1,721,048 research outputs found
High-caloric and chocolate stimuli processing in healthy humans: An integration of functional imaging and electrophysiological findings
Full text linkThere has been a great deal of interest in understanding how the human brain
processes appetitive food cues, and knowing how such cues elicit craving responses is
particularly relevant when current eating behavior trends within Westernized societies are
considered. One substance that holds a special place with regard to food preference is
chocolate, and studies that used functional magnetic resonance imaging (fMRI) and
event-related potentials (ERPs) have identified neural regions and electrical signatures that
are elicited by chocolate cue presentations. This review will examine fMRI and ERP
findings from studies that used high-caloric food and chocolate cues as stimuli, with a
focus on responses observed in samples of healthy participants, as opposed to those with
eating-related pathology. The utility of using high-caloric and chocolate stimuli as a means
of understanding the human reward system will also be highlighted, as these findings may
be particularly important for understanding processes related to pathological overeating
and addiction to illicit substances. Finally, research from our own lab that focused on
chocolate stimulus processing in chocolate cravers and non-cravers will be discussed, as
the approach used may help bridge fMRI and ERP findings so that a more complete
understanding of appetitive stimulus processing in the temporal and spatial domains may
be established
Electrophysiological evidence of early attentional bias to drug-related pictures in chronic cannabis users
No full textBehavioral and electrophysiological correlates of attentional bias to cannabis-related cues were investigated in a marijuana dependent group and a non-user group employing a drug Stroop task in which cannabis-related, negative and neutral images were presented. Behaviorally, cannabis users were less accurate during drug-containing blocks than non-users. Electrophysiologically, in chronic marijuana-users, an early positive ERP enhancement over left frontal scalp (EAP, 200–350 ms) was present in response to drug-containing blocks relative to negative blocks. This effect was absent in the non-user group. Furthermore, drug-containing blocks gave rise to
enhanced voltage of a posterior P300 (300–400 ms), and a posterior sustained slow wave (LPP, 400–700 ms) relative to negative blocks. However, such effects were similar between cannabis users and non-users. Brain source imaging in cannabis users revealed a generator for the EAP effect to drug stimuli in left ventromedial prefrontal
cortex/medial orbitofrontal cortex, a region active in fMRI studies of drug cue-reactivity and a target of the core dopaminergic mesolimbic pathway involved in the processing of substances of abuse. This study identifies the timing and brain localization of an ERP correlate of early attentional capture to drug-related pictures in chronic
marijuana users. The EAP to drug cues may identify a new electrophysiological marker with clinical implications for predicting abstinence versus relapse or to evaluate treatment interventions
On the interaction between sad mood and cognitive control: The effect of induced sadness on electrophysiological modulations underlying Stroop conflict processing
No full textThe present study employed high-density ERPs to examine the effect of induced sad mood on the spatiotemporal correlates of conflict monitoring and resolution in a colour-word Stroop interference task. Neuroimaging evidence and dipole modelling implicates the involvement of the anterior cingulate cortex (ACC) and medial prefrontal cortex (mPFC) regions in conflict-laden interference control. On the basis that these structures have been found to mediate emotion-cognition interactions in negative mood states, it was predicted that Stroop-related cognitive control, which relies heavily on anterior neural sources, would be affected by effective sad mood provocation. Healthy participants (N=14) were induced into transient sadness via use of autobiographical sad scripts, a well-validated mood induction technique (Liotti et al., 2000a, 2002). In accord with previous research, interference effects were shown at both baseline and sad states while Stroop conflict was associated with early (N450) and late (Late Positive Component; LPC) electrophysiological modulations at both states. Sad mood induction attenuated the N450 effect in line with our expectation that it would be susceptible to modulation by mood, given its purported anterior limbic source. The LPC effect was displayed at the typical posterior lateral sites but, as predicted, was not affected by sad mood. However, frontocentral LPC activity-presumably generated from an additional anterior limbic source-was affected at sad state, hinting a role in conflict monitoring. Although the neurophysiological underpinnings of interference control are yet to be clarified, this study provided further insight into emotion-cognition interactions as indexed by Stroop conflict-laden processing
Functional brain organization of preparatory attentional control in visual search
Full text linkLooking for an object that may be present in a cluttered visual display requires an advanced specification of that object to be created and then matched against the incoming visual input. Here, fast event-related fMRI was used to identify the brain networks that are active when preparing to search for a visual target. By isolating the preparation phase of the task it has been possible to show that for an identical stimulus, different patterns of cortical activation occur depending on whether participants anticipate a 'feature' or a 'conjunction' search task. When anticipating a conjunction search task, there was more robust activation in ventral occipital areas, new activity in the transverse occipital sulci and right posterior intraparietal sulcus. In addition, preparing for either type of search activated ventral striatum and lateral cerebellum. These results suggest that when participants anticipate a demanding search task, they develop a different advanced representation of a visually identical target stimulus compared to when they anticipate a nondemanding search
When is giving an impulse? An ERP investigation of intuitive prosocial behavior
Full text linkHuman prosociality is often assumed to emerge from exerting reflective control over initial, selfish impulses. However, recent
findings suggest that prosocial actions can also stem from processes that are fast, automatic and intuitive. Here, we attempt
to clarify when prosocial behavior may be intuitive by examining prosociality as a form of reward seeking. Using
event-related potentials (ERPs), we explored whether a neural signature that rapidly encodes the motivational salience of
an event—the P300—can predict intuitive prosocial motivation. Participants allocated varying amounts of money between
themselves and charities they initially labelled as high- or low-empathy targets under conditions that promoted intuitive or
reflective decision making. Consistent with our predictions, P300 amplitude over centroparietal regions was greater when
giving involved high-empathy targets than low-empathy targets, but only when deciding under intuitive conditions.
Reflective conditions, alternatively, elicited an earlier frontocentral positivity related to response inhibition, regardless of
target. Our findings suggest that during prosocial decision making, larger P300 amplitude could (i) signal intuitive prosocial
motivation and (ii) predict subsequent engagement in prosocial behavior. This work offers novel insight into when prosociality
may be driven by intuitive processes and the roots of such behaviors
Electrophysiological evidence for abnormal error monitoring in recurrent major depressive disorder
No full textPrevious neuroimaging work has identified anterior cingulate cortex (ACC) abnormalities in recurrent major depressive disorder (MDD), implicating a persistent underlying predisposition to depression. Error-monitoring studies in MDD, as indexed by error-related negativity (ERN), have yielded conflicting results, probably because of task differences or confounds in patient samples. ERN patterns were examined in remitted (n=19) and acutely depressed (n=17) patients, classified as a function of illness stage, and their matched controls in a go/no-go task using high-density ERPs. Results showed an abnormally larger ERN (p<.05) in remitted patients, especially in younger cases. Overall, ERN was found to decrease with age across all groups. The findings of increased ERN in remitted depression may implicate an overactive ACC associated with a hypervigilant error-monitoring system. The observed tendency of ERN reduction in a severe depressive state failed to reach statistical significance
Conscious perception of fear in faces: Insights from high-density EEG and Perceptual Awareness Scale with threshold stimuli
Full text linkSpatiotemporal Dynamics of Covert vs. Overt Emotional Face Processing in Dysphoria
Full text linkPeople at risk of developing clinical depression exhibit attentional biases for emotional faces. To clarify whether such effects occur at an early, automatic, or at a late, deliberate processing stage of emotional processing, the present study used high-density electroencephalography during both covert and overt processing of sad, fearful, happy, and neutral expressions in healthy participants with high dysphoria (n = 16) and with low dysphoria (n = 19). A state-of-the-art non-parametric permutation-based statistical approach was then used to explore the effects of emotion, attentional task demands, and group. Behaviorally, participants responded faster and more accurately when overtly categorizing happy faces and they were slower and less accurate when categorizing sad and fearful faces, independent of the dysphoria group. Electrophysiologically, in an early time-window (N170: 140–180 ms), there was a significant main effect for the dysphoria group, with greater negative voltage for the high vs. low dysphoria group over the left-sided temporo-occipital scalp. Furthermore, there was a significant group by emotional interaction, with the high dysphoria group displaying greater negative amplitude N170 for happy than fearful faces. Attentional task demands did not influence such early effects. In contrast, in an intermediate time-window (EPN: 200–400 ms) and in a late time-window (LPP: 500–750 ms) there were no significant main effects nor interactions involving the dysphoria Group. The LPP results paralleled the behavioral results, with greater LPP voltages for sad and fearful relative to happy faces only in the overt task, but similarly so in the two dysphoria groups. This study provides novel evidence that alterations in face processing in dysphoric individuals can be seen at the early stages of face perception, as indexed by the N170, although not in the form of a typical pattern of mood-congruent attentional bias. In contrast, intermediate (EPN) and late (LPP) stages of emotional face processing appear unaffected by dysphoria. Importantly, the early dysphoria effect appears to be independent of the top-down allocation of attention, further supporting the idea that dysphoria may influence a stage of automatic emotional appraisal. It is proposed that it may be a consequence of a shift from holistic to feature-based processing of facial expressions, or may be due to the influence of negative schemas acting as a negative context for emotional facial processing
Electrophysiology of blunted emotional bias in psychopathic personality
No full textDiminished emotional capacity is a core characteristic of psychopathic personality. We examined behavioral and electrophysiological differences in attentional bias to emotional material in 34 healthy individuals rated high or low in psychopathic traits using the short form of the Psychopathic Personality Inventory-Revised (18 high-trait, 16 low-trait). While performing an emotional Stroop task, high-trait participants displayed reduced emotional modulation of the late positive potential (LPP, 400-600 ms), and early anterior positivity (EAP, 200-300 ms) amplitudes. Results suggest blunted bias to affective content in psychopathic personality, characterized by diminished early capture to emotional salience (EAP) and dampened cognitive emotional processing (LPP)
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