Content Of Stimuli Research Articles

The effects of oxytocin on primates’ working memory depend on the emotional valence of contextual factors

Current models suggest that neuropeptide oxytocin modulates the salience of emotional/social stimuli and consequently influences perceptual, attentional and learning processes that underlie social behaviour. Therefore, oxytocin has been considered as a potential treatment in managing social and communication deficits in neuropsychological disorders. Recent studies indicate that effects of oxytocin on social and cognitive functions greatly vary and even lead to opposite outcomes. The factors leading to such variabilities in behavioural effects of oxytocin and their underlying mechanisms remain unclear.Here, we examined the effects of exogenously administered (intranasal) oxytocin (48 IU) on cognitive functions of macaque monkeys within a controlled experimental condition in a randomized crossover study.Monkeys performed a working memory task in which they memorized and subsequently matched stimuli with different emotional/social content (positive, negative, and neutral) at different levels of cognitive difficulties (delay period). Monkeys’ accuracy was lower at longer delay intervals indicating that higher cognitive demands adversely affected their performance. There was a significant difference in accuracy and response time between the three emotional conditions. The effects of oxytocin on monkeys’ performance were dependent on the emotional content of stimuli so that oxytocin enhanced the adverse effects of negative stimuli, however, moderated the effects of positive stimuli. Our findings in monkeys do not support models suggesting a general effect of oxytocin in enhancing salience or heightening of attention to social stimuli and instead suggest that the cognitive effects of oxytocin depend on the emotional valence of contextual factors.

Spatial attention affects the early processing of neutral versus fearful faces when they are task-irrelevant: a classifier study of the EEG C1 component.

EEG studies suggest that the emotional content of visual stimuli is processed rapidly. In particular, the C1 component, which occurs up to 100 ms after stimulus onset and likely reflects activity in primary visual cortex V1, has been reported to be sensitive to emotional faces. However, difficulties replicating these results have been reported. We hypothesized that the nature of the task and attentional condition are key to reconcile the conflicting findings. We report three experiments of EEG activity during the C1 time range elicited by peripherally presented neutral and fearful faces under various attentional conditions: the faces were spatially attended or unattended and were either task-relevant or not. Using traditional event-related potential analysis, we found that the early activity changed depending on facial expression, attentional condition, and task. In addition, we trained classifiers to discriminate the different conditions from the EEG signals. Although the classifiers were not able to discriminate between facial expressions in any condition, they uncovered differences between spatially attended and unattended faces but solely when these were task-irrelevant. In addition, this effect was only present for neutral faces. Our study provides further indication that attention and task are key parameters when measuring early differences between emotional and neutral visual stimuli.

Imagine squeezing a cactus: Cortical activation during affective motor imagery measured by functional near-infrared spectroscopy

The activation of different brain areas during kinaesthetic and visual motor imagery has been extensively studied, whereas little is known about affective motor imagery, i.e. the imagery of pleasant/unpleasant movements. In the present neuroimaging study we investigated cortical activation of kinaesthetic motor imagery (KMI) based on emotional stimulus content by means of functional near infrared spectroscopy (fNIRS). Twenty healthy adult participants were instructed to imagine affective, and neutral motor tasks while multichannel fNIRS was recorded simultaneously. In the affective MI condition they had to imagine e.g. squeezing a cactus with their right hand several times, eliciting an unpleasant emotion. In the neutral condition their task was to imagine squeezing a ball. Significant differences in oxy-hemoglobin [oxy-Hb] concentration changes during KMI including affective objects in different brain regions were found. Specifically activation in left parietal and frontal regions was increased during the imagery of squeezing a cactus which induced a painful feeling. Both areas are also involved in the perception of pain and commonly labelled as parts of the “pain matrix”. Our study provides novel insights in cortical activation patterns during affective motor imagery and its psychological and cognitive mechanisms underlying pain experience.

EEG discrimination of perceptually similar tastes.

Perceptually similar stimuli, despite not being consciously distinguishable, may result in distinct cortical brain activations. Hypothesizing that perceptually similar tastes are discriminable by electroencephalography (EEG), we recorded 22 human participants’ response to equally intense sweet‐tasting stimuli: caloric sucrose, low‐caloric aspartame, and a low‐caloric mixture of aspartame and acesulfame K. Time‐resolved multivariate pattern analysis of the 128‐channel EEG was used to discriminate the taste responses at single‐trial level. Supplementing the EEG study, we also performed a behavioral study to assess the participants’ perceptual ability to discriminate the taste stimuli by a triangle test of all three taste pair combinations. The three taste stimuli were found to be perceptually similar or identical in the behavioral study, yet discriminable from 0.08 to 0.18 s by EEG analysis. Comparing the participants’ responses in the EEG and behavioral study, we found that brain responses to perceptually similar tastes are discriminable, and we also found evidence suggesting that perceptually identical tastes are discriminable by the brain. Moreover, discriminability of brain responses was related to individual participants’ perceptual ability to discriminate the tastes. We did not observe a relation between brain response discriminability and calorie content of the taste stimuli. Thus, besides demonstrating discriminability of perceptually similar and identical tastes with EEG, we also provide the first proof of a functional relation between brain response and perception of taste stimuli at individual level.

Face Repetition Probability Does Not Affect Repetition Suppression in Macaque Inferotemporal Cortex.

Repetition suppression, which refers to reduced neural activity for repeated stimuli, is typically explained by bottom-up or local adaptation mechanisms. However, recent theories have emphasized the role of top-down processes, suggesting that this response reduction reflects the fulfillment of perceptual expectations. To support this, an influential human fMRI study showed that the magnitude of suppression is modulated by the probability of a repetition. No such repetition probability effect was found in macaque inferior temporal (IT) cortex for spiking activity despite the presence of repetition suppression. Contrary to the human fMRI studies that showed an effect of repetition probability, the macaque single-unit study used a large variety of unfamiliar stimuli and the monkeys were not required to attend the stimuli. Here, as in the human fMRI studies, we used faces as stimuli and made the monkeys attend to the stimulus content. We simultaneously recorded spiking activity and local field potentials (LFPs) in the middle lateral face patch (ML) of one monkey (male) and a face-responsive region of another (female). Although we observed significant repetition suppression of spiking activity and high gamma-band LFPs in both animals, there were no effects of repetition probability even when repetitions were task relevant and repetition probability affected behavioral decisions. In conclusion, despite the use of face stimuli and a stimulus-related task, no neural signature of repetition probability was present for faces in a face responsive patch of macaque IT. This further challenges a general perceptual expectation account of repetition suppression.SIGNIFICANCE STATEMENT Repetition suppression is a reduced brain activity for repeated stimuli commonly observed across species. In the predictive coding framework, such suppression is thought to reflect fulfilled perceptual expectations. Although this hypothesis is supported by several human fMRI studies reporting an effect of repetition probability on repetition suppression, this could not be replicated in single-cell recordings in monkey inferior temporal (IT) cortex. Subsequent studies narrowed down the conditions for the effect to requiring attention and being limited to particular stimulus categories such as faces. Here, we show that, even under these conditions, repetition suppression in monkey IT neurons is still unaffected by repetition probability, even in a task with a behavioral effect, challenging the perceptual expectation account of repetition suppression.

Effects of social and affective content on exogenous attention as revealed by event-related potentials

ABSTRACTThe social content of affective stimuli has been proposed as having an influence on cognitive processing and behaviour. This research was aimed, therefore, at studying whether automatic exogenous attention demanded by affective pictures was related to their social value. We hypothesised that affective social pictures would capture attention to a greater extent than non-social affective stimuli. For this purpose, we recorded event-related potentials in a sample of 24 participants engaged in a digit categorisation task. Distracters were affective pictures varying in social content, in addition to affective valence and arousal, which appeared in the background during the task. Our data revealed that pictures depicting high social content captured greater automatic attention than other pictures, as reflected by the greater amplitude and shorter latency of anterior P2, and anterior and posterior N2 components of the ERPs. In addition, social content also provoked greater allocation of processing resources as manifested by P3 amplitude, likely related to the high arousal they elicited. These results extend data from previous research by showing the relevance of the social value of the affective stimuli on automatic attentional processing.

Neural Correlates of Emotion Processing in Word Detection Task.

In our previous study, we have proposed a three-stage model of emotion processing; in the current study, we investigated whether the ERP component may be different when the emotional content of stimuli is task-irrelevant. In this study, a dual-target rapid serial visual presentation (RSVP) task was used to investigate how the emotional content of words modulates the time course of neural dynamics. Participants performed the task in which affectively positive, negative, and neutral adjectives were rapidly presented while event-related potentials (ERPs) were recorded from 18 undergraduates. The N170 component was enhanced for negative words relative to positive and neutral words. This indicates that automatic processing of negative information occurred at an early perceptual processing stage. In addition, later brain potentials such as the late positive potential (LPP) were only enhanced for positive words in the 480–580-ms post-stimulus window, while a relatively large amplitude signal was elicited by positive and negative words between 580 and 680 ms. These results indicate that different types of emotional content are processed distinctly at different time windows of the LPP, which is in contrast with the results of studies on task-relevant emotional processing. More generally, these findings suggest that a negativity bias to negative words remains to be found in emotion-irrelevant tasks, and that the LPP component reflects dynamic separation of emotion valence.

Post-error Brain Activity Correlates With Incidental Memory for Negative Words.

The present study had three main objectives. First, we aimed to evaluate whether short-duration affective states induced by negative and positive words can lead to increased error-monitoring activity relative to a neutral task condition. Second, we intended to determine whether such an enhancement is limited to words of specific valence or is a general response to arousing material. Third, we wanted to assess whether post-error brain activity is associated with incidental memory for negative and/or positive words. Participants performed an emotional stop-signal task that required response inhibition to negative, positive or neutral nouns while EEG was recorded. Immediately after the completion of the task, they were instructed to recall as many of the presented words as they could in an unexpected free recall test. We observed significantly greater brain activity in the error-positivity (Pe) time window in both negative and positive trials. The error-related negativity amplitudes were comparable in both the neutral and emotional arousing trials, regardless of their valence. Regarding behavior, increased processing of emotional words was reflected in better incidental recall. Importantly, the memory performance for negative words was positively correlated with the Pe amplitude, particularly in the negative condition. The source localization analysis revealed that the subsequent memory recall for negative words was associated with widespread bilateral brain activity in the dorsal anterior cingulate cortex and in the medial frontal gyrus, which was registered in the Pe time window during negative trials. The present study has several important conclusions. First, it indicates that the emotional enhancement of error monitoring, as reflected by the Pe amplitude, may be induced by stimuli with symbolic, ontogenetically learned emotional significance. Second, it indicates that the emotion-related enhancement of the Pe occurs across both negative and positive conditions, thus it is preferentially driven by the arousal content of an affective stimuli. Third, our findings suggest that enhanced error monitoring and facilitated recall of negative words may both reflect responsivity to negative events. More speculatively, they can also indicate that post-error activity of the medial prefrontal cortex may selectively support encoding for negative stimuli and contribute to their privileged access to memory.

Age differences in regulating negative emotions via attentional deployment.

Although past theoretical work has proposed age-related gains in emotion regulation, the empirical evidence is not entirely consistent. In two laboratory studies, we investigated age differences in regulating negative emotions through attentional deployment by instructing participants to direct their attention either toward negative (up-regulation) or neutral (down-regulation) pictorial content. The regulation process (visual attention) was measured via eye-tracking and the regulation outcome (emotional experience) was assessed via self-report. We tested emotional arousal and attentional functioning as factors that may affect age differences in attentional deployment. The main analyses revealed that, first, during down-regulation trials, older adults were less likely to direct their attention toward neutral stimulus content than younger adults, but did not experience greater unpleasantness than younger adults. This indicates that older adults may use attentional deployment more efficiently to decrease negative emotions than younger adults. Second, emotional arousal did not affect age differences in emotion regulation process and outcome. Third, we obtained preliminary evidence that for older but not for younger adults, low cognitive control may impair the implementation of attentional deployment. Additional findings suggested that neither younger nor older adults were able to increase unpleasantness by attending toward negative stimulus content. Together, these findings suggest multidirectional age differences in attentional deployment process and outcome and underline the importance of considering age-related vulnerabilities in predicting changes in emotion regulations across the life span. (PsycINFO Database Record

Effects of Instructions on the Early Stages of the Visual Perception of Verbal Stimuli in Health and Schizophrenia

We report here studies of the early stages in the selection of meaningful and meaningless verbal information in one implicit and two explicit tasks on the latency and amplitude of the P100 component of event-related potentials in healthy subjects (n = 99) and patients with schizophrenia in the first psychotic episode (n = 102). Schizophrenia patients displayed greater impairment to the passive perception of meaningful verbal information. Giving instructions made no difference to the properties of the P100 wave from those in healthy subjects. A decrease in the amplitude of the P100 component on perception of words in passive observation conditions seen in patients may be linked with the severity of hallucinations. The relationships of the P100 wave showed that provision of instructions, as compared with passive perception, decreased the time taken for primary analysis of stimuli in healthy subjects regardless of category and relevance, while this occurred only on reading pseudowords in schizophrenia patients. The results obtained here provide evidence of impairments to the automatic attraction of attention to the semantically significant content of verbal stimuli. The studies reported here demonstrated a link between the properties of the P100 wave and behavioral parameters.

Aberrant Cortical Event-Related Potentials During Associative Learning in Rat Models for Presymptomatic Stages of Alzheimer's Disease.

Trace eyeblink conditioning is a hippocampus-dependent associative learning paradigm which is impaired in patients with Alzheimer's disease (AD) and animal AD models. Learning in this paradigm accompanies changes in oscillatory activity in forebrain regions, some of which are loci of pathogenic changes in prodromal AD stages. These observations motivated us to examine how cortical event-related potentials (ERPs) during this paradigm are affected by two features of the asymptomatic, AD-related brain abnormality, entorhinal tau accumulation and mild cholinergic deficit. Adult rats received viral overexpression of P301L mutant human tau in the entorhinal cortex, low-dose scopolamine treatment, or both. Electroencephalograms were recorded with epidural electrodes on the surface of the frontal, parietal, and temporal cortices during differential and reversal trace eyeblink conditioning. All rats developed conditioned responses to one of two stimuli (auditory or visual) paired with mild eyelid shock (CS+), but not to the other stimulus presented alone(CS-). They were also able to adjust the response when the stimulus contingency was reversed. With learning, the amplitude of several ERP components in the frontal and temporal cortices came to differentiate the CS+ from CS-. Scopolamine affected the learning-related change in temporal P2 and other learning-unrelated components in three regions. Entorhinal tau overexpression primary affected the amplitude of temporal visual ERPs and learning-unrelated frontal and temporal auditory ERP components. The double manipulation only affected two components of temporal auditory ERPs. Thus, cortical ERPs during differential associative learning are sensitive to asymptomatic brain abnormality associated with AD.

Is the sunny side up and the dark side down? Effects of stimulus type and valence on a spatial detection task

ABSTRACTIn verbal communication, affective information is commonly conveyed to others through spatial terms (e.g. in “I am feeling down”, negative affect is associated with a lower spatial location). This study used a target location discrimination task with neutral, positive and negative stimuli (words, facial expressions, and vocalizations) to test the automaticity of the emotion-space association, both in the vertical and horizontal spatial axes. The effects of stimulus type on emotion-space representations were also probed. A congruency effect (reflected in reaction times) was observed in the vertical axis: detection of upper targets preceded by positive stimuli was faster. This effect occurred for all stimulus types, indicating that the emotion-space association is not dependent on sensory modality and on the verbal content of affective stimuli.

Impact of affective picture and music stimuli on autonomic responses: characterisation of pauses between emotion blocks

The main goal of this study was to investigate the role of stimulus contents on physiological responses. Usually some pauses between the incentives are considered in an experiment to bring the physiological signals to the base. However, the role of these halts on emotional responses has not been carefully evaluated so far. Therefore, in the current study the effect of pauses between emotional blocks of an inducement was inspected. To this effect, autonomic signals were recorded using two emotion elicitation paradigms: image induction and music excerpts. Several standard and nonlinear features were extracted. The Mann-Whitney U-test was employed to determine the significant differences between the pause segments and rest condition. The results of this study indicated that pause duration between affective blocks of stimuli has a great impact on the emotional autonomic responses. The importance of specialised protocol designing for a specific biomedical signal is concluded from the findings.

Impact of affective picture and music stimuli on autonomic responses: characterisation of pauses between emotion blocks

The main goal of this study was to investigate the role of stimulus contents on physiological responses. Usually some pauses between the incentives are considered in an experiment to bring the physiological signals to the base. However, the role of these halts on emotional responses has not been carefully evaluated so far. Therefore, in the current study the effect of pauses between emotional blocks of an inducement was inspected. To this effect, autonomic signals were recorded using two emotion elicitation paradigms: image induction and music excerpts. Several standard and nonlinear features were extracted. The Mann-Whitney U-test was employed to determine the significant differences between the pause segments and rest condition. The results of this study indicated that pause duration between affective blocks of stimuli has a great impact on the emotional autonomic responses. The importance of specialised protocol designing for a specific biomedical signal is concluded from the findings.

Temporal neural mechanisms underlying conscious access to different levels of facial stimulus contents.

An important issue facing the empirical study of consciousness concerns how the contents of incoming stimuli gain access to conscious processing. According to classic theories, facial stimuli are processed in a hierarchical manner. However, it remains unclear how the brain determines which level of stimulus content is consciously accessible when facing an incoming facial stimulus. Accordingly, with a magnetoencephalography technique, this study aims to investigate the temporal dynamics of the neural mechanism mediating which level of stimulus content is consciously accessible. Participants were instructed to view masked target faces at threshold so that, according to behavioral responses, their perceptual awareness alternated from consciously accessing facial identity in some trials to being able to consciously access facial configuration features but not facial identity in other trials. Conscious access at these two levels of facial contents were associated with a series of differential neural events. Before target presentation, different patterns of phase angle adjustment were observed between the two types of conscious access. This effect was followed by stronger phase clustering for awareness of facial identity immediately during stimulus presentation. After target onset, conscious access to facial identity, as opposed to facial configural features, was able to elicit more robust late positivity. In conclusion, we suggest that the stages of neural events, ranging from prestimulus to stimulus-related activities, may operate in combination to determine which level of stimulus contents is consciously accessed. Conscious access may thus be better construed as comprising various forms that depend on the level of stimulus contents accessed. NEW & NOTEWORTHY The present study investigates how the brain determines which level of stimulus contents is consciously accessible when facing an incoming facial stimulus. Using magnetoencephalography, we show that prestimulus activities together with stimulus-related activities may operate in combination to determine conscious face detection or identification. This finding is distinct from the previous notion that conscious face detection precedes identification and provides novel insights into the temporal dynamics of different levels of conscious face perception.

The role of the cerebellum in explicit and incidental processing of facial emotional expressions: A study with transcranial magnetic stimulation

Growing evidence suggests that the cerebellum plays a critical role in non-motor functions, contributing to cognitive and affective processing. In particular, the cerebellum might represent an important node of the “limbic” network, underlying not only emotion regulation but also emotion perception and recognition. Here, we used transcranial magnetic stimulation (TMS) to shed further light on the role of the cerebellum in emotional perception by specifically testing cerebellar contribution to explicit and incidental emotional processing. In particular, in three different experiments, we found that TMS over the (left) cerebellum impaired participants’ ability to categorize facial emotional expressions (explicit task) and to classify the gender of emotional faces (incidental emotional processing task), but not the gender of neutral faces. Overall, our results indicate that the cerebellum is involved in perceiving the emotional content of facial stimuli, even when this is task irrelevant.

The Effects of Cognitive Reappraisal and Expressive Suppression on Memory of Emotional Pictures.

In the field of emotion research, the influence of emotion regulation strategies on memory with emotional materials has been widely discussed in recent years. However, existing studies have focused exclusively on regulating negative emotion but not positive emotion. Therefore, in the present study, we investigated the influence of emotion regulation strategies for positive emotion on memory. One hundred and twenty college students were selected as participants. Emotional pictures (positive, negative and neutral) were selected from Chinese Affective Picture System (CAPS) as experimental materials. We employed a mixed, 4 (emotion regulation strategies: cognitive up-regulation, cognitive down-regulation, expressive suppression, passive viewing) × 3 (emotional pictures: positive, neutral, negative) experimental design. We investigated the influences of different emotion regulation strategies on memory performance, using free recall and recognition tasks with pictures varying in emotional content. The results showed that recognition and free recall memory performance of the cognitive reappraisal groups (up-regulation and down-regulation) were both better than that of the passive viewing group for all emotional pictures. No significant differences were reported in the two kinds of memory scores between the expressive suppression and passive viewing groups. The results also showed that the memory performance with the emotional pictures differed according to the form of memory test. For the recognition test, participants performed better with positive images than with neutral images. Free recall scores with negative images were higher than those with neutral images. These results suggest that both cognitive reappraisal regulation strategies (up-regulation and down-regulation) promoted explicit memories of the emotional content of stimuli, and the form of memory test influenced performance with emotional pictures.

Do Pavlovian Processes Really Mediate Behavioral Momentum? Some Conflicting Issues

According to the behavioral momentum theory of response strength (Nevin et al., Journal of the Experimental Analysis of Behavior, 53, 359–379, 1990), steady-state responding reflects the contingency between a response and a reinforcer (response–reinforcer relationship), whereas behavior’s resistance to change is mediated by a contingency between a stimulus and the reinforcer (stimulus–reinforcer relationship). It is further presumed in this theory that a Pavlovian conditioned stimulus (CS)–unconditioned stimulus (US) contingency overlaps with the discriminative stimulus (SD), signaling a primary reinforcer (SR+) within the 3-term contingency (SD: response [R]–SR+). The mere arranging of a stimulus–reinforcer relation in an operant preparation, however, does not necessarily imply that the resulting behavioral process is Pavlovian. This article questions how important such Pavlovian CS–SR+ relations really are in governing operant behavior and its resistance to change in view of evidence from the operant and Pavlovian literatures showing dissociation between Pavlovian and operant stimulus control. To this end, we highlight studies published in the Pavlovian associative literature (Holman and Mackintosh, The Quarterly Journal of Experimental Psychology Section B: Comparative and Physiological Psychology, 33, 21–31, 1981; Rescorla, Current Directions in Psychological Science, 1, 66–70, 1992b) as well as at least 1 seldom-cited study published in the Journal of the Experimental Analysis of Behavior (Marcucella, Journal of the Experimental Analysis of Behavior, 36, 51–60, 1981) supporting the view that CS relations embedded in the 3-term operant contingency can act independently of the discriminative stimulus functions of the SD. These CS relations appear to be neither necessary nor sufficient for sustaining operant discriminative control. Pavlovian relations are likely to be artifacts of operant conditioning—not causal mediators. It is suggested that continued and excessive focus on Pavlovian processes that only have meager influence on operant behavior in general, and behavioral momentum more specifically, will likely be an empirical cul-de-sac for improvement of behavioral management for addiction relapse and other behavioral disorders.

Identifying affective levels on music video via completing the missing modality

Emotion tagging is one theme of interest in affective computing, which labels stimuli with human understandable semantic information. Previous works indicate that modality fusion could improve the performance of this kind of tasks. However, acquiring the subjects’ responses is costly and time consuming, leading to that the response modality is absent for large part of multimedia contents, which is required by modality fusion methods. To address this problem, in this paper a novel emotion tagging framework is proposed, which completes the missing response modalities based on the conception of brain encoding. In the framework, an encoding model is built based on the response modality from subjects’ responses and the stimulus modality from stimulus contents. Then the model is applied to those videos whose response modalities are absent to complete the missing response modalities. Modality fusion is finally conducted on stimulus modality and response modality and followed by the classification methods. To test the performance of the proposed framework, DEAP dataset is adopted as a benchmark. In the experiments, three kinds of features are employed as stimulus modalities. Response modality and fused modality are computed under the proposed framework. Affective level identification is conducted as emotion tagging task. The results demonstrate that the accuracies of the proposed framework outperforms the accuracies obtained by using only stimulus modality. The improvements are higher than 5% for all kinds of stimulus modalities in valence and arousal in terms of accuracy. Additionally, the improvement of performance introduces no extra physiological data acquisition, saving economical and timing costs.

Evolutionary and Modern Image Content Differentially Influence the Processing of Emotional Pictures.

From an evolutionary perspective, environmental threats relevant for survival constantly challenged human beings. Current research suggests the evolution of a fear processing module in the brain to cope with these threats. Recently, humans increasingly encountered modern threats (e.g., guns or car accidents) in addition to evolutionary threats (e.g., snakes or predators) which presumably required an adaptation of perception and behavior. However, the neural processes underlying the perception of these different threats remain to be elucidated. We investigated the effect of image content (i.e., evolutionary vs. modern threats) on the activation of neural networks of emotion processing. During functional magnetic resonance imaging (fMRI) 41 participants watched affective pictures displaying evolutionary-threatening, modern-threatening, evolutionary-neutral and modern-neutral content. Evolutionary-threatening stimuli evoked stronger activations than modern-threatening stimuli in left inferior frontal gyrus and thalamus, right middle frontal gyrus and parietal regions as well as bilaterally in parietal regions, fusiform gyrus and bilateral amygdala. We observed the opposite effect, i.e., higher activity for modern-threatening than for evolutionary-threatening stimuli, bilaterally in the posterior cingulate and the parahippocampal gyrus. We found no differences in subjective arousal ratings between the two threatening conditions. On the valence scale though, subjects rated modern-threatening pictures significantly more negative than evolutionary-threatening pictures, indicating a higher level of perceived threat. The majority of previous studies show a positive relationship between arousal rating and amygdala activity. However, comparing fMRI results with behavioral findings we provide evidence that neural activity in fear processing areas is not only driven by arousal or valence, but presumably also by the evolutionary content of the stimulus. This has also fundamental methodological implications, in the sense to suggest a more elaborate classification of stimulus content to improve the validity of experimental designs.