کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
3047593 1185060 2008 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Differentiating phase shift and delay in narrow band coherent signals
موضوعات مرتبط
علوم زیستی و بیوفناوری علم عصب شناسی عصب شناسی
پیش نمایش صفحه اول مقاله
Differentiating phase shift and delay in narrow band coherent signals
چکیده انگلیسی

ObjectiveDifferentiating between a fixed activation pattern (phase shift) and conduction time (time delay) in rhythmic signals has important physiological implications but is methodologically difficult.MethodsDelay was estimated by the maximising coherence method and phase spectra calculated between (i) a narrow band-pass filtered AR2 process and its delayed copy for different phase shifts, (ii) the surface EMGs from two antagonistic forearm muscles with reciprocal alternating activity, and (iii) EEG and EMG data from 11 recordings in five Parkinsonian tremor patients.ResultsEstimated delays between the versions of the AR2 process resembled the real delay and were not significantly biased by the phase-shifts. The reciprocal alternating pattern of muscle activation was shown to be a pure phase-shift without any time delay. The phase between tremor-coherent cortical electrodes and EMG showed opposite signs and differed by 3π/4 − π between the antagonistic muscles. Bidirectional delays between contralateral cortex and EMG did not differ between the antagonists and were in keeping with fast corticospinal transmission and feedback to the cortex for both muscles.ConclusionsPhase shifts and delays reflect different mechanisms in tremor related oscillatory interactions.SignificanceThe maximising coherence method can differentiate between them.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Clinical Neurophysiology - Volume 119, Issue 5, May 2008, Pages 1062–1070
نویسندگان
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