Cortical depth dependence of the BOLD initial dip and poststimulus undershoot in human visual cortex at 7 Tesla. Issue 6 (2nd July 2014)

• Record Type: Journal Article
• Authors: Siero, Jeroen C.W.; Hendrikse, Jeroen; Hoogduin, Hans; Petridou, Natalia; Luijten, Peter; Donahue, Manus J.
• Is Part Of: Magnetic resonance in medicine. Volume 73:Issue 6(2015:Jun.)
• Page Start: 2283
• Page End: 2295
• Publication Date: 2014-07-02
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25349
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25349-sec-1001" sec-type="section"> <title>Purpose</title> <p>Owing to variability in vascular dynamics across cerebral cortex, blood‐oxygenation‐level‐dependent (BOLD) spatial and temporal characteristics should vary as a function of cortical‐depth. Here, the positive response, initial dip (ID), and post‐stimulus undershoot (PSU) of the BOLD response in human visual cortex are investigated as a function of cortical depth and stimulus duration at 7 Tesla (T).</p> </sec> <sec id="mrm25349-sec-2001" sec-type="section"> <title>Methods</title> <p>Gradient‐echo echo‐planar‐imaging BOLD fMRI with high spatial and temporal resolution was performed in 7 healthy volunteers and measurements of the ID, PSU, and positive BOLD response were made as a function of cortical depth and stimulus duration (0.5–8 s). Exploratory analyses were applied to understand whether functional mapping could be achieved using the ID, rather than positive, BOLD signal characteristics</p> </sec> <sec id="mrm25349-sec-4001" sec-type="section"> <title>Results</title> <p>The ID was largest in outer cortical layers, consistent with previously reported upstream propagation of vasodilation along the diving arterioles in animals. The positive BOLD signal and PSU showed different relationships across the cortical depth with respect to stimulus duration.</p> </sec> <sec id="mrm25349-sec-5001" sec-type="section"> <title>Conclusion</title> <p>The ID and PSU were measured in humans at 7T and exhibited similar trends to those recently reported in animals. Furthermore, while evidence is provided for the ID being a potentially useful feature for better understanding BOLD signal dynamics, such as laminar neurovascular coupling, functional mapping based on the ID is extremely difficult. Magn Reson Med 73:2283–2295, 2015. © 2014 Wiley Periodicals, Inc.</p> </sec> </abstract>