Friday, April 27, 2007

ARTICLE UPDATE - The influence of olfactory-induced negative emotion on verbal working memory: Individual differences in neurobehavioral findings

Habel U, Koch K, Pauly K, Kellermann T, Reske M, Backes V, Seiferth NY, Stocker T, Kircher T, Amunts K, Jon Shah N, Schneider F.

Brain Research, in press

The influence of emotion on cognition plays an important role in people's everyday life as well as in psychiatric and neurological disorders. The present study used fMRI to examine the neural correlates of cognitive–emotional interactions and its inter-individual differences. Twenty-one healthy males performed a 0-back/2-back task while negative or neutral emotion was induced by negative/neutral olfactory stimulation. Subjects revealed a differential effect of emotion on cognition; in 9 subjects, negative odor had a deteriorating influence on verbal working memory (“affected group”, AG) while in 12 subjects, performance was not affected in a negative way (“unaffected group”, UAG). Although no brain activation differences emerged during the working memory task, the interaction of working memory and emotion yielded significant differences between the AG and the UAG. The latter showed greater activation in the fronto-parieto-cerebellar working memory (WM) network including the precuneus while the AG demonstrated stronger activation in more “emotional” areas (mainly the temporal and medial frontal cortex) as well as compensatory activations in prefrontal regions known to be essential for the cognitive down-regulation of emotions. Hence, the UAG may have been better able to counteract the detrimental influence of negative stimulation during the 2-back task and to effectively sustain or even increase activation in the task-relevant WM network. Correlation analyses for the whole group supported this interpretation; reduced working memory performance during negative stimulation was accompanied by higher activation in the inferior frontal gyrus whereas less performance impairment was related to higher activation in the precuneus. Results confirm the importance of incorporating individual differences in emotion processing and its interaction with cognitive functions in neuroimaging.

ARTICLE UPDATE - Differential time-dependent effects of emotion on recollective experience and memory for contextual information

Tali Sharot and Andrew P. Yonelinas

Cognition, in press

Emotion has been suggested to slow forgetting via a mechanism that enhances memory consolidation. Here, we investigate whether this time dependent process influences the subjective experience of recollection as well as the ability to retrieve specific contextual details of the study event. To do so we examined recognition for emotional and neutral pictures at two retention intervals and collected remember/know reports and reports about the task that had been performed with the item during encoding. Recollective experience was enhanced for emotional compared to neutral photos after a 24-h delay, but not immediately after encoding. In contrast, memory for the task performed during encoding did not differ between emotional and neutral photos at either time point. The findings indicate that emotion slows the effects of forgetting on the recollective experience associated with studied events, without necessarily slowing the forgetting of specific contextual details of those events.

ARTICLE UPDATE - Affective evaluations of objects are influenced by observed gaze direction and emotional expression

Andrew P. Bayliss, Alexandra Frischen, Mark J. Fenske and Steven P. Tipper

Cognition, in press

Gaze direction signals another person’s focus of interest. Facial expressions convey information about their mental state. Appropriate responses to these signals should reflect their combined influence, yet current evidence suggests that gaze-cueing effects for objects near an observed face are not modulated by its emotional expression. Here, we extend the investigation of perceived gaze direction and emotional expression by considering their combined influence on affective judgments. While traditional response-time measures revealed equal gaze-cueing effects for happy and disgust faces, affective evaluations critically depended on the combined product of gaze and emotion. Target objects looked at with a happy expression were liked more than objects looked at with a disgust expression. Objects not looked at were rated equally for both expressions. Our results demonstrate that facial expression does modulate the way that observers utilize gaze cues: Objects attended by others are evaluated according to the valence of their facial expression.

Tuesday, April 24, 2007

ARTICLE UPDATE - Emotions and False Memories: Valence or Arousal?

Corson, Yves & Verrier, Nadège

Psychological Science, 18, 208-211.

The effects of mood on false memories have not been studied systematically until recently. Some results seem to indicate that negative mood may reduce false recall and thus suggest an influence of emotional valence on false memory. The present research tested the effects of both valence and arousal on recall and recognition and indicates that the effect is actually due to arousal. In fact, whether participants' mood is positive, negative, or neutral, false memories are significantly more frequent under conditions of high arousal than under conditions of low arousal.

Friday, April 20, 2007

ARTICLE UPDATE - Independent Effects of Emotion and Working Memory Load on Visual Activation in the Lateral Occipital Complex

Jan Gläscher, Michael Rose, and Christian Büchel

The Journal of Neuroscience, 27, 4366-4373.

Emotional salience and working memory (WM) load are known to affect object processing in the ventral stream. However, the combined effect, which could be either synergistic or antagonistic, remains unclear. Using functional magnetic resonance imaging and a three-factorial design, we investigated the effects of WM load and emotional salience on object processing in the ventral visual stream. Twenty-three female subjects were shown blocks of task-irrelevant and more or less degraded visual stimuli that varied in emotional valence (negative or neutral) and phase coherence rendering them more or less noisy. Superimposed on these pictures, subjects saw colored squares on which they had to perform a demanding WM task (one-back, two-back). This WM task absorbs attentional resources normally available for the perceptual analysis of visual objects and can therefore be interpreted as a manipulation of attention. We hypothesized that attenuated processing resources in the lateral occipital complex (LOC) for these task-irrelevant pictures under high WM load (Rose et al., 2005) could be regained when they were of negative emotional valence. Our results indicate that both emotional salience and WM load critically depend on a minimum level of phase coherence of the stimuli to affect LOC activation. Furthermore, the influences of emotional salience and WM load do not interact with each other in LOC. Rather, emotional salience exerts a general multiplicative gain effect while preserving the difference in activation between low and high WM load. A connectivity analysis suggests that the emotional modulation might originate in the amygdalo-hippocampal junction.

ARTICLE UPDATE - Affective stimulus properties influence size perception and the Ebbinghaus illusion.

van Ulzen NR, Semin GR, Oudejans RR, Beek PJ.

Psychological Research, in press

In the New Look literature of the 1950s, it has been suggested that size judgments are dependent on the affective content of stimuli. This suggestion, however, has been 'discredited' due to contradictory findings and methodological problems. In the present study, we revisited this forgotten issue in two experiments. The first experiment investigated the influence of affective content on size perception by examining judgments of the size of target circles with and without affectively loaded (i.e., positive, neutral, and negative) pictures. Circles with a picture were estimated to be smaller than circles without a picture, and circles with a negative picture were estimated to be larger than circles with a positive or a neutral picture confirming the suggestion from the 1950s that size perception is influenced by affective content, an effect notably confined to negatively loaded stimuli. In a second experiment, we examined whether affective content influenced the Ebbinghaus illusion. Participants judged the size of a target circle whereby target and flanker circles differed in affective loading. The results replicated the first experiment. Additionally, the Ebbinghaus illusion was shown to be weakest for a negatively loaded target with positively loaded and blank flankers. A plausible explanation for both sets of experimental findings is that negatively loaded stimuli are more attention demanding than positively loaded or neutral stimuli.

ARTICLE UPDATE - Remembering Can Cause Forgetting-but Not in Negative Moods.

Bauml KH, Kuhbandner C.

Psychological Science, 18, 111-115.

Repeated retrieval of a subset of previously observed events can cause forgetting of the nonretrieved events. We examined how affective states experienced during retrieval modulate such retrieval-induced forgetting by inducing positive, negative, and neutral moods in subjects immediately before they attempted to retrieve studied items. On the basis of recent work, we hypothesized that positive moods encourage relational processing, which should increase interference from related events and thus enhance retrieval-induced forgetting. By contrast, negative moods should encourage item-specific processing, which should reduce interference and thus reduce such forgetting. Our results are consistent with these predictions. When subjects were in negative moods, repeated retrieval did not cause forgetting of the nonretrieved material, whereas when subjects were in positive and neutral moods, they showed reliable retrieval-induced forgetting. Our findings suggest that the emotions involved during interrogation of a witness can affect the result of repeated interrogations.

ARTICLE UPDATE - Differential engagement of anterior cingulate cortex subdivisions for cognitive and emotional function.

Mohanty A, Engels AS, Herrington JD, Heller W, Ringo Ho MH, Banich MT, Webb AG, Warren SL, Miller GA.

Psychophysiology, 44, 343-351

Functional differentiation of dorsal (dACC) and rostral (rACC) anterior cingulate cortex for cognitive and emotional function has received considerable indirect support. Using fMRI, parallel tasks, and within-subject analysis, the present study directly tested the proposed specialization of ACC subdivisions. A Task x Region interaction confirmed more dACC activation during color-word distractors and more rACC activation during emotion-word distractors. Activity in ACC subdivisions differentially predicted behavioral performance. Connectivity with prefrontal and limbic regions also supported distinct dACC and rACC roles. Findings provide direct evidence for differential engagement of ACC subdivisions in cognitive and emotional processing and for differential functional connectivity in the implementation of cognitive control and emotion regulation. Results point to an anatomical and functional continuum rather than segregated operations.

ARTICLE UPDATE - Specificity of regional brain activity in anxiety types during emotion processing.

Engels AS, Heller W, Mohanty A, Herrington JD, Banich MT, Webb AG, Miller GA.

Psychophysiology, 44, 352-363.

The present study tested the hypothesis that anxious apprehension involves more left- than right-hemisphere activity and that anxious arousal is associated with the opposite pattern. Behavioral and fMRI responses to threat stimuli in an emotional Stroop task were examined in nonpatient groups reporting anxious apprehension, anxious arousal, or neither. Reaction times were longer for negative than for neutral words. As predicted, brain activation distinguished anxious groups in a left inferior frontal region associated with speech production and in a right-hemisphere inferior temporal area. Addressing a second hypothesis about left-frontal involvement in emotion, distinct left frontal regions were associated with anxious apprehension versus processing of positive information. Results support the proposed distinction between the two types of anxiety and resolve an inconsistency about the role of left-frontal activation in emotion and psychopathology.

Thursday, April 05, 2007

ARTICLE UPDATE - Time course of attentional modulation on automatic emotional processing

Sonia Doallo, Fernando Cadaveira and Socorro Rodríguez Holguín

Neuroscience Letters, in press

In a previous study using event-related potentials (ERPs) [S. Doallo, S. Rodríguez Holguín, F. Cadaveira, Attentional load affects automatic emotional processing: evidence from event-related potentials, Neuroreport 17 (2006) 1797–1801], we reported that differential responses to unattended peripheral affective pictures, as reflected by N1-P2 modulations at posterior regions, are modulated by attentional load at fixation. Here, new analyses of these data were performed to evaluate whether a sustained, broadly distributed, negative shift in the unattended pictures ERP waveforms, which displayed larger amplitudes for emotional stimuli, reflects an additional differential response to the emotional content. Under low-load conditions, unpleasant (versus neutral) pictures elicited greater negativities in the 80–140 ms latency range over frontocentral sites and more centroparietally distributed from 200 to 280 ms. These findings provide further evidence of the time course of emotional processing at unattended locations and its modulation by attentional load.

ARTICLE UPDATE - Modulation of visual processing by attention and emotion: windows on causal interactions between human brain regions

Patrik Vuilleumier and Jon Driver

Philosophical Transactions of the Royal Society B: Biological Sciences, in press

Visual processing is not determined solely by retinal inputs. Attentional modulation can arise when the internal attentional state (current task) of the observer alters visual processing of the same stimuli. This can influence visual cortex, boosting neural responses to an attended stimulus. Emotional modulation can also arise, when affective properties (emotional significance) of stimuli, rather than their strictly visual properties, influence processing. This too can boost responses in visual cortex, as for fear-associated stimuli. Both attentional and emotional modulation of visual processing may reflect distant influences upon visual cortex, exerted by brain structures outside the visual system per se. Hence, these modulations may provide windows onto causal interactions between distant but interconnected brain regions. We review recent evidence, noting both similarities and differences between attentional and emotional modulation. Both can affect visual cortex, but can reflect influences from different regions, such as fronto-parietal circuits versus the amygdala. Recent work on this has developed new approaches for studying causal influences between human brain regions that may be useful in other cognitive domains. The new methods include application of functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) measures in brain-damaged patients to study distant functional impacts of their focal lesions, and use of transcranial magnetic stimulation concurrently with fMRI or EEG in the normal brain. Cognitive neuroscience is now moving beyond considering the putative functions of particular brain regions, as if each operated in isolation, to consider, instead, how distinct brain regions (such as visual cortex, parietal or frontal regions, or amygdala) may mutually influence each other in a causal manner.

ARTICLE UPDATE - Social concepts are represented in the superior anterior temporal cortex.

Roland Zahn, Jorge Moll, Frank Krueger, Edward D. Huey, Griselda Garrido, and Jordan Grafman

PNAS, in press

Social concepts such as "tactless" or "honorable" enable us to describe our own as well as others' social behaviors. The prevailing view is that this abstract social semantic knowledge is mainly subserved by the same medial prefrontal regions that are considered essential for mental state attribution and self-reflection. Nevertheless, neurodegeneration of the anterior temporal cortex typically leads to impairments of social behavior as well as general conceptual knowledge. By using functional MRI, we demonstrate that the anterior temporal lobe represents abstract social semantic knowledge in agreement with this patient evidence. The bilateral superior anterior temporal lobes (Brodmann's area 38) are selectively activated when participants judge the meaning relatedness of social concepts (e.g., honor-brave) as compared with concepts describing general animal functions (e.g., nutritious-useful). Remarkably, only activity in the superior anterior temporal cortex, but not the medial prefrontal cortex, correlates with the richness of detail with which social concepts describe social behavior. Furthermore, this anterior temporal lobe activation is independent of emotional valence, whereas medial prefrontal regions show enhanced activation for positive social concepts. Our results demonstrate that the superior anterior temporal cortex plays a key role in social cognition by providing abstract conceptual knowledge of social behaviors. We further speculate that these abstract conceptual representations can be associated with different contexts of social actions and emotions through integration with frontolimbic circuits to enable flexible evaluations of social behavior.