Dear SPM experts,
I have been analyzed intracracial EEG data using the DCM-IR (induced responses)
and I have a question concerning the interpretation of coupling matrix (A or B).
When the coupling parameters of DCM-IR is negative, we can interpret that
the suppression occurs in the frequency profile. (e.g. Chen et al.,
Neuroimage 2009
reported the suppressive cross-frequency effects from Gamma to Alpha
band in Fig.6.)
However, the time course of the rescaled time-frequency band shows
the positive and negative value relative to the baseline power.
So, the effect of the coupling parameters on TF map can change
depending on the sign of the original time-frequency profile.
My question is that, for example, when we obtain the negative
parameters in the cross-frequency coupling
from Gamma to Alpha band, can we report the increased gamma band
relative to pre-stimulus baseline
at a certain latency time suppresses alpha band and the decreased
gamma band at another latency time
facilitates alpha band ?
Thanks in advance.
Takanori Kochiyama.
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Takanori Kochiyama, Ph.D.
Primate Research Institute, Kyoto University
North Research Building 406,
Kitashirakawa Oiwakecho, Sakyo-ku, Kyoto 606-8502 Japan
E-mail: [log in to unmask]
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