title: The effect of single-pulse transcranial magnetic stimulation and peripheral nerve stimulation on complexity of EMG signal: fractal analysis.
abstract: The aim of this study was to examine whether single-pulse transcranial magnetic stimulation (spTMS) affects the pattern of corticospinal activity once voluntary drive has been restored after spTMS-induced EMG silence. We used fractal dimension (FD) to explore the 'complexity' of the electromyography (EMG) signal, and median frequency of the spectra (MDF) to examine changes in EMG spectral characteristics. FD and MDF of the raw EMG epochs immediately before were compared with those obtained from epochs after the EMG silence. Changes in FD and MDF after spTMS were examined with three levels of muscle contraction corresponding to weak (20-40%), moderate (40-60%) and strong (60-80% of maximal voluntary contraction) and three intensities of stimulation set at 10, 20 and 30% above the resting motor threshold. FD was calculated using the Higuchi fractal dimension algorithm. Finally, to discern the origin of FD changes between the CNS and muscle, we compared the effects of spTMS with the effects of peripheral nerve stimulation (PNS) on FD and MDF. The results show that spTMS induced significant decrease in both FD and MDF of EMG signal after stimulation. PNS did not have any significant effects on FD nor MDF. Changes in TMS intensity did not have any significant effect on FD or MDF after stimulation nor had the strength of muscle contraction. However, increase in contraction strength decreased FD before stimulation but only between weak and moderate contraction. The results suggest that the effects of spTMS on corticospinal activity, underlying voluntary motor output, outlast the TMS stimulus. It appears that the complexity of the EMG signal is reduced after spTMS, suggesting that TMS alters the dynamics of the ongoing corticospinal activity most likely temporarily synchronizing the neural network activity. Further studies are needed to confirm whether observed changes after TMS occur at the cortical level.
authors: Biomedical Center, Torlak Institute, Belgrade, Serbia.
authors: M
authors: M
authors: Cukic
authors: J
authors: J
authors: Oommen
authors: D
authors: D
authors: Mutavdzic
authors: N
authors: N
authors: Jorgovanovic
authors: M
authors: M
authors: Ljubisavljevic
mesh_terms: D000328:Adult; D001703:Biophysics; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D010525:Peripheral Nerves / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
references: Clin Neurophysiol. 2005 Oct;116(10):2266-301
references: 16115797
references: Electroencephalogr Clin Neurophysiol. 1994 Aug;91(2):79-92
references: 7519144
references: Electroencephalogr Clin Neurophysiol. 1991 Aug;81(4):257-62
references: 1714819
references: Yale J Biol Med. 1987 Sep-Oct;60(5):421-35
references: 3424875
references: Eur J Neurosci. 2007 Mar;25(6):1874-81
references: 17408427
references: J Appl Physiol (1985). 1991 Jun;70(6):2351-67
references: 1885430
references: Electroencephalogr Clin Neurophysiol. 1994 Apr;93(2):138-46
references: 7512920
references: Muscle Nerve. 1993 Aug;16(8):849-56
references: 8332138
references: Neuropsychologia. 1971 Mar;9(1):97-113
references: 5146491
references: Exp Brain Res. 1999 Feb;124(4):525-8
references: 10090665
references: J Appl Physiol (1985). 1990 Apr;68(4):1657-67
references: 2347805
references: Exp Brain Res. 1997 Apr;114(2):329-38
references: 9166922
references: J Electromyogr Kinesiol. 2003 Feb;13(1):83-92
references: 12488090
references: Circulation. 2000 Jun 13;101(23):E215-20
references: 10851218
references: Electroencephalogr Clin Neurophysiol. 1996 Dec;101(6):478-82
references: 9020819
references: Physiol Meas. 2002 Feb;23(1):R1-38
references: 11876246
references: Annu Int Conf IEEE Eng Med Biol Soc. 2007;2007:1961-4
references: 18002368
references: Acta Neurol Scand. 1984 Sep;70(3):169-75
references: 6507030
references: J Neurosci Methods. 1995 May;58(1-2):103-8
references: 7475215
references: J Electromyogr Kinesiol. 2005 Apr;15(2):210-21
references: 15664150
references: Comput Biol Med. 1988;18(3):145-56
references: 3396335
references: Annu Int Conf IEEE Eng Med Biol Soc. 2010;2010:4614-7
references: 21096230
references: Biol Cybern. 1997 Nov;77(5):339-50
references: 9418215
references: Crit Rev Biomed Eng. 1984;11(4):251-79
references: 6391814
references: J Physiol. 1989 May;412:449-73
references: 2489409
references: Muscle Nerve. 1994 Aug;17(8):953-4
references: 8041407
references: Arch Oral Biol. 1983;28(4):297-301
references: 6576734
references: Electroencephalogr Clin Neurophysiol. 1990 Apr;75(4):296-305
references: 1691078
references: Int J Med Inform. 1997 Jul;45(3):185-92
references: 9291030
references: J Neuroeng Rehabil. 2010 Oct 21;7:53
references: 20964863
references: Muscle Nerve. 1986 Jul-Aug;9(6):491-500
references: 3736583
references: J Appl Physiol (1985). 1992 Oct;73(4):1211-7
references: 1447061
references: J Rehabil Res Dev. 1997 Oct;34(4):415-26
references: 9323645
references: J Cogn Neurosci. 2008 Apr;20(4):734-40
references: 18052790
references: J Electromyogr Kinesiol. 2009 Oct;19(5):851-63
references: 18824375
references: Exp Physiol. 1991 Mar;76(2):159-200
references: 2059424
references: Crit Rev Biomed Eng. 1993;21(4):313-97
references: 8243094
references: Acta Neurol Scand Suppl. 1981;83:1-60
references: 6945789
references: Exp Brain Res. 1997 Dec;117(3):472-8
references: 9438716
references: Electroencephalogr Clin Neurophysiol. 1984 Sep;58(3):230-9
references: 6205855
references: J Physiol. 1997 Feb 1;498 ( Pt 3):817-23
references: 9051592
references: J Appl Physiol (1985). 2002 Nov;93(5):1753-63
references: 12381763
references: Clin Neurophysiol. 2002 Nov;113(11):1680-7
references: 12417220
references: J Neurophysiol. 2001 Oct;86(4):1983-90
references: 11600655
references: Electroencephalogr Clin Neurophysiol Suppl. 1999;51:120-6
references: 10590942