Human moral decision-making through the lens of Parkinson's disease

Acute lorazepam administration does not significantly affect moral attitudes or judgments

Recent scientific studies exploring the neuropsychological foundations of moral decision-making have shown that moral attitudes and evaluations are significantly influenced by emotion, particularly negative emotionality, as well as personality traits such as neuroticism. Further psychopharmacological research has observed that GABAergic agonists are capable of influencing moral decision-making by modifying anxiety-related emotional negativity and/or through cognitive modulation. The aim of this double-blind, crossover design, placebo-controlled study is to evaluate said GABAergic modulation on moral cognition. Importantly, unlike the aforementioned research, the present study not only utilizes explicit moral evaluation measures [e.g., the Justice Sensitivity Inventory (JSI) and evaluations of moral scenarios], but also uses the morality Implicit Association Test (mIAT) to assess unacknowledged attitudes towards morally charged scenarios. Our results indicate that acute lorazepam administration does not significantly alter moral judgments, including implicit moral attitudes, explicit justice sensitivity, and blame/praise evaluations. Lorazepam-induced changes in moral sensitivity appeared to vary with baseline levels, with individuals exhibiting higher baseline JSI or D scores tending to show greater reductions following administration. These findings support the involvement of GABAergic modulation in moral cognition, albeit without clear behavioral consequences.

Oxytocin, but not vasopressin, decreases willingness to harm others by promoting moral emotions of guilt and shame

Prosocial and moral behaviors have overlapping neural systems and can both be affected in a number of psychiatric disorders, although whether they involve similar neurochemical systems is unclear. In the current registered randomized placebo-controlled trial on 180 adult male and female subjects, we investigated the effects of intranasal administration of oxytocin and vasopressin, which play key roles in influencing social behavior, on moral emotion ratings for situations involving harming others and on judgments of moral dilemmas where others are harmed for a greater good. Oxytocin, but not vasopressin, enhanced feelings of guilt and shame for intentional but not accidental harm and reduced endorsement of intentionally harming others to achieve a greater good. Neither peptide influenced arousal ratings for the scenarios. Effects of oxytocin on guilt and shame were strongest in individuals scoring lower on the personal distress subscale of trait empathy. Overall, findings demonstrate for the first time that oxytocin, but not vasopressin, promotes enhanced feelings of guilt and shame and unwillingness to harm others irrespective of the consequences. This may reflect associations between oxytocin and empathy and vasopressin with aggression and suggests that oxytocin may have greater therapeutic potential for disorders with atypical social and moral behavior.

Genomic analysis of intracranial and subcortical brain volumes yields polygenic scores accounting for variation across ancestries

Subcortical brain structures are involved in developmental, psychiatric and neurological disorders. We performed GWAS meta-analyses of intracranial and nine subcortical brain volumes (brainstem, caudate nucleus, putamen, hippocampus, globus pallidus, thalamus, nucleus accumbens, amygdala and, for the first time, the ventral diencephalon) in 74,898 participants of European ancestry. We identified 254 independent loci associated with these brain volumes, explaining up to 35% of phenotypic variance. We observed gene expression in specific neural cell types across differentiation time points, including genes involved in intracellular signalling and brain ageing-related processes. Polygenic scores for brain volumes showed predictive ability when applied to individuals of diverse ancestries. We observed causal genetic effects of brain volumes with Parkinson's disease and ADHD. Findings implicate specific gene expression patterns in brain development and genetic variants in comorbid neuropsychiatric disorders, which could point to a brain substrate and region of action for risk genes implicated in brain diseases.

Mouse Model of Parkinson's Disease with Bilateral Dorsal Striatum Lesion with 6-Hydroxydopamine Exhibits Cognitive Apathy-like Behavior

Among the symptoms of Parkinson's disease (PD), apathy comprises a set of behavioral, affective, and cognitive features that can be classified into several subtypes. However, the pathophysiology and brain regions that are involved in these different apathy subtypes are still poorly characterized. We examined which subtype of apathy is elicited in a mouse model of PD with 6-hydroxydopamine (6-OHDA) lesions and the behavioral symptoms that are exhibited. Male C57/BL6J mice were allocated to sham (n = 8) and 6-OHDA (n = 13) groups and locally injected with saline or 4 µg 6-OHDA bilaterally in the dorsal striatum. We then conducted motor performance tests and apathy-related behavioral experiments. We then pathologically evaluated tyrosine hydroxylase (TH) immunostaining. The 6-OHDA group exhibited significant impairments in motor function. In the behavioral tests of apathy, significant differences were observed between the sham and 6-OHDA groups in the hole-board test and novelty-suppressed feeding test. The 6-OHDA group exhibited impairments in inanimate novel object preference, whereas social preference was maintained in the three-chamber test. The number of TH+ pixels in the caudate putamen and substantia nigra compacta was significantly reduced in the 6-OHDA group. The present mouse model of PD predominantly showed dorsal striatum dopaminergic neuronal loss and a decrease in novelty seeking as a symptom that is related to the cognitive apathy component.

Pulling the lever in a hurry: the influence of impulsivity and sensitivity to reward on moral decision-making under time pressure

BACKGROUND

Making timely moral decisions can save a life. However, literature on how moral decisions are made under time pressure reports conflicting results. Moreover, it is unclear whether and how moral choices under time pressure may be influenced by personality traits like impulsivity and sensitivity to reward and punishment.

METHODS

To address these gaps, in this study we employed a moral dilemma task, manipulating decision time between participants: one group (N = 25) was subjected to time pressure (TP), with 8 s maximum time for response (including the reading time), the other (N = 28) was left free to take all the time to respond (noTP). We measured type of choice (utilitarian vs. non-utilitarian), decision times, self-reported unpleasantness and arousal during decision-making, and participants' impulsivity and BIS-BAS sensitivity.

RESULTS

We found no group effect on the type of choice, suggesting that time pressure per se did not influence moral decisions. However, impulsivity affected the impact of time pressure, in that individuals with higher cognitive instability showed slower response times under no time constraint. In addition, higher sensitivity to reward predicted a higher proportion of utilitarian choices regardless of the time available for decision.

CONCLUSIONS

Results are discussed within the dual-process theory of moral judgement, revealing that the impact of time pressure on moral decision-making might be more complex and multifaceted than expected, potentially interacting with a specific facet of attentional impulsivity.

Predictive cues elicit a liminal confirmation bias in the moral evaluation of real-world images

Previous research suggested that predictive cues enhance the preference and reduce the response time for congruent targets during bivalent food evaluation, indicating a confirmation bias. Less is known about how prior processing affects subjective moral evaluation. Here, we used three different types of predictive cues to elicit directional vs. non-predictive prior processing and then asked the participants to perform moral evaluations on a continuous scale from -10 ("very immoral") to +10 ("very moral") with a diverse set of real-world images. Our experimental image database balanced the morality of image content and the volatility of the ratings based on the means and standard deviations in a preliminary study. Ratings, response times, and gaze positions were measured to examine the effects of predictive cues on the moral evaluation of real-world images. We found that the moral ratings were in line with the expectations induced by the cues. Compared to the non-predictive condition, the moral evaluation in the directional conditions was more polarized. For neutral images, the predictive cues tilted the evaluations to positive vs. negative, indicating a decisive liminal influence. High-volatility images were impacted more than low-volatility images in ratings as well as response times. Furthermore, the gaze positions during the interval between the predictive cue and the image showed a spatial displacement in line with the cue instruction, indicating a response bias. Together, the results show that predictive cues elicit a liminal confirmation bias in moral image evaluation, much in the same way as in bivalent food evaluation.

Decision-making under ambiguity and risk and executive functions in Parkinson's disease patients: A scoping review of the studies investigating the Iowa Gambling Task and the Game of Dice

Evidence shows that patients affected by Parkinson's disease (PD) display the tendency toward making risky choices. This is due, at least in part, to the pathophysiological characteristics of the disease that affects neural areas underlying decision making (DM), in which a pivotal role is played by nonmotor corticostriatal circuits and dopamine. Executive functions (EFs), which can be impaired by PD as well, may sustain optimal choices in DM processes. However, few studies have investigated whether EFs can support PD patients to make good decisions. Adopting the scoping review approach, the present article is designed to deepen the cognitive mechanisms of DM under conditions of ambiguity and risk (that are conditions common to everyday life decisions) in PD patients without impulse control disorders. We focused our attention on the Iowa Gambling Task and the Game of Dice Task, because they are the most commonly used and reliable tasks to assess DM under ambiguity and under risk, respectively, and analyzed the performances in such tasks and their relationships with EFs tests in PD patients. The analysis supported the relationships between EFs and DM performance, especially when a higher cognitive load is required to make optimal decisions, as it happens under conditions of risk. Possible knowledge gaps and further research directions are suggested to better understand DM mechanisms in PD sustaining patients' cognitive functioning and preventing negative consequences in everyday life derived from suboptimal decisions.

Neuroinflammation in Parkinson's Disease: From Gene to Clinic: A Systematic Review

Parkinson's disease is a neurodegenerative disease whose progression and clinical characteristics have a close bidirectional and multilevel relationship with the process of neuroinflammation. In this context, it is necessary to understand the mechanisms involved in this neuroinflammation-PD link. This systematic search was, hereby, conducted with a focus on the four levels where alterations associated with neuroinflammation in PD have been described (genetic, cellular, histopathological and clinical-behavioral) by consulting the PubMed, Google Scholar, Scielo and Redalyc search engines, including clinical studies, review articles, book chapters and case studies. Initially, 585,772 articles were included, and, after applying the inclusion and exclusion criteria, 84 articles were obtained that contained information about the multilevel association of neuroinflammation with alterations in gene, molecular, cellular, tissue and neuroanatomical expression as well as clinical-behavioral manifestations in PD.

Neural correlates of overvaluation and the effort to save possessions in a novel decision task: An exploratory fMRI study

Introduction

People exhibit a strong attachment to possessions, observed in behavioral economics through loss aversion using new items in the Endowment or IKEA effects and in clinical psychology through pathological trouble discarding domestic items in Hoarding Disorder. These fields rarely intersect, but both document a reticence to relinquish a possessed item, even at a cost, which is associated with feelings of loss but can include enhanced positive states as well.

Methods

To demonstrate the shared properties of these loss-related ownership effects, we developed the Pretzel Decorating Task (PDT), which concurrently measures overvaluation of one's own over others' items and feelings of loss associated with losing a possession, alongside enhanced positive appraisals of one's items and an effort to save them. The PDT was piloted with 31 participants who decorated pretzels and responded to their own or others' items during functional neuroimaging (fMRI). Participants observed one item per trial (self or other) and could work to save it (high or low probability loss) before learning the fate of the item (trashed or saved). Finally, participants rated items and completed hoarding tendency scales.

Results

The hypotheses were supported, as even non-clinical participants overvalued, viewed as nicer, feared losing, and worked harder to save their items over others'-a response that correlated with hoarding tendencies and motor-motivational brain activation. Our region of interest in the nucleus accumbens (NAcc) was engaged when viewing one's own items to the extent that people worked harder to save them and was more active when their items were saved when they felt emotionally attached to possessions in real life. When their items were trashed, NAcc activity negatively correlated with trouble discarding and emotional attachments to possessions. Right anterior insula was more active when working to save one's own over others' items. Extensive motor-motivational areas were engaged when working to save one's own over others' items, including cerebellum, primary motor and somatosensory regions, and retrosplenial/parahippocampal regions-even after controlling for tapping.

Discussion

Our attachments to items are emotional, continuous across typical and pathological populations, and drive us to save possessions that we value.

Disgust as a transdiagnostic index of mental illness: A narrative review of clinical populations

Disgust is a basic emotion of rejection, providing an ancestral defensive mechanism against illness. Based on research that documents altered experiences of disgust across several psychopathological conditions, we conducted a narrative review to address the hypothesis that altered disgust may serve as a transdiagnostic index of mental illness. Our synthesis of the literature from past decades suggests that, compared to healthy populations, patients with mental disorders exhibit abnormal processing of disgust in at least one of the analyzed dimensions. We also outline evidence of alterations in brain areas relevant to disgust processing, such as the insula and the interconnected limbic network. Overall, we provide preliminary support for the hypothesis that altered disgust processing may serve as a transdiagnostic index of mental illness.

The impact of mindfulness meditation on social and moral behavior: Does mindfulness enhance other-oriented motivation or decrease monetary reward salience?

This perspective article provides an overview of the impact of mindfulness meditation (MM) on social and moral behavior. In mindfulness research, prosocial behavior has been operationalized as helping behavior, altruistic redistribution of funds, reparative behavior, or monetary donation. Studies concerning moral behavior are still scarce. Despite inconsistent evidence, several studies found a beneficial effect of mindfulness on prosocial outcomes (i.e., a higher propensity to spend or give away money for the sake of other individuals). However, since the employed tasks were reward-based, participants’ decisions also directly affected their own payoff by reducing it. Crucially, MM also affects self-control circuitry and reduces reward-seeking behaviors and reward salience by making rewards less tempting. We have discussed evidence suggesting how challenging it may be to dissociate the specific weight of enhanced other-oriented motivation from one of the decreased monetary reward salience in explaining meditators’ behavior. Future higher-quality studies are needed to address this open issue.

Morality in the flesh: on the link between bodily self-consciousness, moral identity and (dis)honest behaviour

The sense of owning a body (ownership) and controlling its actions (agency) are two main pillars of bodily self-consciousness (BSC). Although studies suggest that BSC signals and morality may be associated, whether such association has a positive or negative direction remains unclear. To investigate this issue, we conducted two pre-registered, online studies, in which a total of 1309 participants completed BSC- and morality-related questionnaires and undertook a task where they could cheat for monetary gain. We found that participants with high sense of ownership displayed high moral identity, which supports the notion that ownership is used to associate the self with positive characteristics. Moreover, high agency was associated with increased moral identity when sense of power is high. Results regarding deception are less clear, and might relate to the impact of COVID-19. Our results concerning moral identity may inspire policies that rely on changes of corporeal awareness to contrast immorality.

Morality in the flesh: on the link between bodily self-consciousness, moral identity and (dis)honest behaviour

The sense of owning a body (ownership) and controlling its actions (agency) are two main pillars of bodily self-consciousness (BSC). Although studies suggest that BSC signals and morality may be associated, whether such association has a positive or negative direction remains unclear. To investigate this issue, we conducted two pre-registered, online studies, in which a total of 1309 participants completed BSC- and morality-related questionnaires and undertook a task where they could cheat for monetary gain. We found that participants with high sense of ownership displayed high moral identity, which supports the notion that ownership is used to associate the self with positive characteristics. Moreover, high agency was associated with increased moral identity when sense of power is high. Results regarding deception are less clear, and might relate to the impact of COVID-19. Our results concerning moral identity may inspire policies that rely on changes of corporeal awareness to contrast immorality.

Morality in the flesh: on the link between bodily self-consciousness, moral identity and (dis)honest behaviour

The sense of owning a body (ownership) and controlling its actions (agency) are two main pillars of bodily self-consciousness (BSC). Although studies suggest that BSC signals and morality may be associated, whether such association has a positive or negative direction remains unclear. To investigate this issue, we conducted two pre-registered, online studies, in which a total of 1309 participants completed BSC- and morality-related questionnaires and undertook a task where they could cheat for monetary gain. We found that participants with high sense of ownership displayed high moral identity, which supports the notion that ownership is used to associate the self with positive characteristics. Moreover, high agency was associated with increased moral identity when sense of power is high. Results regarding deception are less clear, and might relate to the impact of COVID-19. Our results concerning moral identity may inspire policies that rely on changes of corporeal awareness to contrast immorality.