Do the early attentional components of ERPs reflect attentional bias in depression? It depends on the stimulus presentation time

The assessment of attentional bias to cleanliness stimuli in different versions of the dot-probe task: Evidence for a motivational account

Vogt et al. (2011) investigated the role of goal-relevance in attention. Specifically, they induced the emotional state of disgust and showed an attentional bias (AB) to goal-related stimuli (i.e., cleanliness pictures) using the dot-probe task. In two experiments, we tested (a) an alternative interpretation and (b) the role of an important methodological feature of the dot-probe task. As the effect can be interpreted alternatively as affective counter-regulation (i.e., cleanliness-related pictures attracted attention because they are positive in the negative disgust state), we added positive stimuli to test whether the AB in the disgust state extends to these stimuli. In Experiment 1, we used the location dot-probe task. That is, participants had to categorise the location of the target. It can be argued that this task confounds attentional processes with response priming processes. In Experiment 2, we used a discrimination dot-probe task, that is, participants had to categorise a target feature that varied orthogonally to location, thus eliminating the confound. In Experiment 1, we did not replicate the effect of emotional state on AB for cleanliness stimuli, whereas in Experiment 2, we did. Mean AB scores for positive stimuli were not affected by emotional state. Two conclusions were drawn: First, the result of Experiment 2 supports the motivational account of Vogt and colleagues. Second, the results support the use of the discrimination task for both theoretical reasons (i.e., effects can be more clearly interpreted as based on attentional processes) and empirical reasons (i.e., the location task did not replicate the expected pattern).

Impact of depressed state on attention and language processing during news broadcasts: EEG analysis and machine learning approach

While information enriches daily life, it can also sometimes have a negative impact, depending on an individual's mental state. We recorded electroencephalogram (EEG) signals from depressed and non-depressed individuals classified based on the Beck Depression Inventory-II score while they listened to news to clarify differences in their attention to affective information and the impact of attentional bias on language processing. Results showed that depressed individuals are characterized by delayed attention to positive news and require a more increased load on language processing. The feasibility of detecting a depressed state using these EEG characteristics was evaluated by classifying individuals as depressed and non-depressed individuals. The area under the curve in the models trained by the EEG features used was 0.73. This result shows that individuals' mental states may be assessed based on EEG measured during daily activities like listening to news.

Neurophysiological Correlates for Dynamic Variability Between Vigilance and Avoidance in Test Anxiety

Attention bias (ABs) to threat is essential in the etiology and maintenance of test anxiety. However, little is known about the attention pattern of ABs in test anxiety. The stimulus duration affects the attention pattern in anxiety. Thus, the present research combined the dot-probe paradigm and event-related potentials (ERPs) and varied the stimulus duration (100ms or 500ms) to test the ABs in test anxiety. Consequently, both groups showed a threat N2pc in 100ms and 500ms duration, suggesting that both groups allocated attention to the test-related threat. However, in the 100ms duration, the high test-anxious (HTA) group had smaller target-elicited P1 and greater target-elicited N2 in the threat-congruent condition than in the neutral condition. In the 500ms duration, an earlier threat N2pc and a threat PD followed a greater target P1, and smaller target N2 were pronounced in the HTA group. The current results provided electrophysiological evidence that the HTA group kept a dynamic attention pattern that fluctuated shift between vigilance and avoidance in the 100ms and 500ms duration. The HTA group was more vigilant than the LTA group in the 500ms duration when strategic attention was concerned, proposing that the vigilance in test anxiety was not an automatic process.

Evidence for dynamic attentional bias toward positive emotion-laden words: A behavioral and electrophysiological study

There has been no consensus on the neural dissociation between emotion-label and emotion-laden words, which remains one of the major concerns in affective neurolinguistics. The current study adopted dot-probe tasks to investigate the valence effect on attentional bias toward Chinese emotion-label and emotion-laden words. Behavioral data showed that emotional word type and valence interacted in attentional bias scores with an attentional bias toward positive emotion-laden words rather than positive emotion-label words and that this bias was derived from the disengagement difficulty in positive emotion-laden words. In addition, an attentional bias toward negative emotion-label words relative to positive emotion-label words was observed. The event-related potential (ERP) data demonstrated an interaction between emotional word type, valence, and hemisphere. A significant hemisphere effect was observed during the processing of positive emotion-laden word pairs rather than positive emotion-label, negative emotion-label, and negative emotion-laden word pairs, with positive emotion-laden word pairs eliciting an enhanced P1 in the right hemisphere as compared to the left hemisphere. Our results found a dynamic attentional bias toward positive emotion-laden words; individuals allocated more attention to positive emotion-laden words in the early processing stage and had difficulty disengaging attention from them in the late processing stage.

Negative Bias During Early Attentional Engagement in Major Depressive Disorder as Examined Using a Two-Stage Model: High Sensitivity to Sad but Bluntness to Happy Cues

Negative attentional bias has been well established in depression. However, there is very limited knowledge about whether this depression-relevant negative bias exits during initial attentional allocation, as compared with the converging evidence for the negative bias during sustained attention engagement. This study used both behavioral and electrophysiological measures to examine the initial attention engagement in depressed patients influenced by mood-congruent and mood-incongruent emotions. The dot-probe task was performed with a 100-ms exposure time of the emotional cues (emotional and neutral face pairs). The behavioral results showed that the patients responded faster following valid compared with invalid sad facial cues. Electrophysiological indexes in the frame of the two-stage model of attentional modulation by emotions provided cognitive mechanisms in distinct attention engagement stages: (1) the patients exhibited reduced P1 amplitudes following validly than invalidly happy cues than did the healthy controls, indicating a positive attenuation at an early stage of automatic attention orientation; and (2) the patients exhibited enhanced whereas the controls showed reduced P3 amplitudes following validly than invalidly sad cues, suggesting a mood-congruent negative potentiation in depression at the later stage of top-down voluntary control of attention. Depressed patients show a negative bias in early attentional allocation, reflected by preferred engagement with mood-congruent and diminished engagement with positive emotional cues/stimuli.

Physical aggression and attentional bias to angry faces: An event related potential study

This study aimed to identify the neural correlates of aggression-related attentional selectivity to angry faces in physical aggression. Physical aggression in a non-clinical sample of young men (N = 36) was measured using an aggression questionnaire. Visual attentional bias to angry faces was assessed using a dot-probe task during which angry and neutral faces were presented simultaneously, and EEG was recorded. Median split and correlational analyses were conducted to assess the relationship between physical aggression and attentional bias. Behavioural results indicated that higher levels of physical aggression were associated with greater attentional bias to angry faces. ERP results revealed an interaction where males with higher physical aggression had undifferentiated P3 amplitudes to angry and neutral trials, whereas low physical aggression males exhibited greater P3 amplitude to angry than to neutral trials (effect of probe congruency). Increased levels of physical aggression were also significantly correlated with increased P3 amplitude to probes replacing neutral faces, relative to angry faces. It was concluded that the aggressive males selectively attend to angry faces, and that attentional bias is characterized by undifferentiated P3 amplitude. We propose that this results from an inferior ability to downregulate competing angry face distractors when responding to probes replacing neutral faces (as reflected by the P3 response). These findings indicate that attentional bias to angry faces in individuals with higher physical aggression is characterized by a distinctive ERP signature; this could inform the development of therapeutic interventions seeking to reduce aggression.

Understanding associations between negatively biased attention and depression and social anxiety: positively biased attention is key

Background and objectives: Although research supports the premise that depressed and socially anxious individuals direct attention preferentially toward negative emotional cues, little is known about how attention to positive emotional cues might modulate this negative attention bias risk process. The purpose of this study was to determine if associations between attention biases to sad and angry faces and depression and social anxiety symptoms, respectively, would be strongest in individuals who also show biased attention away from happy faces. Methods: Young adults (N = 151; 79% female; M = 19.63 years) completed self-report measures of depression and social anxiety symptoms and a dot probe task to assess attention biases to happy, sad, and angry facial expressions. Results: Attention bias to happy faces moderated associations between attention to negatively valenced faces and psychopathology symptoms. However, attention bias toward sad faces was positively and significantly related to depression symptoms only for individuals who also selectively attended toward happy faces. Similarly, attention bias toward angry faces was positively and significantly associated with social anxiety symptoms only for individuals who also selectively attended toward happy faces. Conclusions: These findings suggest that individuals with high levels of depression or social anxiety symptoms attend preferentially to emotional stimuli across valences.

Early ERP components to emotional facial expressions in young adult victims of childhood maltreatment

The ability to appropriately recognize the facial expression of emotions is essential for the development of adaptive functioning. Studies suggest that maltreated children are hypersensitive to expression of anger. However, the neural mechanism of emotional face processing in young adults with a history of childhood maltreatment has yet to be explored. To explore whether the history of childhood maltreatment has a potential relationship with processing of emotional facial expressions, the present study used event-related potentials in investigating the early ERP components (P100 and N170) to the processing of emotional (angry, fearful, disgusted, and happy) faces in young adult victims of childhood maltreatment. Seventeen young adults with a history of childhood maltreatment and seventeen age and gender-matched non-maltreated participants performed a modified dot-probe task, using emotional faces paired with neutral faces. Results revealed no significant differences between maltreated group and non-maltreated group in P100 amplitude, but the N170 amplitude in the maltreated group was larger than non-maltreated group when processing angry, fearful, and happy faces. As such, this study provides biological evidence of altered neural processing of emotional facial expressions in young adults with a history of childhood maltreatment.

Attentional bias in MDD: ERP components analysis and classification using a dot-probe task

BACKGROUND AND OBJECTIVE

Strands of evidence have supported existence of negative attentional bias in patients with depression. This study aimed to assess the behavioral and electrophysiological signatures of attentional bias in major depressive disorder (MDD) and explore whether ERP components contain valuable information for discriminating between MDD patients and healthy controls (HCs).

METHODS

Electroencephalography data were collected from 17 patients with MDD and 17 HCs in a dot-probe task, with emotional-neutral pairs as experimental materials. Fourteen features related to ERP waveform shape were generated. Then, Correlated Feature Selection (CFS), ReliefF and GainRatio (GR) were applied for feature selection. For discriminating between MDDs and HCs, k-nearest neighbor (KNN), C4.5, Sequential Minimal Optimization (SMO) and Logistic Regression (LR) were used.

RESULTS

Behaviorally, MDD patients showed significantly shorter reaction time (RT) to valid than invalid sad trials, with significantly higher bias score for sad-neutral pairs. Analysis of split-half reliability in RT indices indicated a strong reliability in RT, while coefficients of RT bias scores neared zero. These behavioral effects were supported by ERP results. MDD patients had higher P300 amplitude with the probe replacing a sad face than a neutral face, indicating difficult attention disengagement from negative emotional faces. Meanwhile, data mining analysis based on ERP components suggested that CFS was the best feature selection algorithm. Especially for the P300 induced by valid sad trials, the classification accuracy of CFS combination with any classifier was above 85%, and the KNN (k = 3) classifier achieved the highest accuracy (94%).

CONCLUSIONS

MDD patients show difficulty in attention disengagement from negative stimuli, reflected by P300. The CFS over other methods leads to a good overall performance in most cases, especially when KNN classifier is used for P300 component classification, illustrating that ERP component may be applied as a tool for auxiliary diagnosis of depression.

Electrophysiological evidence of an attentional bias towards appetitive and aversive words in adults with attention-deficit/hyperactivity disorder

OBJECTIVE

Emotional dysregulation has emerged as a core symptom domain in adults with Attention-Deficit/Hyperactivity Disorder (ADHD). However, the pathophysiological underpinnings remain poorly understood. This study investigated attentional biases to positive and negative emotional words as possible contributing mechanisms.

METHODS

Event-related potentials (ERPSs) and behavioral attention bias indices were recorded from 39 adult patients with ADHD and 41 healthy controls during a verbal dot-probe task with positive-neutral, negative-neutral, and neutral-neutral word pairs.

RESULTS

Cue-locked N2pc amplitudes indicated a significant attentional bias towards emotional words in patients with ADHD and healthy controls. In healthy controls, the bias was only significant in positive trials. In patients, the bias was associated with ADHD severity and self-reported poor emotion regulation skills. ADHD patients also exhibited reduced target-locked P1 amplitudes and inferior behavioral performance compared with healthy controls.

CONCLUSIONS

Our findings provide evidence of an attention bias to positive and negative emotional stimuli in adult patients with ADHD and adverse effects of emotional stimuli on task performance.

SIGNIFICANCE

An attentional bias to emotional stimuli might contribute to emotional reactivity and dysregulation in adult patients with ADHD.

The dot-probe task to measure emotional attention: A suitable measure in comparative studies?

For social animals, attending to and recognizing the emotional expressions of other individuals is of crucial importance for their survival and likely has a deep evolutionary origin. Gaining insight into how emotional expressions evolved as adaptations over the course of evolution can be achieved by making direct cross-species comparisons. To that extent, experimental paradigms that are suitable for investigating emotional processing across species need to be developed and evaluated. The emotional dot-probe task, which measures attention allocation toward emotional stimuli, has this potential. The task is implicit, and subjects need minimal training to perform the task successfully. Findings in nonhuman primates, although scarce, show that they, like humans, have an attentional bias toward emotional stimuli. However, the wide literature on human studies has shown that different factors can have important moderating effects on the results. Due to the large heterogeneity of this literature, these moderating effects often remain unnoticed. We here review this literature and show that subject characteristics and differences in experimental designs affect the results of the dot-probe task. We conclude with specific recommendations regarding these issues that are particularly relevant to take into consideration when applying this paradigm to study animals.

Fronto-Limbic Alterations in Negatively Biased Attention in Young Adults with Subthreshold Depression

Attentional bias toward negative stimuli has been observed in major depression disorders (MDDs). Imaging studies suggest the engagement of fronto-limbic regions like amygdala, anterior cingulate cortex (ACC), and lateral prefrontal cortex, is related to negatively biased attention. However, neural correlates of attentional bias for negative stimuli in individuals with subthreshold depression (SubD), that is individuals who have clinically relevant depressive symptoms but do not fulfill the criteria for MDD, remain unclear. Here, we used functional neuroimaging and the dot-probe task to elucidate the neural substrates of negatively biased attention among individuals with SubD. Behavioral results found that individuals with SubD allocated more attention toward negative stimuli relative to neutral stimuli, which were not observed among non-depressed controls (NCs). Imaging results found greater amygdala and rostral ACC activity in attentional bias toward negative stimuli among participants with SubD compared to NCs; Additionally, participants with SubD showed reduced engagement of bilateral inferior frontal gyrus compared with NCs in the attentional processing of negative stimuli. Together, these results suggest that alteration of fronto-limbic systems relative to controls, known to be related to negative detection and attentional control, is associated with negatively biased attention in individuals with SubD.

Attentional biases in healthy adults: Exploring the impact of temperament and gender

BACKGROUND

Attentional biases such as faster attentional orienting toward negative information were consistently replicated in high-anxious and depressive individuals, but findings in healthy individuals are inconsistent so far.

METHODS

Using a dot-probe paradigm, we investigated whether temperament traits and gender, which are linked to (sub)clinical symptoms and attentional processing, influenced attentional biases in healthy adults.

RESULTS

All participants showed protective attentional biases in terms of orienting their attention away from negative information. In both genders higher values of negative affect were compensated with stronger attentional engagement with positive stimuli. This effect was more pronounced in men than in women. Effortful control fulfilled its regulative function in terms of stronger avoidance of negative stimuli only among men.

LIMITATIONS

Reaction times after probe detection provide only a snapshot of attention and allow only for an indirect assessment of visual attention. Future research should emphasize methods that allow for continuous monitoring of attention allocation, therefore results of the present study await replication in psychophysiological or eye-tracking studies.

CONCLUSION

Our results highlight the importance of considering influencing factors such as gender and temperament traits for attentional biases in healthy adults.

Temperament differentially influences early information processing in men and women: Preliminary electrophysiological evidence of attentional biases in healthy individuals

Preferential processing of threat-related information is a robust finding in anxiety disorders. The observation that attentional biases are also present in healthy individuals suggests factors other than clinical symptoms to play a role. Using a dot-probe paradigm while event-related potentials were recorded in 59 healthy adults, we investigated whether temperament and gender, both related to individual variation in anxiety levels, influence attentional processing. All participants showed protective attentional biases in terms of enhanced attention engagement with positive information, indexed by larger N1 amplitudes in positive compared to negative conditions. Taking gender differences into account, we observed that women showed enhanced attention engagement with negative compared to neutral information, indicated by larger P2 amplitudes in congruent than in incongruent negative conditions. Attentional processing was influenced by the temperament traits negative affect and effortful control. Our results emphasize that gender and temperament modulate attentional biases in healthy adults.

Reward devaluation: Dot-probe meta-analytic evidence of avoidance of positive information in depressed persons

Cognitive theories of depression and anxiety have traditionally emphasized the role of attentional biases in the processing of negative information. The dot-probe task has been widely used to study this phenomenon. Recent findings suggest that biased processing of positive information might also be an important aspect of developing psychopathological symptoms. However, despite some evidence suggesting persons with symptoms of depression and anxiety may avoid positive information, many dot-probe studies have produced null findings. The present review used conventional and novel meta-analytic methods to evaluate dot-probe attentional biases away from positive information and, for comparison, toward negative information, in depressed and anxious individuals. Results indicated that avoidance of positive information is a real effect exhibiting substantial evidential value among persons experiencing psychopathology, with individuals evidencing primary symptoms of depression clearly demonstrating this effect. Different theoretical explanations for these findings are evaluated, including those positing threat-processing structures, even-handedness, self-regulation, and reward devaluation, with the novel theory of reward devaluation emphasized and expanded. These novel findings and theory suggest that avoidance of prospective reward helps to explain the cause and sustainability of depressed states. Suggestions for future research and methodological advances are discussed.

Cognitive Bias by Gender Interaction on N170 Response to Emotional Facial Expressions in Major and Minor Depression

States of depression are considered to relate to a cognitive bias reactivity to emotional events. Moreover, gender effect may influence differences in emotional processing. The current study is to investigate whether there is an interaction of cognitive bias by gender on emotional processing in minor depression (MiD) and major depression (MaD). N170 component was obtained during a visual emotional oddball paradigm to manipulate the processing of emotional information in 33 MiD, 36 MaD, and 32 controls (CN). Compared with CN, in male, both MiD and MaD had lower N170 amplitudes for happy faces, but MaD had higher N170 amplitudes for sad faces; in female, both MiD and MaD had lower N170 amplitudes for happy and neutral faces, but higher N170 amplitudes for sad faces. Compared with MaD in male, MiD had higher N170 amplitudes for happy faces, lower N170 amplitudes for sad faces; in female, MiD only had higher N170 amplitudes for sad faces. Interestingly, a negative relationship was observed between N170 amplitude and the HDRS score for identification of happy faces in depressed patients while N170 amplitude was positively correlated with the HDRS score for sad faces identification. These results provide novel evidence for the mood-brightening effect with an interaction of cognitive bias by gender on emotional processing. It further suggests that female depression may be more vulnerable than male during emotional face processing with the unconscious negative cognitive bias and depressive syndromes may exist on a spectrum of severity on emotional face processing.

Distinct facial processing related negative cognitive bias in first-episode and recurrent major depression: evidence from the N170 ERP component

BACKGROUND

States of depression are associated with increased sensitivity to negative events. For this novel study, we have assessed the relationship between the number of depressive episodes and the dysfunctional processing of emotional facial expressions.

METHODOLOGY/PRINCIPAL FINDINGS

We used a visual emotional oddball paradigm to manipulate the processing of emotional information while event-related brain potentials were recorded in 45 patients with first episode major depression (F-MD), 40 patients with recurrent major depression (R-MD), and 46 healthy controls (HC). Compared with the HC group, F-MD patients had lower N170 amplitudes when identifying happy, neutral, and sad faces; R-MD patients had lower N170 amplitudes when identifying happy and neutral faces, but higher N170 amplitudes when identifying sad faces. F-MD patients had longer N170 latencies when identifying happy, neutral, and sad faces relative to the HC group, and R-MD patients had longer N170 latencies when identifying happy and neutral faces, but shorter N170 latencies when identifying sad faces compared with F-MD patients. Interestingly, a negative relationship was observed between N170 amplitude and the depressive severity score for identification of happy faces in R-MD patients while N170 amplitude was positively correlated with the depressive severity score for identification of sad faces in F-MD and R-MD patients. Additionally, the deficits of N170 amplitude for sad faces positively correlated with the number of depressive episodes in R-MD patients.

CONCLUSION/SIGNIFICANCE

These results provide new evidence that having more recurrent depressive episodes and serious depressive states are likely to aggravate the already abnormal processing of emotional facial expressions in patients with depression. Moreover, it further suggests that the impaired processing as indexed by N170 amplitude for positive face identification may be a potentially useful biomarker for predicting propagation of depression while N170 amplitude for negative face identification could be a potential biomarker for depression recurrence.

Neural correlates of attention to emotional facial expressions in dysphoria

The present study investigated whether dysphoric individuals have a difficulty in disengaging attention from negative stimuli and/or reduced attention to positive information. Sad, neutral and happy facial stimuli were presented in an attention-shifting task to 18 dysphoric and 18 control participants. Reaction times to neutral shapes (squares and diamonds) and the event-related potentials to emotional faces were recorded. Dysphoric individuals did not show impaired attentional disengagement from sad faces or facilitated disengagement from happy faces. Right occipital lateralisation of P100 was absent in dysphoric individuals, possibly indicating reduced attention-related sensory facilitation for faces. Frontal P200 was largest for sad faces among dysphoric individuals, whereas controls showed larger amplitude to both sad and happy as compared with neutral expressions, suggesting that dysphoric individuals deployed early attention to sad, but not happy, expressions. Importantly, the results were obtained controlling for the participants' trait anxiety. We conclude that at least under some circumstances the presence of depressive symptoms can modulate early, automatic stages of emotional processing.

Emotional facial expression processing in depression: data from behavioral and event-related potential studies

Behavioral literature investigating emotional processes in depressive populations (i.e., unipolar and bipolar depression) states that, compared to healthy controls, depressive subjects exhibit disrupted emotional processing, indexed by lower performance and/or delayed response latencies. The development of brain imaging techniques, such as functional magnetic resonance imaging (fMRI), provided the possibility to visualize the brain regions engaged in emotional processes and how they fail to interact in psychiatric diseases. However, fMRI suffers from poor temporal resolution and cognitive function involves various steps and cognitive stages (serially or in parallel) to give rise to a normal performance. Thus, the origin of a behavioral deficit may result from the alteration of a cognitive stage differently situated along the information-processing stream, outlining the importance of access to this dynamic "temporal" information. In this paper, we will illustrate, through depression, the role that should be attributed to cognitive event-related potentials (ERPs). Indeed, owing to their optimal temporal resolution, ERPs can monitor the neural processes engaged in disrupted cognitive function and provide crucial information for its treatment, training of the impaired cognitive functions and guidelines for clinicians in the choice and monitoring of appropriate medication for the patient.

The time course of the influence of valence and arousal on the implicit processing of affective pictures

In the current study, we investigated the time course of the implicit processing of affective pictures with an orthogonal design of valence (negative vs. positive) by arousal (low vs. high). Previous studies with explicit tasks suggested that valence mainly modulates early event-related potential (ERP) components, whereas arousal mainly modulates late components. However, in this study with an implicit task, we observed significant interactions between valence and arousal at both early and late stages over both parietal and frontal sites, which were reflected by three different ERP components: P2a (100-200 ms), N2 (200-300 ms), and P3 (300-400 ms). Furthermore, there was also a significant main effect of arousal on P2b (200-300 ms) over parieto-occipital sites. Our results suggest that valence and arousal effects on implicit affective processing are more complicated than previous ERP studies with explicit tasks have revealed.

Functional anomalies in healthy individuals with a first degree family history of major depressive disorder

BACKGROUND

Individuals with major depressive disorder (MDD) process information with a bias towards negative stimuli. However, little is known on the link between vulnerability to MDD and brain functional anomalies associated with stimulus bias.

METHODS

A cohort of 38 subjects, of which 14 were patients with acute MDD and 24 were healthy controls (HC), were recruited and compared. The HC group included 10 healthy participants with a first degree family history of depression (FHP) and 14 volunteers with no family history of any psychiatric disease (FHN). Blood oxygen level dependence signals were acquired from functional magnetic resonance imaging (fMRI) during performance in a dot-probe task using fearful and neutral stimuli. Reaction times and the number of errors were also obtained.

RESULTS

Although MDD patients and HC showed no behavioral difference, the MDD group exhibited smaller activation in the left middle cingulum. The MDD group also showed smaller activation in the left insula when compared to the HC group or the FHN group. Finally, FHP participants exhibited higher activation in the right Heschl's gyrus compared to FHN participants.

CONCLUSIONS

The present study shows that family risk for MDD is associated with increased activation in the Heschl's gyrus. Our results also suggest that acute MDD is linked to reduced activation in the insula and anterior cingulate cortex during processing of subliminal, not recognizable, masked fearful stimuli. Further research should confirm these results in a larger cohort of participants.