Spatiotemporal Dynamics of Reward and Punishment Effects Induced By Associative Learning

While reward associative learning has been studied extensively across different species, punishment avoidance learning has received far less attention. Of particular interest is how the two types of learning change perceptual processing of the learned stimuli. We designed a task that required participants to learn the association of emotionally neutral images with reward, punishment, and no incentive value outcomes through trial-and-error. During learning, participants received monetary reward, neutral outcomes or avoided punishment by correctly identifying corresponding images. Results showed an early bias in favor of learning reward associations, in the form of higher accuracy and fewer trials needed to reach learning criterion. We subsequently assessed electrophysiological learning effects with a task in which participants viewed the stimuli with no feedback or reinforcement. Critically, we found modulation of two early event-related potential components for reward images: the frontocentral P2 (170–230 ms) and the anterior N2/Early Anterior Positivity (N2/EAP; 210–310 ms). We suggest that reward associations may change stimuli detection and incentive salience as indexed by P2 and N2/EAP. We also reported, on an exploratory basis, a late negativity with frontopolar distribution enhanced by punishment images

Standardization of electroencephalography for multi-site, multi-platform and multi-investigator studies: Insights from the canadian biomarker integration network in depression

Subsequent to global initiatives in mapping the human brain and investigations of neurobiological markers for brain disorders, the number of multi-site studies involving the collection and sharing of large volumes of brain data, including electroencephalography (EEG), has been increasing. Among the complexities of conducting multi-site studies and increasing the shelf life of biological data beyond the original study are timely standardization and documentation of relevant study parameters. We presentthe insights gained and guidelines established within the EEG working group of the Canadian Biomarker Integration Network in Depression (CAN-BIND). CAN-BIND is a multi-site, multi-investigator, and multiproject network supported by the Ontario Brain Institute with access to Brain-CODE, an informatics platform that hosts a multitude of biological data across a growing list of brain pathologies. We describe our approaches and insights on documenting and standardizing parameters across the study design, data collection, monitoring, analysis, integration, knowledge-translation, and data archiving phases of CAN-BIND projects. We introduce a custom-built EEG toolbox to track data preprocessing with open-access for the scientific community. We also evaluate the impact of variation in equipment setup on the accuracy of acquired data. Collectively, this work is intended to inspire establishing comprehensive and standardized guidelines for multi-site studies

A psychophysiological study of approach and avoidance

Despite their importance, processes that govern affect and behavior are sensitive to disruption. This is evident at a clinical level where internalizing and externalizing psychopathologies show dysregulation in inhibition of anxious/depressive symptoms and impulsive-antagonistic behaviors, respectively (Liotti et al,2007; Moadab et al,2010). Healthy participants show similar dysregulation when highly arousing stimulus characteristics detrimentally impact performance in cognitively-demanding tasks (López-Martín, Carretié, 2010). This suggests that cognitive and affective networks draw on similar neural structures wherein more demands on one causes a change in the other (Pessoa, 2008; Vuilleumier, 2005; Ochsner & Gross, 2005). This dissertation framed the intricate and complex pattern of brain activity within the framework of a dual-layer self-regulation mechanism defined by action and affect. This model of self-regulation results in behavioral tendencies that are related either to approaching a desired outcome or avoiding an unpleasant event. An emotionally evocative task manipulation was designed to induce changes in endogenous affect and interfere with cognitive processes. An additional exogenous affect manipulation was embedding within this task through the use of salient facial expressions as stimuli. Due to the implicit aversiveness of this paradigm a separate task was used to create a scenario where participants are driven toward a desired goal. Electrophysiology methods were used to record brain activity which was analyzed using traditional ERP analysis, time-frequency decomposition, beamforming source estimation, power spectrum, and Partial-Least Squares analysis. Results implicate approach and avoidance tendencies to predict brain activity and be differentially related to delta, theta, and alpha oscillations. Theta processes related to the central executive network and map onto action, delta processes related to salience and affective networks and map onto affect, while alpha processes related to both saliency and executive control networks (i.e. the interaction between cognition and emotion) and map onto both action and affect loops. This body of work was able to address three main categories of research questions: 1) the effect of endogenous and exogenous emotion manipulations and their relationship with approach and avoidance; 2) the dynamics and impact of ongoing emotional experience; and 3) the 5-dimensional role of oscillatory changes in response to endogenous affective manipulation

The effect of impulsivity and emotion on brain electrophysiology

Research in emotion has found a modulation in ERP components for affective stimuli (positive and negative valence). In verbal Go/No-Go paradigms this effect has not been reliable for trails requiring response inhibition (No-Go). This is possibly due to the salience of the chosen words. Using words chosen with specific criteria, the current study found a strong emotional modulation for Go and No-Go trials. Time-frequency analysis was performed resulting in an effect of the theta frequency only. The findings support the idea that inclusion of emotionally salient information is associated with reallocation of neural resources. In addition, the results of this study suggest that neural resources are recruited for the processing of valence information, regardless of task demands

Spatiotemporal Dynamics of Covert Versus Overt Processing of Happy, Fearful and Sad Facial Expressions

Behavioral and electrophysiological correlates of the influence of task demands on the processing of happy, sad, and fearful expressions were investigated in a within-subjects study that compared a perceptual distraction condition with task-irrelevant faces (e.g., covert emotion task) to an emotion task-relevant categorization condition (e.g., overt emotion task). A state-of-the-art non-parametric mass univariate analysis method was used to address the limitations of previous studies. Behaviorally, participants responded faster to overtly categorized happy faces and were slower and less accurate to categorize sad and fearful faces; there were no behavioral differences in the covert task. Event-related potential (ERP) responses to the emotional expressions included the N170 (140–180 ms), which was enhanced by emotion irrespective of task, with happy and sad expressions eliciting greater amplitudes than neutral expressions. EPN (200–400 ms) amplitude was modulated by task, with greater voltages in the overt condition, and by emotion, however, there was no interaction of emotion and task. ERP activity was modulated by emotion as a function of task only at a late processing stage, which included the LPP (500–800 ms), with fearful and sad faces showing greater amplitude enhancements than happy faces. This study reveals that affective content does not necessarily require attention in the early stages of face processing, supporting recent evidence that the core and extended parts of the face processing system act in parallel, rather than serially. The role of voluntary attention starts at an intermediate stage, and fully modulates the response to emotional content in the final stage of processing