Wang J, Nicol T, Skoe E, Sams M, Kraus N.
Journal of Cognitive Neuroscience, in press
In order to understand how emotional state influences the listener's physiological response to speech, subjects looked at emotion-evoking pictures while 32-channel EEG evoked responses (ERPs) to an unchanging auditory stimulus ("danny") were collected. The pictures were selected from the International Affective Picture System database. They were rated by participants and differed in valence (positive, negative, neutral), but not in dominance and arousal. Effects of viewing negative emotion pictures were seen as early as 20 msec (p = .006). An analysis of the global field power highlighted a time period of interest (30.4-129.0 msec) where the effects of emotion are likely to be the most robust. At the cortical level, the responses differed significantly depending on the valence ratings the subjects provided for the visual stimuli, which divided them into the high valence intensity group and the low valence intensity group. The high valence intensity group exhibited a clear divergent bivalent effect of emotion (ERPs at Cz during viewing neutral pictures subtracted from ERPs during viewing positive or negative pictures) in the time region of interest (r() = .534, p < .01). Moreover, group differences emerged in the pattern of global activation during this time period. Although both groups demonstrated a significant effect of emotion (ANOVA, p = .004 and .006, low valence intensity and high valence intensity, respectively), the high valence intensity group exhibited a much larger effect. Whereas the low valence intensity group exhibited its smaller effect predominantly in frontal areas, the larger effect in the high valence intensity group was found globally, especially in the left temporal areas, with the largest divergent bivalent effects (ANOVA, p < .00001) in high valence intensity subjects around the midline. Thus, divergent bivalent effects were observed between 30 and 130 msec, and were dependent on the subject's subjective state, whereas the effects at 20 msec were evident only for negative emotion, independent of the subject's behavioral responses. Taken together, it appears that emotion can affect auditory function early in the sensory processing stream.
Monday, October 20, 2008
ARTICLE UPDATE - The valence strength of negative stimuli modulates visual novelty processing: Electrophysiological evidence from an event-related pot
Yuan J, Yang J, Meng X, Yu F, Li H.
Neuroscience, in press
In natural settings, the occurrence of unpredictable infrequent events is often associated with emotional reactions in the brain. Previous research suggested a special sensitivity of the brain to valence differences in emotionally negative stimuli. Thus, the present study hypothesizes that valence changes in infrequent negative stimuli would have differential effects on visual novelty processing. Event-related potentials (ERPs) were recorded for highly negative (HN), moderately negative (MN) and Neutral infrequent stimuli, and for the frequent standard stimulus while subjects performed a frequent/infrequent categorization task, irrespective of the emotional valence of the infrequent stimuli. The infrequent-frequent difference waves, which index visual novelty processing, displayed larger N2 amplitudes during HN condition than during MN condition which, in turn, elicited greater N2 amplitude than the Neutral condition. Similarly, in the infrequent-frequent difference waves, the frontocentral P3a and parietal LPC (late positive complex) elicited by the HN condition were more negative than those by MN stimuli, which elicited more negative amplitudes than the Neutral condition. This suggests that negative emotions of diverse strength, as induced by negative stimuli of varying valences, are clearly different in their impact on visual novelty processing. Novel stimuli of increased negativity elicited more attentional resources during the early novelty detection, and recruited increased inhibitive and evaluative processing during the later stages of response decision and reaction readiness, relative to novel stimuli of reduced negativity.
Neuroscience, in press
In natural settings, the occurrence of unpredictable infrequent events is often associated with emotional reactions in the brain. Previous research suggested a special sensitivity of the brain to valence differences in emotionally negative stimuli. Thus, the present study hypothesizes that valence changes in infrequent negative stimuli would have differential effects on visual novelty processing. Event-related potentials (ERPs) were recorded for highly negative (HN), moderately negative (MN) and Neutral infrequent stimuli, and for the frequent standard stimulus while subjects performed a frequent/infrequent categorization task, irrespective of the emotional valence of the infrequent stimuli. The infrequent-frequent difference waves, which index visual novelty processing, displayed larger N2 amplitudes during HN condition than during MN condition which, in turn, elicited greater N2 amplitude than the Neutral condition. Similarly, in the infrequent-frequent difference waves, the frontocentral P3a and parietal LPC (late positive complex) elicited by the HN condition were more negative than those by MN stimuli, which elicited more negative amplitudes than the Neutral condition. This suggests that negative emotions of diverse strength, as induced by negative stimuli of varying valences, are clearly different in their impact on visual novelty processing. Novel stimuli of increased negativity elicited more attentional resources during the early novelty detection, and recruited increased inhibitive and evaluative processing during the later stages of response decision and reaction readiness, relative to novel stimuli of reduced negativity.
ARTICLE UPDATE - The role of valence and frequency in the emotional Stroop task.
Kahan TA, Hely CD.
Psychological Bulletin & Review, 15, 956-960
People are generally slower to name the color of emotion-laden words than they are to name that of emotionally neutral words. However, an analysis of this emotional Stroop effect (Larsen, Mercer, & Balota, 2006) indicates that the emotion-laden words used are sometimes longer, have lower frequencies, and have smaller orthographic neighborhoods than the emotionally neutral words. This difference in word characteristics raises the possibility that the emotional Stroop effect is partly caused by lexical rather than by emotional aspects of the stimuli-a conclusion supported by the finding that reaction times to name the color of low-frequency words are longer than those for high-frequency words (Burt, 2002). To examine the relative contributions of valence and frequency in color naming, we had 64 participants complete an experiment in which each of these variables was manipulated in a 3 x 2 factorial design; length, orthographic neighborhood density, and arousal were balanced. The data indicate that valence and word frequency interact in contributing to the emotional Stroop effect.
Psychological Bulletin & Review, 15, 956-960
People are generally slower to name the color of emotion-laden words than they are to name that of emotionally neutral words. However, an analysis of this emotional Stroop effect (Larsen, Mercer, & Balota, 2006) indicates that the emotion-laden words used are sometimes longer, have lower frequencies, and have smaller orthographic neighborhoods than the emotionally neutral words. This difference in word characteristics raises the possibility that the emotional Stroop effect is partly caused by lexical rather than by emotional aspects of the stimuli-a conclusion supported by the finding that reaction times to name the color of low-frequency words are longer than those for high-frequency words (Burt, 2002). To examine the relative contributions of valence and frequency in color naming, we had 64 participants complete an experiment in which each of these variables was manipulated in a 3 x 2 factorial design; length, orthographic neighborhood density, and arousal were balanced. The data indicate that valence and word frequency interact in contributing to the emotional Stroop effect.
Wednesday, October 15, 2008
ARTICLE UPDATE - How Does Reward Expectation Influence Cognition in the Human Brain?
James B. Rowe, Doris Eckstein, Todd Braver and Adrian M. Owen
Journal of Cognitive Neuroscience,20, 1980-1992
The prospect of reward changes how we think and behave. We investigated how this occurs in the brain using a novel continuous performance task in which fluctuating reward expectations biased cognitive processes between competing spatial and verbal tasks. Critically, effects of reward expectancy could be distinguished from induced changes in task-related networks. Behavioral data confirm specific bias toward a reward-relevant modality. Increased reward expectation improves reaction time and accuracy in the relevant dimension while reducing sensitivity to modulations of stimuli characteristics in the irrelevant dimension. Analysis of functional magnetic resonance imaging data shows that the proximity to reward over successive trials is associated with increased activity of the medial frontal cortex regardless of the modality. However, there are modality-specific changes in brain activity in the lateral frontal, parietal, and temporal cortex. Analysis of effective connectivity suggests that reward expectancy enhances coupling in both early visual pathways and within the prefrontal cortex. These distributed changes in task-related cortical networks arise from subjects' representations of future events and likelihood of reward.
Journal of Cognitive Neuroscience,20, 1980-1992
The prospect of reward changes how we think and behave. We investigated how this occurs in the brain using a novel continuous performance task in which fluctuating reward expectations biased cognitive processes between competing spatial and verbal tasks. Critically, effects of reward expectancy could be distinguished from induced changes in task-related networks. Behavioral data confirm specific bias toward a reward-relevant modality. Increased reward expectation improves reaction time and accuracy in the relevant dimension while reducing sensitivity to modulations of stimuli characteristics in the irrelevant dimension. Analysis of functional magnetic resonance imaging data shows that the proximity to reward over successive trials is associated with increased activity of the medial frontal cortex regardless of the modality. However, there are modality-specific changes in brain activity in the lateral frontal, parietal, and temporal cortex. Analysis of effective connectivity suggests that reward expectancy enhances coupling in both early visual pathways and within the prefrontal cortex. These distributed changes in task-related cortical networks arise from subjects' representations of future events and likelihood of reward.
Saturday, October 11, 2008
ARTICLE UPDATE - Fear relevancy, strategy use, and probabilistic learning of cue-outcome associations.
Thomas LA, LaBar KS.
Learning & Memory, 15, 777-784
The goal of this study was to determine how the fear relevancy of outcomes during probabilistic classification learning affects behavior and strategy use. Novel variants of the "weather prediction" task were created, in which cue cards predicted either looming fearful or neutral outcomes in a between-groups design. Strategy use was examined by goodness-of-fit estimates of response patterns across trial blocks to mathematical models of simple, complex, and nonidentifiable strategies. Participants in the emotional condition who were fearful of the outcomes had greater skin conductance responses compared with controls and performed worse, used suboptimal strategies, and had less insight into the predictive cue features during initial learning. In contrast, nonfearful participants in the emotional condition used more optimal strategies than the other groups by the end of the two training days. Results have implications for understanding how individual differences in fear relevancy alter the impact of emotion on feedback-based learning.
Learning & Memory, 15, 777-784
The goal of this study was to determine how the fear relevancy of outcomes during probabilistic classification learning affects behavior and strategy use. Novel variants of the "weather prediction" task were created, in which cue cards predicted either looming fearful or neutral outcomes in a between-groups design. Strategy use was examined by goodness-of-fit estimates of response patterns across trial blocks to mathematical models of simple, complex, and nonidentifiable strategies. Participants in the emotional condition who were fearful of the outcomes had greater skin conductance responses compared with controls and performed worse, used suboptimal strategies, and had less insight into the predictive cue features during initial learning. In contrast, nonfearful participants in the emotional condition used more optimal strategies than the other groups by the end of the two training days. Results have implications for understanding how individual differences in fear relevancy alter the impact of emotion on feedback-based learning.
ARTICLE UPDATE - Electrophysiological correlates of affective blindsight.
Gonzalez Andino SL, Grave de Peralta Menendez R, Khateb A, Landis T, Pegna AJ.
Neuroimage, in press
An EEG investigation was carried out in a patient with complete cortical blindness who presented affective blindsight, i.e. who performed above chance when asked to guess the emotional expressions on a series of faces. To uncover the electrophysiological mechanisms involved in this phenomenon we combined multivariate pattern recognition (MPR) with local field potential estimates provided by electric source imaging (ELECTRA). All faces, including neutral faces, elicited distinctive oscillatory EEG patterns that were correctly identified by the MPR algorithm as belonging to the class of facial expressions actually presented. Consequently, neural responses in this patient are not restricted to emotionally laden faces. Earliest non-specific differences between faces occur from 70 ms onwards in the superior temporal polysensory area (STP). Emotion-specific responses were found after 120 ms in the right anterior areas with right amygdala activation observed only later ( approximately 200 ms). Thus, affective blindsight might be mediated by subcortical afferents to temporal areas as suggested in some studies involving non-emotional stimuli. The early activation of the STP in the patient constitutes evidence for fast activation of higher order visual areas in humans despite bilateral V1 destruction. In addition, the absence of awareness of any visual experience in this patient suggests that neither the extrastriate visual areas, nor the prefrontal cortex activation alone are sufficient for conscious perception, which might require recurrent processing within a network of several cerebral areas including V1.
Neuroimage, in press
An EEG investigation was carried out in a patient with complete cortical blindness who presented affective blindsight, i.e. who performed above chance when asked to guess the emotional expressions on a series of faces. To uncover the electrophysiological mechanisms involved in this phenomenon we combined multivariate pattern recognition (MPR) with local field potential estimates provided by electric source imaging (ELECTRA). All faces, including neutral faces, elicited distinctive oscillatory EEG patterns that were correctly identified by the MPR algorithm as belonging to the class of facial expressions actually presented. Consequently, neural responses in this patient are not restricted to emotionally laden faces. Earliest non-specific differences between faces occur from 70 ms onwards in the superior temporal polysensory area (STP). Emotion-specific responses were found after 120 ms in the right anterior areas with right amygdala activation observed only later ( approximately 200 ms). Thus, affective blindsight might be mediated by subcortical afferents to temporal areas as suggested in some studies involving non-emotional stimuli. The early activation of the STP in the patient constitutes evidence for fast activation of higher order visual areas in humans despite bilateral V1 destruction. In addition, the absence of awareness of any visual experience in this patient suggests that neither the extrastriate visual areas, nor the prefrontal cortex activation alone are sufficient for conscious perception, which might require recurrent processing within a network of several cerebral areas including V1.
ARTICLE UPDATE - The combined effect of gaze direction and facial expression on cueing spatial attention.
Pecchinenda A, Pes M, Ferlazzo F, Zoccolotti P.
Emotion, 8, 628-634
Empirical evidence shows an effect of gaze direction on cueing spatial attention, regardless of the emotional expression shown by a face, whereas a combined effect of gaze direction and facial expression has been observed on individuals' evaluative judgments. In 2 experiments, the authors investigated whether gaze direction and facial expression affect spatial attention depending upon the presence of an evaluative goal. Disgusted, fearful, happy, or neutral faces gazing left or right were followed by positive or negative target words presented either at the spatial location looked at by the face or at the opposite spatial location. Participants responded to target words based on affective valence (i.e., positive/negative) in Experiment 1 and on letter case (lowercase/uppercase) in Experiment 2. Results showed that participants responded much faster to targets presented at the spatial location looked at by disgusted or fearful faces but only in Experiment 1, when an evaluative task was used. The present findings clearly show that negative facial expressions enhance the attentional shifts due to eye-gaze direction, provided that there was an explicit evaluative goal present.
Emotion, 8, 628-634
Empirical evidence shows an effect of gaze direction on cueing spatial attention, regardless of the emotional expression shown by a face, whereas a combined effect of gaze direction and facial expression has been observed on individuals' evaluative judgments. In 2 experiments, the authors investigated whether gaze direction and facial expression affect spatial attention depending upon the presence of an evaluative goal. Disgusted, fearful, happy, or neutral faces gazing left or right were followed by positive or negative target words presented either at the spatial location looked at by the face or at the opposite spatial location. Participants responded to target words based on affective valence (i.e., positive/negative) in Experiment 1 and on letter case (lowercase/uppercase) in Experiment 2. Results showed that participants responded much faster to targets presented at the spatial location looked at by disgusted or fearful faces but only in Experiment 1, when an evaluative task was used. The present findings clearly show that negative facial expressions enhance the attentional shifts due to eye-gaze direction, provided that there was an explicit evaluative goal present.
ARTICLE UPDATE - Directed forgetting of emotional words.
Minnema MT, Knowlton BJ.
Emotion, 8, 643-652
Emotional material may induce processing limitations affecting memory performance. In the present study, the authors investigated how the emotional content of words influences the degree to which participants can be directed to forget them. In Experiment 1, the authors found that negative-valence words were recalled better when participants were told to forget them than when they were told to remember them. This effect was only obtained when a study-list of negative words was presented after the cue to remember or forget the first list. The effect was correlated with negative mood as assessed by the PANAS. Similar results were obtained in Experiment 2, in which the induction of negative arousal by a mild stressor abolished the directed forgetting of words when the following study list was comprised of negative words. These results support the idea that directed forgetting relies on cognitive control processes that may be disrupted by negative emotion.
Emotion, 8, 643-652
Emotional material may induce processing limitations affecting memory performance. In the present study, the authors investigated how the emotional content of words influences the degree to which participants can be directed to forget them. In Experiment 1, the authors found that negative-valence words were recalled better when participants were told to forget them than when they were told to remember them. This effect was only obtained when a study-list of negative words was presented after the cue to remember or forget the first list. The effect was correlated with negative mood as assessed by the PANAS. Similar results were obtained in Experiment 2, in which the induction of negative arousal by a mild stressor abolished the directed forgetting of words when the following study list was comprised of negative words. These results support the idea that directed forgetting relies on cognitive control processes that may be disrupted by negative emotion.
ARTICLE UPDATE - Trouble crossing the bridge: Altered interhemispheric communication of emotional images in anxiety.
Compton RJ, Carp J, Chaddock L, Fineman SL, Quandt LC, Ratliff JB.
Emotion, 8, 684-692.
Worry is thought to involve a strategy of cognitive avoidance, in which internal verbalization acts to suppress threatening emotional imagery. This study tested the hypothesis that worry-prone individuals would exhibit patterns of between-hemisphere communication that reflect cognitive avoidance. Specifically, the hypothesis predicted slower transfer of threatening images from the left to the right hemisphere among worriers. Event-related potential (ERP) measures of interhemispheric transfer time supported this prediction. Left-to-right hemisphere transfer times for angry faces were relatively slower for individuals scoring high in self-reported worry compared with those scoring low, whereas transfer of happy and neutral faces did not differ between groups. These results suggest that altered interhemispheric communication may constitute one mechanism of cognitive avoidance in worry.
Emotion, 8, 684-692.
Worry is thought to involve a strategy of cognitive avoidance, in which internal verbalization acts to suppress threatening emotional imagery. This study tested the hypothesis that worry-prone individuals would exhibit patterns of between-hemisphere communication that reflect cognitive avoidance. Specifically, the hypothesis predicted slower transfer of threatening images from the left to the right hemisphere among worriers. Event-related potential (ERP) measures of interhemispheric transfer time supported this prediction. Left-to-right hemisphere transfer times for angry faces were relatively slower for individuals scoring high in self-reported worry compared with those scoring low, whereas transfer of happy and neutral faces did not differ between groups. These results suggest that altered interhemispheric communication may constitute one mechanism of cognitive avoidance in worry.
ARTICLE UPDATE - Interpretation bias in social anxiety as detected by event-related brain potentials.
Moser JS, Hajcak G, Huppert JD, Foa EB, Simons RF.
Emotion, 8, 693-700
Little is known about psychophysiological correlates of interpretation bias in social anxiety. To address this issue, the authors measured event-related brain potentials (ERPs) in high and low socially anxious individuals during a task wherein ambiguous scenarios were resolved with either a positive or negative ending. Specifically, the authors examined modulations of the P600, an ERP that peaks approximately 600 ms following stimulus onset and indexes violations of expectancy. Low-anxious individuals were characterized by an increased P600 to negative in comparison with positive sentence endings, suggesting a positive interpretation bias. In contrast, the high-anxious group evidenced equivalent P600 magnitude for negative and positive sentence endings, suggesting a lack of positive interpretation bias. Similar, but less reliable results emerged in earlier time windows, that is, 200-500 ms poststimulus. Reaction time, occurring around 900 ms poststimulus, failed to show a reliable interpretation bias. Results suggest that ERPs can detect interpretation biases in social anxiety before the emission of behavioral responses.
Emotion, 8, 693-700
Little is known about psychophysiological correlates of interpretation bias in social anxiety. To address this issue, the authors measured event-related brain potentials (ERPs) in high and low socially anxious individuals during a task wherein ambiguous scenarios were resolved with either a positive or negative ending. Specifically, the authors examined modulations of the P600, an ERP that peaks approximately 600 ms following stimulus onset and indexes violations of expectancy. Low-anxious individuals were characterized by an increased P600 to negative in comparison with positive sentence endings, suggesting a positive interpretation bias. In contrast, the high-anxious group evidenced equivalent P600 magnitude for negative and positive sentence endings, suggesting a lack of positive interpretation bias. Similar, but less reliable results emerged in earlier time windows, that is, 200-500 ms poststimulus. Reaction time, occurring around 900 ms poststimulus, failed to show a reliable interpretation bias. Results suggest that ERPs can detect interpretation biases in social anxiety before the emission of behavioral responses.
Subscribe to:
Posts (Atom)