These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Characterizing the relationship between BOLD contrast and regional cerebral blood flow measurements by varying the stimulus presentation rate.
    Author: Rees G, Howseman A, Josephs O, Frith CD, Friston KJ, Frackowiak RS, Turner R.
    Journal: Neuroimage; 1997 Nov; 6(4):270-8. PubMed ID: 9417970.
    Abstract:
    This paper investigates the relationship between the blood oxygenation level dependent (BOLD) contrast effect and regional cerebral blood flow using the techniques of functional MRI (fMRI) and positron emission tomography (PET). A passive listening paradigm with parametric variation in word presentation rate was used to investigate the rate dependency of both BOLD contrast fMRI and H215O PET in primary auditory cortex. We attempted to equate the stimulus presentation acoustic environments by using prerecorded echoplanar imaging sounds during the PET paradigm. We show that there is a linear relationship between word presentation rate and cerebral blood flow in primary auditory cortex, whereas the relationship between BOLD contrast and stimulus presentation rate is highly nonlinear, showing a saturable effect. Two possible explanations for our results are discussed: a nonlinearity in the relationship between BOLD contrast and deoxyhemoglobin concentration or a nonlinear rate dependency of the physiological mechanisms causing changes in deoxyhemoglobin concentration.
    [Abstract] [Full Text] [Related] [New Search]