Adapting behavior to environmental demands is a fundamental aspect of survival. In the face of unfamiliar potential dangers, organisms display a wide range of defensive mechanisms, such as using contextual information to prepare for upcoming threats and extrapolating from previous experiences with similar encounters. Importantly, these different types of threat-related information place distinct demands on the attentional system, potential, context-related threat induces a state of hypervigilance, whereas imminent, acute threat requires selective attention. While these individual mechanisms are increasingly well understood, their interactions remain elusive, particularly at the neurophysiological level. Therefore, the current study aimed to orthogonally combine threat generalization with aversive contextual information and measure correlates of defensive behavior on a subjective, autonomic, and electrocortical level. Fifty-two human participants completed a threat generalization paradigm followed by a context phase in which the conditioned visual cues were presented against aversive or neutral background images, respectively. Results revealed successful threat generalization for subjective and pupillary responses with overall heightened responses for cues presented in aversive compared to neutral contexts. For visuocortical activity as measured by steady-state visually evoked potentials, this response pattern was separated into different frequencies. While the fundamental frequency showed the general main effect of aversive contexts, the second harmonic followed a generalization gradient, suggesting a segregation of competing attentional demands via neural harmonics. Together, these findings provide new insights into adaptive defensive behavior in complex situations, characterized by an additive model of different defensive processes.
Anxiety is characterized by anxious anticipation and heightened vigilance to uncertain threat. However, if threat is not reliably indicated by a specific cue, the context in which threat was previously experienced becomes its best predictor, leading to anxiety. A suitable means to induce anxiety experimentally is context conditioning. In one context (CTX+), an unpredictable aversive stimulus (US) is repeatedly presented, in contrast to a second context (CTX−), in which no US is ever presented. In this EEG study, we investigated attentional mechanisms during acquisition and extinction learning in 38 participants, who underwent a context conditioning protocol. Flickering video stimuli (32 s clips depicting virtual offices representing CTX+/−) were used to evoke steady-state visual evoked potentials (ssVEPs) as an index of visuocortical engagement with the contexts. Analyses of the electrocortical responses suggest a successful induction of the ssVEP signal by video presentation in flicker mode. Furthermore, we found clear indices of context conditioning and extinction learning on a subjective level, while cortical processing of the CTX+ was unexpectedly reduced during video presentation. The differences between CTX+ and CTX− diminished during extinction learning. Together, these results indicate that the dynamic sensory input of the video presentation leads to disruptions in the ssVEP signal, which is greater for motivationally significant, threatening contexts.
Fear and anxiety are crucial for adaptive responding in life-threatening situations. Whereas fear is a phasic response to an acute threat accompanied by selective attention, anxiety is characterized by a sustained feeling of apprehension and hypervigilance during situations of potential threat. In the current literature, fear and anxiety are usually considered mutually exclusive, with partially separated neural underpinnings. However, there is accumulating evidence that challenges this distinction between fear and anxiety, and simultaneous activation of fear and anxiety networks has been reported. Therefore, the current study experimentally tested potential interactions between fear and anxiety. Fifty-two healthy participants completed a differential fear conditioning paradigm followed by a test phase in which the conditioned stimuli were presented in front of threatening or neutral contextual images. To capture defense system activation, we recorded subjective (threat, US-expectancy), physiological (skin conductance, heart rate) and visuocortical (steady-state visual evoked potentials) responses to the conditioned stimuli as a function of contextual threat. Results demonstrated successful fear conditioning in all measures. In addition, threat and US-expectancy ratings, cardiac deceleration, and visuocortical activity were enhanced for fear cues presented in threatening compared with neutral contexts. These results are in line with an additive or interactive rather than an exclusive model of fear and anxiety, indicating facilitated defensive behavior to imminent danger in situations of potential threat.
Measures of visuocortical activity during aversive generalization learning revealed sharpened representations of facial identity, reflecting inhibitory interactions between neuronal populations that represent facial features associated with threat versus safety.
In this study we compared steady-state visual evoked potentials during the NPU-threat task between high and low anxious individuals. All participants allocated increased attentional resources to the central P-threat cue, replicating previous findings. Importantly, LA individuals exhibited larger ssVEP amplitudes to contextual threat (U and P) than to contextual safety cues, while HA individuals did not differentiate among contextual cues in general. These findings support the notion of aberrant sensory processing of unpredictable threat in anxiety disorders, as this processing pattern is already evident in individuals at risk of these disorders