantify normative and aberrant behaviors. Such parameters of behavior and neurobiology are required for a potentially successful RDoC construct, especially if heritability is established, because of the need to link with genomic systems. We proceed to illustrate how a social cognition measure can be used within the RDoC framework by presenting a task of facial emotion identification. We show that performance is sensitive to normative individual differences related to age and sex and to deficits associated with schizophrenia and other psychotic disorders. Neuroimaging studies with this task demonstrate that it recruits limbic and frontal regulatory activation in healthy samples as well as abnormalities in psychiatric populations. Evidence for its heritability was documented in genomic family studies and in patients with the 22q11.2 deletion syndrome. Measures that meet such criteria can help build translational bridges between cellular molecular mechanisms and behavior that elucidate aberrations related to psychopathology. Such links will transcend current diagnostic classifications and ultimately lead to a mechanistically based diagnostic nomenclature. Establishing such bridges will provide the elements necessary for early detection and scientifically grounded intervention.

To Stroop or not to Stroop: Sex-related differences in brain-behavior associations during early childhood

Executive functions (EFs) are linked with optimal cognitive and social-emotional development. Despite behavioral evidence of sex differences in early childhood EF, little is known about potential sex differences in corresponding brain-behavior associations. The present study examined changes in 4-year-olds' 6-9 Hz EEG power in response to increased executive processing demands (i.e., "Stroop-like" vs. "non-Stroop" day-night tasks). Although there were no sex differences in task performance, an examination of multiple scalp electrode sites revealed that boys exhibited more widespread changes in EEG power as compared to girls. Further, multiple regression analyses controlling for maternal education and non-EF performance indicated that individual differences in boys' and girls' EF performance were associated with different frontal neural correlates (i.e., different frontal scalp sites and different measures of EEG power). These data reveal valuable information concerning sex differences in the neural systems underlying executive processing during early childhood.

Emotional correlates of unirhinal odour identification

It seems self-evident that smell profoundly shapes emotion, but less clear is the nature of this interaction. Here, we sought to determine whether the ability to identify odours co-varies with self-reported feelings of empathy and emotional expression recognition, as predicted if the two capacities draw on common resource. Thirty-six neurotypical volunteers were administered the Alberta Smell Test, the Interpersonal Reactivity Index and an emotional expression recognition task. Statistical analyses indicated that feelings of emotional empathy positively correlated with odour discrimination in right nostril, while the recognition of happy and fearful facial expressions positively correlated with odour discrimination in left nostril. These results uncover new links between olfactory discrimination and emotion which, given the ipsilateral configuration of the olfactory projections, point towards intra- rather than inter-hemispheric interaction. The results also provide novel support for the proposed lateralization of emotional empathy and the recognition of facial expression, and give reason to further explore the diagnostic sensitivity of smell tests because reduced sensitivity to others' emotions can mark the onset of certain neurological diseases.

Lateralization for Processing Facial Emotions in Gay Men, Heterosexual Men, and Heterosexual Women

This study tested whether male sexual orientation and gender nonconformity influenced functional cerebral lateralization for the processing of facial emotions. We also tested for the effects of sex of poser and emotion displayed on putative differences. Thirty heterosexual men, 30 heterosexual women, and 40 gay men completed measures of demographic variables, recalled childhood gender nonconformity (CGN), IQ, and the Chimeric Faces Test (CFT). The CFT depicts vertically split chimeric faces, formed with one half showing a neutral expression and the other half showing an emotional expression and performance is measured using a "laterality quotient" (LQ) score. We found that heterosexual men were significantly more right-lateralized when viewing female faces compared to heterosexual women and gay men, who did not differ significantly from each other. Heterosexual women and gay men were more left-lateralized for processing female faces. There were no significant group differences in lateralization for male faces. These results remained when controlling for age and IQ scores. There was no significant effect of CGN on LQ scores. These data suggest that gay men are feminized in some aspects of functional cerebral lateralization for facial emotion. The results were discussed in relation to the selectivity of functional lateralization and putative brain mechanisms underlying sexual attraction towards opposite-sex and same-sex targets.

Mesocortical dopamine depletion and anxiety-related behavior in the rat: sex and hemisphere differences

The mesocortical dopamine (DA) system of the rat plays an important role in prefrontal cortex (PFC) regulation of stress and emotion and exhibits functional hemispheric asymmetry for such processing. Since few studies examine sex differences in this context, we compared the effects of left vs. right unilateral PFC DA depletion in males and females in several behavioral situations associated with anxiety or aversion. Adult rats received unilateral injections of 6-hydroxydopamine (6-OHDA) or vehicle in the ventromedial (vm) PFC. Behavioral tests included a predator odor burying test, elevated plus maze and sucrose consumption with simple taste aversion. Tissue analysis confirmed that vmPFCs injected with 6-OHDA were depleted of DA (75-85%) compared to controls. Burying behavior and sucrose consumption were affected only by left lesions, similarly in both sexes. However, risk assessment behaviors were affected by right lesions in opposite directions in males and females. Behaviors modified preferentially by the left cortex thus showed less evidence of sex differences than those modulated by the right. While mesocortical DA depletion effects are lateralized, the nature of these effects can vary with sex and specific behavior. Such findings may be clinically significant, given the large gender differences in the incidence of mood and anxiety disorders, which also show many lateralized prefrontal abnormalities.

Cognitive processes associated with compulsive buying behaviours and related EEG coherence

The behavioural and cognitive phenomena associated with Compulsive Buying (CB) have been investigated previously but the underlying neurophysiological cognitive process has received less attention. This study specifically investigated the electrophysiology of CB associated with executive processing and cue-reactivity in order to reveal differences in neural connectivity (EEG Coherence) and distinguish it from characteristics of addiction or mood disorder. Participants (N=24, M=25.38 yrs, S.D.=7.02 yrs) completed the Sensitivity to Punishment Sensitivity to Reward Questionnaire and a visual memory task associated with shopping items. Sensitivities to reward and punishment were examined with EEG coherence measures for preferred and non-preferred items and compared to CB psychometrics. Widespread EEG coherence differences were found in numerous regions, with an apparent left shifted lateralisation for preferred and right shifted lateralisation for non-preferred items. Different neurophysiological networks presented with CB phenomena, reflecting cue reactivity and episodic memory, from increased arousal and attachment to items.

Diffusion properties of major white matter tracts in young, typically developing children

Brain development occurs rapidly during the first few years of life involving region-specific changes in both gray matter and white matter. Due to the inherent difficulties in acquiring magnetic resonance imaging data in young children, little is known about the properties of white matter in typically developing toddlers. In the context of an ongoing study of young children with autism spectrum disorder, we collected diffusion-weighted imaging data during natural nocturnal sleep in a sample of young (mean age=35months) typically developing male and female (n=41 and 25, respectively) children. Axial diffusivity, radial diffusivity, mean diffusivity and fractional anisotropy were measured at 99 points along the length of 18 major brain tracts. Influences of hemisphere, age, sex, and handedness were examined. We find that diffusion properties vary significantly along the length of the majority of tracks. We also identify hemispheric and sex differences in diffusion properties in several tracts. Finally, we find the relationship between age and diffusion parameters changes along the tract length illustrating variability in age-related white-matter development at the tract level.

Effect of emotional valence on episodic memory stages as indexed by event-related potentials

Several investigations have shown that emotional events show superior recall than non-emotional ones. However, the cortical mechanisms underlying the episodic recall of emotional scenes are still poorly understood. Our main aim was to compare the magnitude of the Event-Related brain Potentials (ERP) old-new effect related to emotionally unpleasant, pleasant and neutral photographic images. As expected, correct recognition of all types of images elicited three topographically distinct ERP components sensitive to the classical old-new recognition effect. The results revealed that the behavioral performances were mainly sensitive to arousal, while the ERP old/new effect over posterior regions (300 – 1000 ms) was exclusively affected by unpleasantness. A later component (1000 – 1400 ms) showed an inverted old/ new effect at parietal sites, which was also sensitive to unpleasantness. These results imply that ERP reflecting episodic conscious recollection and post-retrieval monitoring are clearly affected both by valence and arousal.

Electrophysiological indices of emotion processing during retrieval of autobiographical memories by school-age children

We used event-related potentials (ERPs) to examine emotion processing during retrieval of emotional autobiographical memories by school-age children. We initiated processing of the emotional experiences using neutral cue words. On one-third of trials, children were instructed to think of a memory of a negative event, and on another third of trials, they were instructed to think of a memory of a positive event. We then recorded ERPs from 32 electrode sites as the children processed the emotional memories again later in the testing session. The 7- to 10-year-old children generated memories appropriate to the valences specified in the instructions. Neural responses differed as a function of the emotional valence of the events associated with the cues and as a function of gender. In the sample as a whole, differential processing of positive relative to negative and neutral emotions was apparent at posterior electrode sites 1,000-1,500 ms after stimulus onset. For girls, the effect was apparent beginning at 500 ms. No differences between the neural responses to negative and neutral stimuli were observed. At frontal electrode sites, girls evidenced faster processing of positive than of negative emotion, whereas boys evidenced faster processing of negative than of positive emotion. In conclusion, we discuss the possible origins of gender-differential patterns of neural processing.

The temporal electrocortical profile of emotive facial processing in depressed males and females and healthy controls

BACKGROUND

Previous work indicates that emotive processing, such as of facial expressions, may be altered in major depressive disorder (MDD). Individuals with MDD tend to exhibit a mood-congruent processing bias, though MDD may also be characterized by blunted emotive processing in general. Females tend to exhibit enhanced facial emotive processing than males. Few groups have examined the temporal electrophysiological event-related potential (ERP)-indexed profiles, spanning preconscious to sustained, conscious processing of facial expressions in MDD; systematic comparisons of ERPs to emotive stimuli between depressed males and females are also lacking.

METHODS

This study examined the temporal ERP profile to a simple expression recognition task in depressed adult males and females (N=52; 29 females) and controls (N=43; 23 females).

RESULTS

The MDD group rated facial expressions as sadder overall than controls. Females exhibited enhanced and speeded pre- and conscious face processing than males. Subtle group differences emerged to specific expressions at mid-latency ERPs (N2, P2) indicating both blunted late pre-conscious perceptual processing of expressions and prolonged processing of intensely sad faces.

LIMITATIONS

A more involved emotive processing task, employing threatening faces, may have revealed more robust group ERP differences. Menstrual cycle should also be controlled for in future work.

CONCLUSIONS

This is the first study to systematically assess the temporal ERP profile, including of ERPs preceding the face-sensitive N170/VPP, to expressions in MDD. Overall, early perceptual and late conscious expression processing did not differ fundamentally between groups. Altered emotive processing may be a candidate index for monitoring and predicting antidepressant treatment outcome.

A review on sex differences in processing emotional signals

Interest in sex-related differences in psychological functioning has again come to the foreground with new findings about their possible functional basis in the brain. Sex differences may be one way how evolution has capitalized on the capacity of homologous brain regions to process social information between men and women differently. This paper focuses specifically on the effects of emotional valence, sex of the observed and sex of the observer on regional brain activations. We also discuss the effects of and interactions between environment, hormones, genes and structural differences of the brain in the context of differential brain activity patterns between men and women following exposure to seen expressions of emotion and in this context we outline a number of methodological considerations for future research. Importantly, results show that although women are better at recognizing emotions and express themselves more easily, men show greater responses to threatening cues (dominant, violent or aggressive) and this may reflect different behavioral response tendencies between men and women as well as evolutionary effects. We conclude that sex differences must not be ignored in affective research and more specifically in affective neuroscience.

Sex-related memory recall and talkativeness for emotional stimuli

Recent studies have evidenced an increasing interest in sex-related brain mechanisms and cerebral lateralization subserving emotional memory, language processing, and conversational behavior. We used event-related-potentials (ERP) to examine the influence of sex and hemisphere on brain responses to emotional stimuli. Given that the P300 component of ERP is considered a cognitive neuroelectric phenomenon, we compared left and right hemisphere P300 responses to emotional stimuli in men and women. As indexed by both amplitude and latency measures, emotional stimuli elicited more robust P300 effects in the left hemisphere in women than in men, while a stronger P300 component was elicited in the right hemisphere in men compared to women. Our findings show that the variables of sex and hemisphere interacted significantly to influence the strength of the P300 component to the emotional stimuli. Emotional stimuli were also best recalled when given a long-term, incidental memory test, a fact potentially related to the differential P300 waves at encoding. Moreover, taking into account the sex-related differences in language processing and conversational behavior, in the present study we evaluated possible talkativeness differences between the two genders in the recollection of emotional stimuli. Our data showed that women used a higher number of words, compared to men, to describe both arousal and neutral stories. Moreover, the present results support the view that sex differences in lateralization may not be a general feature of language processing but may be related to the specific condition, such as the emotional content of stimuli.

Boys do it the right way: sex-dependent amygdala lateralization during face processing in adolescents

Previous studies have observed a sex-dependent lateralization of amygdala activation related to emotional memory. Specifically, it was shown that the activity of the right amygdala correlates significantly stronger with memory for images judged as arousing in men than in women, and that there is a significantly stronger relationship in women than in men between activity of the left amygdala and memory for arousing images. Using a large sample of 235 male adolescents and 235 females matched for age and handedness, we investigated the sex-specific lateralization of amygdala activation during an emotional face perception fMRI task. Performing a formal sex by hemisphere analysis, we observed in males a significantly stronger right amygdala activation as compared to females. Our results indicate that adolescents display a sex-dependent lateralization of amygdala activation that is also present in basic processes of emotional perception. This finding suggests a sex-dependent development of human emotion processing and may further implicate possible etiological pathways for mental disorders most frequent in adolescent males (i.e., conduct disorder).

Gender differences in the neural correlates of humor processing: implications for different processing modes

Humor is a complex phenomenon of human social cognition with large inter-individual variability. Gender differences in emotion processing are a common finding in functional neuroimaging studies, and have been documented in behavioral studies of humor, but have received limited attention in functional neuroimaging studies on humor. Using blood oxygenation level dependent (BOLD) contrasts with high-field (3T) functional magnetic resonance imaging (fMR) we investigated 29 healthy subjects (14 female, 15 male) during the processing of humorous cartoons. In women, the ventral system implicated ín detection and appraisal of emotion was activated, including amygdala, insula, and Anterior Cingulate Cortex (ACC). Men showed activation in both the ventral and dorsal processing systems. The results indicate that women process humor though limbic reactivity, involving appraisal of its emotional features, while men apply more evaluative, executive resources to humor processing.

Gender affects body language reading

Body motion is a rich source of information for social cognition. However, gender effects in body language reading are largely unknown. Here we investigated whether, and, if so, how recognition of emotional expressions revealed by body motion is gender dependent. To this end, females and males were presented with point-light displays portraying knocking at a door performed with different emotional expressions. The findings show that gender affects accuracy rather than speed of body language reading. This effect, however, is modulated by emotional content of actions: males surpass in recognition accuracy of happy actions, whereas females tend to excel in recognition of hostile angry knocking. Advantage of women in recognition accuracy of neutral actions suggests that females are better tuned to the lack of emotional content in body actions. The study provides novel insights into understanding of gender effects in body language reading, and helps to shed light on gender vulnerability to neuropsychiatric and neurodevelopmental impairments in visual social cognition.

Toward emotion aware computing: an integrated approach using multichannel neurophysiological recordings and affective visual stimuli

This paper proposes a methodology for the robust classification of neurophysiological data into four emotional states collected during passive viewing of emotional evocative pictures selected from the International Affective Picture System. The proposed classification model is formed according to the current neuroscience trends, since it adopts the independency of two emotional dimensions, namely arousal and valence, as dictated by the bidirectional emotion theory, whereas it is gender-specific. A two-step classification procedure is proposed for the discrimination of emotional states between EEG signals evoked by pleasant and unpleasant stimuli, which also vary in their arousal/intensity levels. The first classification level involves the arousal discrimination. The valence discrimination is then performed. The Mahalanobis (MD) distance-based classifier and support vector machines (SVMs) were used for the discrimination of emotions. The achieved overall classification rates were 79.5% and 81.3% for the MD and SVM, respectively, significantly higher than in previous studies. The robust classification of objective emotional measures is the first step toward numerous applications within the sphere of human-computer interaction.

Are females more responsive to emotional stimuli? A neurophysiological study across arousal and valence dimensions

Men and women seem to process emotions and react to them differently. Yet, few neurophysiological studies have systematically investigated gender differences in emotional processing. Here, we studied gender differences using Event Related Potentials (ERPs) and Skin Conductance Responses (SCR) recorded from participants who passively viewed emotional pictures selected from the International Affective Picture System (IAPS). The arousal and valence dimension of the stimuli were manipulated orthogonally. The peak amplitude and peak latency of ERP components and SCR were analyzed separately, and the scalp topographies of significant ERP differences were documented. Females responded with enhanced negative components (N100 and N200), in comparison to males, especially to the unpleasant visual stimuli, whereas both genders responded faster to high arousing or unpleasant stimuli. Scalp topographies revealed more pronounced gender differences on central and left hemisphere areas. Our results suggest a difference in the way emotional stimuli are processed by genders: unpleasant and high arousing stimuli evoke greater ERP amplitudes in women relatively to men. It also seems that unpleasant or high arousing stimuli are temporally prioritized during visual processing by both genders.

Sex influences on the neurobiology of learning and memory

In essentially every domain of neuroscience, the generally implicit assumption that few, if any, meaningful differences exist between male and female brain function is being challenged. Here we address how this development is influencing studies of the neurobiology of learning and memory. While it has been commonly held that males show an advantage on spatial tasks, and females on verbal tasks, there is increasing evidence that sex differences are more widespread than previously supposed. Differing performance between the sexes have been observed on a number of common learning tasks in both the human and animal literature, many neither purely spatial nor verbal. We review sex differences reported in various areas to date, while attempting to identify common features of sexually dimorphic tasks, and to place these differences in a neurobiological context. This discussion focuses on studies of four classes of memory tasks for which sex differences have been frequently reported: spatial, verbal, autobiographical, and emotional memory. We conclude that the female verbal advantage extends into numerous tasks, including tests of spatial and autobiographical abilities, but that a small but significant advantage may exist for general episodic memory. We further suggest that for some tasks, stress evokes sex differences, which are not normally observed, and that these differences are mediated largely by interactions between stress and sex hormones.

Imaging stress effects on memory: a review of neuroimaging studies

OBJECTIVE

To review and give an overview of neuroimaging studies that look at the role of stress (hormones) on memory.

METHOD

An overview will be given of imaging studies that looked at the role of stress (hormones) on memory. Stress is here defined as the acute provocation of the sympathetic adrenal medullar system and the hypothalamic-pituitary-adrenal axis in experimental designs. Stress hormone levels can be raised endogenously in response to stimulus material (for example, pictures and films) or social evaluative threat situations (stress tasks). Other studies use the exogenous application of drugs to enhance or decrease stress hormone levels. Finally, we review studies on chronic stress and memory.

RESULTS

Stress or emotional arousal, leading to increased noradrenaline or cortisol levels, led to better memory performance when it is applied during perception or encoding. Brain regions involved in this process were medial temporal lobe regions such as amygdala and hippocampus, and several parts of the prefrontal cortex (PFC). High stress levels accompanied by high cortisol levels during retrieval led to impaired memory performance. Sex effects on memory as well as lateralization effects on brain activation were found.

CONCLUSION

High stress levels during encoding and consolidation of emotional material involve increased amygdala and hippocampus activation. The role of the anterior cingulate cortex and other parts of the PFC during perception and encoding of arousing material appears to be a modulating one. However, additional research is needed to shed more light on the nature of the brain changes during stress, especially during retrieval.