High resolution fMRI identifies distinct patterns in myogenic (breath hold) and neurogenic (visual) BOLD responses

Motivation: Vascular biases in BOLD fMRI hinder the interpretation of neural activity from hemodynamics. Correction methods based on myogenic challenges hold promise in improving specificity, but their limitations for high-resolution imaging have not been fully explored. Goal(s): To compare neurogenic and myogenic responses and quantify the extent to which biases can be removed in high-resolution imaging. Approach: We imaged visual and breathhold responses and compared the amplitude and delay of responses across V1 and across cortical depths. Results: Amplitude calibration virtually eliminated intercortical and interregional biases even in small ROIs within V1. Delay calibration was not effective, due to different delay patterns across conditions. Impact: BOLD amplitude calibration with breathhold tasks can suppress biases in BOLD estimates across cortical depths and ROIs. However, our work highlights fundamental differences in the dynamics of myogenic and neurogenic responses that precluded satisfactory calibration of hemodynamic delays.