Appetitive-aversive interactions during visual processing

Reward learning and negative emotion during rapid attentional competition

Takemasa Yokoyama, Srikanth Padmala, and Luiz Pessoa. Front Psychol., February 2015.

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Learned stimulus-reward associations influence how attention is allocated, such that stimuli rewarded in the past are favored in situations involving limited resources and competition. At the same time, task-irrelevant, high-arousal negative stimuli capture attention and divert resources away from tasks resulting in poor behavioral performance. Yet, investigations of how reward learning and negative stimuli affect perceptual and attentional processing have been conducted in a largely independent fashion. We have recently reported that performance-based monetary rewards reduce negative stimuli interference during perception. The goal of the present study was to investigate how stimuli associated with past monetary rewards compete with negative stimuli during a subsequent attentional task when, critically, no performance-based rewards were at stake. Across two experiments, we found that target stimuli that were associated with high reward reduced the interference effect of potent, negative distractors. Similar to our recent findings with performance-based rewards, our results demonstrate that reward-associated stimuli reduce the deleterious impact of negative stimuli on behavior.

Reward and threat competition

Pervasive competition between threat and reward in the brain.

Jong Moon Choi, Srikanth Padmala, Philip Spechler and Luiz Pessoa.Social Cognitive and Affective Neuroscience.June 2014.

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In the current functional MRI study, we investigated interactions between reward and threat processing. Visual cues at the start of each trial informed participants about the chance of winning monetary reward and/or receiving a mild aversive shock. We tested two competing hypothesis: according to the salience hypothesis, in the condition involving both reward and threat, enhanced activation would be observed because of increased salience; according to the competition hypothesis, the processing of reward and threat would trade-off against each other, leading to reduced activation. Analysis of skin conductance data during a delay phase revealed an interaction between reward and threat processing, such that the effect of reward was reduced during threat and the effect of threat was reduced during reward. Analysis of imaging data during the same task phase revealed interactions between reward and threat processing in several regions, including the midbrain/ventral tegmental area, caudate, putamen, bed nucleus of the stria terminalis, anterior insula, middle frontal gyrus and dorsal anterior cingulate cortex. Taken together, our findings reveal conditions during which reward and threat trade-off against each other across multiple sites. Such interactions are suggestive of competitive processes and may reflect the organization of opponent systems in the brain.

Functional diversity of brain regions and brain networks

Describing functional diversity of brain regions and brain networks.

Michael L. Anderson, Josh Kinnison, and Luiz Pessoa. NeuroImage. 2013 June; 73:50-8.

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Despite the general acceptance that functional specialization plays an important role in brain function, there is little consensus about its extent in the brain. We sought to advance the understanding of this question by employing a data-driven approach that capitalizes on the existence of large databases of neuroimaging data. We quantified the diversity of activation in brain regions as a way to characterize the degree of functional specialization. To do so, brain activations were classified in terms of task domains, such as vision, attention, and language, which determined a region’s functional fingerprint. We found that the degree of diversity varied considerably across the brain. We also quantified novel properties of regions and of networks that inform our understanding of several task-positive and task-negative networks described in the literature, including defining functional fingerprints for entire networks and measuring their functional assortativity, namely the degree to which they are composed of regions with similar functional fingerprints. Our results demonstrate that some brain networks exhibit strong assortativity, whereas other networks consist of relatively heterogeneous parts. In sum, rather than characterizing the contributions of individual brain regions using task-based functional attributions, we instead quantified their dispositional tendencies, and related those to each region’s affiliative properties in both task-positive and task-negative contexts.

Network-level analysis of emotional and motivational processing

Network organization unfolds over time during periods of anxious anticipation

Brenton McMenamin, Sandra Langeslag, Mihai Sirbu, Srikanth Padmala, and Luiz Pessoa. The Journal of Neuroscience, August 2014.

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Entering a state of anxious anticipation triggers widespread changes across large-scale networks in the brain. The temporal aspects of this transition into an anxious state are poorly understood. To address this question, an instructed threat of shock paradigm was used while recording functional MRI in humans to measure how activation and functional connectivity change over time across the salience, executive, and task-negative networks and how they interact with key regions implicated in emotional processing; the amygdala and bed nucleus of the stria terminalis (BNST). Transitions into threat blocks were associated with transient responses in regions of the salience network and sustained responses in a putative BNST site, among others. Multivariate network measures of communication were computed, revealing changes to network organization during transient and sustained periods of threat, too. For example, the salience network exhibited a transient increase in network efficiency followed by a period of sustained decreased efficiency. The amygdala became more central to network function (as assessed via betweenness centrality) during threat across all participants, and the extent to which the BNST became more central during threat depended on self-reported anxiety. Together, our study unraveled a progression of responses and network-level changes due to sustained threat. In particular, our results reveal how network organization unfolds with time during periods of anxious anticipation.

Mission Statement

Our long-range goal is to contribute to a better understanding of the basic mechanisms by which emotional/motivational and cognitive brain systems interact in the generation of complex behavior. As a step forward to this goal, we are currently investigating how tasks that require “top-down control” and emotional/motivational processing interact in the brain. Cognitive and emotional/motivational systems have been largely considered to function separately from one another. However, a deeper understanding of the brain function and associated behavior requires studying interactions between these systems. Recent techniques, including functional neuroimaging (such as fMRI), allow the study of several brain systems simultaneously and pave the way for the study of interactions in the brain. By studying cognitive-emotional interactions we expect to make contributions to understanding the neural basis of behavior. At the same time, we expect our work to have clinical implications. For example, by providing a better understanding of cognitive-emotional interactions during normal behavior, our research can help understand the mechanisms that potentially go awry in many debilitating mental illnesses.