Pleasant Stimuli Research Articles

Disrupted basolateral amygdala circuits supports negative valence bias in depressive states

Negative bias is an essential characteristic of depressive episodes leading patients to attribute more negative valence to environmental cues. This negative bias affects all levels of information processing including emotional response, attention and memory, leading to the development and maintenance of depressive symptoms. In this context, pleasant stimuli become less attractive and unpleasant ones more aversive, yet the related neural circuits underlying this bias remain largely unknown. By studying a mice model for depression chronically receiving corticosterone (CORT), we showed a negative bias in valence attribution to olfactory stimuli that responds to antidepressant drug. This result paralleled the alterations in odor value assignment we observed in bipolar depressed patients. Given the crucial role of amygdala in valence coding and its strong link with depression, we hypothesized that basolateral amygdala (BLA) circuits alterations might support negative shift associated with depressive states. Contrary to humans, where limits in spatial resolution of imaging tools impair easy amygdala segmentation, recently unravelled specific BLA circuits implicated in negative and positive valence attribution could be studied in mice. Combining CTB and rabies-based tracing with ex vivo measurements of neuronal activity, we demonstrated that negative valence bias is supported by disrupted activity of specific BLA circuits during depressive states. Chronic CORT administration induced decreased recruitment of BLA-to-NAc neurons preferentially involved in positive valence encoding, while increasing recruitment of BLA-to-CeA neurons preferentially involved in negative valence encoding. Importantly, this dysfunction was dampened by chemogenetic hyperactivation of BLA-to-NAc neurons. Moreover, altered BLA activity correlated with durable presynaptic connectivity changes coming from the paraventricular nucleus of the thalamus, recently demonstrated as orchestrating valence assignment in the amygdala. Together, our findings suggest that specific BLA circuits alterations might support negative bias in depressive states and provide new avenues for translational research to understand the mechanisms underlying depression and treatment efficacy.

Disentangling inhibition toward food and non-food stimuli across two hunger levels: An fNIRS study

While individuals tend to display poorer inhibitory control toward food-related than neutral stimuli, it is unclear whether this challenge is specific to food or extends to other pleasant stimuli. Uncertainty also remains regarding the general impact of hunger on inhibition. To address these questions, we used a within-subjects design whereby 44 healthy adults completed two go/no-go tasks including no-go images of highly palatable foods and no-go images of animals matched for valence and physical properties. Both tasks were completed one week apart in either a fed or a fasted state. Prefrontal cortex activity was measured using functional near-infrared spectroscopy. Poorer behavioral inhibition was observed when participants needed to withhold their response to images of food compared to animals, regardless of hunger state. In addition, more commission errors were made in the fasted compared to the fed condition, regardless of the type of image to avoid responding to. Responses to go trials were slower when these trials were interspersed with food compared to animal no-go trials. However, hunger did not influence go response time. Greater activation was observed in the dorsolateral prefrontal cortex during blocks of trials with (vs. without) no-go images, but brain activity did not differ according to the type of no-go image. The effect of hunger on prefrontal brain activity was also not significant. Exploratory correlations showed that food-related inhibition deficits were positively related to self-reported impulsivity, but unrelated to body mass index. This study suggests that even among healthy adults, food-related inhibitory control may have a unique behavioral signature beyond general inhibition toward pleasant stimuli. Hunger also exerts an independent influence on general inhibitory capabilities, highlighting the importance of carefully controlling hunger levels in inhibition studies.

Dementia Care Nursing for Apathetic Older Patients: A Qualitative Study.

The number of patients hospitalized with dementia is increasing, but one symptom, apathy, tends to be overlooked and unaddressed. Thus, this study determines how nurses certified in dementia nursing engage with older patients with dementia who exhibit apathy during hospitalization. A qualitative study using semi-structured interviews with 10 dementia care nurses in Japan was conducted. Through conventional content analysis, 10 categories were generated. They included (1) initiating patient engagement when their physiological or daily-life problems become more pronounced, (2) assessing and identifying the causes of decreased motivation from multiple perspectives, (3) assessing patients from multiple perspectives to determine the best way to start supporting them, (4) providing reassurance through basic dementia care, (5) incorporating pleasant stimuli into the hospital environment, (6) providing care based on patients' circumstances and abilities by collaborating with multiple professionals. Nurses initiate involvement with patients when their daily life problems become more pronounced. They conduct comprehensive assessments from multiple perspectives and collaborate with other professionals to ensure patient care and safety. They also extend their support to patients' families and maintain long-term involvement. Apathetic older patients benefit from basic nursing care practices and a patient-centered approach, which do not require specialization or additional costs and resources.

Altered pattern of theta and gamma oscillation to visual stimuli in patients with postconcussion syndrome.

Although many patients with mild traumatic brain injury (mTBI) suffer from postconcussional syndrome (PCS) including abnormal emotional responses, most conventional imaging studies fail to detect any causative brain lesion. We hypothesized that event-related electroencephalography (EEG) recordings with time-frequency analysis would show a distinguishable pattern in patients with mTBI with PCS compared with normal healthy controls. EEG signals were collected from a total of 18 subjects: eight patients with mTBI with PCS and 10 healthy control subjects. The signals were recorded while the subjects were presented with affective visual stimuli, including neutral, pleasant, and unpleasant emotional cues. Event-related spectral perturbation analysis was performed to calculate frontal midline theta activity and posterior midline gamma activity, followed by statistical analysis to identify whether patients with mTBI with PCS have distinct patterns of theta or gamma oscillations in response to affective stimuli. Compared with the healthy control group, patients with mTBI with PCS did not show a significant increase in the power of frontal theta activity in response to the pleasant stimuli, indicating less susceptibility toward pleasant cues. Moreover, the patient group showed attenuated gamma oscillatory activity, with no clear alteration in gamma oscillations in response to either pleasant or unpleasant cues. This study demonstrates that patients with mTBI with PCS exhibited altered patterns of oscillatory activities in the theta and gamma bands in response to affective visual stimuli compared with the normal control group. The current finding implicates that these distinguishable patterns of brain oscillation may represent the mechanism behind various psychiatric symptoms in patients with mTBI.NEW & NOTEWORTHY Patients with mild traumatic brain injury (mTBI) with postconcussional syndrome (PCS) exhibited altered patterns of changes in oscillatory activities in the theta and gamma bands in response to visual affective stimuli. Distinguishable patterns of brain oscillation may represent the mechanism behind various psychiatric symptoms in patients with mTBI.

Anhedonia reflects an encoding deficit for pleasant stimuli in schizophrenia: Evidence from the emotion-induced memory trade-off eye-tracking paradigm.

The present study explored the hypothesis that anhedonia reflects an emotional memory impairment for pleasant stimuli, rather than diminished hedonic capacity in individuals with schizophrenia (SZ). Participants included 30 SZ and 30 healthy controls (HCs) subjects who completed an eye-tracking emotion-induced memory trade-off task where contextually relevant pleasant, unpleasant, or neutral items were inserted into the foreground of neutral background scenes. Passive viewing and poststimulus elaboration blocks were administered to assess differential encoding mechanisms, and immediate and 1-week recognition testing phases were completed to assess the effects of delay interval. Participants also made self-reports of positive emotion, negative emotion, and arousal in response to the stimuli. Results indicated that SZ experienced stimuli similarly to HC. Both groups demonstrated the typical emotion-induced memory trade-off during the passive viewing and poststimulus elaboration encoding blocks, as indicated by more hits for emotional than neutral items and fewer hits for backgrounds paired with emotional than neutral items. Eye-tracking data also indicated that both groups were more likely to fixate earlier and have longer dwell time on emotional than neutral items. At the 1-week delay, the emotion-induced memory trade-off was eliminated in both groups, and SZ showed fewer overall hits across valence conditions. Greater severity of anhedonia was specifically associated with impaired recognition for pleasant stimuli at the immediate recognition phase. Findings suggest that anhedonia in SZ is associated with emotional memory impairment, particularly a deficit in encoding positive stimuli. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Exploring Aesthetic Perception in Impaired Aging: A Multimodal Brain-Computer Interface Study.

In the field of neuroscience, brain-computer interfaces (BCIs) are used to connect the human brain with external devices, providing insights into the neural mechanisms underlying cognitive processes, including aesthetic perception. Non-invasive BCIs, such as EEG and fNIRS, are critical for studying central nervous system activity and understanding how individuals with cognitive deficits process and respond to aesthetic stimuli. This study assessed twenty participants who were divided into control and impaired aging (AI) groups based on MMSE scores. EEG and fNIRS were used to measure their neurophysiological responses to aesthetic stimuli that varied in pleasantness and dynamism. Significant differences were identified between the groups in P300 amplitude and late positive potential (LPP), with controls showing greater reactivity. AI subjects showed an increase in oxyhemoglobin in response to pleasurable stimuli, suggesting hemodynamic compensation. This study highlights the effectiveness of multimodal BCIs in identifying the neural basis of aesthetic appreciation and impaired aging. Despite its limitations, such as sample size and the subjective nature of aesthetic appreciation, this research lays the groundwork for cognitive rehabilitation tailored to aesthetic perception, improving the comprehension of cognitive disorders through integrated BCI methodologies.

Attentional bias to threat: an investigation of psychological predictors beyond trait anxiety

AbstractAttentional bias to threat (ABT) refers to the tendency to more rapidly orient attention to threatening stimuli, as compared to neutral or pleasant stimuli. Issues with the reliability of this phenomenon have been raised and little is currently known about individual differences that may contribute to ABT. This online study aimed to replicate ABT in trait anxiety and identify psychological predictors of ABT using both dot probe and flanker tasks comprising emotional images. Undergraduate students completed various psychological questionnaires, followed by the ABT tasks. Contrary to expectations, faster responses and enhanced accuracy for positive stimuli were found in a low trait anxiety sub-sample (n = 33) in the dot probe task, while overall slower performance among a high trait anxiety sub-sample (n = 34) was found in the flanker task. Higher ratings of state anxiety and stress and lower ratings of calmness were associated with greater flanker ABT scores in the overall sample (N = 111), while higher scores on facets of trait mindfulness and personality were associated with greater dot probe ABT scores. Trait anxiety was not associated with either ABT score. These findings highlight the difficulties replicating ABT in anxious individuals using behavioural tasks and indicate the importance of measuring state and trait psychological experiences when investigating ABT in experimental settings. Further replication of predictors is required.

Opioid Receptor Mu 1 Gene (OPRM1) A118G Polymorphism and Emotional Modulation of Pain.

The A118G polymorphism in the opioid receptor mu 1 gene (OPRM1) is associated with decreased opioid receptor availability, altered emotion, and increased pain. Given that emotions modulate pain (positive emotions inhibit pain, negative emotions enhance pain), we predicted that G allele carriers would experience impaired emotional modulation of pain compared to non-G allele carriers. Emotional pictures (ie, erotica, neutral, attack) from the International Affective Picture System were used by permission from the authors to experimentally manipulate emotions in 64 adult participants while painful electrocutaneous stimulations were delivered in a cross-sectional study. Ratings of arousal and valence/pleasure were made in response to pictures, and pain ratings and a physiological measure of spinal nociception (ie, nociceptive flexion reflex, NFR) were collected in response to painful stimulations. Secondary analyses were conducted to examine the relationship between the A118G polymorphism and emotional modulation of pain/NFR. Exposure to emotional pictures elicited similar changes in valence, but G-carriers rated erotic pictures as more arousing. In non-carriers, pain was facilitated by attack pictures and pain and NFR were inhibited by erotic pictures relative to neutral pictures. Among G-carriers, pain was facilitated by negative emotional pictures but there was no pain or NFR inhibition by positive emotional pictures. The altered response to pleasant stimuli further supports the role of opioids in appetitive behavior and describes how the A118G polymorphism may prevent carriers from inhibiting pain during pleasure.

The Role of Coherent Robot Behavior and Embodiment in Emotion Perception and Recognition During Human-Robot Interaction: Experimental Study.

Social robots are becoming increasingly important as companions in our daily lives. Consequently, humans expect to interact with them using the same mental models applied to human-human interactions, including the use of cospeech gestures. Research efforts have been devoted to understanding users' needs and developing robot's behavioral models that can perceive the user state and properly plan a reaction. Despite the efforts made, some challenges regarding the effect of robot embodiment and behavior in the perception of emotions remain open. The aim of this study is dual. First, it aims to assess the role of the robot's cospeech gestures and embodiment in the user's perceived emotions in terms of valence (stimulus pleasantness), arousal (intensity of evoked emotion), and dominance (degree of control exerted by the stimulus). Second, it aims to evaluate the robot's accuracy in identifying positive, negative, and neutral emotions displayed by interacting humans using 3 supervised machine learning algorithms: support vector machine, random forest, and K-nearest neighbor. Pepper robot was used to elicit the 3 emotions in humans using a set of 60 images retrieved from a standardized database. In particular, 2 experimental conditions for emotion elicitation were performed with Pepper robot: with a static behavior or with a robot that expresses coherent (COH) cospeech behavior. Furthermore, to evaluate the role of the robot embodiment, the third elicitation was performed by asking the participant to interact with a PC, where a graphical interface showed the same images. Each participant was requested to undergo only 1 of the 3 experimental conditions. A total of 60 participants were recruited for this study, 20 for each experimental condition for a total of 3600 interactions. The results showed significant differences (P<.05) in valence, arousal, and dominance when stimulated with the Pepper robot behaving COH with respect to the PC condition, thus underlying the importance of the robot's nonverbal communication and embodiment. A higher valence score was obtained for the elicitation of the robot (COH and robot with static behavior) with respect to the PC. For emotion recognition, the K-nearest neighbor classifiers achieved the best accuracy results. In particular, the COH modality achieved the highest level of accuracy (0.97) when compared with the static behavior and PC elicitations (0.88 and 0.94, respectively). The results suggest that the use of multimodal communication channels, such as cospeech and visual channels, as in the COH modality, may improve the recognition accuracy of the user's emotional state and can reinforce the perceived emotion. Future studies should investigate the effect of age, culture, and cognitive profile on the emotion perception and recognition going beyond the limitation of this work.

The Intrigue of Intermittent Reward and Cost: Unveiling Their Influence in Real Life

This paper examines the role of Intermittent Cost (Punishment) in influencing the behavior of children who exhibit aggressive behavior through a laboratory Experiment. In the experiment, children in the treatment group were randomly placed in solitary confinement for attacking others. It is expected that Intermittent costs will reduce children’s aggressive behavior. The paper will also explore how Intermittent Cost and Reward work in the brain, finding that when people experience pleasurable stimuli, the brain starts secreting dopamine, so much so that it affects our behavior and expectations. In addition, experiments have found that when rewards are intermittent, the brain experiences higher arousal levels. This explains why people always crave cookies or continue to use social media and gamble. Finally, this paper will also discuss the possible application of Intermittent Cost and Reward in different aspects, which can help us formulate some policies and increase the flexibility of users.

Adiposity and Insulin Resistance Moderate Brain Electrophysiology and Affect Regulation in Young Adults

AbstractBackgroundObesity and insulin resistance (IR) may negatively influence affect regulation in young adulthood. The paucity of studies that have investigated such associations have predominantly used functional magnetic resonance imaging. However, electroencephalography (EEG) can evaluate neural signatures in real‐time that may be complementary. Thus, this study investigated how adiposity and IR moderated brain activity and underlying affect regulation using EEG.MethodReal‐time EEG was recorded in 28 lean and obese young adults with and without IR (18‐39 years, 46.4% female). Two event‐related potential (ERP) components of affect regulation, early posterior negativity (EPN) and late positive potential (LPP), were quantified from EEG data. Participants completed the Interactional Picture Affective System task to measure affect regulation, from which mean valence ratings and stimulus‐to‐response‐onset reaction times were calculated. ERP components and affect regulation parameters were then contrasted in three conditions, as follows: 1) Negative – Neutral; 2) Positive – Neutral; and 3) Negative – Positive. Height, weight, body fat percentage (%BF), and serum proteomics were collected. Fasting glucose and insulin readings were obtained to quantify Homeostatic Model Assessment for Insulin Resistance (HOMA‐IR). Hierarchical moderated regression analysis was utilized to test the interrelationships between adiposity, IR, neural activity, and affect regulation.ResultAcross all contrasted conditions, HOMA‐IR and %BF were found to moderate the relationships between frontal and parietal LPP amplitudes during the late latency window and affect regulation. Specifically, higher late frontal LPP amplitudes were associated with less negative and more positive valence ratings to unpleasant and pleasant stimuli, respectively, among participants with low, but not high, IR and %BF levels. In the Negative – Neutral and Negative – Positive conditions, lower late parietal LPP amplitudes were also associated with less negative overall valence ratings in response to unpleasant stimuli, but only in lean, insulin sensitive participants. These results overall suggest that modulation of negative and positive affectivity only occurs in lean young adults without IR.ConclusionYoung adults with greater adiposity and IR showed worse affect regulation than those without obesity and IR. Furthermore, AD‐associated characteristics may start early in life, and EEG signatures may be a useful neuroimaging approach for tracking such events.

Disgust-reduction evaluative conditioning (DREC) and brain stimulation in patients with contamination-based obsessive-compulsive disorder: a protocol for a randomized control trial

BackgroundThe negative emotional valence of a stimulus can be altered if paired with a pleasant stimulus, a phenomenon referred to as evaluative conditioning. Disgust, as a central emotion in obsessive-compulsive disorder (OCD), particularly in the contamination subtype, may be an appropriate target for such a method. We know that disgust processing and OCD pathophysiology share in some brain areas, including the orbitofrontal cortex, as the neuromodulation techniques targeted in this area have been able to decrease OCD symptoms. We aim to conduct a randomized clinical trial to investigate the evaluative conditioning effect on disgust reduction in patients with contamination-based OCD when administered with or without neuromodulation targeted orbitofrontal cortex.MethodIn a single-blind randomized control trial (RCT), 55 patients with contamination-based OCD will be randomly assigned to four arms. In a factorial design, they will receive 10 sessions of evaluative conditioning training (either sham or real) plus cathodal transcranial direct current stimulation (tDCS) over the orbitofrontal cortex (either sham or real). The intensity of disgust experience and clinical symptoms will be investigated as primary outcomes and quantitative electroencephalogram and cognitive functions as secondary outcomes. The data will be collected at three assessment levels: baseline, after completing intervention sessions, and 2-month follow-up.DiscussionThe present RCT is the first study that applies evaluative conditioning training in the OCD clinical sample. It will clarify the effect of the evaluative conditioning method alone and with tDCS on disgust reduction in patients with contamination-based OCD. It will provide initial evidence for such an emotion modulation method in the OCD population. The effect of this emotion-focused protocol on cognitive functions and electroencephalogram components is also of interest.Trial registrationClinicalTrials.gov, NCT05907369. Registered on 16 June 2023. Retrospectively registered.

Identification of areas of the brain activated by active stimulation in hairless skin

In the past few decades, neuroscientists have studied the physiological basis of pleasant touch. Unmyelinated low-threshold mechanoreceptors are central to the study of the physiological basis of pleasant touch. Research on pleasant stimuli has mostly focused on passive stimuli, and the brain activation sites for active pleasant stimuli are not clear. Therefore, the purpose of this study was to identify brain activation sites during active pleasant stimulation of hairless skin using functional magnetic resonance imaging. Forty-two healthy subjects aged 19 years or older were asked to actively grasp in five stimulus tasks. The comfort and sensations that occurred during the tasks were investigated using a questionnaire. Significant activation was found in the middle frontal gyrus when the hair ball and slime ball were grasped, while there was significant activation in the amygdala when grasping a squeeze ball compared to the tennis ball. In a questionnaire survey of the subjects, there was a significant difference in the comfort score between the tennis ball and the squeeze ball, but no significant correlation was found between the comfort scores and the brain sites of activation. Therefore, although active stimulation with the squeeze ball significantly activated the amygdala, it was not clear that the amygdala was significantly activated by active pleasant stimulation. In the future, it will be necessary to investigate the texture of the squeeze ball in more detail, and to increase the number of subjects for further study.

Music and speech time perception of musically trained individuals: The effects of audio type, duration of musical training, and rhythm perception.

The perception of time is a subjective experience influenced by various factors such as individual psychology, external stimuli, and personal experiences, and it is often assessed with the use of the reproduction task that involves individuals estimating and reproducing the duration of specific time intervals. In the current study, we examined the ability of 97 musically trained participants to reproduce the durations of temporal intervals that were filled with music or speech stimuli. The results revealed a consistent pattern of durations being underestimated, and an association was observed between the duration of musical training and the level of accuracy in reproducing both music and speech tracks. In addition, speech tracks were overall reproduced more accurately, and as longer, than music tracks. Structural models suggested the presence of two, highly correlated, dimensions of time perception for speech and music stimuli that were related to the duration of musical training, but not with self-reported rhythm perception. The possible effects of arousal and pleasantness of stimuli on time perception are discussed within the framework of an internal clock model.

O012 The Impact of Sleep Restriction on Reward learning in Healthy Adults

Abstract Sleep disruption can lead to enhanced reactivity towards pleasurable stimuli and impaired discrimination between rewarding and punishing cues. Thus, sleep may play a mechanistic role in the development and exacerbation of pathological reward-related behaviours (e.g., gambling, substance use, etc.). The study aimed to explore the impact of sleep restriction on reward processing. Involving a 7-night at-home sleep monitoring protocol, participants were randomly assigned an experimental condition: sleep restriction (5-hr time in bed/night; SR) or well-rested (9-hr/night; WR). Adherence to the prescribed sleep schedules was assessed daily. On the eighth day participants completed a battery of reward- learning tasks, 2-hrs post-habitual wake. Participants were healthy adults (n = 45, mean age = 25.4 yrs, 64% female). Total sleep time for the SR group (n = 18) was 297.4 mins, whilst the WR was 485.8 mins (n = 27). For the probabilistic reward task, response bias (RB) did not significantly differ between the SR and WR groups during the overall task (p = 0.28), or during blocks one (p = 0.26) or two (p = 0.90). However, at block three, the SR group showed higher RB as compared to the WR group (p = 0.03), indicating SR participants exhibited a systematic preference for the frequently rewarded cues, relative to the WR group. These preliminary results suggest initial reward responsiveness is not impacted by SR, but over time SR may produce heightened sensitivity to rewarding cues. This may indicate a role for sleep disruption in the maintenance of maladaptive appetitive behaviours.

Emotional Experience of People With Schizophrenia and People at Risk for Psychosis

Psychotic symptoms are associated with subjective reports of aberrant emotion, such as excessive fear or anhedonia, but whether these aberrations reflect aberrant emotional experience of normative stimuli is uncertain both for individuals with schizophrenia and those at risk for psychosis. To provide a meta-analysis of study samples of emotional experience in individuals with schizophrenia and those at risk for psychosis as assessed in laboratory-based emotion-induction studies. MEDLINE and PsycINFO databases were searched for articles published from January 1986 and Google Scholar citations of a relevant earlier meta-analysis until August 2022. Reference lists were manually searched for additional studies. Included studies measured positive or negative emotional experience in response to standardized emotionally evocative stimuli and compared participants diagnosed with schizophrenia or participants at risk for psychosis with healthy controls. The meta-analysis was registered with PROSPERO and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines. Data were extracted by 2 independent coders, and random-effects analyses were conducted. Outcomes were 3 scales of emotional experience (unipolar positive emotion, unipolar negative emotion, bipolar valence), analyzed separately for pleasant, neutral, and unpleasant stimuli. A meta-analysis was conducted for differences between the 2 clinical groups combined and controls. Subgroup differences (schizophrenia vs at risk) and the influence of several other variables were tested in moderator analyses. This systematic review and meta-analysis included data from 111 studies and 6913 participants (schizophrenia: 2848 [41.2%]; at risk: 877 [12.7%]; healthy controls: 3188 [46.1%]). Compared with controls, people with schizophrenia and those at risk for psychosis experienced pleasant stimuli as less positive (unipolar positive: standardized mean difference [SMD] Hedges g = -0.19; P =.001; bipolar valence: SMD Hedges g = -0.28; P <.001) and more negative (Hedges g = 0.52; P <.001), neutral stimuli as more negative (Hedges g = 0.55; P <.001), and unpleasant stimuli as both more positive (unipolar positive: SMD Hedges g = 0.23; P =.005; bipolar valence: Hedges g = 0.12; P =.01) and more negative (Hedges g = 0.22; P <.001). Moderator analyses indicated a less aberrant emotional experience for odors than for visual stimuli (unipolar negative, pleasant z score = -2.97; P =.003; unipolar negative, neutral z score = -2.70; P =.007), an association between higher negative symptoms and diminished positive emotion for pleasant stimuli in schizophrenia (z score = -2.98; P =.003), and that subgroup differences were limited to neutral stimuli. Results suggest a pattern of aberrant emotional experience of normative stimuli in schizophrenia and that this already was observable before disorder onset. In particular, the aberrant experience of pleasant stimuli needs to be considered as an intervention target.

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.

Alpha-band oscillations and emotion: A review of studies on picture perception.

Although alpha-band activity has long been a focus of psychophysiological research, its modulation by emotional value during picture perception has only recently been studied systematically. Here, we review these studies and report that the most consistent alpha oscillatory pattern indexing emotional processing is an enhanced desynchronization (ERD) over posterior sensors when viewing emotional compared with neutral pictures. This enhanced alpha ERD is not specific to unpleasant picture content, as previously proposed for other measures of affective response, but has also been observed for pleasant stimuli. Evidence suggests that this effect involves a desynchronization of the upper alpha band and of the lower beta frequencies (10-20 Hz). The emotional modulation of alpha ERD occurs even after massive stimulus repetition and when emotional cues serve as task-irrelevant distractors, consistent with the hypothesis that evaluative processes are mandatory in emotional picture processing. A similar enhanced ERD has been observed for other significant cues (e.g., conditioned aversive stimuli, or in anticipation of a potential threat), suggesting that it reflects cortical excitability associated with the engagement of the motivational systems.

Reaction time as an outcome measure during online fear conditioning: Effects of number of trials, age, and levels of processing

Recent studies have shown that fear conditioning experiments can be successfully conducted online. However, there is limited evidence that measures other than subjective ratings of threat expectancy can be collected, which means that online research may not be able to adequately replace laboratory experiments. In the current study, we conducted an online fear conditioning experiment consisting of habituation, acquisition, extinction and 48 h delayed extinction recall using ratings of threat expectancy and conditional stimulus pleasantness, and probe reaction time as outcome measures. The conditional stimuli were categories of words and a levels of processing manipulation explored whether words that were processed at a deeper level during extinction evoked smaller differential threat responses during extinction recall. Although the levels of processing manipulation did not produce a significant outcome, we found that extinction recall was successfully operationalised in our study. Reaction time indicated differential responding during both acquisition and extinction recall, and age of participants was correlated in one of two experiments with differential threat expectancy and reaction time, such that older participants showed better safety learning. The outcomes of this experiment provide multiple novel tools for researchers to explore fear conditioning, especially in an online environment.

The effect of ketamine on affective modulation of the startle reflex and its resting-state brain correlates

Ketamine is a rapid-acting antidepressant that also influences neural reactivity to affective stimuli. However, the effect of ketamine on behavioral affective reactivity is yet to be elucidated. The affect-modulated startle reflex paradigm (AMSR) allows examining the valence-specific aspects of behavioral affective reactivity. We hypothesized that ketamine alters the modulation of the startle reflex during processing of unpleasant and pleasant stimuli and weakens the resting-state functional connectivity (rsFC) within the modulatory pathway, namely between the centromedial nucleus of the amygdala and nucleus reticularis pontis caudalis. In a randomized, double-blind, placebo-controlled, cross-over study, thirty-two healthy male participants underwent ultra-high field resting-state functional magnetic resonance imaging at 7 T before and 24 h after placebo and S-ketamine infusions. Participants completed the AMSR task at baseline and one day after each infusion. In contrast to our hypothesis, ketamine infusion did not impact startle potentiation during processing of unpleasant stimuli but resulted in diminished startle attenuation during processing of pleasant stimuli. This diminishment significantly correlated with end-of-infusion plasma levels of ketamine and norketamine. Furthermore, ketamine induced a decrease in rsFC within the modulatory startle reflex pathway. The results of this first study on the effect of ketamine on the AMSR suggest that ketamine might attenuate the motivational significance of pleasant stimuli in healthy participants one day after infusion.