Jozien Goense1, Hellmut Merkle2,
Nikos Logothetis1,3
1Department of Physiology of Cognitive
Processes, Max-Planck Institute for Biological Cybernetics, Tuebingen,
Germany; 2Laboratory of Functional and Molecular Imaging, NINDS,
NIH, Bethesda, MD, United States; 3Division of Imaging Science and
Biomedical Engineering, University of Manchester, Manchester, United Kingdom
The
BOLD signal is a weak signal, and hence if no BOLD signal is found in an area
this does not necessarily mean there is no neural activity in that area.
Signal dropout, artifacts, instability, physiological noise, RF-coil
inhomogeneity etc. can all reduce the SNR locally leading to decreased
detectability of the BOLD signal Here we illustrate that calculation of the
spatial distribution of the detection for a given set of experimental conditions
allows us to estimate the confidence by which absence of an fMRI signal can
be interpreted as an absence of neural activity.
Keywords