Saturday, July 26, 2008

ARTICLE UPDATE - Neural processing of vocal emotion and identity.

Spreckelmeyer KN, Kutas M, Urbach T, Altenmüller E, Münte TF.

Brain & Cognition, in press

The voice is a marker of a person's identity which allows individual recognition even if the person is not in sight. Listening to a voice also affords inferences about the speaker's emotional state. Both these types of personal information are encoded in characteristic acoustic feature patterns analyzed within the auditory cortex. In the present study 16 volunteers listened to pairs of non-verbal voice stimuli with happy or sad valence in two different task conditions while event-related brain potentials (ERPs) were recorded. In an emotion matching task, participants indicated whether the expressed emotion of a target voice was congruent or incongruent with that of a (preceding) prime voice. In an identity matching task, participants indicated whether or not the prime and target voice belonged to the same person. Effects based on emotion expressed occurred earlier than those based on voice identity. Specifically, P2 ( approximately 200ms)-amplitudes were reduced for happy voices when primed by happy voices. Identity match effects, by contrast, did not start until around 300ms. These results show an early task-specific emotion-based influence on the early stages of auditory sensory processing.

Friday, July 18, 2008

ARTICLE UPDATE - Discriminating between changes in bias and changes in accuracy for recognition memory of emotional stimuli.

Grider RC, Malmberg KJ.

Memory & Cognition, 36, 933-946

A debate has emerged as to whether recognition of emotional stimuli is more accurate or more biased than recognition of nonemotional stimuli. Teasing apart changes in accuracy versus changes in bias requires a measurement model. However, different models have been adopted by different researchers, and this has contributed to the current debate. In this article, different measurement models are discussed, and the signal detection model that is most appropriate for recognition is adopted to investigate the effects of valence and arousal on recognition memory performance, using receiver operating characteristic analyses. In addition, complementary two-alternative forced choice experiments were conducted in order to generalize the empirical findings and interpret them under a relatively relaxed set of measurement assumptions. Across all experiments, accuracy was greater for highly valenced stimuli and stimuli with high arousal value. In addition, a bias to endorse positively valenced stimuli was observed. These results are discussed within an adaptive memory framework that assumes that emotion plays an important role in the allocation of attentional resources.

ARTICLE UPDATE - Emotional states influence the neural processing of affective language.

Pratt NL, Kelly SD.

Social Neuroscience, 3, 1-9

The present study investigated whether emotional states influence the neural processing of language. Event-related potentials recorded the brain's response to positively and negatively valenced words (e.g., love vs. death) while participants were directly induced into positive and negative moods. ERP electrodes in frontal scalp regions of the brain distinguished positive and negative words around 400 ms poststimulus. The amplitude of this negative waveform showed a larger negativity for positive words compared to negative words in the frontal electrode region when participants were in a positive, but not negative, mood. These findings build on previous research by demonstrating that people process affective language differently when in positive and negative moods, and lend support to recent views that emotion and cognition interact during language comprehension.

ARTICLE UPDATE - Asymmetrical frontal ERPs, emotion, and behavioral approach/inhibition sensitivity.

Peterson CK, Gable P, Harmon-Jones E.

Social Neuroscience, 113-124

The present study sought to extend past research on frontal brain asymmetry and individual differences by examining relationships of individual differences in behavioral inhibition/approach system (BIS/BAS) sensitivity with asymmetrical frontal event-related brain responses to startle probes presented during viewing of affective pictures. One hundred and ten participants were shown unpleasant, neutral, and pleasant affective pictures, and presented startle probes during picture presentations. Individual differences in BIS sensitivity related to relatively greater right frontal N100 amplitude to startle probes presented during pleasant and unpleasant pictures, whereas individual differences in BAS sensitivity related to reduced left frontal P300 amplitude to startle probes presented during pleasant pictures. The results of this study suggest that BIS sensitivity is related to greater relative right frontal cortical activity during affective states, while BAS sensitivity is related to greater relative left frontal cortical activity during appetitive states.

ARTICLE UPDATE - Friend or foe? Brain systems involved in the perception of dynamic signals of menacing and friendly social approaches.

Carter EJ, Pelphrey KA.

Social Neuroscience, 3, 151-163

During every social approach, humans must assess each other's intentions. Facial expressions provide cues to assist in these assessments via associations with emotion, the likelihood of affiliation, and personality. In this functional magnetic resonance imaging (fMRI) study, participants viewed animated male characters approaching them in a hallway and making either a happy or an angry facial expression. An expected increase in amygdala and superior temporal sulcus activation to the expression of anger was found. Notably, two other social brain regions also had an increased hemodynamic response to anger relative to happiness, including the lateral fusiform gyrus and a region centered in the middle temporal gyrus. Other brain regions showed little differentiation or an increased level of activity to the happy stimuli. These findings provide insight into the brain mechanisms involved in reading the intentions of other human beings in an overtly social context. In particular, they demonstrate brain regions sensitive to social signals of dominance and affiliation.

Thursday, July 10, 2008

ARTICLE UPDATE - Distinguishing expected negative outcomes from preparatory control in the human orbitofrontal cortex.

Ursu S, Clark KA, Stenger VA, Carter CS.

Brain Research, in press

The human orbitofrontal cortex (OFC) plays a critical role in adapting behavior according to the context provided by expected outcomes of actions. However, several aspects of this function are still poorly understood. In particular, it is unclear to what degree any subdivisions of the OFC are specifically engaged when negatively valenced outcomes are expected, and to what extent such areas might be involved in preparatory active control of behavior. We examined these issues in two complementary functional magnetic resonance imaging (fMRI) studies in which we simultaneously and independently manipulated monetary incentives for correct performance, and demands for active preparation of cognitive control. In both experiments, preparation for performance was associated with lateral PFC activity in response to high incentives, regardless of their valence, as well as in response to increased task demands. In contrast, areas of the OFC centered around the lateral orbital sulcus responded maximally to negatively perceived prospects, even when such prospects were associated with decreases in preparatory cognitive control. These results provide direct support for theoretical models which posit that the OFC contributes to behavioral regulation by representing the value of anticipated outcomes, but does not implement active control aimed at avoiding or pursuing outcomes. Furthermore, they provide additional converging evidence that the lateral OFC is involved in representing specifically the affective impact of anticipated negative outcomes.

ARTICLE UPDATE - The effect of appraisal level on processing of emotional prosody in meaningless speech.

Bach DR, Grandjean D, Sander D, Herdener M, Strik WK, Seifritz E.

Neuroimage, in press

In visual perception of emotional stimuli, low- and high-level appraisal processes have been found to engage different neural structures. Beyond emotional facial expression, emotional prosody is an important auditory cue for social interaction. Neuroimaging studies have proposed a network for emotional prosody processing that involves a right temporal input region and explicit evaluation in bilateral prefrontal areas. However, the comparison of different appraisal levels has so far relied upon using linguistic instructions during low-level processing, which might confound effects of processing level and linguistic task. In order to circumvent this problem, we examined processing of emotional prosody in meaningless speech during gender labelling (implicit, low-level appraisal) and emotion labelling (explicit, high-level appraisal). While bilateral amygdala, left superior temporal sulcus and right parietal areas showed stronger blood oxygen level-dependent (BOLD) responses during implicit processing, areas with stronger BOLD responses during explicit processing included the left inferior frontal gyrus, bilateral parietal, anterior cingulate and supplemental motor cortex. Emotional versus neutral prosody evoked BOLD responses in right superior temporal gyrus, bilateral anterior cingulate, left inferior frontal gyrus, insula and bilateral putamen. Basal ganglia and right anterior cingulate responses to emotional versus neutral prosody were particularly pronounced during explicit processing. These results are in line with an amygdala-prefrontal-cingulate network controlling different appraisal levels, and suggest a specific role of the left inferior frontal gyrus in explicit evaluation of emotional prosody. In addition to brain areas commonly related to prosody processing, our results suggest specific functions of anterior cingulate and basal ganglia in detecting emotional prosody, particularly when explicit identification is necessary.

ARTICLE UPDATE - Regulating the expectation of reward via cognitive strategies.

Delgado MR, Gillis MM, Phelps EA.

Nature Neuroscience, in press

Previous emotion regulation research has been successful in altering aversive emotional reactions. It is unclear, however, whether such strategies can also efficiently regulate expectations of reward arising from conditioned stimuli, which can at times be maladaptive (for example, drug cravings). Using a monetary reward-conditioning procedure with cognitive strategies, we observed attenuation in both the physiological (skin conductance) and neural correlates (striatum) of reward expectation as participants engaged in emotion regulation.

ARTICLE UPDATE - Individual differences in disgust sensitivity modulate neural responses to aversive/disgusting stimuli.

Mataix-Cols D, An SK, Lawrence NS, Caseras X, Speckens A, Giampietro V, Brammer MJ, Phillips ML.

European Journal of Neuroscience, 27, 3050-3058.

Little is known about how individual differences in trait disgust sensitivity modulate the neural responses to disgusting stimuli in the brain. Thirty-seven adult healthy volunteers completed the Disgust Scale (DS) and viewed alternating blocks of disgusting and neutral pictures from the International Affective Picture System while undergoing fMRI scanning. DS scores correlated positively with activations in brain regions previously associated with disgust (anterior insula, ventrolateral prefrontal cortex-temporal pole, putamen-globus pallidus, dorsal anterior cingulate, and visual cortex) and negatively with brain regions involved in the regulation of emotions (dorsolateral and rostral prefrontal cortices). The results were not confounded by biological sex, anxiety or depression scores, which were statistically controlled for. Disgust sensitivity, a behavioral trait that is normally distributed in the general population, predicts the magnitude of the individual's neural responses to a broad range of disgusting stimuli. The results have implications for disgust-related psychiatric disorders.

ARTICLE UPDATE - How emotion affects older adults' memories for event details.

Kensinger EA.

Memory, in press

As adults age, they tend to have problems remembering the details of events and the contexts in which events occurred. This review presents evidence that emotion can enhance older adults' abilities to remember episodic detail. Older adults are more likely to remember affective details of an event (e.g., whether something was good or bad, or how an event made them feel) than they are to remember non-affective details, and they remember more details of emotional events than of non-emotional ones. Moreover, in some instances, emotion appears to narrow the age gap in memory performance. It may be that memory for affective context, or for emotional events, relies on cognitive and neural processes that are relatively preserved in older adults.