High Arousal States Research Articles

Distinct Mindfulness States Produce Dissociable Effects on Neural Markers of Emotion Processing: Evidence From the Late Positive Potential

BackgroundMindfulness has long been theorized to benefit emotion regulation, but despite the ubiquity of the claim, there is little empirical evidence demonstrating how mindfulness modulates the neurophysiology of emotion processing. The current study aimed to fill this gap in knowledge by leveraging a novel research approach capable of discretizing mindfulness into distinct states of open monitoring (OM) and focused attention (FA) to distinguish their influence on multimodal subjective and objective measures of emotion processing. MethodsUtilizing a fully within-participant picture viewing state induction protocol (N = 30), we compared the effects of OM and FA, rigorously contrasted against an active control, on the visually evoked late positive potential (LPP), a neural index of motivated attention. Bayesian mixed modeling was used to distinguish OM versus FA effects on the early and late sustained LPP while evaluating the influence of subjective arousal ratings as a within-participant moderator of the state inductions. ResultsWhen negative picture trials were retrospectively rated as more subjectively arousing, the OM induction reduced the late sustained LPP response, whereas the FA induction enhanced the LPP. ConclusionsAcute manipulation of OM and FA states may reduce and enhance motivated attention to aversive stimuli during conditions of high subjective arousal, respectively. Functional distinctions between different mindfulness states on emotion processing may be most dissociable after accounting for within-participant variability in how stimuli are appraised. These results support the future potential of the state induction protocol for parsing the neural affective mechanisms that underlie mindfulness training programs and interventions.

Staying in control: Characterizing the mechanisms underlying cognitive control in high and low arousal states.

Throughout the day, humans show natural fluctuations in arousal that impact cognitive function. To study the behavioural dynamics of cognitive control during high and low arousal states, healthy participants performed an auditory conflict task during high-intensity physical exercise (N = 39) or drowsiness (N = 33). In line with the pre-registered hypotheses, conflict and conflict adaptation effects were preserved during both altered arousal states. Overall task performance was markedly poorer during low arousal, but not for high arousal. Modelling behavioural dynamics with drift diffusion analysis revealed evidence accumulation and non-decision time decelerated, and decisional boundaries became wider during low arousal, whereas high arousal was unexpectedly associated with a decrease in the interference of task-irrelevant information processing. These findings show how arousal differentially modulates cognitive control at both sides of normal alertness, and further validate drowsiness and physical exercise as key experimental models to disentangle the interaction between physiological fluctuations on cognitive dynamics.

Evaluating the predictions of an interoceptive inference model of bulimia nervosa

ObjectiveBulimia nervosa (BN) is associated with loss-of-control (LOC) eating episodes that frequently occur in response to negative emotions. According to recent neurocomputational models, this link could be explained by a failure to accurately update beliefs about the body in states of high arousal. Specifically, these interoceptive inference models suggest that under-relying on signals from one’s body about sensory experience (“low sensory precision”) and/or over-relying on previously held beliefs (“excessively precise priors”) lead to inaccurate perception and maladaptive behaviors. We conducted an initial test of these core predictions of the interoceptive inference model in BN using self-report measures.MethodsWe compared women with BN (n = 30) and age-, BMI-, and full-scale IQ-matched controls (n = 31) on trust in sensory information from the body and two types of beliefs about what can be done to regulate high negative affect. Within the BN group, we tested interrelations among these measures and explored their associations with LOC eating frequency.ResultsCompared with healthy controls, the BN group reported lower levels of trust in sensory information and stronger beliefs that once upset, there is little one can do, apart from eating, to self-regulate. These beliefs were associated with each other and with lower body trust. Beliefs about the uncontrollability of emotion were associated with more frequent subjective binge-eating episodes.ConclusionsFindings provide initial support for the core predictions of an interoceptive inference account of BN: low trust in sensory information (“sensory precision”) may promote an overreliance on maladaptive “prior beliefs” about the effects of eating on negative emotions, ultimately interfering with accurate updating of beliefs about other strategies that could regulate emotions and maintain LOC eating. Low body trust, strong expectations about emotions, and their neurocomputational underpinnings could be promising combined treatment targets for BN.

The Existential Challenges of Stress, Trauma, and Psychopathology and Their Integration to the Self: A Self-Determination Theory Perspective

AbstractIn much current research on stress, trauma, and psychopathology, there is a converging interest in the role of the stress response in engendering trauma, emotional dysregulation, and mental illness. Both the acute stressors known from post-traumatic stress disorder (PTSD) and the early-life, persistent stressors involved in complex PTSD, may create a stress response that is not properly downregulated. This leaves the person in a permanent state of high arousal and hypervigilance, common characteristics of many psychiatric disorders. It is suggested that such stressors are examples of the challenges that confront everyone: trivial, optimal, or overwhelming. Trivial challenges are mundane, optimal challenges invite learning and development, and overwhelming challenges may lead to trauma and mental ill-being. For a promising perspective on life’s challenges, we turn to Self-Determination Theory (SDT). In SDT, mental health and human flourishing derive from the satisfaction of three basic psychological needs: for autonomy, competence and relatedness, as well as from the integration of experiences and challenges to the self. It is proposed in this paper that the overwhelming challenges involved in trauma and psychopathology are experiences that frustrate or thwart psychological needs and thus fail to integrate to the self. Such experiences may still be internalized, albeit as “introjects”—“thrown in,” swallowed whole, not digested properly. They remain outside of the self, exerting pressure on it through guilt, shame, ego-involvement, pride, etc., in the process producing much anguish and mental pain. Thus, as challenges are part and parcel of the human experience, trauma and psychopathology appear as outcomes of human development, rather than as essentially incomprehensible aberrations.

An Interactive Feeder to Induce and Assess Emotions from Vocalisations of Chickens.

Understanding the emotional states of animals is a long-standing research endeavour that has clear applications in animal welfare. Vocalisations are emerging as a promising way to assess both positive and negative emotional states. However, the vocal expression of emotions in birds is a relatively unexplored research area. The goal of this study was to develop an interactive feeding system that would elicit positive and negative emotional states, and collect recordings of the vocal expression of these emotions without human interference. In this paper, the mechatronic design and development of the feeder is described. Design choices were motivated by the desire for the hens to voluntarily interact with the feeder and experience the different stimuli that were designed to induce (1) positive low-arousal, (2) positive high-arousal, (3) negative low-arousal, and (4) negative high-arousal states. The results showed that hens were motivated to engage with the feeder despite the risk of receiving negative stimuli and that this motivation was sustained for at least 1 week. The potential of using the interactive feeder to analyse chicken vocalisations related to emotional valence and arousal is being explored, offering a novel proof of concept in animal welfare research. Preliminary findings suggest that hens vocalised in response to all four stimulus types, with the number of vocalisations, but not the probability of vocalising, distinguishing between low- and high-arousal states. Thus, the proposed animal-computer interaction design has potential to be used as an enrichment device and for future experiments on vocal emotions in birds.

Effect of emotional stimulus on response inhibition in people with mild cognitive impairment: an event-related potential study.

A few studies are emerging to explore the issue of how aging promotes emotional response inhibition. However, there is a lack of empirical study concerning the impact of pathological cognitive impairment on emotional response inhibition. The present study investigated the effect of emotion on response inhibition in people with mild cognitive impairment, the stage of cognitive impairment before dementia. We used two emotional stop-signal tasks to explore whether the dual competition framework considering limited cognitive resources could explain the relationship between emotion and response inhibition in mild cognitive impairment. The results showed that negative emotions prolonged N2 latency. The Go trial accuracy was reduced in the high-arousal negative conditions and the stop-signal reaction time was prolonged under high-arousal conditions. This study also verified impaired response inhibition in mild cognitive impairment and found that negative emotions prolonged P3 latency in mild cognitive impairment. Emotional information interferes with response inhibition in mild cognitive impairment populations, possibly because emotional information captures more attentional resources, thus interfering with response inhibition that relies on common-pool resources.

Sensory neurons couple arousal and foraging decisions in Caenorhabditis elegans

Foraging animals optimize feeding decisions by adjusting both common and rare behavioral patterns. Here, we characterize the relationship between an animal’s arousal state and a rare decision to leave a patch of bacterial food. Using long-term tracking and behavioral state classification, we find that food leaving decisions in Caenorhabditis elegans are coupled to arousal states across multiple timescales. Leaving emerges probabilistically over minutes from the high arousal roaming state, but is suppressed during the low arousal dwelling state. Immediately before leaving, animals have a brief acceleration in speed that appears as a characteristic signature of this behavioral motif. Neuromodulatory mutants and optogenetic manipulations that increase roaming have a coupled increase in leaving rates, and similarly acute manipulations that inhibit feeding induce both roaming and leaving. By contrast, inactivating a set of chemosensory neurons that depend on the cGMP-gated transduction channel TAX-4 uncouples roaming and leaving dynamics. In addition, tax-4-expressing sensory neurons promote lawn-leaving behaviors that are elicited by feeding inhibition. Our results indicate that sensory neurons responsive to both internal and external cues play an integrative role in arousal and foraging decisions.

Sensory neurons couple arousal and foraging decisions in Caenorhabditis elegans.

Foraging animals optimize feeding decisions by adjusting both common and rare behavioral patterns. Here, we characterize the relationship between an animal's arousal state and a rare decision to leave a patch of bacterial food. Using long-term tracking and behavioral state classification, we find that food leaving decisions in Caenorhabditis elegans are coupled to arousal states across multiple timescales. Leaving emerges probabilistically over minutes from the high arousal roaming state, but is suppressed during the low arousal dwelling state. Immediately before leaving, animals have a brief acceleration in speed that appears as a characteristic signature of this behavioral motif. Neuromodulatory mutants and optogenetic manipulations that increase roaming have a coupled increase in leaving rates, and similarly acute manipulations that inhibit feeding induce both roaming and leaving. By contrast, inactivating a set of chemosensory neurons that depend on the cGMP-gated transduction channel TAX-4 uncouples roaming and leaving dynamics. In addition, tax-4-expressing sensory neurons promote lawn-leaving behaviors that are elicited by feeding inhibition. Our results indicate that sensory neurons responsive to both internal and external cues play an integrative role in arousal and foraging decisions.

Noradrenaline tracks emotional modulation of attention in human amygdala

The noradrenaline (NA) system is one of the brain's major neuromodulatory systems; it originates in a small midbrain nucleus, the locus coeruleus (LC), and projects widely throughout the brain.1,2 The LC-NA system is believed to regulate arousal and attention3,4 and is a pharmacological target in multiple clinical conditions.5,6,7 Yet our understanding of its role in health and disease has been impeded by a lack of direct recordings in humans. Here, we address this problem by showing that electrochemical estimates of sub-second NA dynamics can be obtained using clinical depth electrodes implanted for epilepsy monitoring. We made these recordings in the amygdala, an evolutionarily ancient structure that supports emotional processing8,9 and receives dense LC-NA projections,10 while patients (n= 3) performed a visual affective oddball task. The task was designed to induce different cognitive states, with the oddball stimuli involving emotionally evocative images,11 which varied in terms of arousal (low versus high) and valence (negative versus positive). Consistent with theory, the NA estimates tracked the emotional modulation of attention, with a stronger oddball response in a high-arousal state. Parallel estimates of pupil dilation, a common behavioral proxy for LC-NA activity,12 supported a hypothesis that pupil-NA coupling changes with cognitive state,13,14 with the pupil and NA estimates being positively correlated for oddball stimuli in a high-arousal but not a low-arousal state. Our study provides proof of concept that neuromodulator monitoring is now possible using depth electrodes in standard clinical use.

Increases in negative affective arousal precede lower self-esteem in patients with borderline personality disorder but not in patients with depressive disorders: an experience sampling approach

BackgroundInstability in self-esteem and instability in affect are core features of borderline personality disorder (BPD). For decades, researchers and theorists have been interested in the temporal dynamics between these constructs. Some hypothesize that changes in affective states should precede changes in self-esteem (Linehan, Cognitive-behavioral treatment of borderline personality disorder. Diagnosis and treatment of mental disorders, 1993), while others suggest that changes in self-esteem should precede changes in affective states (Kernberg, Borderline conditions and pathological narcissism, 1975).MethodsIn this study, we investigated the temporal relations between negative affective arousal states and current self-esteem in daily life. Patients with BPD (n = 42) or depressive disorders (DD; n = 40), and non-clinical controls (NCC; n = 40) were assessed every 15 min for 13 h.ResultsAs expected, dynamic structural equation modeling showed higher levels of average daily negative affective arousal and lower levels of average daily self-esteem in the BPD group compared with the NCC group, and scores in the DD group were in-between the BPD and the NCC groups. In line with predictions based on Linehan’s (Cognitive-behavioral treatment of borderline personality disorder. Diagnosis and treatment of mental disorders, 1993) model of affective dysregulation in BPD, negative affective arousal (t) and subsequent self-esteem (t+ 1) were significantly linked only in the BPD group, implying that higher negative affective arousal is followed by lower current self-esteem in the next measurement (ca. 15 min later). Importantly, self-esteem (t) and subsequent negative affective arousal (t + 1) were not significantly related (Kernberg, Borderline conditions and pathological narcissism, 1975).ConclusionsOur findings suggest close dynamic temporal relations between affective instability and self-esteem instability in BPD, which highlights the importance of providing patients with means to effectively modulate high negative affective arousal states.

Associations between immune competence phenotype and stress response in sheep

Immune competence in domestic sheep is gaining more attention in genetic selection programs that seek to enhance flock immunity and animal welfare. A goal of many programs is to identify behavioral phenotypes that indicate stress-coping strength, as well as disease resilience. The current study set out to explore the relationship between immune responsiveness, physiological stress, and behavioral response among sheep that had been selected for ‘low’ (LR) or ‘high’ (HR) response to cell-mediated and antibody-mediate reactivity to a clostridial vaccine. Multiparous ewes were placed in four experiments which exposed the animals to various threats including, dog presence, human proximity, visual isolation from flock, and physical restraint. To evaluate the consistency of behavioral phenotypes, all ewes were placed in the test circuit one year later. Basal body temperature (via iButton) and serum cortisol concentrations were collected prior to and after the circuit each year. Immune group (HR vs. LR) was not found to be related to behavioral performance during the dog, human, isolation, or restraint challenge. Immune group categorization was also unrelated to pre- and post-cortisol concentrations, and the change in cortisol concentrations during testing. There was a negative relationship identified between response to visual isolation and change in cortisol response during testing, indicating that sheep which were more active or agitated during visual isolation from the flock experienced less of an increase in serum cortisol levels and were perhaps experiencing a negative, high arousal state compared to less reactive sheep (e.g., freeze behavior) (χ2(4, N=99) = 42.72, P <0.0001). There was also a post hoc, positive relationship identified between weight measurements and immune group, such that individuals with greater body weight were more likely to be in the high immune responsiveness group (P= 0.01). Specifically, for every unit increase in weight, there was a ~49% chance of being categorized in the HR group. This is relevant for selection programs because producers that seek to enhance immune responsiveness and performance may be able to select sheep that carry a greater body mass, and while not found in the present study, could lead to greater flock immunity.

AITST—Affective EEG-based person identification via interrelated temporal–spatial transformer

Compared with other biometrics, such as fingerprints and irises, EEG signals contain richer identity information due to their high subject dependence. In this study, we proposed an affective EEG-based person identification by using an affective interrelated temporal–spatial transformer (AITST) to overcome the influence of different emotional states in affective EEG-based person identification. The AITST contains an interrelated temporal–spatial attention that can preserve the interrelationships of temporal and spatial domains while extracting temporal and spatial features of the EEG signal. We evaluated the proposed AITST on the public emotional database DEAP. The experimental results show that our AITST can reach an average recognition accuracy of 98.94±0.04% in the low valence, low arousal state, 99.06±0.02% in low valence, high arousal state, 98.97±0.02% in high valence, low arousal state, and 99.21±0.03% in the high valence, high arousal state, significantly outperforming the other compared models and overcoming the influence of different emotional states. Furthermore, we explored the contribution of different frequency bands, different emotional states and different features of EEG for EEG-based person identification. The results showed that gamma band of EEG, power spectrum density (PSD), and high arousal state have the greatest contribution to affective EEG-based person identification. Source code is available at https://github.com/JerryKingQAQ/AITST.

Moderate-intensity cardiovascular exercise performed before motor practice attenuates offline implicit motor learning in stroke survivors but not age-matched neurotypical adults.

The acute impact of cardiovascular exercise on implicit motor learning of stroke survivors is still unknown. We investigated the effects of cardiovascular exercise on implicit motor learning of mild-moderately impaired chronic stroke survivors and neurotypical adults. We addressed whether exercise priming effects are time-dependent (e.g., exercise before or after practice) in the encoding (acquisition) and recall (retention) phases. Forty-five stroke survivors and 45 age-matched neurotypical adults were randomized into three sub-groups: BEFORE (exercise, then motor practice), AFTER (motor practice, then exercise), and No-EX (motor practice alone). All sub-groups practiced a serial reaction time task (five repeated and two pseudorandom sequences per day) on three consecutive days, followed 7days later by a retention test (one repeated sequence). Exercise was performed on a stationary bike, (one 20-min bout per day) at 50% to 70% heart rate reserve. Implicit motor learning was measured as a difference score (repeated-pseudorandom sequence response time) during practice (acquisition) and recall (delayed retention). Separate analyses were performed on the stroke and neurotypical groups using linear mixed-effects models (participant ID was a random effect). There was no exercise-induced benefit on implicit motor learning for any sub-group. However, exercise performed before practice impaired encoding in neurotypical adults and attenuated retention performance of stroke survivors. There is no benefit to implicit motor learning of moderately intense cardiovascular exercise for stroke survivors or age-matched neurotypical adults, regardless of timing. Practice under a high arousal state and exercise-induced fatigue may have attenuated offline learning in stroke survivors.

Emotion-Triggered impulsivity relates to speech dysfluency during high arousal states

Emotion-triggered impulsivity is robustly tied to psychopathologies. We hypothesized that one form of emotion-triggered impulsivity, Feelings Trigger Action, would be correlated with speech disfluencies during high arousal. Participants with a range of internalizing and externalizing symptoms completed a stressful speech task in which they were videorecorded while discussing a controversial topic. Skin conductance was gathered toindexarousal. Consistent with hypotheses, Feelings Trigger Action scores related to modestly higher levels of speech repairs when participants were experiencing relatively higher arousal (N = 198). There was some evidence that a second form of emotion-triggered impulsivity also related to more speech errors during high arousal. Findings provide early evidence that speech disfluencies might be one manifestation of emotion-triggered impulsivity. Limitations and direction for future research are considered.

Who disengages from emotion and when? An EMA study of how urgency and distress intolerance relate to daily emotion regulation.

Overreliance on disengagement emotion regulation strategies (e.g., emotion avoidance, emotion suppression) has been shown to relate to poor clinical outcomes. Two traits characterized by difficulties in goal-directed responses to emotion-urgency and distress intolerance-may help explain who is likely to disengage from emotion and when. These traits are associated with diverse forms of psychopathology and greater reliance on disengagement strategies. Gaps remain about how these traits relate to emotion regulation in daily life. The present study uses ecological momentary assessment (EMA) to determine the associations of urgency and distress intolerance with momentary high arousal negative affect and momentary attempts to regulate negative emotions. Participants (N = 101) were college students who endorsed at least weekly behaviors often characterized by emotion dysregulation (e.g., self-harm, binging/purging, alcohol/drug use). Participants completed trait measures at baseline and EMA surveys of momentary affect and emotion regulation, six times daily for 4 days. Results indicated that at certain levels, urgency and distress intolerance moderated the relationship between high arousal negative affect and disengagement from emotion: low urgency scores related to relatively greater disengagement from emotion following reported high arousal negative affect, whereas high distress intolerance scores related to relatively greater disengagement following high arousal negative affect. Findings support the role of both urgency and distress intolerance in the relationship between high arousal negative affect and disengagement, which implicates the utility of clinical interventions that focus on emotion regulation, especially during high arousal states. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Bringing nature into hospital architecture: Machine learning-based EEG analysis of the biophilia effect in virtual reality

In recent years, there has been a growing interest in investigating the influence of biophilic design on occupants' psychological comfort and well-being in the built environment. Biophilic principles aim to leverage the therapeutic effects of nature to alleviate distress, depression, anxiety, and pain. The impact of biophilic design can vary depending on the outcome measures and the design context, but studies examining diverse forms of biophilic design in hospital rooms have been limited. The study investigated how the incorporation of biophilic design elements in a virtual reality (VR) hospital patient room affects emotional and brain responses. The purpose of this experiment was to measure interactive emotions in an experimental setting, using a combination of electroencephalogram (EEG) and VR methods. A machine learning approach and statistical analysis were applied to differentiate emotional changes related to biophilic design. Seventy-five participants were divided into three groups to investigate the distinct effects of three types of biophilic design. EEG recordings were taken during experimental conditions to determine how biophilic design affects brain and emotional states. The Positive and Negative Affect Scale (PANAS) and State-Trait Anxiety Inventory - state (STAI-s) were used to measure changes in emotion and anxiety state. The results of the machine learning application on EEG data showed that classification accuracy above 90% included the frontal region in all classification conditions, indicating that biophilic design causes changes in brain function in this region. For the classification of the control room and digital wall room, and the control room and both plant and digital wall room, alpha power for frontal regions was included with above 90% classification accuracy. The results of the statistical analysis of the EEG data found that low-frequency band, which is associated with a relaxed state, was increased by biophilic design, while high-frequency band, which is associated with high arousal state, was reduced. These findings suggested that biophilic design in a hospital room can reduce tension. The results from PANAS and STAI-s showed that biophilic design can induce positive emotional changes. The results of PANAS suggested that adding plant walls can reduce negative emotions due to their calming effect on the human nervous system. Using both plant walls and digital elements in healthcare environments can have a complementary effect on emotional well-being by reducing negative emotions while enhancing positive emotions. The study can potentially contribute to building a deeper and unified knowledge base for developing evidence-based designs to improve mental health and well-being. Moreover, the study provides insights into the potential benefits of different forms of biophilic design and their impact on human well-being.

Arousal and locomotion differently modulate activity of somatostatin neurons across cortex.

Arousal powerfully influences cortical activity, in part by modulating local inhibitory circuits. Somatostatin-expressing inhibitory interneurons (SOM) are particularly well-situated to shape local population activity in response to shifts in arousal, yet the relationship between arousal state and SOM activity has not been characterized outside of sensory cortex. To determine whether SOM activity is similarly modulated by behavioral state across different levels of the cortical processing hierarchy, we compared the behavioral modulation of SOM neurons in auditory cortex (AC), a primary sensory region, and posterior parietal cortex (PPC), an association-level region of cortex, in mice. Behavioral state modulated activity differently in AC and PPC. In PPC, transitions to high arousal were accompanied by large increases in activity across the full PPC neural population, especially in SOM neurons. In AC, arousal transitions led to more subtle changes in overall activity, as individual SOM and Non-SOM neurons could be either positively or negatively modulated during transitions to high arousal states. The coding of sensory information in population activity was enhanced during periods of high arousal in AC, but not PPC. Our findings suggest unique relationships between activity in local circuits and arousal across cortex, which may be tailored to the roles of specific cortical regions in sensory processing or the control of behavior.Significance statementThe effects of arousal on brain networks are profound, but vary across regions. Somatostatin neurons may carry out some of the effects of arousal on local network activity in sensory cortex, by modulating response gain and decorrelating population activity. However, SOM neurons have not been well studied outside of sensory cortex, and so it is unknown whether SOM neurons are similarly affected by shifts in brain state throughout the cortex. Here, we have revealed specialization in the relationship between arousal and activity in SOM neurons that could contribute to the diversity of arousal-related impacts on local computation across cortical regions.

Investigation of the Effect of Students' Nodding on Their Arousal Levels in On-Demand Lectures.

Due to COVID-19, various lecture styles are being explored. On-demand lectures are attracting increasing attention due to advantages such as being able to watch without restrictions due to location and time. In contrast, on-demand lectures have disadvantages, such as no interaction with the lecturer, so the quality of on-demand lectures should be improved. Our previous study showed that when participants nod without showing their faces in a real-time remote lecture, their heart rate state changes to arousal and nodding can increase arousal. In this paper, we hypothesize that nodding during on-demand lectures increases participants' arousal levels, and we investigate the relationship between natural and forced nodding and the level of arousal based on heart rate information. Students taking on-demand lectures rarely nod naturally, so we used entrainment to encourage nodding by showing a video of another participant nodding, and by forcing the participants to nod when the other participant nodded in the video. The results showed that only participants who nodded spontaneously changed the value of pNN50, an index of the arousal level, which reflected a state of high arousal after one minute. Thus, participants' nodding in on-demand lectures can increase their arousal levels; however, the nodding must be spontaneous, not forced.

A database of heterogeneous faces for studying naturalistic expressions

Facial expressions are thought to be complex visual signals, critical for communication between social agents. Most prior work aimed at understanding how facial expressions are recognized has relied on stimulus databases featuring posed facial expressions, designed to represent putative emotional categories (such as ‘happy’ and ‘angry’). Here we use an alternative selection strategy to develop the Wild Faces Database (WFD); a set of one thousand images capturing a diverse range of ambient facial behaviors from outside of the laboratory. We characterized the perceived emotional content in these images using a standard categorization task in which participants were asked to classify the apparent facial expression in each image. In addition, participants were asked to indicate the intensity and genuineness of each expression. While modal scores indicate that the WFD captures a range of different emotional expressions, in comparing the WFD to images taken from other, more conventional databases, we found that participants responded more variably and less specifically to the wild-type faces, perhaps indicating that natural expressions are more multiplexed than a categorical model would predict. We argue that this variability can be employed to explore latent dimensions in our mental representation of facial expressions. Further, images in the WFD were rated as less intense and more genuine than images taken from other databases, suggesting a greater degree of authenticity among WFD images. The strong positive correlation between intensity and genuineness scores demonstrating that even the high arousal states captured in the WFD were perceived as authentic. Collectively, these findings highlight the potential utility of the WFD as a new resource for bridging the gap between the laboratory and real world in studies of expression recognition.

Cortical-brainstem interplay during speech perception in older adults with and without hearing loss.

Real time modulation of brainstem frequency-following responses (FFRs) by online changes in cortical arousal state via the corticofugal (top-down) pathway has been demonstrated previously in young adults and is more prominent in the presence of background noise. FFRs during high cortical arousal states also have a stronger relationship with speech perception. Aging is associated with increased auditory brain responses, which might reflect degraded inhibitory processing within the peripheral and ascending pathways, or changes in attentional control regulation via descending auditory pathways. Here, we tested the hypothesis that online corticofugal interplay is impacted by age-related hearing loss. We measured EEG in older adults with normal-hearing (NH) and mild to moderate hearing-loss (HL) while they performed speech identification tasks in different noise backgrounds. We measured α power to index online cortical arousal states during task engagement. Subsequently, we split brainstem speech-FFRs, on a trial-by-trial basis, according to fluctuations in concomitant cortical α power into low or high α FFRs to index cortical-brainstem modulation. We found cortical α power was smaller in the HL than the NH group. In NH listeners, α-FFRs modulation for clear speech (i.e., without noise) also resembled that previously observed in younger adults for speech in noise. Cortical-brainstem modulation was further diminished in HL older adults in the clear condition and by noise in NH older adults. Machine learning classification showed low α FFR frequency spectra yielded higher accuracy for classifying listeners' perceptual performance in both NH and HL participants. Moreover, low α FFRs decreased with increased hearing thresholds at 0.5-2 kHz for clear speech but noise generally reduced low α FFRs in the HL group. Collectively, our study reveals cortical arousal state actively shapes brainstem speech representations and provides a potential new mechanism for older listeners' difficulties perceiving speech in cocktail party-like listening situations in the form of a miss-coordination between cortical and subcortical levels of auditory processing.