Dissociating Neural Correlates of Conscious Perception and Reportability Using Color Afterimages
Poster No:
2021
Submission Type:
Abstract Submission
Authors:
Rajneet Kaur1, Amrendra Singh1
Institutions:
1Centre of Behavioral and Cogntive Sciences, University of Allahabad, Prayagraj, India
First Author:
Co-Author:
Amrendra Singh, Dr.
Centre of Behavioral and Cogntive Sciences, University of Allahabad
Prayagraj, India
Centre of Behavioral and Cogntive Sciences, University of Allahabad
Prayagraj, India
Introduction:
Recent research highlights the roles of frontal and posterior brain regions in visual awareness. The Global Neuronal Workspace Theory emphasizes frontal regions, such as the prefrontal cortex and anterior insula, in top-down attention modulation, executive control, and integrating sensory inputs with awareness (Brown et al., 2019; Seth, 2019). These areas are crucial for reporting and sustaining conscious perception. In contrast, the Integrated Information Theory attributes visual awareness to posterior regions like the parietal lobe and occipital cortex, responsible for initial sensory processing and awareness formation (Dembski, Koch, & Pitts, 2021). A key challenge in this field arises from report-related processes (e.g., motor planning) confounding awareness-specific activity. While tasks assessing neural correlates of conscious perception in report and no-report paradigms attempt to address this, many fail to provide robust evidence for awareness in no-report conditions (Duman et al., 2022).
A major limitation of these studies is the absence of a quantitative measure of awareness in no-report conditions. In the present study, we aim to address this gap by using a color afterimages task, which offers a unique opportunity to investigate the persistence of visual awareness beyond the physical stimulus (Leopold & Logothetis, 1999). In this task, participants report their subjective experiences of the afterimages in both report and no-report conditions.
This study explores how frontal and posterior brain regions contribute to conscious perception by comparing neural activation in report and no-report conditions. It aims to uncover neural correlates of reportability and pure awareness, offering insights into the brain mechanisms underlying visual consciousness.
A major limitation of these studies is the absence of a quantitative measure of awareness in no-report conditions. In the present study, we aim to address this gap by using a color afterimages task, which offers a unique opportunity to investigate the persistence of visual awareness beyond the physical stimulus (Leopold & Logothetis, 1999). In this task, participants report their subjective experiences of the afterimages in both report and no-report conditions.
This study explores how frontal and posterior brain regions contribute to conscious perception by comparing neural activation in report and no-report conditions. It aims to uncover neural correlates of reportability and pure awareness, offering insights into the brain mechanisms underlying visual consciousness.
Methods:
Participants
Twenty-seven right-handed volunteers (14 females, mean age = 22 years, SD = 2.52) with normal or corrected vision participated in the study.
Stimuli and Task
Stimuli included block letters ("S," "H") and numbers ("6," "9") (Fig. 1a). Trials featured 27 stimuli over 20 seconds, each shown for 500 ms with a 250 ms blank. Participants counted "S" occurrences. Report and no-report tasks included three blocks: local, global, and baseline (no stimuli). Report tasks required afterimage onset/offset responses, while no-report tasks involved passive observation. (see fig 1(b).
fMRI Data Acquisition
Data were collected on a 3T SIEMENS Skyra scanner using EPI for functional and MPRAGE for structural images.
fMRI Preprocessing and Analysis:
SPM12 was used for preprocessing (realignment, slice-time correction, normalization, smoothing). GLM analysis modeled task conditions with boxcar functions convolved with the HRF. Results were thresholded at p<0.001, with FDR correction (q<0.05).
Twenty-seven right-handed volunteers (14 females, mean age = 22 years, SD = 2.52) with normal or corrected vision participated in the study.
Stimuli and Task
Stimuli included block letters ("S," "H") and numbers ("6," "9") (Fig. 1a). Trials featured 27 stimuli over 20 seconds, each shown for 500 ms with a 250 ms blank. Participants counted "S" occurrences. Report and no-report tasks included three blocks: local, global, and baseline (no stimuli). Report tasks required afterimage onset/offset responses, while no-report tasks involved passive observation. (see fig 1(b).
fMRI Data Acquisition
Data were collected on a 3T SIEMENS Skyra scanner using EPI for functional and MPRAGE for structural images.
fMRI Preprocessing and Analysis:
SPM12 was used for preprocessing (realignment, slice-time correction, normalization, smoothing). GLM analysis modeled task conditions with boxcar functions convolved with the HRF. Results were thresholded at p<0.001, with FDR correction (q<0.05).
Results:
Behavioral Results
Task type (report vs. no-report) did not affect the subjective experience of afterimages, including color and clarity. This indicates no difference in subjective visual awareness between the two conditions.
fMRI Results
The contrast Report > No-Report revealed significant activation in regions linked to higher-order cognitive functions and motor processes during explicit visual awareness reporting. The Right Superior Frontal Gyrus (medial segment/anterior cingulate gyrus) and Right Superior Frontal Gyrus were active, reflecting roles in executive control, decision-making, and attention maintenance.
The Right Anterior Insula and Right Supramarginal Gyrus were engaged, indicating roles in salience detection and sensory-motor integration. Subcortical regions, including the Left Thalamus Proper, and sensory-motor areas like the Left Central Operculum, showed significant activity, highlighting their role in integrating visual inputs for conscious reporting (see fig 2).
Task type (report vs. no-report) did not affect the subjective experience of afterimages, including color and clarity. This indicates no difference in subjective visual awareness between the two conditions.
fMRI Results
The contrast Report > No-Report revealed significant activation in regions linked to higher-order cognitive functions and motor processes during explicit visual awareness reporting. The Right Superior Frontal Gyrus (medial segment/anterior cingulate gyrus) and Right Superior Frontal Gyrus were active, reflecting roles in executive control, decision-making, and attention maintenance.
The Right Anterior Insula and Right Supramarginal Gyrus were engaged, indicating roles in salience detection and sensory-motor integration. Subcortical regions, including the Left Thalamus Proper, and sensory-motor areas like the Left Central Operculum, showed significant activity, highlighting their role in integrating visual inputs for conscious reporting (see fig 2).
Conclusions:
These findings suggest that explicit reporting of visual awareness recruits a network of higher-order and sensory-motor regions that extend beyond the sensory processing observed in the no-report condition.
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI) 2
Perception, Attention and Motor Behavior:
Consciousness and Awareness 1
Keywords:
Cognition
Consciousness
FUNCTIONAL MRI
Other - Perception, Attention, Neural-Corelates-of-Conciousness
1|2Indicates the priority used for review
Abstract Information
By submitting your proposal, you grant permission for the Organization for Human Brain Mapping (OHBM) to distribute your work in any format, including video, audio print and electronic text through OHBM OnDemand, social media channels, the OHBM website, or other electronic publications and media.
The Open Science Special Interest Group (OSSIG) is introducing a reproducibility challenge for OHBM 2025. This new initiative aims to enhance the reproducibility of scientific results and foster collaborations between labs. Teams will consist of a “source” party and a “reproducing” party, and will be evaluated on the success of their replication, the openness of the source work, and additional deliverables. Click here for more information. Propose your OHBM abstract(s) as source work for future OHBM meetings by selecting one of the following options:
Please indicate below if your study was a "resting state" or "task-activation” study.
Healthy subjects only or patients (note that patient studies may also involve healthy subjects):
Was this research conducted in the United States?
Were any human subjects research approved by the relevant Institutional Review Board or ethics panel? NOTE: Any human subjects studies without IRB approval will be automatically rejected.
Were any animal research approved by the relevant IACUC or other animal research panel? NOTE: Any animal studies without IACUC approval will be automatically rejected.
Please indicate which methods were used in your research:
For human MRI, what field strength scanner do you use?
Which processing packages did you use for your study?
Provide references using APA citation style.
Seth, A. K. (2019). The conscious brain: How attention and awareness shape our experience. Trends in Cognitive Sciences, 23(5), 379-393
Dembski, C., Koch, C., & Pitts, M. (2021). Perceptual awareness negativity: a physiological correlate of sensory consciousness. Trends in cognitive sciences, 25(8), 660–670. https://doi.org/10.1016/j.tics.2021.05.009
Duman, I., Ehmann, I. S., Gonsalves, A. R., Gültekin, Z., Van den Berckt, J., & van Leeuwen, C. (2022). The No-Report Paradigm: A Revolution in Consciousness Research?. Frontiers in human neuroscience, 16, 861517. https://doi.org/10.3389/fnhum.2022.861517