Activation of the amygdala and anterior cingulate during nonconscious processing of sad versus happy faces

Unconsciously perceived fear in peripheral vision alerts the limbic system: a MEG study

BACKGROUND

In ecological situations, threatening stimuli often come out from the peripheral vision. Such aggressive messages must trigger rapid attention to the periphery to allow a fast and adapted motor reaction. Several clues converge to hypothesize that peripheral danger presentation can trigger off a fast arousal network potentially independent of the consciousness spot.

METHODOLOGY/PRINCIPAL FINDINGS

In the present MEG study, spatio-temporal dynamics of the neural processing of danger related stimuli were explored as a function of the stimuli position in the visual field. Fearful and neutral faces were briefly presented in the central or peripheral visual field, and were followed by target faces stimuli. An event-related beamformer source analysis model was applied in three time windows following the first face presentations: 80 to 130 ms, 140 to 190 ms, and 210 to 260 ms. The frontal lobe and the right internal temporal lobe part, including the amygdala, reacted as soon as 80 ms of latency to fear occurring in the peripheral vision. For central presentation, fearful faces evoked the classical neuronal activity along the occipito-temporal visual pathway between 140 and 190 ms.

CONCLUSIONS

Thus, the high spatio-temporal resolution of MEG allowed disclosing a fast response of a network involving medial temporal and frontal structures in the processing of fear related stimuli occurring unconsciously in the peripheral visual field. Whereas centrally presented stimuli are precisely processed by the ventral occipito-temporal cortex, the related-to-danger stimuli appearing in the peripheral visual field are more efficient to produce a fast automatic alert response possibly conveyed by subcortical structures.

Sadness enhances the experience of pain via neural activation in the anterior cingulate cortex and amygdala: an fMRI study

Pain is a multidimensional experience. Human pain perception can be modulated by subjective emotional responses. We examined this association within the context of a neuroimaging study, using functional MRI to examine neural responses to electrical pain-inducing stimuli in 15 healthy subjects (6 females; age range=20-30 years). Pain-inducing stimuli were presented during different emotional contexts, which were induced via the continuous presentation (5 s) of sad, happy, or neutral pictures of faces. We found that subjective pain ratings were higher in the sad emotional context than in the happy and neutral contexts, and that pain-related activation in the ACC was more pronounced in the sad context relative to the happy and neutral contexts. Psychophysiological interaction (PPI) and dynamic causal modeling (DCM) analyses demonstrated amygdala to ACC connections during the experience of pain in the sad context. These findings serve to highlight the neural mechanisms that may be relevant to understanding the broader relationship between somatic complaints and negative emotion.

Emotion specific modulation of automatic amygdala responses by 5-HTTLPR genotype

A functional polymorphism in the serotonin transporter gene (5-HTTLPR) has been reported to modulate amygdala responsiveness to negative environmental cues. However, it remains unclear whether 5-HTTLPR modulates amygdala responses specifically to negative stimuli or rather to emotionally salient stimuli in general. In 44 healthy subjects, amygdala responses to subliminally presented happy and sad facial expressions were assessed by means of fMRI at 3 Tesla. All subjects were genotyped for 5-HTTLPR and the recently discovered 5-HTT rs25531. We observed a robust emotion by genotype group interaction in the right amygdala. Risk allele carriers (S or L(G)) showed similar amygdala responses to happy faces compared to homozygous L(A)L(A) carriers but increased amygdala responses to sad faces. The right amygdala was the only anatomical region across the whole brain demonstrating this interaction at a reasonable threshold. It appears that whereas 5-HTT gene variation modulates automatic amygdala responsiveness to sad faces, no such association was found for happy faces. We conclude that 5-HTTLPR genotype predominantly impacts the central processing predominantly of negative environmental cues but not of emotionally salient stimuli in general.

Altered affective response in marijuana smokers: an FMRI study

More than 94 million Americans have tried marijuana, and it remains the most widely used illicit drug in the nation. Investigations of the cognitive effects of marijuana report alterations in brain function during tasks requiring executive control, including inhibition and decision-making. Endogenous cannabinoids regulate a variety of emotional responses, including anxiety, mood control, and aggression; nevertheless, little is known about smokers' responses to affective stimuli. The anterior cingulate and amygdala play key roles in the inhibition of impulsive behavior and affective regulation, and studies using PET and fMRI have demonstrated changes within these regions in marijuana smokers. Given alterations in mood and perception often observed in smokers, we hypothesized altered fMRI patterns of response in 15 chronic heavy marijuana smokers relative to 15 non-marijuana smoking control subjects during the viewing of masked happy and fearful faces. Despite no between-group differences on clinical or demographic measures, smokers demonstrated a relative decrease in both anterior cingulate and amygdalar activity during masked affective stimuli compared to controls, who showed relative increases in activation within these regions during the viewing of masked faces. Findings indicate that chronic heavy marijuana smokers demonstrate altered activation of frontal and limbic systems while viewing masked faces, consistent with autoradiographic studies reporting high CB-1 receptor density in these regions. These data suggest differences in affective processing in chronic smokers, even when stimuli are presented below the level of conscious processing, and underscore the likelihood that marijuana smokers process emotional information differently from those who do not smoke, which may result in negative consequences.

Masked smoking-related images modulate brain activity in smokers

The questions of whether and how indiscriminate drug-related stimuli could influence drug-users are important to our understanding of addictive behavior, but the answers are still inconclusive. In the present preliminary functional magnetic resonance imaging study using a backward masking paradigm, the effect of indiscriminate smoking-related stimuli on 10 smokers and 10 nonsmokers was examined. The BOLD response showed a significant reduction (P = 0.001) in the right amygdala of smokers when they viewed but did not perceive masked smoking-related stimuli, while no significant differences were found in the nonsmoker group. More voxels in anterior cingulate cortex were negatively correlated with the amygdala during the masked smoking-related picture condition in smokers but not in nonsmokers, whereas more positively correlated voxels were observed during the masked neutral condition. The BOLD response in drug-users indicates the amygdala responds to drug-related stimuli that are below the perceptual threshold. The functional connectivity data suggest a functional interaction between the amygdala and the anterior cingulate cortex when drug users view 33 ms back-masked drug-related stimuli. This observation suggests that the amygdala plays an important role in the indiscriminate drug-related cue process.

Brain structures activated by overt and covert emotional visual stimuli

Research data suggest that the amygdala and some related brain structures modulate the processing of emotional visual stimuli even when they are not consciously perceived. In this study, we examined neural responses to investigate whether and how other brain areas anatomically connected to the amygdala might become activated during both overt and covert presentation of conditioned emotional visual stimuli. In the covert presentation, a conditioned angry face was shown for 15 ms followed by a neutral masking face (CSmask). In the overt condition, an angry face associated with a painful stimulus (CS+), a happy (H) and a neutral face (N) were presented for 75 ms. Based on results of functional magnetic resonance imaging (fMRI) in 10 healthy volunteers, we show evidence that a network of brain structures anatomically connected to the amygdala (including the anterior insula, the fusiform gyrus and the superior temporal sulcus) are involved in the subliminal processing of visual emotional stimuli. Of particular interest was the dissociation between the anterior and posterior insula: the anterior insula responded to both overt and covert presentation of the conditioned stimulus, whereas the posterior insula responded only to the overt presentation of the face associated with a painful electrical stimulation. This response pattern suggests that the anterior insula, the fusiform gyrus and the temporal sulcus cooperate with the amygdala in the unconscious processing of pain-conditioned stimuli.

The neurophysiological bases of emotion: An fMRI study of the affective circumplex using emotion-denoting words

OBJECTIVE

We aimed to study the neural processing of emotion-denoting words based on a circumplex model of affect, which posits that all emotions can be described as a linear combination of two neurophysiological dimensions, valence and arousal. Based on the circumplex model, we predicted a linear relationship between neural activity and incremental changes in these two affective dimensions.

METHODS

Using functional magnetic resonance imaging, we assessed in 10 subjects the correlations of BOLD (blood oxygen level dependent) signal with ratings of valence and arousal during the presentation of emotion-denoting words.

RESULTS

Valence ratings correlated positively with neural activity in the left insular cortex and inversely with neural activity in the right dorsolateral prefrontal and precuneus cortices. The absolute value of valence ratings (reflecting the positive and negative extremes of valence) correlated positively with neural activity in the left dorsolateral and medial prefrontal cortex (PFC), dorsal anterior cingulate cortex, posterior cingulate cortex, and right dorsal PFC, and inversely with neural activity in the left medial temporal cortex and right amygdala. Arousal ratings and neural activity correlated positively in the left parahippocampus and dorsal anterior cingulate cortex, and inversely in the left dorsolateral PFC and dorsal cerebellum.

CONCLUSION

We found evidence for two neural networks subserving the affective dimensions of valence and arousal. These findings clarify inconsistencies from prior imaging studies of affect by suggesting that two underlying neurophysiological systems, valence and arousal, may subserve the processing of affective stimuli, consistent with the circumplex model of affect.

Temporal pole activity during perception of sad faces, but not happy faces, correlates with neuroticism trait

It is known that the temporal cortex is involved in perception of emotional facial expressions, and the involvement is relatively independent of the emotional valence of those expressions. The present study revealed a valence-dependent aspect of the temporal cortex through individual differences analyses involving the neuroticism trait, one of the representative affective personality traits. Functional MRI was administered while subjects classified expressions of faces, and neuroticism scores were obtained from individual subjects. Significant brain activity was observed in the temporal pole (TP) during perception of both happy and sad expressions relative to neutral expressions. Correlational analyses revealed that TP activity during perception of sad expressions, but not happy expressions, correlated with the neuroticism scores. These results demonstrate differential roles for the temporal cortex in perception of happy and sad faces, and suggest that TP recruitment during understanding of negative emotions is dependent on the personality of the individuals.

Neural signature of the conscious processing of auditory regularities

Can conscious processing be inferred from neurophysiological measurements? Some models stipulate that the active maintenance of perceptual representations across time requires consciousness. Capitalizing on this assumption, we designed an auditory paradigm that evaluates cerebral responses to violations of temporal regularities that are either local in time or global across several seconds. Local violations led to an early response in auditory cortex, independent of attention or the presence of a concurrent visual task, whereas global violations led to a late and spatially distributed response that was only present when subjects were attentive and aware of the violations. We could detect the global effect in individual subjects using functional MRI and both scalp and intracerebral event-related potentials. Recordings from 8 noncommunicating patients with disorders of consciousness confirmed that only conscious individuals presented a global effect. Taken together these observations suggest that the presence of the global effect is a signature of conscious processing, although it can be absent in conscious subjects who are not aware of the global auditory regularities. This simple electrophysiological marker could thus serve as a useful clinical tool.

Distinct effects of {delta}9-tetrahydrocannabinol and cannabidiol on neural activation during emotional processing

CONTEXT

Cannabis use can both increase and reduce anxiety in humans. The neurophysiological substrates of these effects are unknown.

OBJECTIVE

To investigate the effects of 2 main psychoactive constituents of Cannabis sativa (Delta9-tetrahydrocannabinol [Delta9-THC] and cannabidiol [CBD]) on regional brain function during emotional processing.

DESIGN

Subjects were studied on 3 separate occasions using an event-related functional magnetic resonance imaging paradigm while viewing faces that implicitly elicited different levels of anxiety. Each scanning session was preceded by the ingestion of either 10 mg of Delta9-THC, 600 mg of CBD, or a placebo in a double-blind, randomized, placebo-controlled design.

PARTICIPANTS

Fifteen healthy, English-native, right-handed men who had used cannabis 15 times or less in their life.

MAIN OUTCOME MEASURES

Regional brain activation (blood oxygenation level-dependent response), electrodermal activity (skin conductance response [SCR]), and objective and subjective ratings of anxiety.

RESULTS

Delta9-Tetrahydrocannabinol increased anxiety, as well as levels of intoxication, sedation, and psychotic symptoms, whereas there was a trend for a reduction in anxiety following administration of CBD. The number of SCR fluctuations during the processing of intensely fearful faces increased following administration of Delta9-THC but decreased following administration of CBD. Cannabidiol attenuated the blood oxygenation level-dependent signal in the amygdala and the anterior and posterior cingulate cortex while subjects were processing intensely fearful faces, and its suppression of the amygdalar and anterior cingulate responses was correlated with the concurrent reduction in SCR fluctuations. Delta9-Tetrahydrocannabinol mainly modulated activation in frontal and parietal areas.

CONCLUSIONS

Delta9-Tetrahydrocannabinol and CBD had clearly distinct effects on the neural, electrodermal, and symptomatic response to fearful faces. The effects of CBD on activation in limbic and paralimbic regions may contribute to its ability to reduce autonomic arousal and subjective anxiety, whereas the anxiogenic effects of Delta9-THC may be related to effects in other brain regions.

The phenomenology of bipolar disorder: what drives the high rate of medical burden and determines long-term prognosis?

Bipolar disorder (BD) has been classically described as one of episodic mood disturbances. New evidence suggests that a chronic course and multisystem involvement is the rule, rather than the exception, and that together with disturbances of circadian rhythms, mood instability, cognitive impairment, a high rate of medical burden is often observed. The current diagnostic approach for BD neither describes the multisystem involvement that the recent literature has highlighted nor points toward potential predictors of long- term outcome. In light of the new evidence that the long-term course of BD is associated with a high prevalence of psychiatric comorbidity and an increased mortality from medical disease, we propose a multidimensional approach that includes several symptom domains, namely affective instability, circadian rhythm dysregulation, and cognitive and executive dysfunction, presenting in various combinations that give shape to each individual presentation, and offers potential indicators of overall long-term prognosis.

Unconscious processing of facial affect in children and adolescents

In a previous study, with adults, we demonstrated that the amygdala and anterior cingulate gyrus are differentially responsive to happy and sad faces presented subliminally. Because the ability to perceive subtle facial signals communicating sadness is an important aspect of prosocial development, and is critical for empathic behavior, we examined this phenomenon from a developmental perspective using a backward masking paradigm. While undergoing functional magnetic resonance imaging (fMRI), 10 healthy adolescent children were presented with a series of happy and sad facial expressions, each lasting 20 ms and masked immediately by a neutral face to prevent conscious awareness of the affective expression. Relative to fixation baseline, masked sad faces activated the right amygdala, whereas masked happy faces failed to activate any of the regions of interest. Direct comparison between masked happy and sad faces revealed valence specific differences in the anterior cingulate gyrus. When the data were compared statistically to our previous sample of adults, the adolescent group showed significantly greater activity in the right amygdala relative to the adults during the masked sad condition. Groups also differed in several non-hypothesized regions. Development of unconscious perception from adolescence into adulthood appears to be accompanied by reduced activity within limbic affect processing systems, and perhaps increased involvement of other cortical and cerebellar systems.

Exploration of core features of a human face by healthy and autistic adults analyzed by visual scanning

Autism is a neurodevelopmental disorder characterized by disorders in social interaction and emotional reciprocity which can be explained by impairments of the ability to understand the mental states of others ("theory of mind") and recognition of facial expressions. These impairments may be related to the difficulties with face recognition characteristic of this disorder. Face perception plays a critical role in the development of social interaction and understanding of the internal emotional state of others. It depends on initial oculomotor exploration. The aim of this study was to quantify ocular behaviour in 11 adults with autism and 23 healthy subjects (15-35 years) while exploring neutral faces and faces expressing an emotion using an eye tracking method. The strategy used to explore faces was also studied. All subjects spent significantly more time on the eye region than on the rest of the face. However, subjects with autism spent less time on the eye region than healthy subjects. The latter used a strategy based on their own eye dominance when exploring faces. All healthy subjects significantly began their exploration of a face by looking at the eye in the contralateral visual field to their dominant eye. This strategy seemed to be impaired in patients with autism. To conclude, these results contrast with earlier reports regarding the lack of interest in the eye region in patients with autism, and demonstrate for the first time that perception of the face is dependent on eye dominance.

Functional grouping and cortical-subcortical interactions in emotion: a meta-analysis of neuroimaging studies

We performed an updated quantitative meta-analysis of 162 neuroimaging studies of emotion using a novel multi-level kernel-based approach, focusing on locating brain regions consistently activated in emotional tasks and their functional organization into distributed functional groups, independent of semantically defined emotion category labels (e.g., "anger," "fear"). Such brain-based analyses are critical if our ways of labeling emotions are to be evaluated and revised based on consistency with brain data. Consistent activations were limited to specific cortical sub-regions, including multiple functional areas within medial, orbital, and inferior lateral frontal cortices. Consistent with a wealth of animal literature, multiple subcortical activations were identified, including amygdala, ventral striatum, thalamus, hypothalamus, and periaqueductal gray. We used multivariate parcellation and clustering techniques to identify groups of co-activated brain regions across studies. These analyses identified six distributed functional groups, including medial and lateral frontal groups, two posterior cortical groups, and paralimbic and core limbic/brainstem groups. These functional groups provide information on potential organization of brain regions into large-scale networks. Specific follow-up analyses focused on amygdala, periaqueductal gray (PAG), and hypothalamic (Hy) activations, and identified frontal cortical areas co-activated with these core limbic structures. While multiple areas of frontal cortex co-activated with amygdala sub-regions, a specific region of dorsomedial prefrontal cortex (dmPFC, Brodmann's Area 9/32) was the only area co-activated with both PAG and Hy. Subsequent mediation analyses were consistent with a pathway from dmPFC through PAG to Hy. These results suggest that medial frontal areas are more closely associated with core limbic activation than their lateral counterparts, and that dmPFC may play a particularly important role in the cognitive generation of emotional states.

Functional magnetic resonance imaging of temporally distinct responses to emotional facial expressions

Understanding the temporal dynamics of brain function contributes to models of learning and memory as well as the processing of emotions and habituation. In this article, we present a novel analysis technique to investigate spatiotemporal patterns of activation in response to blocked presentations of emotional stimuli. We modeled three temporal response functions (TRFs), which were maximally sensitive to the onset, early or sustained temporal component of a given block type. This analysis technique was applied to a data set of 29 subjects who underwent functional magnetic resonance imaging while responding to fearful, happy, and sad facial expressions. We identified brain regions that uniquely fit each of the three TRFs for each emotional condition and compared the results to the standard approach, which was based on the canonical hemodynamic response function. We found that voxels within the precuneus fit the onset TRF but did not fit the early or the sustained TRF in all the emotional conditions. On the other hand, voxels within the amygdala fit the sustained TRF, but not the onset or early TRF, during presentation of fearful stimuli, suggesting a spatiotemporal dissociation between these structures. This technique provides researchers with an additional tool in order to investigate the temporal dynamics of neural circuits.

The rostral anterior cingulate cortex modulates the efficiency of amygdala-dependent fear learning

BACKGROUND

The rostral anterior cingulate cortex (rACC) and the amygdala consistently emerge from neuroimaging studies as brain regions crucially involved in normal and abnormal fear processing. To date, however, the role of the rACC specifically during the acquisition of auditory fear conditioning still remains unknown. The aim of this study is to investigate a possible top-down control of a specific rACC sub-region over amygdala activation during pavlovian fear acquisition.

METHODS

We performed excitotoxic lesions, temporal inactivation, and activation of a specific sub-region of the rACC that we identified by tracing studies as supporting most of the connectivity with the basolateral amygdala (r(Amy)-ACC). The effects of these manipulations over amygdala function were investigated with a classical tone-shock associative fear conditioning paradigm in the rat.

RESULTS

Excitotoxic lesions and transient inactivation of the r(Amy)-ACC pre-training selectively produced deficits in the acquisition of the tone-shock associative learning (but not context). This effect was specific for the acquisition phase. However, the deficit was found to be transient and could be overcome by overtraining. Conversely, pre-training transient activation of the r(Amy)-ACC facilitated associative learning and increased fear expression.

CONCLUSIONS

Our results suggest that a subregion of the rACC is key to gating the efficiency of amygdala-dependent auditory fear conditioning learning. Because r(Amy)-ACC inputs were confirmed to be glutamatergic, we propose that recruitment of this brain area might modulate overall basolateral amygdala excitatory tone during conditioned stimulus-unconditioned stimulus concomitant processing. In the light of clinical research, our results provide new insight on the effect of inappropriate rACC recruitment during emotional events.

The adolescent brain: insights from functional neuroimaging research

With the development of functional neuroimaging tools, the past two decades have witnessed an explosion of work examining functional brain maps, mostly in the adult brain. Against this backdrop of work in adults, developmental research begins to gather a substantial body of knowledge about brain maturation. The purpose of this review is to present some of these findings from the perspective of functional neuroimaging. First, a brief survey of available neuroimaging techniques (i.e., fMRI, MRS, MEG, PET, SPECT, and infrared techniques) is provided. Next, the key cognitive, emotional, and social changes taking place during adolescence are outlined. The third section gives examples of how these behavioral changes can be understood from a neuroscience perspective. The conclusion places this functional neuroimaging research in relation to clinical and molecular work, and shows how answers will ultimately come from the combined efforts of these disciplines.

Working memory for social cues recruits orbitofrontal cortex and amygdala: a functional magnetic resonance imaging study of delayed matching to sample for emotional expressions

During everyday interactions, we continuously monitor and maintain information about different individuals and their changing emotions in memory. Yet to date, working memory (WM) studies have primarily focused on mechanisms for maintaining face identity, but not emotional expression, and studies investigating the neural basis of emotion have focused on transient activity, not delay related activity. The goal of this functional magnetic resonance imaging study was to investigate WM for two critical social cues: identity and emotion. Subjects performed a delayed match-to-sample task that required them to match either the emotional expression or the identity of a face after a 10 s delay. Neuroanatomically, our predictions focused on the orbitofrontal cortex (OFC) and the amygdala, as these regions have previously been implicated in emotional processing and long-term memory, and studies have demonstrated sustained OFC and medial temporal lobe activity during visual WM. Consistent with previous studies, transient activity during the sample period representing emotion and identity was found in the superior temporal sulcus and inferior occipital cortex, respectively. Sustained delay-period activity was evident in OFC, amygdala, and hippocampus, for both emotion and identity trials. These results suggest that, although initial processing of emotion and identity is accomplished in anatomically segregated temporal and occipital regions, sustained delay related memory for these two critical features is held by the OFC, amygdala and hippocampus. These regions share rich connections, and have been shown previously to be necessary for binding features together in long-term memory. Our results suggest a role for these regions in active maintenance as well.

Prelude to passion: limbic activation by "unseen" drug and sexual cues

BACKGROUND

The human brain responds to recognizable signals for sex and for rewarding drugs of abuse by activation of limbic reward circuitry. Does the brain respond in similar way to such reward signals even when they are "unseen", i.e., presented in a way that prevents their conscious recognition? Can the brain response to "unseen" reward cues predict the future affective response to recognizable versions of such cues, revealing a link between affective/motivational processes inside and outside awareness?

METHODOLOGY/PRINCIPAL FINDINGS

We exploited the fast temporal resolution of event-related functional magnetic resonance imaging (fMRI) to test the brain response to "unseen" (backward-masked) cocaine, sexual, aversive and neutral cues of 33 milliseconds duration in male cocaine patients (n = 22). Two days after scanning, the affective valence for visible versions of each cue type was determined using an affective bias (priming) task. We demonstrate, for the first time, limbic brain activation by "unseen" drug and sexual cues of only 33 msec duration. Importantly, increased activity in an large interconnected ventral pallidum/amygdala cluster to the "unseen" cocaine cues strongly predicted future positive affect to visible versions of the same cues in subsequent off-magnet testing, pointing both to the functional significance of the rapid brain response, and to shared brain substrates for appetitive motivation within and outside awareness.

CONCLUSIONS/SIGNIFICANCE

These findings represent the first evidence that brain reward circuitry responds to drug and sexual cues presented outside awareness. The results underscore the sensitivity of the brain to "unseen" reward signals and may represent the brain's primordial signature for desire. The limbic brain response to reward cues outside awareness may represent a potential vulnerability in disorders (e.g., the addictions) for whom poorly-controlled appetitive motivation is a central feature.

Role of GABA in anxiety and depression

This review assesses the parallel data on the role of gamma-aminobutyric acid (GABA) in depression and anxiety. We review historical and new data from both animal and human experimentation which have helped define the key role for this transmitter in both these mental pathologies. By exploring the overlap in these conditions in terms of GABAergic neurochemistry, neurogenetics, brain circuitry, and pharmacology, we develop a theory that the two conditions are intrinsically interrelated. The role of GABAergic agents in demonstrating this interrelationship and in pointing the way to future research is discussed.

A meta-analytic review of emotion recognition and aging: implications for neuropsychological models of aging

This meta-analysis of 28 data sets (N=705 older adults, N=962 younger adults) examined age differences in emotion recognition across four modalities: faces, voices, bodies/contexts, and matching of faces to voices. The results indicate that older adults have increased difficulty recognising at least some of the basic emotions (anger, sadness, fear, disgust, surprise, happiness) in each modality, with some emotions (anger and sadness) and some modalities (face-voice matching) creating particular difficulties. The predominant pattern across all emotions and modalities was of age-related decline with the exception that there was a trend for older adults to be better than young adults at recognising disgusted facial expressions. These age-related changes are examined in the context of three theoretical perspectives-positivity effects, general cognitive decline, and more specific neuropsychological change in the social brain. We argue that the pattern of age-related change observed is most consistent with a neuropsychological model of adult aging stemming from changes in frontal and temporal volume, and/or changes in neurotransmitters.

5-HTTLPR biases amygdala activity in response to masked facial expressions in major depression

The amygdala is a key structure in a limbic circuit involved in the rapid and unconscious processing of facial emotions. Increased amygdala reactivity has been discussed in the context of major depression. Recent studies reported that amygdala activity during conscious emotion processing is modulated by a functional polymorphism in the serotonin transporter gene (5-HTTLPR) in healthy subjects. In the present study, amygdala reactivity to displays of emotional faces was measured by means of fMRI at 3T in 35 patients with major depression and 32 healthy controls. Conscious awareness of the emotional stimuli was prevented via backward-masking to investigate automatic emotion processing. All subjects were genotyped for the 5-HTTLPR polymorphism. Risk allele carriers (S or L(G)) demonstrated increased amygdala reactivity to masked emotional faces, which in turn was significantly correlated with life-time psychiatric hospitalization as an index of chronicity. This might indicate that genetic variations of the serotonin transporter could increase the risk for depression chronification via altering limbic neural activity on a preattentive level of emotion processing.

Intact emotion facilitation for nonsocial stimuli in autism: is amygdala impairment in autism specific for social information?

Atypical amygdala development may play a key role in the emergence of social disability and other symptoms of autism (Baron-Cohen et al., 2000; Schultz, 2005). The mechanisms by which this may occur have received little attention, however, and most support from behavioral and imaging studies has been concerned with socially relevant stimuli such as faces. Given the complexity of amygdala function and its known role in many other emotional tasks, we examined whether individuals with autism would demonstrate impaired performance on several tasks that have been shown to require activation of the amygdala but that do not have any explicit social meaning. Relative to a typical comparison group matched for age and IQ, our sample of 37 adolescents and adults with autism (mean age=19.7 years) demonstrated equivalent facilitation for perception and learning of emotionally relevant stimuli. On each of four tasks, there were significant main effects of emotion condition on performance for both groups. Future research regarding atypical amygdala function and emotion processing in autism should consider whether the response to nonsocial emotion factors (including negative valence or high arousal) may be intact, despite difficulties in responding to socially relevant stimuli.

Face emotion labeling deficits in children with bipolar disorder and severe mood dysregulation

Children with narrow phenotype bipolar disorder (NP-BD; i.e., history of at least one hypomanic or manic episode with euphoric mood) are deficient when labeling face emotions. It is unknown if this deficit is specific to particular emotions, or if it extends to children with severe mood dysregulation (SMD; i.e., chronic irritability and hyperarousal without episodes of mania). Thirty-nine NP-BD, 31 SMD, and 36 control subjects completed the emotional expression multimorph task, which presents gradations of facial emotions from 100% neutrality to 100% emotional expression (happiness, surprise, fear, sadness, anger, and disgust). Groups were compared in terms of intensity of emotion required before identification occurred and accuracy. Both NP-BD and SMD youth required significantly more morphs than controls to label correctly disgusted, surprised, fearful, and happy faces. Impaired face labeling correlated with deficient social reciprocity skills in NP-BD youth and dysfunctional family relationships in SMD youth. Compared to controls, patients with NP-BD or SMD require significantly more intense facial emotion before they are able to label the emotion correctly. These deficits are associated with psychosocial impairments. Understanding the neural circuitry associated with face-labeling deficits has the potential to clarify the pathophysiology of these disorders.

Facial emotion discrimination across the menstrual cycle in women with premenstrual dysphoric disorder (PMDD) and controls

BACKGROUND

Depressed patients show mood-congruent errors in the identification of emotion in facial expressions. Errors consist of impaired performance (recognition errors) and negative bias (seeing faces as sadder than they are). This abnormal processing may both reflect and contribute to the negative affective state. In this study, we administered an emotional recognition in facial expression task to women with premenstrual dysphoric disorder (PMDD) to determine whether processing errors similar to those in depression were present and whether they were confined to the luteal phase (i.e., state dependent).

METHODS

The Facial Discrimination Task (FDT) was administered in the follicular and luteal phases to women with PMDD (n=28) and asymptomatic controls (n=27).

RESULTS

ANOVA with repeated measures identified significantly increased negative judgments (both performance errors and bias) in women with PMDD during the luteal phase (more neutral to sad misjudgments and higher negative bias index) as well as impaired "specificity" of judgments [an inability to discriminate neutral from emotional stimuli] (diagnosis by phase interactions, p<0.05), findings similar to those observed in depression. No menstrual cycle effects were seen in controls, and no differences between patients and controls were seen on a control task (age assessment of pictured subjects).

LIMITATIONS

The levels of significance obtained were modest and would not withstand correction for multiple comparisons.

CONCLUSION

Women with PMDD display a luteal phase-dependent impairment (negative bias) in the processing of non-verbal affective information. This negative bias may contribute to the generation of negative mood states during the luteal phase and could suggest the presence of dysfunction in those brain regions whose coordinated activity mediates the recognition of emotion in facial expression.

A functional MRI study of happy and sad affective states induced by classical music

The present study investigated the functional neuroanatomy of transient mood changes in response to Western classical music. In a pilot experiment, 53 healthy volunteers (mean age: 32.0; SD = 9.6) evaluated their emotional responses to 60 classical musical pieces using a visual analogue scale (VAS) ranging from 0 (sad) through 50 (neutral) to 100 (happy). Twenty pieces were found to accurately induce the intended emotional states with good reliability, consisting of 5 happy, 5 sad, and 10 emotionally unevocative, neutral musical pieces. In a subsequent functional magnetic resonance imaging (fMRI) study, the blood oxygenation level dependent (BOLD) signal contrast was measured in response to the mood state induced by each musical stimulus in a separate group of 16 healthy participants (mean age: 29.5; SD = 5.5). Mood state ratings during scanning were made by a VAS, which confirmed the emotional valence of the selected stimuli. Increased BOLD signal contrast during presentation of happy music was found in the ventral and dorsal striatum, anterior cingulate, parahippocampal gyrus, and auditory association areas. With sad music, increased BOLD signal responses were noted in the hippocampus/amygdala and auditory association areas. Presentation of neutral music was associated with increased BOLD signal responses in the insula and auditory association areas. Our findings suggest that an emotion processing network in response to music integrates the ventral and dorsal striatum, areas involved in reward experience and movement; the anterior cingulate, which is important for targeting attention; and medial temporal areas, traditionally found in the appraisal and processing of emotions.

Impaired facial emotion recognition and reduced amygdalar volume in schizophrenia

Structural abnormalities of the amygdala and impaired facial emotion recognition have been reported in schizophrenia. Most studies demonstrated reduced amygdalar volumes in schizophrenia patients, and difficulty in recognizing negative facial emotions has also been reported. However, findings on the deficit in facial emotion recognition have been inconsistent, and the relationships between this impairment and amygdalar volume reduction remain unclear. In this study, we investigated these relationships by performing volumetric analysis of the amygdala and evaluation of facial emotion recognition performance in the same subjects with schizophrenia. The sample group comprised 20 schizophrenia patients and 20 matched healthy controls. We measured the volumes of the amygdalae with high-resolution magnetic resonance imaging (MRI) at 3.0 Tesla. Additionally, we included a task that evaluated the subjects' ability to recognize the intensity of basic facial emotions. We found that impaired facial emotion recognition in schizophrenia patients is emotion-specific (sadness, surprise, disgust, and anger). Moreover, the volume of each amygdala on either side of the brain was reduced. Finally, we found a correlation between left amygdalar volume and the recognition of sadness in facial expressions. This study demonstrated that amygdala dysfunction may contribute to impaired facial emotion recognition in schizophrenia.

Dynamic organization of the emotional brain: responsivity, stability, and instability

Models of emotion processing have commonly been formulated as dichotomies such as approach versus avoidance. These models and associated research on evolutionary adaptation, awareness, motivational arousal, and cortical-subcortical brain systems are reviewed. A continuum model of emotional-significance processing is proposed to integrate current dichotomies and reflect the highly interconnected nature of brain systems. This model highlights a spectrum from "mismatches," signifying potential danger, to "matches," signifying safety and the expectation of reward. Subcortical-cortical interactions and autonomic arousal modulation support mismatch and match processing across a temporal continuum from milliseconds (in which processing is automatic and arguably nonconscious) to tenths of a second (in which responses are facilitated and contextual evaluation commences) to minutes and hours (when memory consolidation and neural plasticity occur). Variations at distinct points along this continuum, with contributions from constitutional and genetic factors, may contribute to individual differences in emotional stability and instability in neuropsychiatric disorders.

Recognition of happy facial affect in panic disorder: an fMRI study

BACKGROUND

This study investigated activation of the anterior cingulate cortex (ACC) and amygdala during the presentation of happy facial affect images in patients with panic disorder (PD) as measured by blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI).

METHODS

Eight patients with PD and eight sex-matched controls were recruited for the study. Scanning was performed on a general electric (GE) Signa 1.5T scanner retrofitted with a whole body echo planar coil. Using a quadrature head coil, echo planar images and high-resolution MR images were acquired.

RESULTS

After covarying for age, examination of group differences revealed greater ACC activation bilaterally in patients with PD compared to controls in response to happy faces. However, there were no differences in amygdala activation between the groups. These findings contrasted with regional brain activation in response to neutral faces where there were was also greater bilateral ACC activation in the PD group, but only 44 ACC voxels showed significant increases as opposed to 509 voxels for the happy condition. There were no between group differences in activation in the amygdala.

CONCLUSION

This is the first fMRI study to our knowledge that demonstrates ACC abnormalities in response to happy facial affect recognition in PD.

Threat sensitivity as assessed by automatic amygdala response to fearful faces predicts speed of visual search for facial expression

It has been argued that the amygdala represents an integral component of a vigilance system that is primarily involved in the perception of ambiguous stimuli of biological relevance. The present investigation was conducted to examine the relationship between automatic amygdala responsivity to fearful faces which may be interpreted as an index of trait-like threat sensitivity and spatial processing characteristics of facial emotions. During 3T fMRI scanning, pictures of human faces bearing fearful, angry, and happy expressions were presented to 20 healthy volunteers using a backward masking procedure based on neutral facial expressions. Subsequently, a computer-based face-in-the-crowd task using schematic face stimuli was administered. The neural response of the (right) amygdala to masked fearful faces correlated consistently with response speed to negative and neutral faces. Neither amygdala activation during the masked presentation of angry faces nor amygdala activation during the presentation of happy faces was correlated with any of the response latencies in the face-in-the-crowd task. Our results suggest that amygdala responsivity to masked facial expression is differentially related to the general visual search speed for facial expression. Neurobiologically defined threat sensitivity seems to represent an important determinant of visual scanning behaviour.

Disgust and happiness recognition correlate with anteroventral insula and amygdala volume respectively in preclinical Huntington's disease

Patients with Huntington's disease (HD) can show disproportionate impairments in recognizing facial signals of disgust, but the neural basis of this deficit remains unclear. Functional imaging studies have implicated the anterior insula in the ability to recognize disgust, but have identified other structures as well, including the basal ganglia. In view of variable insula and basal ganglia volume changes in HD, we used voxel-based morphometry to map regional variations in gray matter (GM) volume in participants carrying the mutation for HD, and correlated this with their performance on a test of facial emotion recognition for six basic emotions (disgust, fear, anger, happiness, sadness, surprise). The volume of the anteroventral insula was strongly correlated with performance on the disgust recognition task. The amygdala volume (bilaterally) correlated with the ability to recognize happy facial expressions. There was marked specificity of the regional correlations for the emotion involved. Recognition of other emotion expressions, or more general cognitive or motor performance as measured by a standardized rating scale, did not correlate with regional brain volume in this group. Control participants showed no effect for any measure. The strong linear correlations for disgust and happiness recognition imply direct involvement of the anterior insula in disgust appreciation, and a similar role for the amygdala in recognizing happy facial expressions. The absence of a significant correlation with the basal ganglia suggests a less critical role for these structures in disgust recognition than has previously been suggested. The findings also highlight the role of neurodegenerative diseases combined with statistical imaging techniques in elucidating the brain basis of behavior and cognition.

Face processing without awareness in the right fusiform gyrus

We investigated brain activity evoked by faces which were not consciously perceived by subjects. Subdural electrophysiological recordings and functional neuroimaging studies have each demonstrated face-specific processing in the fusiform gyrus (FFG) of humans. Using pattern masks, a stimulus can be presented but not consciously perceived, and thus can be used to assay obligatory or automatic processes. Here, using event-related functional magnetic resonance imaging and pattern masking, we observed that masked faces but not masked objects activated the right FFG. Other regions activated by consciously perceived unmasked faces were not activated when faces were masked. These data provide strong evidence for an automatic face-processing region in the right FFG.

Fearful and sexual pictures not consciously seen modulate the startle reflex in human beings

BACKGROUND

Animal and human studies consistently have demonstrated that the startle reflex elicited by intense auditory stimulation is enhanced by the previous presentation of fear-evoking stimuli. There is also growing and varied evidence of the nonconscious processing of fear stimuli in human beings eliciting brain and autonomic fear responses.

METHODS

We report two studies using the startle probe paradigm and the backward-masking procedure to examine the modulation of the eye-blink component of the startle reflex by consciously and nonconsciously presented emotional pictures.

RESULTS

Conscious and nonconscious presentation of fearful pictures amplified the magnitude of the startle reflex in both studies. The opposite tendency was observed for conscious and nonconscious presentation of sexually attractive pictures in the second study.

CONCLUSIONS

These findings support the notion that negative (and possibly positive) biologically relevant stimuli can be nonconsciously processed, presumably via amygdala activation, and can affect behavioral responding.

Impaired sadness recognition is linked to social interaction deficit in autism

Can autistic individuals use motion cues to identify simple emotions from 2D abstract animations? We compared emotion recognition ability using a novel test involving computerised animations, and a more conventional emotion recognition test using facial expressions. Adults with autism and normal controls, matched for age and verbal IQ, participated in two experiments. First, participants viewed a series of short (5s) animations. These featured an 'emotional' triangle, interacting with a circle. They were designed to evoke an attribution of emotion to the triangle, which was rated both in terms of anger, happiness, sadness or fear from its pattern of movement, and how animate ("living") it appeared to be. Second, emotion recognition was tested from standardised photographs of facial expressions. In both experiments, adults with autism were significantly impaired relative to comparisons in their perception of sadness. This is the first demonstration that, in autism, individuals can have difficulties both in the interpretation of facial expressions and in the recognition of equivalent emotions based on the movement of abstract stimuli. Poor performance in the animations task was significantly correlated with the degree of impairment in reciprocal social interaction, assessed by the Autism Diagnostic Observation Schedule. Our findings point to a deficit in emotion recognition in autism, extending beyond the recognition of facial expressions, which is associated with a functional impairment in social interaction skills. Our results are discussed in the context of the results of neuroimaging studies that have used animated stimuli and images of faces.

Emotion regulation in children and adolescents: boundaries between normalcy and bipolar disorder

Much controversy has surrounded the diagnosis of bipolar disorder (BD) in children and adolescents. However, recent work from an affective neuroscience perspective has advanced what is known about the boundaries of emotion regulation in BD compared to typically developing youth. In this article, we first briefly review the clinical issues that have contributed to this diagnostic controversy. Second, we discuss our phenotyping system, which can be used to guide neurobiological research designed to address these controversial issues. Third, we review what is known about the fundamentals of emotion regulation in human and nonhuman primate models. Fourth, we present recent data demonstrating how children and adolescents with BD differ from those without psychopathology on measures of emotion regulation. Taken as a whole, this work implicates a neural circuit encompassing the prefrontal cortex, amygdala, and striatum in the pathophysiology of pediatric BD.

Amygdala reactivity predicts automatic negative evaluations for facial emotions

The amygdala is a key structure in a limbic circuit involved in the rapid and unconscious processing of facial emotions. In the present study, the role of the amygdala in automatic, involuntary appraisal processes, which are believed to be a crucial component of emotion processing, was investigated in 23 healthy subjects. Amygdala activity was recorded in response to masked displays of angry, sad, and happy facial expressions using functional magnetic resonance imaging (fMRI). In a subsequent experiment, the subjects performed a masked affective priming task that characterizes automatic emotion processing by investigating the biasing effect of subliminally presented emotional faces on evaluative ratings to subsequently presented neutral stimuli. In the affective priming task, significant valence-congruent evaluation manipulation was observed. Subjects rated neutral targets more positively if they were primed by happy faces. Significant correlations were found between amygdala responses to masked negative facial expressions and negative evaluation shifts elicited by the corresponding emotion quality in the affective priming task. Spontaneous amygdala reactivity to facial emotions appears to be a determinant of automatic negative evaluative response tendencies. This finding might shed some light on how amygdala hyperresponsivity contributes to negative cognitive biases commonly observed in affective disorders.

Emotion recognition from dynamic emotional displays following anterior cingulotomy and anterior capsulotomy for chronic depression

Four patients that had received an anterior cingulotomy (ACING) and five patients that had received both an ACING and an anterior capsulotomy (ACAPS) as an intervention for chronic, treatment refractory depression were presented with a series of dynamic emotional stimuli and invited to identify the emotion portrayed. Their performance was compared with that of a group of non-surgically treated patients with major depression (n=17) and with a group of matched, never-depressed controls (n=22). At the time of testing, four of the nine neurosurgery patients had recovered from their depressive episode, whereas five remained depressed. Analysis of emotion recognition accuracy revealed no significant differences between depressed and non-depressed neurosurgically treated patients. Similarly, no significant differences were observed between the patients treated with ACING alone and those treated with both ACING and ACAPS. Comparison of the emotion recognition accuracy of the neurosurgically treated patients and the depressed and healthy control groups revealed that the surgically treated patients exhibited a general impairment in their recognition accuracy compared to healthy controls. Regression analysis revealed that participants' emotion recognition accuracy was predicted by the number of errors they made on the Stroop colour-naming task. It is plausible that the observed deficit in emotion recognition accuracy was a consequence of impaired attentional control, which may have been a result of the surgical lesions to the anterior cingulate cortex.

Cognitive Coping Style Modulates Neural Responses to Emotional Faces in Healthy Humans: A 3-T fMRI Study

Repression designates coping strategies that aim to shield the organism from distressing stimuli by disregarding their aversive characteristics. In contrast, sensitization comprises coping strategies that are employed to reduce situational uncertainty such as analyzing the environment. Functional magnetic resonance imaging was used to study neural correlates of coping styles during the perception of threatening and nonthreatening socially relevant information. Pictures of human faces bearing fearful (ambiguously threatening), angry (unambiguously threatening), happy (nonthreatening), and neutral expressions were presented masked and unmasked. Two groups of subjects were examined who were defined as consistent repressors versus consistent sensitizers with the Mainz Coping Inventory. Sensitizers tended to exhibit stronger neural responses in the amygdala to unmasked fearful faces compared with repressors. Overall, repressors were cortically more responsive to fearful (ambiguously threatening) and happy (nonthreatening) facial expressions than sensitizers, whereas sensitizers presented an enhanced responsivity to angry faces in several prefrontal areas, that is, unambiguously threatening expressions. Results from time series analyses suggest that sensitizers could exhibit less top-down cortical regulation of the amygdala than repressors in the processing of fearful faces. An increased responsivity of the amygdala to ambiguously threatening stimuli may represent a biological determinant of sensitizers' feelings of uncertainty.

Neurobiology of memory and anxiety: from genes to behavior

Interaction of anxiety and memory represents an essential feature of CNS functioning. This paper reviews experimental data coming from neurogenetics, neurochemistry, and behavioral pharmacology (as well as parallel clinical findings) reflecting different mechanisms of memory-anxiety interplay, including brain neurochemistry, circuitry, pharmacology, neuroplasticity, genes, and gene-environment interactions. It emphasizes the complexity and nonlinearity of such interplay, illustrated by a survey of anxiety and learning/memory phenotypes in various genetically modified mouse models that exhibit either synergistic or reciprocal effects of the mutation on anxiety levels and memory performance. The paper also assesses the putative role of different neurotransmitter systems and neuropeptides in the regulation of memory processes and anxiety, and discusses the role of neural plasticity in these mechanisms.

The rostral anterior cingulate cortex modulates depression but not anxiety-related behaviour in the rat

A growing body of functional imaging studies suggests that human depression and anxiety symptoms are associated with functional abnormalities in the circuitry formed by the rostral anterior cingulate cortex (rACC) and its direct limbic and paralimbic connections. In rodents however, the role of the rACC (rCG1/rCG2) remains unknown in depression-related behaviours and elusive in acute anxiety. In order to address this, we specifically lesioned the rat rCG1/rCG2, and assessed the behavioural outcome using a modified forced swim test (FST) and the elevated plus maze (EPM), tests for depression and anxiety related behaviours respectively. Lesions of the rostral anterior cingulate cortex significantly increased the time spent immobile in the FST without affecting climbing or swimming performances, suggesting a pro-depressant effect. On the contrary, none of the parameters measured in the EPM was affected by the lesion. These data point to an involvement of the rCG1/rCG2 in depression-related coping behaviours.