Thursday, December 27, 2007

ARTICLE UPDATE - What Are You Feeling? Using Functional Magnetic Resonance Imaging to Assess the Modulation of Sensory and Affective Responses during

Lamm C, Nusbaum HC, Meltzoff AN, Decety J.

PLoS ONE, 2, e1292

BACKGROUND: Recent neuroscientific evidence suggests that empathy for pain activates similar neural representations as the first-hand experience of pain. However, empathy is not an all-or-none phenomenon but it is strongly malleable by interpersonal, intrapersonal and situational factors. This study investigated how two different top-down mechanisms - attention and cognitive appraisal - affect the perception of pain in others and its neural underpinnings. METHODOLOGY/PRINCIPAL FINDINGS: We performed one behavioral (N = 23) and two functional magnetic resonance imaging (fMRI) experiments (N = 18). In the first fMRI experiment, participants watched photographs displaying painful needle injections, and were asked to evaluate either the sensory or the affective consequences of these injections. The role of cognitive appraisal was examined in a second fMRI experiment in which participants watched injections that only appeared to be painful as they were performed on an anesthetized hand. Perceiving pain in others activated the affective-motivational and sensory-discriminative aspects of the pain matrix. Activity in the somatosensory areas was specifically enhanced when participants evaluated the sensory consequences of pain. Perceiving non-painful injections into the anesthetized hand also led to signal increase in large parts of the pain matrix, suggesting an automatic affective response to the putatively harmful stimulus. This automatic response was modulated by areas involved in self/other distinction and valence attribution - including the temporo-parietal junction and medial orbitofrontal cortex. CONCLUSIONS/SIGNIFICANCE: Our findings elucidate how top-down control mechanisms and automatic bottom-up processes interact to generate and modulate other-oriented responses. They stress the role of cognitive processing in empathy, and shed light on how emotional and bodily awareness enable us to evaluate the sensory and affective states of others.

ARTICLE UPDATE - Remembering the good times: neural correlates of affect regulation.

Cooney RE, Joormann J, Atlas LY, Eugène F, Gotlib IH.

Neuroreport, 18, 1171-1174

The ability to regulate one's mood state effectively is critical to emotional and physical health. Recent investigations have sought to delineate the neural mechanisms by which individuals regulate mood states and emotions, positing a critical role of a dorsal system that includes the dorsolateral prefrontal cortex and anterior cingulate. This study extended these efforts by examining the neural correlates of retrieving positive autobiographical memories while experiencing a negative mood state in a sample of healthy female adults. We demonstrated that mood-incongruent recall is associated with activation in ventrolateral and ventromedial prefrontal cortices (including orbitofrontal cortex and subgenual cingulate). These findings suggest that mood-incongruent recall differs from other affect regulation strategies by influencing mood through a ventral regulatory network.

Thursday, December 20, 2007

ARTICLE UPDATE - The effects of nonconsciously priming emotion concepts on behavior.

Zemack-Rugar Y, Bettman JR, Fitzsimons GJ.

Journal of Personality and Social Psychology, 93, 927-939

Current empirical evidence regarding nonconsciously priming emotion concepts is limited to positively versus negatively valenced affect. This article demonstrates that specific, equally valenced emotion concepts can be nonconsciously activated, remain inaccessible to conscious awareness, and still affect behavior in an emotion-specific fashion. In Experiment 1A, participants subliminally primed with guilty emotion adjectives showed lower indulgence than did participants subliminally primed with sad emotion adjectives; even after the addition of a 5-min time delay, these results were replicated in Experiment 1B. Participants in the different priming conditions showed no differences in their subjective emotion ratings and were unaware of the emotion prime or concept activation. Experiments 2A and 2B replicated these findings using a helping measure, demonstrating that individuals primed with guilt adjectives show more helping than do individuals primed with sadness adjectives. In all studies, effects were moderated by individuals' specific emotion-response habits and characteristics.

ARTICLE UPDATE - Predictors of amygdala activation during the processing of emotional stimuli: A meta-analysis of 385 PET and fMRI studies.

Costafreda SG, Brammer MJ, David AS, Fu CH.

Brain Research Review, in press (Note that this link will direct you to download this article in pdf format. So it might not work for everyone)

Although amygdala activity has been purported to be modulated by affective and non-affective factors, considerable controversy remains on its precise functional nature. We conducted a meta-analysis of 385 functional neuroimaging studies of emotional processing, examining the effects of experimental characteristics on the probability of detecting amygdala activity. All emotional stimuli were associated with higher probability of amygdala activity than neutral stimuli. Comparable effects were observed for most negative and positive emotions, however there was a higher probability of activation for fear and disgust relative to happiness. The level of attentional processing affected amygdala activity, as passive processing was associated with a higher probability of activation than active task instructions. Gustatory-olfactory and visual stimulus modalities increased the probability of activation relative to internal stimuli. Aversive learning increased the probability of amygdala activation as well. There was some evidence of hemispheric specialization with a relative left-lateralization for stimuli containing language and a relative right-lateralization for masked stimuli. Methodological variables, such as type of analysis and magnet strength, were also independent predictors of amygdala activation.

ARTICLE UPDATE - Neural response to emotional pictures is unaffected by concurrent task difficulty: An event-related potential study.

Hajcak G, Dunning JP, Foti D.

Behavioural Neuroscience, 121, 1156-1162

The late positive potential (LPP) is an event-related potential that is enhanced when viewing arousing (pleasant and unpleasant) pictures compared to neutral pictures. The affective modulation of the LPP is believed to reflect the increased attention to, and perceptual processing of, emotional stimuli. The present study examined whether concurrent task difficulty (performing mathematics) would modulate the LPP while participants viewed emotionally arousing stimuli. Results indicated that the LPP was larger following pleasant and unpleasant stimuli than it was following neutral stimuli; moreover, the magnitude of this increase was not influenced by concurrent task difficulty. This finding suggests that the affective modulation of neural activity during picture viewing is relatively automatic and is insusceptible to competing task demands. Results are further discussed in terms of the LPP's role in motivated attention and implications for research on emotion regulation.

Friday, December 14, 2007

ARTICLE UPDATE - Affective picture perception: Emotion, context, and the late positive potential.

Pastor MC, Bradley MM, Löw A, Versace F, Moltó J, Lang PJ.

Brain Research, in press

Event-related potentials (ERP) were measured when pleasant, neutral or unpleasant pictures were presented in the context of similarly valenced stimuli, and compared to ERPs elicited when the same pictures were viewed in an intermixed context. An early ERP component (150-300 ms) measured over occipital and fronto-central sensors was specific to viewing pleasant pictures and was not affected by presentation context. Replicating previous studies, emotional pictures prompted a larger late positive potential (LPP, 400-700 ms) and a larger positive slow wave (1-6 s) over centro-parietal sensors that also did not differ by presentation context. On the other hand, ERPs elicited when viewing neutral pictures varied as a function of context, eliciting somewhat larger LPPs when presented in blocks, and prompting smaller slow waves over occipital sensors. Taken together, the data indicate that emotional pictures prompt increased attention and orienting that is unaffected by its context of presentation, whereas neutral pictures are more vulnerable to context manipulations.

ARTICLE UPDATE - Simultaneous recording of EEG and facial muscle reactions during spontaneous emotional mimicry.

Achaibou A, Pourtois G, Schwartz S, Vuilleumier P.

Neuropsychologia, in press

The perception of emotional facial expressions induces covert imitation in emotion-specific muscles of the perceiver's face. Neural processes involved in these spontaneous facial reactions remain largely unknown. Here we concurrently recorded EEG and facial EMG in 15 participants watching short movie clips displaying either happy or angry facial expressions. EMG activity was recorded for the zygomaticus major (ZM) that elevates the lips during a smile, and the corrugator supercillii (CS) that knits the eyebrows during a frown. We found increased EMG activity of CS in response to angry expressions, and enhanced EMG activity of ZM for happy expressions, replicating earlier EMG studies. More importantly, we found that the amplitude of an early visual evoked potential (right P1) was larger when ZM activity to happy faces was high, and when CS activity to angry faces was high, as compared to when muscle reactions were low. Conversely, the amplitude of right N170 component was smaller when the intensity of facial imitation was high. These combined EEG-EMG results suggest that early visual processing of face expression may determine the magnitude of subsequent facial imitation, with dissociable effects for P1 and N170. These findings are discussed against the classical dual-route model of face recognition.

ARTICLE UPDATE - Serotoninergic regulation of emotional and behavioural control processes.

Cools R, Roberts AC, Robbins TW.

Trends in Cognitive Sciences, in press

5-Hydroxytryptamine (5-HT, serotonin) has long been implicated in a wide variety of emotional, cognitive and behavioural control processes. However, its precise contribution is still not well understood. Depletion of 5-HT enhances behavioural and brain responsiveness to punishment or other aversive signals, while disinhibiting previously rewarded but now punished behaviours. Findings suggest that 5-HT modulates the impact of punishment-related signals on learning and emotion (aversion), but also promotes response inhibition. Exaggerated aversive processing and deficient response inhibition could underlie distinct symptoms of a range of affective disorders, namely stress- or threat-vulnerability and compulsive behaviour, respectively. We review evidence from studies with human volunteers and experimental animals that begins to elucidate the neurobiological systems underlying these different effects.

Friday, December 07, 2007

ARTICLE UPDATE- Subliminal smells can guide social preferences.

Li W, Moallem I, Paller KA, Gottfried JA.

Psychological Science, 18, 1044-1049

It is widely accepted that unconscious processes can modulate judgments and behavior, but do such influences affect one's daily interactions with other people? Given that olfactory information has relatively direct access to cortical and subcortical emotional circuits, we tested whether the affective content of subliminal odors alters social preferences. Participants rated the likeability of neutral faces after smelling pleasant, neutral, or unpleasant odors delivered below detection thresholds. Odor affect significantly shifted likeability ratings only for those participants lacking conscious awareness of the smells, as verified by chance-level trial-by-trial performance on an odor-detection task. Across participants, the magnitude of this priming effect decreased as sensitivity for odor detection increased. In contrast, heart rate responses tracked odor valence independently of odor awareness. These results indicate that social preferences are subject to influences from odors that escape awareness, whereas the availability of conscious odor information may disrupt such effects.

ARTICLE UPDATE - An investigation of the cognitive and experiential features of intrusive memories in depression.

Williams AD, Moulds ML.

Memory, 15, 912-920

Intrusive autobiographical memories of negative past events are a clinical feature common to post-traumatic stress disorder (PTSD) and depression. Recent investigations provide increasing evidence that shared cognitive processes are linked to the maintenance of intrusive memories in both conditions. Still absent from the existing literature, however, is a systematic examination of the basic content and defining characteristics of intrusive memories in depression. This study sought to: (i) outline the content and features of intrusive memories in depression, and (ii) investigate whether intrusion characteristics linked to the persistence of intrusive memories in PTSD are also characteristic of intrusive memories in depression. A sample of undergraduate students (n=250) were interviewed and assessed for the presence of an intrusive memory in the past week, and completed a battery of measures that indexed cognitive and affective responses to the memory. Consistent with prediction, intrusive memories contained high levels of sensory experience and were marked by a sense of "nowness". In accord with studies with PTSD samples, sensory features accounted for unique variance in the prediction of depression severity, over and above that accounted for by intrusion frequency. This pattern of findings was replicated in a dysphoric (BDI-II>/=12) sub-sample of participants. Our results underscore the value of drawing on theoretical conceptualisations and empirical findings from the post-traumatic stress literature to extend our understanding of intrusive memories in depression.

ARTICLE UPDATE - Under what conditions can human affective conditioning occur without contingency awareness? Test of the evaluative conditioning parad

Dawson ME, Rissling AJ, Schell AM, Wilcox R.

Emotion, 7, 755-766

The role of conscious cognitive processes in human affective conditioning remains controversial, with several theories arguing that such conditioning can occur without awareness of the conditioned stimulus (CS)-unconditioned stimulus (UCS) contingency. One specific type of affective conditioning in which unaware conditioning is said to occur is "evaluative conditioning." The present experiment tested the role of contingency awareness by embedding an evaluative conditioning paradigm in a distracting masking task while obtaining, in addition to subjective ratings of affect, both psychophysiological (skin conductance and startle eyeblink) and indirect behavioral (affective priming) measures of conditioning, along with a trial-by-trial measure of awareness from 55 college student participants. Aware participants showed conditioning with all of the measures; unaware participants failed to show conditioning with all measures. The behavioral, neurophysiological, and therapeutic implications of these findings are discussed.

ARTICLE UPDATE - The influence of sad mood on cognition.

Chepenik LG, Cornew LA, Farah MJ.

Emotion, 7, 802-811

Neuroimaging has identified an overlapping network of brain regions whose activity is modulated by mood and cognition. Studies of depressed individuals have shown changes in perception, attention, memory, and executive functions. This suggests that mood has a pervasive effect on cognition. Direct evidence of the effect of sad mood on cognition is surprisingly limited, however. Published studies have generally addressed a single cognitive ability per study because the fleeting nature of laboratory-induced mood precludes extended testing, and robust findings are limited to mood effects on memory for emotional stimuli. In this study, sad mood was induced and prolonged, enabling the effects of mood to be assessed for an array of abilities, including those that share neural substrates with sad mood and those affected by depression. Sad mood affected memory for emotional words and facial emotion recognition, but not the other processes measured, with a significant nonuniformity of effect over tasks. These results are consistent with circumscribed effects of sad mood on certain emotion-related cognitive processes, but not on cognition more generally.

ARTICLE UPDATE - Amygdala reactivity to masked negative faces is associated with automatic judgmental bias in major depression: a 3 T fMRI study.

Dannlowski U, Ohrmann P, Bauer J, Kugel H, Arolt V, Heindel W, Kersting A, Baune BT, Suslow T.

Journal of Psychiatry Neuroscience, in press

OBJECTIVE: In a previous study, we demonstrated that amygdala reactivity to masked negative facial emotions predicts negative judgmental bias in healthy subjects. In the present study, we extended the paradigm to a sample of 35 inpatients suffering from depression to investigate the effect of amygdala reactivity on automatic negative judgmental bias and clinical characteristics in depression. METHODS: Amygdala activity was recorded in response to masked displays of angry, sad and happy facial expressions by means of functional magnetic resonance imaging at 3 T. In a subsequent experiment, the patients performed an 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. RESULTS: Significant associations between (right) amygdala reactivity and automatic negative judgmental bias were replicated in our patient sample (r = -0.59, p < 0.001). Further, negatively biased evaluative processing was associated with severity and longer course of illness (r = -0.57, p = 0.001). CONCLUSION: Amygdala hyperactivity is a neural substrate of negatively biased automatic emotion processing that could be a determinant for a more severe disease course.

ARTICLE UPDATE - Relative left frontal activation to appetitive stimuli: Considering the role of individual differences.

Gable P, Harmon-Jones E.

Psychophysiology, in press

Experiments examining asymmetrical frontal activity in response to affective pictures have produced inconsistent results. These inconsistencies may have occurred because the pictorial stimuli may not have evoked strong emotional or motivational tendencies for all individuals. In the current study, participants were asked to indicate their liking for dessert and the time since they had last eaten to assess individual differences in emotion and motivation. Then, they were shown dessert pictures or neutral pictures while EEG activity was recorded. Results indicated that the individual differences predicted greater left than right frontal activity (inverse of the alpha power) within the first second as well as all 12 s of viewing of the dessert pictures.