Karen Julia Mullinger1, Claire M. Stevenson1,
Susan T. Francis1, Richard W. Bowtell1
1Sir Peter Mansfield Magnetic Resonance
Center, School of Physics and Astronomy, University of Nottingham,
Nottingham, Nottinghamshire, United Kingdom
Haemodynamic
and electrical responses may show unpredictable variations over repeated
trials due to habituation or modulation of attention. Here we investigate if these effects can be
measured in the somatosensory cortex using simultaneous EEG/fMRI. An average of 10 trials was required to
ensure detection of the evoked response.
With this averaging, attenuation of the BOLD response was observed
suggesting habituation, but the evoked response did not reflect this. Variance of the evoked response was
assessed and found to be similar to that of the baseline prohibiting the
determination of whether the evoked response attenuates as observed for BOLD.