Representation of perceived sound valence in the human brain

Perceived emotional valence of sensory stimuli influences their processing in various cortical and subcortical structures. Recent evidence suggests that negative and positive valences are processed separately, not along a single linear continuum. Here, we examined how brain is activated when subjects are listening to auditory stimuli varying parametrically in perceived valence (very unpleasant-neutral-very pleasant). Seventeen healthy volunteers were scanned in 3 Tesla while listening to International Affective Digital Sounds (IADS-2) in a block design paradigm. We found a strong quadratic U-shaped relationship between valence and blood oxygen level dependent (BOLD) signal strength in the medial prefrontal cortex, auditory cortex, and amygdala. Signals were the weakest for neutral stimuli and increased progressively for more unpleasant or pleasant stimuli. The results strengthen the view that valence is a crucial factor in neural processing of emotions. An alternative explanation is salience, which increases with both negative and positive valences.     

Cerebral blood flow changes associated with attribution of emotional valence to pleasant, unpleasant, and neutral visual stimuli in a PET study of normal subjects.

OBJECTIVE: To assist in the development of a model for the psychopathology of emotions, the present study sought to identify the neural circuits associated with the evaluation of visual stimuli for emotional valence. METHOD: Seventeen healthy individuals were shown three sets of emotionally laden pictures carrying pleasant, unpleasant, and neutral content. While subjects evaluated the picture set for emotional valence, regional cerebral blood flow was measured with the use of [15O] water positron emission tomography. Subjective ratings of the emotional valence of the picture sets were recorded. Data were analyzed by comparing the images acquired during the neutral condition with the unpleasant and pleasant image sets and the unpleasant and pleasant conditions with each other. RESULTS: Processing of pleasant stimuli was associated with increased blood flow in the dorsal-lateral, orbital, and medial frontal cortex relative to the unpleasant condition and in the cingulate, precuneus, and visual cortex relative to the neutral condition. Evaluation of unpleasant stimuli activated the amygdala, visual cortex, and cerebellum relative to the pleasant condition and the nucleus accumbens, precuneus, and visual cortex relative to the neutral condition. CONCLUSIONS: Observing and assigning emotional value to unpleasant stimuli produced activations in subcortical limbic regions, whereas evaluation of pleasant stimuli produced activations in cortical limbic areas. These findings are consistent with the notion of a subcortical and archaic danger recognition system and a system detecting pleasantness in events and situations that is phylogenetically younger, involving primarily the prefrontal cortex.     

Differences in neural activity when processing emotional arousal and valence in autism spectrum disorders

Individuals with autism spectrum disorders (ASD) often have difficulty recognizing and interpreting facial expressions of emotion, which may impair their ability to navigate and communicate successfully in their social, interpersonal environments. Characterizing specific differences between individuals with ASD and their typically developing (TD) counterparts in the neural activity subserving their experience of emotional faces may provide distinct targets for ASD interventions. Thus we used functional magnetic resonance imaging (fMRI) and a parametric experimental design to identify brain regions in which neural activity correlated with ratings of arousal and valence for a broad range of emotional faces. Participants (51 ASD, 84 TD) were group‐matched by age, sex, IQ, race, and socioeconomic status. Using task‐related change in blood‐oxygen‐level‐dependent (BOLD) fMRI signal as a measure, and covarying for age, sex, FSIQ, and ADOS scores, we detected significant differences across diagnostic groups in the neural activity subserving the dimension of arousal but not valence. BOLD‐signal in TD participants correlated inversely with ratings of arousal in regions associated primarily with attentional functions, whereas BOLD‐signal in ASD participants correlated positively with arousal ratings in regions commonly associated with impulse control and default‐mode activity. Only minor differences were detected between groups in the BOLD signal correlates of valence ratings. Our findings provide unique insight into the emotional experiences of individuals with ASD. Although behavioral responses to face‐stimuli were comparable across diagnostic groups, the corresponding neural activity for our ASD and TD groups differed dramatically. The near absence of group differences for valence correlates and the presence of strong group differences for arousal correlates suggest that individuals with ASD are not atypical in all aspects of emotion‐processing. Studying these similarities and differences may help us to understand the origins of divergent interpersonal emotional experience in persons with ASD. Hum Brain Mapp 37:443–461, 2016. © 2015 Wiley Periodicals, Inc.     

Selective numbing and hyperarousal in male and female Bosnian refugees with PTSD

Emotional numbing is an important symptom of PTSD, but it is not clear whether it affects both positive and negative affect equally or not. To address this question we administered Lang's Looking at Pictures test, in which a series of pictures are rated for valence (pleasant-unpleasant) and arousal (high-low), to 10 male and 11 female Bosnian refugees suffering from PTSD (DSM-IV criteria) and to control groups of 11 male and 10 female Bosnian refugees with similar trauma exposure but without PTSD or any other major mental illness. The mean valence ratings for unpleasant, neutral, and pleasant pictures of both PTSD and control males and females were similar to normal ratings. Likewise, the mean arousal ratings for unpleasant, neutral, and pleasant pictures of both male and female controls were similar to normals, with both unpleasant and pleasant pictures rated more arousing than neutral pictures. In contrast, in both males and females with PTSD pleasant pictures were rated as almost completely non-arousing. Thus, in Bosnian refugees affective numbing is seen primarily with pleasant or positive 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. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.     

Brain activity underlying emotional valence and arousal: a response-related fMRI study

Emotional behavior is organized along two psychophysiologic dimensions: (1) valence, varying from negative to positive, and (2) arousal, varying from low to high. Behavioral responses along these dimensions are assumed to be mediated by different brain circuits. We recorded startle reflex modulation and skin conductance responses in healthy volunteers during functional magnetic resonance imaging (fMRI) while they viewed a set of emotional pictures and took verbal ratings of the emotional valence and arousal of each picture after scanning. Response-related multiple correlation analysis revealed differential brain activity in five brain regions. Startle reflex changes, associated with the valence of a stimulus, correlated with activity in the amygdala, while verbal reports of negative emotional valence varied with insular activity. Peripheral physiologic and verbal responses along the arousal dimension varied with thalamic and frontomedial activity. Peripheral physiologic responses along both dimensions correlated with activity in somatosensory association areas in the anterior parietal cortex. In the valence dimension, activity in the left anterior parietal cortex was associated with highly correlating peripheral physiologic and verbal responses, suggesting that verbal reports of emotional valence might depend partly on brain circuits representing peripheral physiologic changes. Our data provide direct evidence for a functional segregation of brain structures underlying peripheral physiologic responses and verbal ratings along the emotional dimensions of valence and arousal.     

Different representations of pleasant and unpleasant odours in the human brain

Odours are important in emotional processing; yet relatively little is known about the representations of the affective qualities of odours in the human brain. We found that three pleasant and three unpleasant odours activated dissociable parts of the human brain. Pleasant but not unpleasant odours were found to activate a medial region of the rostral orbitofrontal cortex. Further, there was a correlation between the subjective pleasantness ratings of the six odours given during the investigation with activation of a medial region of the rostral orbitofrontal cortex. In contrast, a correlation between the subjective unpleasantness ratings of the six odours was found in regions of the left and more lateral orbitofrontal cortex. Moreover, a double dissociation was found with the intensity ratings of the odours, which were not correlated with the BOLD signal in the orbitofrontal cortex, but were correlated with the signal in medial olfactory cortical areas including the pyriform and anterior entorhinal cortex. Activation was also found in the anterior cingulate cortex, with a middle part of the anterior cingulate activated by both pleasant and unpleasant odours, and a more anterior part of the anterior cingulate cortex showing a correlation with the subjective pleasantness ratings of the odours. Thus the results suggest that there is a hedonic map of the sense of smell in brain regions such as the orbitofrontal cortex, and these results have implications for understanding the psychiatric and related problems that follow damage to these brain areas.     

Do brain responses to emotional images and cigarette cues differ? An fMRI study in smokers

Chronic smoking is thought to cause changes in brain reward systems that result in overvaluation of cigarette-related stimuli and undervaluation of natural rewards. We tested the hypotheses that, in smokers, brain circuits involved in emotional processing: (i) would be more active during exposure to cigarette-related than neutral pictures; and (ii) would be less active to pleasant compared with cigarette-related pictures, suggesting a devaluation of intrinsically pleasant stimuli. We obtained whole-brain blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging data from 35 smokers during the presentation of pleasant (erotica and romance), unpleasant (mutilations and sad), neutral, and cigarette-related pictures. Whole-brain analyses showed significantly larger BOLD responses during presentation of cigarette-related pictures relative to neutral ones within the secondary visual areas, the cingulate gyrus, the frontal gyrus, the dorsal striatum, and the left insula. BOLD responses to erotic pictures exceeded responses to cigarette-related pictures in all clusters except the insula. Within the left insula we observed larger BOLD responses to cigarette-related pictures than to all other picture categories. By including intrinsically pleasant and unpleasant pictures in addition to neutral ones, we were able to conclude that the presentation of cigarette-related pictures activates brain areas supporting emotional processes, but we did not find evidence of overall reduced activation of the brain reward systems in the presence of intrinsically pleasant stimuli.     

Personality modulates the effects of emotional arousal and valence on brain activation

The influence of personality on the neural correlates of emotional processing is still not well characterized. We investigated the relationship between extraversion and neuroticism and emotional perception using functional magnetic resonance imaging (fMRI) in a group of 23 young, healthy women. Using a parametric modulation approach, we examined how the blood oxygenation level dependent (BOLD) signal varied with the participants' ratings of arousal and valence, and whether levels of extraversion and neuroticism were related to these modulations. In particular, we wished to test Eysenck's biological theory of personality, which links high extraversion to lower levels of reticulothalamic-cortical arousal, and neuroticism to increased reactivity of the limbic system and stronger reactions to emotional arousal. Individuals high in neuroticism demonstrated reduced sustained activation in the orbitofrontal cortex (OFC) and attenuated valence processing in the right temporal lobe while viewing emotional images, but an increased BOLD response to emotional arousal in the right medial prefrontal cortex (mPFC). These results support Eysenck's theory, as well as our hypothesis that high levels of neuroticism are associated with attenuated reward processing. Extraversion was inversely related to arousal processing in the right cerebellum, but positively associated with arousal processing in the right insula, indicating that the relationship between extraversion and arousal is not as simple as that proposed by Eysenck.     

Brain activity during expectancy of emotional stimuli: an fMRI study

We studied the neural activation associated with the expectancy of emotional stimuli using whole brain fMRI. Fifteen healthy subjects underwent fMRI scanning during which they performed a warned reaction task using emotional pictures carrying pleasant, unpleasant, or neutral content. The task involved an expected or unexpected condition. Data were analyzed by comparing the images acquired under the different conditions. In the expected condition, compared with the unexpected condition, significant activation was observed in the medial, inferior and dorsolateral prefrontal cortex. Whereas the expectancy of pleasant stimuli produced activation in the left dorsolateral and left medial prefrontal cortex as well as in the right cerebellum, the expectancy of unpleasant stimuli produced activation in the right inferior and right medial prefrontal cortex, the right amygdala, the left anterior cingulate cortex, and bilaterally in the visual cortex. These results suggest that the expectancy of emotional stimuli is mediated by the prefrontal area including the medial, inferior, and dorsolateral prefrontal cortex. Furthermore, our data suggest that left frontal activation is associated with the expectancy of pleasant stimuli and that right frontal activation is associated with the expectancy of unpleasant stimuli. Finally, our findings suggest that the amygdala and anterior cingulate cortex may play an important role in the expectancy of unpleasant stimuli and that the input of this negative information is modulated by these specific brain areas.     

Spatiotemporal dynamics of affective picture processing revealed by intracranial high‐gamma modulations

Our comprehension of the neural mechanisms underlying emotional information processing has largely benefited from noninvasive electrophysiological and functional neuroimaging techniques in recent years. However, the spatiotemporal dynamics of the neural events occurring during emotional processing remain imprecise due to the limited combination of spatial and temporal resolution provided by these techniques. This study examines the modulations of high‐frequency activity of intracranial electroencephalography recordings associated with affective picture valence, in epileptic patients awaiting neurosurgery. Recordings were obtained from subdural grids and depth electrodes in eight patients while they viewed a series of unpleasant, pleasant and neutral pictures from the International Affective Picture System. Broadband high‐gamma (70–150 Hz) power was computed for separate 100‐ms time windows and compared according to ratings of emotional valence. Compared to emotionally neutral or pleasant pictures, unpleasant stimuli were associated with an early and long‐lasting (≈200–1,000 ms) bilateral increase in high‐gamma activity in visual areas of the occipital and temporal lobes, together with a late and transient (≈500–800 ms) decrease found bilaterally in the lateral prefrontal cortex (PFC). Pleasant pictures were associated with increased gamma activity in the occipital cortex, compared to the emotionally neutral stimuli. Consistent with previous studies, our results provide direct evidence of emotion‐related modulations in the visual ventral pathway during picture processing. Results in the lateral PFC also shed light on the neural mechanisms underlying its role in negative emotions processing. This study demonstrates the utility of intracranial high‐gamma modulations to study emotional process with a high spatiotemporal precision. Hum Brain Mapp, 36:16–28, 2015.. © 2014 Wiley Periodicals, Inc.     

Neural correlates of emotional recognition memory in schizophrenia: effects of valence and arousal

Schizophrenia patients are often impaired in their memory for emotional events compared with healthy subjects. Investigations of the neural correlates of emotional memory in schizophrenia patients are scarce in the literature. The present study aimed to compare cerebral activations in schizophrenia patients and healthy controls during memory retrieval of emotional images that varied in both valence and arousal. In a study with functional magnetic resonance imaging, 37 schizophrenia patients were compared with 37 healthy participants while performing a yes/no recognition paradigm with positive, negative (differing in arousal intensity) and neutral images. Schizophrenia patients performed worse than healthy controls in all experimental conditions. They showed less cerebral activation in limbic and prefrontal regions than controls during retrieval of negatively valenced stimuli, but had a similar pattern of brain activation compared with controls during retrieval of positively valenced stimuli (particularly in the high arousal condition) in the cerebellum, temporal lobe and prefrontal cortex. Both groups demonstrated increased brain activations in the high relative to low arousing conditions. Our results suggest atypical brain function during retrieval of negative pictures, but intact functional circuitry of positive affect during episodic memory retrieval in schizophrenia patients. The arousal data revealed that schizophrenia patients closely resemble the control group at both the behavioral and neurofunctional level.     

Changes in emotional empathy, affective responsivity, and behavior following severe traumatic brain injury

This study was designed to examine the relationship between deficits in empathy, emotional responsivity, and social behavior in adults with severe traumatic brain injury (TBI). A total of 21 patients with severe TBI and 25 control participants viewed six film clips containing pleasant, unpleasant, and neutral content whilst facial muscle responses, skin conductance, and valence and arousal ratings were measured. Emotional empathy (the Balanced Emotional Empathy Scale, BEES: self-report) and changes in drive and control in social situations (The Current Behaviour Scale, CBS: relative report) were also assessed. In comparison to control participants, those in the TBI group reported less ability to empathize emotionally and had reduced facial responding to both pleasant and unpleasant films. They also exhibited lowered autonomic arousal, as well as abnormal ratings of valence and arousal, particularly to unpleasant films. Relative reported loss of emotional control was significantly associated with heightened empathy, while there was a trend to suggest that impaired drive (or motivation) may be related to lower levels of emotional empathy. The results represent the first to suggest that level of emotional empathy post traumatic brain injury may be associated with behavioral manifestations of disorders of drive and control.     

Anterior cingulate and medial prefrontal cortex response to systematically controlled tonal dissonance during passive music listening

Several studies have attempted to investigate how the brain codes emotional value when processing music of contrasting levels of dissonance; however, the lack of control over specific musical structural characteristics (i.e., dynamics, rhythm, melodic contour or instrumental timbre), which are known to affect perceived dissonance, rendered results difficult to interpret. To account for this, we used functional imaging with an optimized control of the musical structure to obtain a finer characterization of brain activity in response to tonal dissonance. Behavioral findings supported previous evidence for an association between increased dissonance and negative emotion. Results further demonstrated that the manipulation of tonal dissonance through systematically controlled changes in interval content elicited contrasting valence ratings but no significant effects on either arousal or potency. Neuroscientific findings showed an engagement of the left medial prefrontal cortex (mPFC) and the left rostral anterior cingulate cortex (ACC) while participants listened to dissonant compared to consonant music, converging with studies that have proposed a core role of these regions during conflict monitoring (detection and resolution), and in the appraisal of negative emotion and fear‐related information. Both the left and right primary auditory cortices showed stronger functional connectivity with the ACC during the dissonant portion of the task, implying a demand for greater information integration when processing negatively valenced musical stimuli. This study demonstrated that the systematic control of musical dissonance could be applied to isolate valence from the arousal dimension, facilitating a novel access to the neural representation of negative emotion.     

Dissociation of emotional processes in response to visual and olfactory stimuli following frontotemporal damage

Contemporary neuropsychological studies have stressed the widely distributed and multicomponential nature of human affective processes. Here, we examined facial electromyographic (EMG) (zygomaticus and corrugator muscle activity), autonomic (skin conductance and heart rate) and subjective measures of affective valence and arousal in patient TG, a 30 year-old man with left anterior mediotemporal and left orbitofrontal lesions resulting from a traumatic brain injury. Both TG and a normal control group were exposed to hedonically valenced visual and olfactory stimuli. In contrast with control subjects, facial EMG and electrodermal activity in TG did not differentiate among pleasant, unpleasant and neutral pictures. In addition, the controls reacted spontaneously with larger corrugator EMG activity and higher skin conductance to unpleasant odors. By contrast, the subjective feeling states (pleasure and arousal ratings) remained preserved in TG. The covariation between facial and self-report measures of negative valence was also a function of the nature of the olfactory task in the patient only. Taken together, the data suggest a functional dissociation between brain substrates supporting generation of emotion and those supporting representation of emotion.     

Why don’t you feel how I feel? Insight into the absence of empathy after severe Traumatic Brain Injury

Although the existence of empathy deficits in people with traumatic brain injury (TBI) is generally well accepted, it has been a topic of limited investigation. The current study examined the relationship between self-reported emotional and cognitive empathy and psychophysiological responding to emotionally evocative pictures in 20 patients with severe TBI and 22 control participants. Eighteen pictures with alternating pleasant, unpleasant and neutral content selected from the International Affective Picture System (IAPS) were presented whilst facial muscle responses, skin conductance, and valence and arousal ratings were measured. Self-reported emotional and cognitive empathy questionnaires were also administered. In comparison to control participants, those in the TBI group displayed a reduction in the ability to empathize both emotionally and cognitively, and evidence that these two aspects of empathy may be interconnected was established. Further, TBI participants showed reduced facial responding to unpleasant pictures, while also rating them as less unpleasant and arousing than controls. In addition, they exhibited lowered autonomic arousal to all pictures, regardless of affective valence. Interestingly, hypoarousal to pleasant pictures in particular was found to be related to the absence of empathy observed after TBI, and is consistent with the view that impaired emotional responsivity is associated with impairment to the empathy network. The results represent a further step towards understanding what processes shape empathy.     

Pain influences hedonic assessment of visual inputs

It is acknowledged that the emotional state created by visual inputs can modulate the way we feel pain; however, little is known about how acute pain influences the emotional assessment of what we see. In this study healthy subjects scored affective images while receiving painful or innocuous electrical shocks. Painful stimuli did not make unpleasant images more unpleasant, but rendered pleasant pictures significantly less pleasant. Brain responses to visual inputs (64-channels electroencephalogram) mirrored behavioural results, showing pain-induced effects in the orbitofrontal cortex, the subgenual portion of the cingulate gyrus, the anterior prefrontal and the temporal cortices, exclusively during presentation of pleasant images. In addition to this specific effect on pleasant pictures, pain also produced non-specific effects upon all categories of images, engaging cerebral areas associated with attention, alertness and motor preparation (middle-cingulate, supplemental motor, prefrontal cortex). Thus, pain appears to have a dual influence on visual processing: a non-specific effect related to orienting phenomena; and a more specific action exerted on supra-modal limbic areas involved in the production of affective states. The latter correlated with changes in the subjective appraisal of visual stimuli, and may underlie not only the change in their subjective assessment but also reactive processes aimed at coping with unpleasant contexts.     

Expecting unpleasant stimuli – An fMRI study

Expecting forthcoming events and preparing adequate responses are important cognitive functions that help the individual to deal with the environment. The emotional valence of an event is decisive for the resulting action. Revealing the underlying mechanisms may help to understand the dysfunctional information processing in depression and anxiety that are associated with negative expectation of the future. We were interested in selective brain activity during the expectation of unpleasant visual stimuli. Twelve healthy female subjects were biased to expect and then perceive emotionally unpleasant, pleasant or neutral stimuli during functional magnetic resonance imaging. Expecting unpleasant stimuli relative to expecting pleasant and neutral stimuli resulted in activation of mainly cingulate cortex, insula, prefrontal areas, thalamus, hypothalamus and striatum. While certain areas were also active during subsequent presentation of the emotional stimuli, distinct regions of the anterior cingulate gyrus and the thalamus were solely active during expectation of the unpleasant stimuli. The identified areas may reflect a network for internal adaptation and preparation processes in order to react adequately to expected unpleasant events. They are known as well to be altered in depression. Disorders of this network may be relevant for psychiatric disorders such as depression.     

Expecting unpleasant stimuli--an fMRI study

Expecting forthcoming events and preparing adequate responses are important cognitive functions that help the individual to deal with the environment. The emotional valence of an event is decisive for the resulting action. Revealing the underlying mechanisms may help to understand the dysfunctional information processing in depression and anxiety that are associated with negative expectation of the future. We were interested in selective brain activity during the expectation of unpleasant visual stimuli. Twelve healthy female subjects were biased to expect and then perceive emotionally unpleasant, pleasant or neutral stimuli during functional magnetic resonance imaging. Expecting unpleasant stimuli relative to expecting pleasant and neutral stimuli resulted in activation of mainly cingulate cortex, insula, prefrontal areas, thalamus, hypothalamus and striatum. While certain areas were also active during subsequent presentation of the emotional stimuli, distinct regions of the anterior cingulate gyrus and the thalamus were solely active during expectation of the unpleasant stimuli. The identified areas may reflect a network for internal adaptation and preparation processes in order to react adequately to expected unpleasant events. They are known as well to be altered in depression. Disorders of this network may be relevant for psychiatric disorders such as depression.     

Dissociation of emotional processes in response to visual and olfactory stimuli following frontotemporal damage

Contemporary neuropsychological studies have stressed the widely distributed and multicomponential nature of human affective processes. Here, we examined facial electromyographic (EMG) (zygomaticus and corrugator muscle activity), autonomic (skin conductance and heart rate) and subjective measures of affective valence and arousal in patient TG, a 30 year-old man with left anterior mediotemporal and left orbitofrontal lesions resulting from a traumatic brain injury. Both TG and a normal control group were exposed to hedonically valenced visual and olfactory stimuli. In contrast with control subjects, facial EMG and electrodermal activity in TG did not differentiate among pleasant, unpleasant and neutral pictures. In addition, the controls reacted spontaneously with larger corrugator EMG activity and higher skin conductance to unpleasant odors. By contrast, the subjective feeling states (pleasure and arousal ratings) remained preserved in TG. The covariation between facial and self-report measures of negative valence was also a function of the nature of the olfactory task in the patient only. Taken together, the data suggest a functional dissociation between brain substrates supporting generation of emotion and those supporting representation of emotion.