On the origin of sustained negative BOLD response

Area of Science:

• Neuroimaging
• Neurophysiology
• Vascular Biology

Background:

• The sustained negative BOLD response (NBR) is observed in specific brain regions during functional magnetic resonance imaging (fMRI) tasks.
• The precise origin of NBR and its link to neural and vascular/metabolic dynamics remain subjects of debate.
• Existing evidence from human and non-human primates suggests NBR may represent a decrease in neuronal activity below baseline.

Purpose of the Study:

• To investigate the underlying mechanisms of the sustained negative BOLD response (NBR).
• To clarify the relationship between vascular/metabolic changes and neural activity during NBR.
• To evaluate the interpretation of NBR as a marker of decreased neuronal activity.

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) to assess brain activity.
• Reviewed converging evidence from human and non-human primate studies.
• Emphasized the need for multimodal approaches to investigate NBR.

Main Results:

• NBR in several brain regions can be linked to a reduction in neuronal activity below basal levels.
• The phenomenon is not solely attributable to vascular changes.
• Direct experimental evidence is limited, necessitating cautious interpretation.

Conclusions:

• The sustained negative BOLD response (NBR) likely reflects a decrease in underlying neuronal activity.
• While not purely a vascular phenomenon, further multimodal research is essential for definitive understanding.
• Continued investigation is crucial to fully elucidate the neurovascular basis of NBR.