Investigation of the neurovascular coupling in positive and negative BOLD responses in human brain at 7 T

Neuroimage. 2014 Aug 15;97:349-62. doi: 10.1016/j.neuroimage.2014.04.022. Epub 2014 Apr 15.

Abstract

Decreases in stimulus-dependent blood oxygenation level dependent (BOLD) signal and their underlying neurovascular origins have recently gained considerable interest. In this study a multi-echo, BOLD-corrected vascular space occupancy (VASO) functional magnetic resonance imaging (fMRI) technique was used to investigate neurovascular responses during stimuli that elicit positive and negative BOLD responses in human brain at 7 T. Stimulus-induced BOLD, cerebral blood volume (CBV), and cerebral blood flow (CBF) changes were measured and analyzed in 'arterial' and 'venous' blood compartments in macro- and microvasculature. We found that the overall interplay of mean CBV, CBF and BOLD responses is similar for tasks inducing positive and negative BOLD responses. Some aspects of the neurovascular coupling however, such as the temporal response, cortical depth dependence, and the weighting between 'arterial' and 'venous' contributions, are significantly different for the different task conditions. Namely, while for excitatory tasks the BOLD response peaks at the cortical surface, and the CBV change is similar in cortex and pial vasculature, inhibitory tasks are associated with a maximum negative BOLD response in deeper layers, with CBV showing strong constriction of surface arteries and a faster return to baseline. The different interplays of CBV, CBF and BOLD during excitatory and inhibitory responses suggests different underlying hemodynamic mechanisms.

Keywords: 7 Tesla MRI; Cerebral blood volume; Negative BOLD response; SS-SI-VASO; Vascular compartments; Vascular space occupancy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Blood Vessels / anatomy & histology
  • Blood Vessels / ultrastructure
  • Brain / anatomy & histology*
  • Capillaries / anatomy & histology
  • Capillaries / ultrastructure
  • Cerebrovascular Circulation / physiology
  • Echo-Planar Imaging / methods*
  • Eye Movements / physiology
  • Female
  • Haplorhini
  • Humans
  • Image Processing, Computer-Assisted / methods
  • Male
  • Neurons / ultrastructure
  • Oxygen / blood*
  • Visual Cortex / anatomy & histology
  • Young Adult

Substances

  • Oxygen