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Spatially congruent negative BOLD responses to different stimuli do not summate in visual cortex
Ross Wilson1, Andrea Thomas1, Stephen D Mayhew1
1Centre for Human Brain Health (CHBH), School of Psychology, University of Birmingham, Birmingham, UK.
Neuroimage
|May 22, 2020
Summary
Negative BOLD responses (NBR) do not add up when multiple stimuli are presented. This suggests that brain deactivation pathways operate as a single system, driven by the strongest stimulus.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Functional Magnetic Resonance Imaging (fMRI)
Background:
- The negative BOLD response (NBR) is observed during cognitive and sensory tasks, potentially indicating suppressed brain activity.
- Understanding the pathways and properties of NBR is crucial for interpreting brain function during task performance.
Purpose of the Study:
- To investigate the additive properties of NBR in the sensory cortex.
- To determine if NBR arise from single or multiple generative pathways.
Main Methods:
- fMRI was used to measure brain activity in subjects viewing checkerboard stimuli in the foveal and middle-eccentricity areas of the visual field, both separately and concurrently.
- Analysis focused on the spatial overlap and amplitude of positive BOLD responses (PBR) and NBR.
Main Results:
- Neither PBR nor NBR exhibited additive properties when stimuli were combined.
- NBR amplitude for combined stimuli equaled that of the strongest single stimulus, indicating a lack of summation.
- NBR occurred in ipsilateral and contralateral regions relative to the PBR.
Conclusions:
- The non-additive nature of NBR suggests a single underlying pathway for stimulus-driven deactivation.
- Brain deactivation appears to operate as a binary system, with the strongest stimulus dictating the inhibitory signal.
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