Lamina-dependent calibrated BOLD response in human primary motor cortex.

Area of Science:

• Neuroimaging
• Systems Neuroscience
• Human Physiology

Background:

• Layer-dependent fMRI is crucial for separating feedforward and feedback neural activity.
• Gradient-recalled echo (GRE) BOLD signal is biased by large draining veins, limiting laminar resolution.
• Accurate laminar fMRI requires methods insensitive to large vascular effects.

Purpose of the Study:

• To evaluate the Davis model for quantitative, lamina-dependent fMRI of evoked oxidative metabolism.
• To assess the applicability, advantages, and limitations of the Davis model in laminar fMRI.
• To obtain metabolic brain activity in the primary motor cortex on a laminar scale without vascular contamination.

Main Methods:

• Functional magnetic resonance imaging (fMRI) during a unilateral finger-tapping task.
• Application of the Davis model to quantify evoked oxidative metabolism (CMRO2).
• Analysis of calibration parameter (M) and CMRO2 changes across cortical depth.

Main Results:

• Average M was (11±2)% and average CMRO2 change was (30±7)% during finger tapping.
• Distinct variation patterns of M and CMRO2 were observed across cortical depths.
• An uncoupling between BOLD signal and metabolic changes was found across cortical depth.
• Tight coupling between CMRO2 and cerebral blood volume (CBV) was conserved across cortical layers.

Conclusions:

• The Davis model provides lamina-dependent metabolic estimates free from large draining vein contamination.
• This method offers high consistency and reproducibility for laminar fMRI studies.
• The Davis model advances the accurate investigation of cortical layer-specific neural activity.