Functional motor mapping using corticokinetic coherence in MEG
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1
ULB Hôpital Erasme, MEG Unit, Belgium
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2
ULB Hôpital Erasme, Neurosurgery Unit, Belgium
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3
Helsinki University of Technology, Brain Research Unit, Finland
Corticomuscular coherence is commonly used for functional motor-cortex mapping with magnetoencephalography (MEG). Typically, MEG and electromyographic signals are measured during isometric contraction of the muscles. In some subjects, however, corticomuscular coherence is very weak and does not allow identification of the motor cortex. Here we present a novel method, corticokinetic coherence, in which coherence is computed between cortical activity and the kinetics of voluntary movements. Six healthy right-handed subjects (range 23–40 yrs) were measured with a whole-scalp neuromagnetometer (Vectorview & Maxshield; Elekta Neuromag Oy, Helsinki, Finland). Hand movements were monitored by means of a 3-axis accelerometer attached to the index finger. Subjects were asked to make self-paced flexions/extensions of right-hand fingers at the rate of around 3 Hz for 3 min. Signals were acquired at 1 kHz with 0.1–330 Hz bandwidth. Cumulative density functions (1–195 Hz, time window 2048 ms) were computed between MEG and accelerometer signals. Cortical sources explaining the peaks of the cumulative density functions were fitted using individual spherical head models, and later superimposed on the co-registered structural magnetic resonance images. Both coherence and accelerometer spectra showed peaks around 3–4 Hz and 6–8 Hz, corresponding to the frequencies of hand movements. Coherence values (range 0.32–0.77; mean 0.55) exceeded the statistical threshold in all subjects. The sources of the coherent MEG signals were located in the left rolandic sulcus, at the hand motor area. The observed coherence between the rolandic MEG signals and hand motion kinetics followed by an accelerometer was stronger than what has been reported for cortex–muscle coherence in healthy volunteers. This novel corticokinetic coherence appears to be a promising and sensitive method for reliable and convenient MEG mapping of the human primary motor cortex.
Conference:
Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010.
Presentation Type:
Poster Presentation
Topic:
Sensory Processing and Functional Connectivity
Citation:
Bourguignon
M,
De Tiège
X,
Op De Beeck
M,
Pirotte
B,
Van Bogaert
P,
Goldman
S,
Hari
R and
Jousmäki
V
(2010). Functional motor mapping using corticokinetic coherence in MEG.
Front. Neurosci.
Conference Abstract:
Biomag 2010 - 17th International Conference on Biomagnetism .
doi: 10.3389/conf.fnins.2010.06.00146
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Received:
25 Mar 2010;
Published Online:
25 Mar 2010.
*
Correspondence:
Mathieu Bourguignon, ULB Hôpital Erasme, MEG Unit, Brussels, Belgium, mabourgu@ulb.ac.be