Central and Divided Visual Field Presentation of Emotional Images to Measure Hemispheric Differences in Motivated Attention
November 16th, 2017
This study compared central versus divided visual field presentations of emotional images to assess differences in motivated attention between the two hemispheres. The late positive potential (LPP) was recorded using electroencephalography (EEG) and event-related potentials (ERPs) methodologies to assess motivated attention.
The overall goal of this divided visual field event related potential methodology is to observe the unique contribution of each hemisphere of the brain to the processing of emotional stimuli as measured by the late positive potential, or LPP. This method can help to answer key questions in the field of lateralized processing of emotion such as, What are the unique contributions of each hemisphere to the motivated attention network for processing unpleasant versus pleasant stimuli? The main advantage of this technique is that it allows you to assess the processing differences between the two hemispheres of the brain with a fine temporal resolution.
Demonstrating the procedure will be Nick Lunny, a grad student in my lab. Zach Gemelli, an undergraduate research assistant in my lab will be playing the role of the participant. Begin by escorting the participant into the testing room and having them read and complete an informed consent.
Then have the participant complete a demographic survey to provide sex, age, handedness, native language, vision and neurological history in order to assess inclusion for the study. Next, apply electroencephalography, or EEG electrodes, onto the participant's scalp according to the international 10-20 system. Then, seat the participant in a dark, electrically shielded sound attenuated room.
Use a chin rest to stabilize the head and minimize movement. Then, instruct the participant to passively view the image stimuli without shifting their eyes away from the center of the screen. Instruct the participant that a recognition quiz will follow the stimuli, so it is important that they pay attention.
Finally, display a fixation cross at the center of the screen to help the participant fixate. For the central visual field, CVF paradigm, have the participant passively view the image stimuli in four experimental blocks of 45 trials each at the center of the screen. Note each block has an equal number of stimuli from the valence arousal conditions.
On the other hand, if the participant is randomized to the divided visual field, DVF paradigm, randomly present each image, once in the left visual field and once in the right visual field. Pair each image stimulus with the simultaneous presentation of a solid brown rectangle identical in stimulus dimensions on the opposite side of the fixation in order to reduce reflexive saccades to the stimulus. Next, present each stimulus and its paired brown rectangle with their inside edge three degrees of visual angle from the fixation.
Finally, backward mask both the stimulus and the brown rectangle using the same criteria and procedure as was done for the CVF paradigm. The late positive potential, or LPP, in the early epic was significantly larger to unpleasant and pleasant images, which did not differ from each other, compared to neutral images. And high arousing images evoked larger LPP responses than medium arousing images.
In the late epic, the LPP was significantly larger to high arousing unpleasant images compared to all other images. Further, the LPP was found to be larger in the early epic compared to the late epic for all image presentations except for high arousing unpleasant images presented to the left hemisphere. The left hemisphere engages high arousing unpleasant images for longer, possibly to create an action plan in response to the images.
For the divided visual field procedure, it is important that the participant's eyes stay fixated at the center of the screen to optimize lateralized stimulus processing. For successful divided visual field presentations, carefully control stimulus size, presentation duration and location on the screen. Balance the presentation of your stimulus with the filler stimulus and use backward masking to optimize lateralized stimulus processing.
The divided visual field procedure can be used with vent related potentials to investigate lateralized processing of emotion as well as investigate the unique and interactive effects of valence and arousal on the motivated attention network. Divided visual field procedures, in combination with event related potential techniques, can also be used to answer additional questions about a variety of theories of lateralized processing and visual spacial processing systems in the brain.
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Overview
This study investigates the differences in motivated attention between the two hemispheres of the brain by comparing central and divided visual field presentations of emotional images. The late positive potential (LPP) is measured using electroencephalography (EEG) and event-related potentials (ERPs) methodologies.
Key Study Components
Area of Science
- Neuroscience
- Electrophysiology
- Emotion Processing
Background
- The study focuses on lateralized processing of emotional stimuli.
- It aims to understand how each hemisphere contributes to motivated attention.
- The late positive potential (LPP) serves as a key measure in this research.
- This methodology allows for fine temporal resolution in assessing brain activity.
Purpose of Study
- To explore the unique contributions of each hemisphere in processing emotional stimuli.
- To differentiate between responses to pleasant and unpleasant stimuli.
- To enhance understanding of the motivated attention network.
Methods Used
- Divided visual field presentations of emotional images.
- Electroencephalography (EEG) for recording brain activity.
- Event-related potentials (ERPs) to assess responses.
- Involvement of participants in a controlled testing environment.
Main Results
- Differences in LPP responses were observed between hemispheres.
- Findings suggest distinct processing pathways for emotional stimuli.
- Results contribute to the understanding of lateralized emotional processing.
- The methodology proved effective in revealing temporal dynamics of brain responses.
Conclusions
- The study highlights the importance of hemisphere-specific processing in emotional attention.
- It provides insights into how emotional stimuli are processed differently across the brain.
- Future research may build on these findings to explore further implications in neuroscience.
Frequently Asked Questions
Executive Industry Relevance
Understanding hemispheric specialization in emotional processing provides mechanistic insights for target validation in neuropsychiatric drug discovery. This methodology enables de-risking of hypotheses regarding lateralized brain function by offering a non-imaging, electrophysiological approach with fine temporal resolution. It supports early discovery efforts to clarify pathway engagement and predict translational relevance of compounds targeting motivated attention networks.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Interrogates therapeutic hypotheses about hemispheric contributions to emotional processing pathways.
- Operational Value: Enables biological de-risking of targets through measurable LPP responses to valence and arousal manipulations.
- Predictive Value: Supports portfolio triage by differentiating compound effects on motivated attention networks across hemispheres.
Screening & Assay Development
- Assay Readiness: Prepares validated neurophysiological readouts for downstream screening of modulators of emotional attention.
- Quantitative Output: Provides LPP amplitude and latency metrics as dependent variables for compound screening.
- Reproducibility: Standardized stimulus presentation and backward masking enhance cross-lab consistency.
Translational & Preclinical Research
- Disease Relevance: Aligns with disorders involving hemispheric asymmetry in emotional processing, such as anxiety and depression.
- Translational Continuity: Bridges discovery findings to preclinical models by identifying conserved lateralized attention signatures.
- Risk-Adjusted Advancement: Informs go/no-go decisions based on target engagement in motivated attention circuits.
Pipeline & Workflow Integration
The method fits within the discovery continuum from target hypothesis testing to lead optimization, particularly for CNS compounds affecting emotional regulation.
- Discovery Biology: Tests mechanistic hypotheses about hemispheric specialization in motivated attention networks.
- Screening: Delivers ERP-based quantitative readouts suitable for high-fidelity compound screening.
- Analytics: Enables comparison of LPP responses across stimulus conditions to assess compound-induced shifts in attention.
- Translational Research: Supports biomarker alignment by linking LPP patterns to emotional processing endophenotypes.
- Enterprise Reuse: Establishes a reusable electrophysiological platform for evaluating CNS-active compounds across projects.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in target validation by reducing mechanistic ambiguity in emotional processing pathways.
- Operational Value: Delivers standardized, scalable ERP acquisition with minimal dependence on neuroimaging infrastructure.
- Strategic Value: Improves capital efficiency by enabling early biological de-risking of CNS targets.
- Portfolio Impact: Facilitates risk-adjusted prioritization of compounds based on hemispheric specificity of action.
Implementation Considerations
- Requires expertise in EEG/ERP acquisition and emotional stimulus validation.
- Depends on electrically shielded environments and precise visual stimulus control systems.
- Necessitates cross-team standardization of stimulus timing, size, and masking protocols.
- Involves adaptation considerations for clinical populations with attentional or oculomotor deficits.
- Limited to paradigms where passive viewing suffices; active tasks may require protocol modification.
