Voxel-Wise Linearity Analysis of Increments and Decrements in BOLD Responses in Human Visual Cortex Using a Contrast Adaptation Paradigm.

Yun Lin,Pei Sun,Justin L Gardner,Xi Zhou,Yuji Naya

doi:10.3389/fnhum.2021.541314

Abstract

The linearity of BOLD responses is a fundamental presumption in most analysis procedures for BOLD fMRI studies. Previous studies have examined the linearity of BOLD signal increments, but less is known about the linearity of BOLD signal decrements. The present study assessed the linearity of both BOLD signal increments and decrements in the human primary visual cortex using a contrast adaptation paradigm. Results showed that both BOLD signal increments and decrements kept linearity to long stimuli (e.g., 3 s, 6 s), yet, deviated from linearity to transient stimuli (e.g., 1 s). Furthermore, a voxel-wise analysis showed that the deviation patterns were different for BOLD signal increments and decrements: while the BOLD signal increments demonstrated a consistent overestimation pattern, the patterns for BOLD signal decrements varied from overestimation to underestimation. Our results suggested that corrections to deviations from linearity of transient responses should consider the different effects of BOLD signal increments and decrements.

Highlights

Among the different types of brain imaging techniques, blood oxygen level dependent (BOLD) functional magnetic resonance imaging is known as a powerful and non-invasive technique for the detection of brain neural activities (Deyoe et al, 1994; Logothetis et al, 2001; Logothetis and Wandell, 2004)
To combine the functional magnetic resonance imaging (fMRI) data from three runs, the mean BOLD signal level for each run was calculated after removing the first 90 volumes, and the percent signal changes were calculated relative to the mean BOLD signal level
Results suggested that linearity was violated for the BOLD signal increments and decrements to the transient visual stimuli, and different deviation patterns were found across BOLD response types, stimulus durations, and voxels

Summary

Introduction

Among the different types of brain imaging techniques, blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) is known as a powerful and non-invasive technique for the detection of brain neural activities (Deyoe et al, 1994; Logothetis et al, 2001; Logothetis and Wandell, 2004). With BOLD fMRI becoming one of the most common brain mapping tools since 1992 (Bandettini et al, 1992; Blamire et al, 1992; Kwong et al, 1992; Ogawa et al, 1992), different data analysis procedures have been developed to better study the observations that are obtained by this imaging technique, with most of them presuming a temporal linear relationship between the stimuli and BOLD responses (Friston et al, 1994a,b; Poline and Brett, 2012) The present study focuses on the investigation of the superposition property of BOLD signal decrements, shedding light on the data analysis procedures for the BOLD signal decrements

Methods

Results

Conclusion