Open AccessFrequency dependence of the functional MRI response after electrical median nerve stimulation
Author(s) -
Kampe Knut K.W.,
Jones Richard A.,
Auer Dorothee P.
Publication year - 2000
Publication title -
human brain mapping
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.005
H-Index - 191
eISSN - 1097-0193
pISSN - 1065-9471
DOI - 10.1002/(sici)1097-0193(200002)9:2<106::aid-hbm5>3.0.co;2-y
Subject(s) - stimulation , somatosensory system , neuroscience , blood oxygen level dependent , electrophysiology , median nerve , functional magnetic resonance imaging , psychology , nuclear magnetic resonance , medicine , nuclear medicine , anatomy , physics
Localizing sensorimotor areas with high resolution functional MRI is of considerable interest for a wide range of medical applications from the preoperative planning of neurosurgical interventions to determining the course of neuroplastic reorganisation after brain lesions. We examined the effect of the stimulation frequency on the blood oxygen level dependent (BOLD) fMRI response and on perfusion weighted fMRI using electrical median nerve stimulation at 5, 15, 40, and 100 Hz. BOLD fMRI was performed using a single shot gradient echo EPI sequence to acquire 15 contiguous slices. For the qualitative flow sensitive studies, a single slice inversion recovery prepared spin echo echoplanar sequence (IR‐SE EPI) was used. In the primary sensorimotor cortex, a linear increase of the fMRI‐BOLD response, affecting both the number of activated pixels and the amplitude of the signal changes, was seen with increasing stimulation frequencies. The qualitative in‐flow sensitive studies, using the IR‐SE EPI sequence, indicate that the tissue perfusion also increases over the same range of frequencies. This implicates that larger fMRI responses can be obtained if electrical median nerve stimulation is performed at higher frequencies. The results are compared with electrophysiological data, which show a decrease of the early somatosensory evoked potentials at higher frequencies. Hum. Brain Mapping 9:106–114, 2000. © 2000 Wiley‐Liss, Inc.