Sex-related functional asymmetry of the ventromedial prefrontal cortex in regard to decision-making under risk and ambiguity

The comparison of decision-making in ambiguous situations and galvanic skin responses as somatic markers in patients with posterior cortex epilepsy and mesial temporal lobe epilepsy with hippocampal sclerosis

INTRODUCTION

Decision-making behaviors of patients with mesial temporal lobe epilepsy (MTLE) is a subject that has been studied frequently. However, determining the neuropsychological profiles of patients with different types of epilepsy is also important. Our main purpose was to examine the decision-making behaviors of patients with posterior cortex epilepsy (PCE) through the assumptions of somatic marker hypothesis (SMH) and to compare their performances with those of a MTLE group and a control group.

METHOD

Participants comprised of 13 patients with PCE (mean age 30.92 ± 9.99 years); 14 patients with MTLE with hippocampal sclerosis (MTLE-HS) (mean age 25.53 ± 7.40 years) and 15 controls (mean age 24.60 ± 8.45 years). Decision-making performances were assessed with the Iowa gambling test (IGT) and anticipatory skin responses before each choice were recorded. A comprehensive neuropsychological test battery was also given to all participants in order to examine the relationship of decision-making with other cognitive functions.

RESULTS

Anticipatory responses before choosing from disadvantageous decks were significantly larger than choosing from advantageous decks in the PCE group (p = 0.00). No significant difference was found between the PCE and control group's total net scores. IGT total net scores was significantly correlated with Stroop test interference time (p = 0.03).

CONCLUSION

The study reveals that cognitive impairments of patients with PCE are not limited to brain's posterior areas' functions, and provides evidence for the current paradigm which understands epilepsy as a network disorder.

Functional Connectivity Basis and Underlying Cognitive Mechanisms for Gender Differences in Guilt Aversion

Prosocial behavior is pivotal to our society. Guilt aversion, which describes the tendency to reduce the discrepancy between a partner's expectation and his/her actual outcome, drives human prosocial behavior as does well-known inequity aversion. Although women are reported to be more inequity averse than men, gender differences in guilt aversion remain unexplored. Here, we conducted a functional magnetic resonance imaging (fMRI) study (n = 52) and a large-scale online behavioral study (n = 4723) of a trust game designed to investigate guilt and inequity aversions. The fMRI study demonstrated that men exhibited stronger guilt aversion and recruited right dorsolateral prefrontal cortex (DLPFC)-ventromedial PFC (VMPFC) connectivity more for guilt aversion than women, while VMPFC-dorsal medial PFC (DMPFC) connectivity was commonly used in both genders. Furthermore, our regression analysis of the online behavioral data collected with Big Five and demographic factors replicated the gender differences and revealed that Big Five Conscientiousness (rule-based decision) correlated with guilt aversion only in men, but Agreeableness (empathetic consideration) correlated with guilt aversion in both genders. Thus, this study suggests that gender differences in prosocial behavior are heterogeneous depending on underlying motives in the brain and that the consideration of social norms plays a key role in the stronger guilt aversion in men.

Molecular laterality encodes stress susceptibility in the medial prefrontal cortex

Functional lateralization of the prefrontal cortex has been implicated in stress and emotional disorders, yet underlying gene expression changes remains unknown. Here, we report molecular signatures lateralized by chronic social defeats between the two medial prefrontal cortices (mPFCs). Stressed mice show 526 asymmetrically expressed genes between the mPFCs. This cortical asymmetry selectively occurs in stressed mice with depressed social activity, but not in resilient mice with normal behavior. We have isolated highly asymmetric genes including connective tissue growth factor (CTGF), a molecule that modulates wound healing at the periphery. Knockdown of CTGF gene in the right mPFC by shRNA led to a stress-resistant behavioral phenotype. Overexpression of CTGF in the right mPFC using viral transduction induces social avoidance while the left mPFC thereof prevent stress-induced social avoidance. Our study provides a molecular window into the mechanism of stress-induced socioemotional disorders, which can pave the way for new interventions by targeting cortical asymmetry.

Influence of ovarian hormones on value-based decision-making systems: Contribution to sexual dimorphisms in mental disorders

Women and men exhibit differences in behavior when making value-based decisions. Various hypotheses have been proposed to explain these findings, stressing differences in functional lateralization of the brain, functional activation, neurotransmitter involvement and more recently, sex hormones. While a significant interaction of neurotransmitter systems and sex hormones has been shown for both sexes, decision-making in women might be particularly affected by variations of ovarian hormones. In this review we have gathered information from animal and human studies on how ovarian hormones affect decision-making processes in females by interacting with neurotransmitter systems at functionally relevant brain locations and thus modify the computation of decision aspects. We also review previous findings on impaired decision-making in animals and clinical populations with substance use disorder and depression, emphasizing how little we know about the role of ovarian hormones in aberrant decision-making.

Risk-taking bias in human decision-making is encoded via a right-left brain push-pull system

A person's decisions vary even when options stay the same, like when a gambler changes bets despite constant odds of winning. Internal bias (e.g., emotion) contributes to this variability and is shaped by past outcomes, yet its neurobiology during decision-making is not well understood. To map neural circuits encoding bias, we administered a gambling task to 10 participants implanted with intracerebral depth electrodes in cortical and subcortical structures. We predicted the variability in betting behavior within and across patients by individual bias, which is estimated through a dynamical model of choice. Our analysis further revealed that high-frequency activity increased in the right hemisphere when participants were biased toward risky bets, while it increased in the left hemisphere when participants were biased away from risky bets. Our findings provide electrophysiological evidence that risk-taking bias is a lateralized push-pull neural system governing counterintuitive and highly variable decision-making in humans.

Let's call the whole thing off: evaluating gender and sex differences in executive function

The executive functions allow for purposeful, deliberate, and intentional interactions with the world-attention and focus, impulse control, decision making, and working memory. These measures have been correlated with academic outcomes and quality of life, and are impacted by deleterious environmental events throughout the life span, including gestational and early life insults. This review will address the topic of sex differences in executive function including a discussion of differences arising in response to developmental programming. Work on gender differences in human studies and sex differences in animal research will be reviewed. Overall, we find little support for significant gender or sex differences in executive function. An important variable that factors into the interpretation of potential sex differences include differing developmental trajectories. We conclude by discussing future directions for the field and a brief discussion of biological mechanisms.

Contributions of medial prefrontal cortex to decision making involving risk of punishment

The prefrontal cortex (PFC) plays an important role in several forms of cost-benefit decision making. Its contributions to decision making under risk of explicit punishment, however, are not well understood. A rat model was used to investigate the role of the medial PFC (mPFC) and its monoaminergic innervation in a Risky Decision-making Task (RDT), in which rats chose between a small, "safe" food reward and a large, "risky" food reward accompanied by varying probabilities of mild footshock punishment. Inactivation of mPFC increased choice of the large, risky reward when the punishment probability increased across the session ("ascending RDT"), but decreased choice of the large, risky reward when the punishment probability decreased across the session ("descending RDT"). In contrast, enhancement of monoamine availability via intra-mPFC amphetamine reduced choice of the large, risky reward only in the descending RDT. Systemic administration of amphetamine reduced choice of the large, risky reward in both the ascending and descending RDT; however, this reduction was not attenuated by concurrent mPFC inactivation, indicating that mPFC is not a critical locus of amphetamine's effects on risk taking. These findings suggest that mPFC plays an important role in adapting choice behavior in response to shifting risk contingencies, but not necessarily in risk-taking behavior per se.

Sex differences in the functional lateralization of emotion and decision making in the human brain

Dating back to the case of Phineas Gage, decades of neuropsychological research have shown that the ventromedial prefrontal cortex (vmPFC) is crucial to both real-world social functioning and abstract decision making in the laboratory (see, e.g., Stuss et al., ; Bechara et al., 1994; Damasio et al., ). Previous research has shown that the relationship between the laterality of individuals' vmPFC lesions and neuropsychological performance is moderated by their sex, whereby there are more severe social, emotional, and decision-making impairments in men with right-side vmPFC lesions and in women with left-side vmPFC lesions (Tranel et al., 2005; Sutterer et al., 2015). We conducted a selective review of studies examining the effect of vmPFC lesions on emotion and decision making and found further evidence of sex-related differences in the lateralization of function not only in the vmPFC but also in other neurological structures associated with decision making and emotion. This Mini-Review suggests that both sex and laterality effects warrant more careful consideration in the scientific literature. © 2016 Wiley Periodicals, Inc.

Human lesion studies of ventromedial prefrontal cortex

Studies of neurological patients with focal lesions involving ventromedial prefrontal cortex (vmPFC) have demonstrated a critical role for this brain area in various aspects of cognition, emotion, and behavior. In this article, we review the key themes, methods, and findings from neuropsychological research on vmPFC lesion patients. Early case studies demonstrated profound disruptions in personality and behavior following vmPFC damage, including blunted affect, poor decision-making, and inappropriate social behavior. Subsequent laboratory investigations with groups of vmPFC lesion patients have revealed deficits in a host of interrelated functions, such as value-based decision-making, future and counterfactual thinking, physiological arousal to emotional stimuli, emotion recognition, empathy, moral judgment, and memory confabulation. The compendium of findings described here demonstrates that vmPFC is crucial for diverse aspects of adaptive function.

Sex and HIV serostatus differences in decision making under risk among substance-dependent individuals

HIV+ individuals with and without substance use disorders make significantly poorer decisions when information about the probability and magnitude of wins and losses is not available. We administered the Game of Dice Task, a measure of decision making under risk that provides this information explicitly, to 92 HIV+ and 134 HIV- substance-dependent men and women. HIV+ participants made significantly poorer decisions than HIV- participants, but this deficit appeared more prominent among HIV+ women. These data indicate that decision making under risk is impaired among HIV+ substance-dependent individuals (SDIs). Potential factors for the HIV+ women's relatively greater impairment are discussed.

Sex-Differences, Handedness, and Lateralization in the Iowa Gambling Task

In a widely used decision-making task, the Iowa Gambling Task (IGT), male performance is observed to be superior to that of females, and is attributed to right lateralization (i.e., right hemispheric dominance). It is as yet unknown whether sex-differences in affect and motor lateralization have implications for sex-specific lateralization in the IGT, and specifically, whether sex-difference in performance in the IGT changes with right-handedness or with affect lateralization (decision valence, and valence-directed motivation). The present study (N = 320; 160 males) examined the effects of right-handedness (right-handedness vs. non-right-handedness) as a measure of motor lateralization, decision valence (reward vs. punishment IGT), and valence-directedness of task motivation (valence-directed vs. non-directed instructions), as measures of affective lateralization on IGT decision making. Analyses of variance revealed that both male and female participants showed valence-induced inconsistencies in advantageous decision-making; however, right-handed females made more disadvantageous decisions in a reward IGT. These results suggest that IGT decision-making may be largely right-lateralized in right-handed males, and show that sex and lateralized differences (motor and affect) have implications for sex-differences in IGT decision-making. Implications of the results are discussed with reference to lateralization and sex-differences in cognition.