To assess autonomic dysfunction, skin sympathetic nerve
activity (SSNA) of four patients with Guillain-Barré syndrome was microneurographically studied in the acute and remission phase. Autonomic symptoms such as sinus tachycardia, palmar hyperhidrosis, hypertension, and orthostatic hypotension were present in the acute
phase, but all subsided during remission. Basal resting SSNA and the
responses to various physical and mental stimuli were all increased in
the acute phase and returned almost to normal during remission. Rate of
response in sweat rate and blood flow against SSNA were kept
proportionally constant during both the acute and remission phases.
These findings suggest that some autonomic nerve symptoms of
Guillain-Barré syndrome, particularly during the acute phase,
are due to increased SSNA.
In humans, sympathetic vasoconstrictor nerves in the skin contribute to resting vascular tone and mediate reflex vasoconstrictor responses to body cooling. Although it is well recognized that type 2 diabetes mellitus (T2DM) is associated with peripheral neurovascular changes, it is unclear to what extent the thermal responsiveness of the cutaneous vasoconstrictor system is altered in individuals with relatively uncomplicated T2DM. We tested the hypothesis that skin sympathetic nerve activity (SSNA) is decreased at baseline and during body cooling in individuals with T2DM compared to healthy controls (C) of similar age and body size. We measured SSNA (microneurography) and skin blood flow (laser-Doppler flowmetry) in the innervated area in 8 T2DM and 12 C subjects at baseline and during 3–4 minutes of rapid whole body cooling via water-perfused suit. SSNA (total integrated activity) increased, and cutaneous vascular conductance decreased in both groups during body cooling (P < 0.01 for both). However, SSNA was not different between groups during either baseline or body cooling conditions (P = NS). The deltas in SSNA between baseline and body cooling were similar between groups: T2DM: 55 ± 27 and C: 57 ± 12 units (P = NS). We conclude that reflex cutaneous sympathetic and vascular responses to rapid whole body cooling are preserved in relatively healthy individuals with T2DM.
skin sympathetic nerve activity; thermoregulation; skin blood flow; vasoconstriction
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 1) would be more active during exposure to cigarette-related than neutral pictures, and 2) would be less active to pleasant compared to cigarette-related pictures, suggesting a devaluation of intrinsically pleasant stimuli. We obtained whole brain blood-oxygenation-level-dependent functional magnetic resonance imaging (BOLD fMRI) 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.
pictures; smoking; nicotine; emotions; insula
Parkinson’s disease (PD) is a neurodegenerative disease that affects motor, cognitive, and emotional functioning. Previous studies reported reduced skin conductance responses in PD patients, compared to healthy older adults when viewing emotionally arousing pictures. Attenuated skin conductance changes in PD may reflect peripheral autonomic dysfunction (e.g., reduced nerve endings at the sweat gland) or, alternatively, a more central emotional deficit. The aim of the current study was to investigate a second measure of sympathetic arousal—change in pupil dilation. Eye movements, a motor-based correlate of emotional processing, were also assessed. Results indicated that pupil dilation was significantly greater when viewing emotional, compared to neutral pictures for both PD patients and controls. On the other hand, PD patients made fewer fixations with shorter scan paths, particularly when viewing pleasant pictures. These results suggest that PD patients show normal sympathetic arousal to affective stimuli (indexed by pupil diameter), but differences in motor correlates of emotion (eye movements.)
emotion; arousal; Parkinson’s disease; pupil; eye movement
Re-entrant modulation of visual cortex has been suggested as a critical process for enhancing perception of emotionally arousing visual stimuli. This study explores how the time information inherent in large-scale electrocortical measures can be used to examine the functional relationships among the structures involved in emotional perception. Granger causality analysis was conducted on steady-state visual evoked potentials elicited by emotionally arousing pictures flickering at a rate of 10 Hz. This procedure allows one to examine the direction of neural connections. Participants viewed pictures that varied in emotional content, depicting people in neutral contexts, erotica, or interpersonal attack scenes. Results demonstrated increased coupling between visual and cortical areas when viewing emotionally arousing content. Specifically, intraparietal to inferotemporal and precuneus to calcarine connections were stronger for emotionally arousing picture content. Thus, we provide evidence for re-entrant signal flow during emotional perception, which originates from higher tiers and enters lower tiers of visual cortex.
affective arousal; electroencephalography; emotion; Granger causality; steady-state potentials
Menopausal hot flashes can seriously disrupt the lives of symptomatic women. The physiological mechanisms of the hot flash efferent responses, particularly in the cutaneous circulation, are not completely understood. The aim of this study was to examine the mechanisms of increases in skin blood flow during the postmenopausal hot flash in symptomatic women.
Healthy postmenopausal women rested in a temperature controlled laboratory while responses prior to and during hot flashes were recorded for three unique protocols. Protocols 1 and 2: Women were locally pretreated with an intradermal injection of botulinum toxin A (BTX; blocks the release of neurotransmitters from sympathetic cholinergic nerves) in the forearm (protocol 1) and in the glabellar region (protocol 2). Protocol 3: Skin sympathetic nerve activity from the peroneal nerve was recorded, along with skin blood flow and sweating within the region innervated by that neural signal. Skin blood flow was indexed using laser-Doppler flowmetry at BTX-treated and adjacent untreated control sites. The onset of a hot flash was objectively identified as a transient and pronounced elevation of sternal sweat rate.
The elevation in forearm (protocol 1) and glabellar skin blood flow (protocol 2) during hot flashes were attenuated at BTX sites relative to adjacent untreated sites (P<0.05 for both protocols). In protocol 3, skin sympathetic nerve activity significantly increased during hot flashes and returned to pre-flash levels following the hot flashes.
Elevations in skin blood flow during the postmenopausal hot flash are neurally mediated primarily through BTX sensitive nerves; presumably sympathetic cholinergic.
Skin Blood Flow; Sympathetic Cholinergic; Menopause
Despite a large number of functional neuroimaging investigations of emotion processing in schizophrenia, very few have included women. In the present study 21 schizophrenia and 23 healthy women underwent functional MRI (3T) on two occasions (during the follicular and luteal phase of their menstrual cycle) while viewing blocks of emotionally negative, positive and neutral images. During exposure to negatively charged images patients showed relatively less activations than controls during the luteal phase, but no between-group differences were observed during the follicular phase. In contrast, the exposure to positively valenced material produced no significant interaction, but the main effect of group; schizophrenia patients exhibited less activation than healthy controls during both phases of the menstrual cycle. This is the first study demonstrating that atypical neural activations associated with emotion processing in women diagnosed with schizophrenia depend on the menstrual cycle phase and on the affective valence of presented stimuli.
Primary Sjögren's Syndrome (PSS) is a highly prevalent autoimmune disease, typically manifesting as lymphocytic infiltration of the exocrine glands leading to chronically impaired lacrimal and salivary secretion. Sjögren's Syndrome nuclear autoantigen 1 (SSNA1 or NA14) is a major specific target for autoantibodies in PSS but the precise function and clinical relevance of this protein are largely unknown. Orthologues of the gene are absent from many of the commonly used model organisms but are present in Chlamyodomonas reinhardtii (in which it has been termed DIP13) and most protozoa. We report the functional characterisation of the orthologue of SSNA1 in the kinetoplastid parasite, Trypanosoma brucei. Both TbDIP13 and human SSNA1 are small coiled-coil proteins which are predicted to be remote homologues of the actin-binding protein tropomyosin. We use comparative proteomic methods to identify potential interacting partners of TbDIP13. We also show evidence that TbDIP13 is able to self-assemble into fibril-like structures both in vitro and in vivo, a property which may contribute to its immunogenicity. Endogenous TbDIP13 partially co-localises with acetylated α-tubulin in the insect procyclic stage of the parasite. However, deletion of the DIP13 gene in cultured bloodstream and procyclic stages of T. brucei has little effect on parasite growth or morphology, indicating either a degree of functional redundancy or a function in an alternative stage of the parasite life cycle.
Microneurography was performed in median nerve sensory fascicles with concentric needle electrodes and with conventional tungsten microneedles. The latter electrodes preferentially recorded activity from the myelinated fibres in the whole fascicle. By contrast, due to its special design, a concentric needle can record activity selectively from even a small part of a fascicle. High amplitude signals in C fibres can be discriminated close to Schwann cells that envelope unmyelinated axons. Apart from being biased for activity in thin fibres, the concentric needles can also record signals from nearby myelinated fibres. The palmar receptive fields of such fibre groups were not congruent with the areas traditionally attributed to multiunit skin afferents in humans, namely the innervation zone(s) of one or two adjacent digital nerve(s). Instead, the multiunit fields often comprised small parts of a digital nerve innervation area, frequently only the pulp of a finger. Single units were always localised within previously screened multiunit areas. Contrary to some previously accepted tenets it is probable that single unit activity in myelinated fibres in these studies is recorded extra-axonally near to a node of Ranvier. The findings also suggest the presence of a somatotopy in human limb nerve fascicles, comparable to that previously established in the spinal cord and the somatosensory cortex.
Pupil diameter was monitored during picture viewing to assess effects of hedonic valence and emotional arousal on pupillary responses. Autonomic activity (heart rate and skin conductance) was concurrently measured to determine whether pupillary changes are mediated by parasympathetic or sympathetic activation. Following an initial light reflex, pupillary changes were larger when viewing emotionally arousing pictures, regardless of whether these were pleasant or unpleasant. Pupillary changes during picture viewing covaried with skin conductance change, supporting the interpretation that sympathetic nervous systemactivity modulates these changes in the context of affective picture viewing. Taken together, the data provide strong support for the hypothesis that the pupil’s response during affective picture viewing reflects emotional arousal associated with increased sympathetic activity.
Pupil; Arousal; Emotion; Pleasure; Sympathetic; Skin conductance
A dissociation between voluntary and emotional facial innervation is described in a patient with a pure motor stroke due to a unilateral ischaemic pontine infarction. Voluntary facial innervation of the contralateral orbicularis oris muscle was affected whereas emotionally induced innervation of the same muscle was spared. This report provides evidence that fibres conveying voluntary and emotional commands are still separated in the pons. Whereas corticobulbar tracts carry the information for voluntary facial innervation, efferents from the amygdala and the lateral hypothalamus are candidates for the somatomotor aspects of emotions.
We investigated how viewing task-irrelevant emotional pictures affects the performance of a subsequent non-emotional visual detection task. Subjects performed target-detection trials following the offset of individual unpleasant, pleasant and neutral pictures. Sustained interference occurred when subjects viewed blocked unpleasant pictures (mutilated bodies). Such slowing down of reaction time appeared to “build up” with time, consistent with the instatement of a defensive emotional state. With a randomized picture presentation, only a transient interference effect was observed, consistent with increased attentional demands during the processing of unpleasant pictures. During blocked presentation of affiliative pleasant pictures, reaction times were faster, suggesting the activation of appetitive motivational systems. Ultimately, both attentional and motivational systems are intricately tied in the brain and, together, determine behavior.
We used microelectrode recordings of muscle sympathetic nerve activity (MSNA) from the peroneal nerve in the leg during arm exercise in conscious humans to test the concept that central command and muscle afferent reflexes produce mass sympathetic discharge at the onset of exercise. Nonischemic rhythmic handgrip and mild arm cycling produced graded increases in heart rate and arterial pressure but did not increase MSNA, whereas ischemic handgrip and moderate arm cycling dramatically increased MSNA. There was a slow onset and offset of the MSNA responses, which suggested metaboreceptor mediation. When forearm ischemia was continued after ischemic handgrip, MSNA remained elevated (muscle chemoreflex stimulation) but heart rate returned to control (elimination of central command). The major new conclusions are that: the onset of dynamic exercise does not produce mass, uniform sympathetic discharge in humans, and muscle chemoreflexes and central command appear to produce differential effects on sympathetic and parasympathetic responses.
Schizophrenia has been associated with disturbed levels of sex-steroid hormones, including estrogen and testosterone. In the present study we have examined the implication of a less studied hormone progesterone. Forty-three patients with schizophrenia (21 women) and 43 control participants (21 women) underwent functional MRI while viewing emotionally positive, negative, and neutral images. Blood samples were taken prior to the scanning session to evaluate progesterone levels. Simple regression analyses between levels of progesterone and brain activations associated with emotion processing were performed using SPM5. A positive correlation was found between progesterone levels and brain activations during processing of emotionally charged images in both healthy and schizophrenia men, but no significant relationship was revealed in women. These preliminary results indicate that progesterone is significantly associated with brain activations during processing of positive and negative affect in healthy and schizophrenia men, but not in women. Further investigation is warranted.
Cocaine-induced cardiovascular emergencies are mediated by excessive adrenergic stimulation. Animal studies suggest that cocaine not only blocks norepinephrine reuptake peripherally but also inhibits the baroreceptors, thereby reflexively increasing sympathetic nerve discharge. However, the effect of cocaine on sympathetic nerve discharge in humans is unknown. In 12 healthy volunteers, we recorded blood pressure and sympathetic nerve discharge to the skeletal muscle vasculature using intraneural microelectrodes (peroneal nerve) during intranasal cocaine (2 mg/kg, n = 8) or lidocaine (2%, n = 4), an internal local anesthetic control, or intravenous phenylephrine (0.5-2.0 microg/kg, n = 4), an internal sympathomimetic control. Experiments were repeated while minimizing the cocaine-induced rise in blood pressure with intravenous nitroprusside to negate sinoaortic baroreceptor stimulation. After lidocaine, blood pressure and sympathetic nerve discharge were unchanged. After cocaine, blood pressure increased abruptly and remained elevated for 60 min while sympathetic nerve discharge initially was unchanged and then decreased progressively over 60 min to a nadir that was only 2+/-1% of baseline (P < 0.05); however, plasma venous norepinephrine concentrations (n = 5) were unchanged up to 60 min after cocaine. Sympathetic nerve discharge fell more rapidly but to the same nadir when blood pressure was increased similarly with phenylephrine. When the cocaine-induced increase in blood pressure was minimized (nitroprusside), sympathetic nerve discharge did not decrease but rather increased by 2.9 times over baseline (P < 0.05). Baroreflex gain was comparable before and after cocaine. We conclude that in conscious humans the primary effect of intranasal cocaine is to increase sympathetic nerve discharge to the skeletal muscle bed. Furthermore, sinoaortic baroreflexes play a pivotal role in modulating the cocaine-induced sympathetic excitation. The interplay between these excitatory and inhibitory neural influences determines the net effect of cocaine on sympathetic discharge targeted to the human skeletal muscle circulation.
Emotional and motivational dysfunction is fundamental to schizophrenia, and yet the nature and scope of associated deficits are not well understood. This study assessed the integrity of emotional responding from the perspective of its underlying motivational systems during different phases of schizophrenia. Evaluative, somatic, and autonomic responses were measured during viewing of pictures categorized by emotional content, including threat, mutilation, contamination, illness, pollution, mild erotica, families, food and nature. Participants were 13 patients at ultra high-risk or prodromal for psychosis, 40 first-episode schizophrenia patients, 37 chronic schizophrenia patients, and 74 healthy comparison subjects. Irrespective of phase of illness, schizophrenia patients showed a robust and normal pattern of response across multiple systems, with differential engagement of the defensive and appetitive systems as a function of the motivational significance assigned to specific emotional contexts. Although the integrity of core motivational states also appeared to be intact in prodromal patients, a less consistent pattern of response was observed. As continuing efforts are made to identify emotional and motivational abnormalities in schizophrenia, identified deficits will likely be independent of a fundamental dysfunction in basic emotion and motivation response systems and involve integration with higher order processes.
schizophrenia; emotion; motivation; attention; startle reflex
Functional brain imaging studies have demonstrated amygdala and insula hyper-reactivity to probes of social threat in participants with generalized social anxiety disorder (gSAD). The amygdala and insula are known to serve broad functions in emotional processing, including integration of affective information. However, few studies have examined brain responses in socially anxious participants during general emotional processing. We examined brain response to emotionally evocative images in patients with gSAD and matched healthy controls.
Eleven patients with gSAD who were not taking psychotropic medications and did not have psychiatric comorbidities and 11 matched healthy controls underwent functional magnetic resonance imaging while viewing blocks of emotionally salient (positive, negative, neutral) pictures.
Participants with gSAD exhibited enhanced bilateral amygdala and insula reactivity to negative (v. neutral) images compared with healthy controls who did not exhibit enhanced reactivity. Within the gSAD group, the extent of amygdala activation was correlated with social anxiety severity, whereas the extent of insula activation was correlated with trait anxiety.
The small sample size may have limited our ability to detect group differences in other relevant brain regions and in behavioural measures.
In addition to prior findings of probes of social information processing, our findings suggest that the amygdala and insula responses are hyper-reactive to general emotional images with negative emotional content and that these brain regions may play divergent roles in their representation of different phenotypes.
Neuropathic pain can be divided into sympathetically maintained pain (SMP) and sympathetically independent pain (SIP). Rats with tibial and sural nerve transection (TST) produce neuropathic pain behaviors, including spontaneous pain, tactile allodynia, and cold allodynia. The present study was undertaken to examine whether rats with TST would represent SMP- or SIP-dominant neuropathic pain by lumbar surgical sympathectomy. The TST model was generated by transecting the tibial and sural nerves, leaving the common peroneal nerve intact. Animals were divided into the sympathectomy group and the sham group. For the sympathectomy group, the sympathetic chain was removed bilaterally from L2 to L6 one week after nerve transection. The success of the sympathectomy was verified by measuring skin temperature on the hind paw and by infra red thermography. Tactile allodynia was assessed using von Frey filaments, and cold allodynia was assessed using acetone drops. A majority of the rats exhibited withdrawal behaviors in response to tactile and cold stimulations after nerve stimulation. Neither tactile allodynia nor cold allodynia improved after successful sympathectomy, and there were no differences in the threshold of tactile and cold allodynia between the sympathectomy and sham groups. Tactile allodynia and cold allodynia in the neuropathic pain model of TST are not dependent on the sympathetic nervous system, and this model can be used to investigate SIP syndromes.
Neuropathic pain; sympathetically independent pain; sympathetically maintained pain; sympathectomy; tibial nerve; sural nerve; transection
The extent of the attentional blink effect on detection rates in rapid serial visual presentations is modulated by the emotionality of the stimuli. Emotionally salient stimuli are detected more often, even if presented in the attentional blink period, and elicit an enlarged P3 response, which has been interpreted as enhanced consolidation. This effect correlates with individual differences in trait affectivity such as anxiety or dysphoria. Here, we ask if it is also related to the capacity to detect emotions in others, i.e., to interpersonal social traits. We therefore presented emotional and neutral images depicting social scenes as targets in an attentional blink design and measured detection rates and event-related potentials. In addition, we recorded self-reports of empathy as measured by the Interpersonal Reactivity Index. The results show enhanced performance for emotional stimuli and increased P3 amplitudes, which correlated with individual differences in empathy. The data suggest that self-reported empathy goes along with enhanced processing of emotion in social stimuli, even under stimulus conditions that are suboptimal for conscious target detection.
P3 event-related potential; electroencephalography; event-related potentials; empathy; attentional blink; emotions
Prospective memory (PM) describes the ability to execute a previously planned action at the appropriate point in time. Although behavioral studies clearly showed that prospective memory performance is affected by the emotional significance attributed to the intended action, no study so far investigated the brain mechanisms subserving the modulatory effect of emotional salience on PM performance. The general aim of the present study was to explore brain regions involved in prospective memory processes when PM cues are associated with emotional stimuli. In particular, based on the hypothesised critical role of the prefrontal cortex in prospective memory in the presence of emotionally salient stimuli, we expected a stronger involvement of aPFC when the retrieval and execution of the intended action is cued by an aversive stimulus. To this aim BOLD responses of PM trials cued by aversive facial expressions were compared to PM trials cued by neutral facial expressions. Whole brain analysis showed that PM task cued by aversive stimuli is differentially associated with activity in the right lateral prefrontal area (BA 10) and in the left caudate nucleus. Moreover a temporal shift between the response of the caudate nucleus that preceded that of aPFC was observed. These findings suggest that the caudate nucleus might provide an early analysis of the affective properties of the stimuli, whereas the anterior lateral prefrontal cortex (BA10) would be involved in a slower and more deliberative analysis to guide goal-directed behaviour.
The sympathetic nervous system has been implicated in pain associated with painful diabetic neuropathy. However, therapeutic intervention targeted at the sympathetic nervous system has not been established. We thus tested the hypothesis that sympathetic nerve blocks significantly reduce pain in a patient with painful diabetic neuropathy who has failed multiple pharmacological treatments. The diagnosis of small fiber sensory neuropathy was based on clinical presentations and confirmed by skin biopsies. A series of 9 lumbar sympathetic blocks over a 26-month period provided sustained pain relief in his legs. Additional thoracic paravertebral blocks further provided control of the pain in the trunk which can occasionally be seen in severe diabetic neuropathy cases, consequent to extensive involvement of the intercostal nerves. These blocks provided sustained and significant pain relief and improvement of quality of life over a period of more than two years. We thus provided the first clinical evidence supporting the notion that sympathetic nervous system plays a critical role in painful diabetic neuropathy and sympathetic blocks can be an effective management modality of painful diabetic neuropathy. We concluded that the sympathetic nervous system is a valuable therapeutic target of pharmacological and interventional modalities of treatments in painful diabetic neuropathy patients.
Single unit activity in primary spindle afferent nerve fibres from finger and foot flexors was recorded with tungsten microelectrodes inserted into the median and peroneal nerves of healthy subjects. During voluntary fast alternating finger and foot movements, simulating the tremor of Parkinsonism, two types of discharges were seen in the Ia afferent fibres: (1) stretch responses occurring during the flexor relaxation phases, and (2) discharges occurring during the flexor contraction phases. Contrary to the stretch responses the spindle contraction discharges could be eliminated by a partial lidocaine block of the muscle nerve proximal to the recording site, indicating that they resulted from fusimotor activation of intrafusal fibres. On the basis of the temporal relations between the beginning and end of individual EMG-bursts, the start of the spindle contraction discharges and the latency of the stretch reflex in the muscles concerned, the following conclusions were drawn: the recurrent extrafusal contractions in movements of this type are initiated by the fast direct alpha route, but individual contraction phases generally last long enough to be influenced subsequently by the coactivated fusimotor loop through the spindles. It is postulated that this gamma loop influence during alternating movements helps to keep flexor and extensor muscles working in a regular reciprocal fashion with contractions adjusted in strength to the external loads.
Due to the unique neural projections of the olfactory system, odours have the ability to directly influence affective processes. Furthermore, it has been shown that emotional states can influence various non-emotional cognitive tasks, such as memory and planning. However, the link between emotional and cognitive processes is still not fully understood. The present study used the olfactory pathway to induce a negative emotional state in humans to investigate its effect on inhibitory control performance in a standard, single-trial manual Stroop colour-word interference task. An unpleasant (H2S) and an emotionally neutral (Eugenol) odorant were presented in two separate experimental runs, both in blocks alternating with ambient air, to 25 healthy volunteers, while they performed the cognitive task.
Presentation of the unpleasant odorant reduced Stroop interference by reducing the reaction times for incongruent stimuli, while the presentation of the neutral odorant had no effect on task performance.
The odour-induced negative emotional state appears to facilitate cognitive processing in the task used in the present study, possibly by increasing the amount of cognitive control that is being exerted. This stands in contrast to other findings that showed impaired cognitive performance under odour-induced negative emotional states, but is consistent with models of mood-congruent processing.
Velocardiofacial syndrome (VCFS) is caused by a micro-deletion of over 40 genes at the q11.2 locus of chromosome 22 and is a risk factor for the development of schizophrenia and other psychiatric disorders. COMT, one of the genes located in the deleted region, has been considered as a major candidate gene for genetic susceptibility in psychiatric diseases. Its functional polymorphism Val108/158Met has been shown to affect prefrontal function and working memory and has been associated with emotional dysregulation. We utilized a functional magnetic resonance imaging (fMRI) event-related paradigm to asses COMT genotype and gender-moderated effects on the neural activation that are elicited by viewing emotionally salient images charged with pleasant, unpleasant, and neutral content. Since estrogen down-regulates COMT activity resulting in lower COMT activity in women than men, we hypothesized an allele-by-gender interaction effect on neural activation. Participants included 43 VCFS individuals (Val/Male=9, Val/Female=17, Met/Male=9, Met/Female=8). We observed a gender effect on processing positive emotions, in that girls activated the cingulate gyrus more than boys. We further observed a significant gender-by-allele interaction effect on neural function specific to the frontal lobe during the processing of pleasant stimuli, and specific to limbic regions during the processing of unpleasant stimuli. Our results suggest that in VCFS, the effect of the COMT Val108/158Met polymorphism is moderated by gender during the processing of emotional stimuli and could contribute to the understanding of the way in which this COMT polymorphism affects vulnerability to neuropsychiatric disorders.
Emotional stimuli are preferentially processed over neutral stimuli. Previous studies, however, disagree on whether emotional stimuli capture attention preattentively or whether the processing advantage is dependent on allocation of attention. The present study investigated attention and emotion processes by measuring brain responses related to eye movement events while 11 participants viewed images selected from the International Affective Picture System (IAPS). Brain responses to emotional stimuli were compared between serial and parallel presentation. An “emotional” set included one image with high positive or negative valence among neutral images. A “neutral” set comprised four neutral images. The participants were asked to indicate which picture—if any—was emotional and to rate that picture on valence and arousal. In the serial condition, the event-related potentials (ERPs) were time-locked to the stimulus onset. In the parallel condition, the ERPs were time-locked to the first eye entry on an image. The eye movement results showed facilitated processing of emotional, especially unpleasant information. The EEG results in both presentation conditions showed that the LPP (“late positive potential”) amplitudes at 400–500 ms were enlarged for the unpleasant and pleasant pictures as compared to neutral pictures. Moreover, the unpleasant scenes elicited stronger responses than pleasant scenes. The ERP results did not support parafoveal emotional processing, although the eye movement results suggested faster attention capture by emotional stimuli. Our findings, thus, suggested that emotional processing depends on overt attentional resources engaged in the processing of emotional content. The results also indicate that brain responses to emotional images can be analyzed time-locked to eye movement events, although the response amplitudes were larger during serial presentation.
attention; emotion; EEG; eye movements; co-registration; fixation-related potentials; free viewing; LPP