Adaptation of Threat Responses Within the Negative Valence Framework

Neural circuit basis of pathological anxiety

Anxiety disorders are the most prevalent mental health conditions worldwide. Unfortunately, the understanding of the precise neurobiological mechanisms that underlie these disorders remains limited. Current diagnostic classifications, based on observable symptoms rather than underlying pathophysiology, do not capture the heterogeneity within and across anxiety disorders. Recent advances in functional neuroimaging have provided new insights into the neural circuits implicated in pathological anxiety, revealing dysfunctions that cut across traditional diagnostic boundaries. In this Review, we synthesize evidence that highlights abnormalities in neurobehavioural systems related to negative valence, positive valence, cognitive systems and social processes. We emphasize that pathological anxiety arises not only from heightened reactivity in acute threat ('fear') circuits but also from alterations in circuits that mediate distant (potential) and sustained threat, reward processing, cognitive control and social processing. We discuss how circuit vulnerabilities can lead to the emergence and maintenance of pathological anxiety. Once established, these neural abnormalities can be exacerbated by maladaptive behaviours that prevent extinction learning and perpetuate anxiety disorders. By delineating the specific neural mechanisms in each neurobiological system, we aim to contribute to a more comprehensive understanding of the neurobiology of anxiety disorders, potentially informing future research directions in this field.

Effects of bottom-up and top-down attentional processes on change blindness for COVID-related stimuli: influence of heart rate variability

Introduction

Top-down mechanisms that regulate attentional control are influenced by task demands and individuals' goals, while bottom-up processes are influenced by salient stimuli. Analogous networks are involved in both processes (e.g., frontostriatal areas). However, they are affected differently by the emotional salience of stimuli, which determines the allocation of attention. This study aims to determine whether the recent pandemic experience continues to exert an influence on cognitive processes. To this end, the study will determine attentional biases toward pandemic-related stimuli compared to negative and neutral stimuli. Furthermore, the study will investigate whether pandemic-related stimuli influence top-down and bottom-up attentional processes and whether the latter affect autonomic control as indexed by Heart Rate Variability (HRV).

Methods

Ninety-six undergraduate students completed a Flicker Task with stimuli categorized by emotional valence (neutral, negative non-COVID, negative COVID-related). This paradigm involves the presentation of two different pictures, which are identical except for a specific detail. The task required to detect the specific detail that has been changed. Given that the task employs images of natural scenes, participants tend to focus more on specific areas of the scene than others. As a result, changes in central interest (CI) areas are detected more rapidly than changes in marginal interest (MI) areas. Participants' response times (RTs) at the task and their HRV data were used to assess attentional performance and the associated autonomic nervous system activity.

Results

The results indicate slower responses to COVID-related stimuli than negative and neutral stimuli for both CI and MI changes, requiring the involvement of bottom-up (CI changes) and top-down (MI changes) processes. The HRV was associated with a slower detection of CI changes in COVID-related scenes.

Discussion

These findings highlight the intricate interplay between emotional salience, attentional mechanisms, and physiological responses to threatening stimuli. Contextual factors, particularly those related to pandemic-related stress, influence attentional processing and its relationship with autonomic activity.

Fear, defense, and emotion: A neuroethological understanding of the negative valence research domain criteria

We describe the close correspondence between predatory imminence continuum theory (PICT) and the National Institute of Mental Health's Research Domain Criteria (RDoC) for negative valence. RDoC's negative valence constructs relate aversively motivated behavioral reactions to various levels of threat. PICT divides defensive responses into distinct modes that vary along a continuum of the psychological closeness of predatory threat. While there is a close correspondence between PICT modes and negative valence threat constructs, based on PICT, we describe some potential elaborations of RDoC constructs. Both have consonant views of fear and anxiety and provide explicit distinctions between these emotional states, relating them to specific defensive behaviors and functions. We describe recent data that causally implicate human subjective emotional states with amygdala activity, which is also critical for defensive behavior. We conclude that attention to neuroethological views of defense can advance our understanding of the etiology and treatment of anxiety and stress disorders. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Decoding the language of fear: Unveiling objective and subjective indicators in rodent models through a systematic review and meta-analysis

While rodent models are vital for studying mental disorders, the underestimation of construct validity of fear indicators has led to limitations in translating to effective clinical treatments. Addressing this gap, we systematically reviewed 5054 articles from the 1960 s, understanding underlying theoretical advancement, and selected 68 articles with at least two fear indicators for a three-level meta-analysis. We hypothesized correlations between different indicators would elucidate similar functions, while magnitude differences could reveal distinct neural or behavioral mechanisms. Our findings reveal a shift towards using freezing behavior as the primary fear indicator in rodent models, and strong, moderate, and weak correlations between freezing and conditioned suppression ratios, 22-kHz ultrasonic vocalizations, and autonomic nervous system responses, respectively. Using freezing as a reference, moderator analysis shows treatment types and fear stages significantly influenced differences in magnitudes between two indicators. Our analysis supports a two-system model of fear in rodents, where objective and subjective fears could operate on a threshold-based mechanism.

Entrance-sealing behavior in the home cage: a defensive response to potential threats linked to the serotonergic system and manifestation of repetitive/stereotypic behavior in mice

The security of animal habitats, such as burrows and nests, is vital for their survival and essential activities, including eating, mating, and raising offspring. Animals instinctively exhibit defensive behaviors to protect themselves from imminent and potential threats. In 1963, researchers reported wild rats sealing the entrances to their burrows from the inside using materials such as mud, sand, and vegetation. This behavior, known as "entrance sealing (ES)," involves repetitive movements of their nose/mouth and forepaws and is likely a proactive measure against potential intruders, which enhances burrow security. These observations provide important insights into the animals' ability to anticipate potential threats that have not yet occurred and take proactive actions. However, this behavior lacks comprehensive investigation, and the neural mechanisms underpinning it remain unclear. Hypothalamic perifornical neurons expressing urocortin-3 respond to novel objects/potential threats and modulate defensive responses to the objects in mice, including risk assessment and burying. In this study, we further revealed that chemogenetic activation of these neurons elicited ES-like behavior in the home-cage. Furthermore, behavioral changes caused by activating these neurons, including manifestations of ES-like behavior, marble-burying, and risk assessment/burying of a novel object, were effectively suppressed by selective serotonin-reuptake inhibitors. The c-Fos analysis indicated that ES-like behavior was potentially mediated through GABAergic neurons in the lateral septum. These findings underscore the involvement of hypothalamic neurons in the anticipation of potential threats and proactive defense against them. The links of this security system with the manifestation of repetitive/stereotypic behaviors and the serotonergic system provide valuable insights into the mechanisms underlying the symptoms of obsessive-compulsive disorder.

Negative valence systems: sustained threat and the predatory imminence continuum

This review describes the relationship between the National Institute of Mental Health (U.S.A.) Research Domain Criteria (RDoC) Negative Valence System related to responses to threat and the Predatory Imminence Continuum model of antipredator defensive behavior. While the original RDoC constructs of Potential Threat (anxiety) and Acute Threat (fear) fit well with the pre-encounter and post-encounter defense modes of the predatory imminence model, the Sustained Threat construct does not. Early research on the bed nuclei of the stria terminalis (BST) suggested that when fear responding needed to be sustained for a prolonged duration this region was important. However, follow-up studies indicated that the BST becomes critical not because responses needed to be sustained but rather when the stimuli triggering fear were more difficult to learn about, particularly when aversive stimuli were difficult to accurately predict. Instead, it is argued that the BST and the hippocampus act to expand the range of conditions that can trigger post-encounter defense (Acute Threat). It is further suggested that sustained threat refers to situations where the predatory imminence continuum becomes distorted causing defensive behavior to intrude into times when organisms should be engaging in other adaptive behaviors. Stress is seen as something that can cause a long-term disturbance of the continuum and this disturbance is a state of sustained threat.