Anisotropy in the visual cortex investigated by neuronavigated transcranial magnetic stimulation

被引:50
作者
Kammer, Thomas [1 ]
Vorwerg, Michael
Herrnberger, Baerbel
机构
[1] Univ Tubingen, Hertie Inst Clin Brain Res, Dept Cognit Neurol, Tubingen, Germany
[2] Univ Ulm, Dept Psychiat, D-89075 Ulm, Germany
关键词
phosphene thresholds; visual cortex; gyrus orientation; TMS; pulse form; current orientation;
D O I
10.1016/j.neuroimage.2007.03.001
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Responses to transcranial magnetic stimulation (TMS) of the motor cortex depend on the direction of the induced current with an optimum perpendicular to the orientation of the precentral gyrus. Little is known about anisotropy in other cortical regions. We measured phosphene thresholds in the visual cortex using a frameless neurona-vigation system. Comparing horizontal and vertical current orientation as well as monophasic and biphasic pulses in 7 subjects, we found lower thresholds with biphasic pulses and a tendency for lower thresholds with horizontal currents. When varying current directions in steps of 45 degrees centered on a hot spot over the occipital cortex, in 10 out of 12 measurements optimal current orientation ran perpendicular to the underlying gyrus (mean deviation 14.6 degrees). Optimal current orientation was determined as the orientation of the second eigenvector from the covariance matrix of the stimulation sites that had been shifted along the respective current direction by the amount of the measured threshold. Individual cortical architecture was obtained by segmentation of a 3d anatomical MR scan, with large interindividual differences among the orientations of the stimulated gyrus. As with the motor system, the optimum threshold with biphasic pulses was flipped about 1801 compared to the optimum with monophasic pulses (p <.02) throughout subjects, suggesting both similar anisotropic properties of networks in the visual and motor cortices and the existence of anisotropic behaviour in any cortical region. As a consequence, optimal TMS application should always take into account the individual orientation of the gyrus to be stimulated. (c) 2007 Elsevier Inc. All rights reserved.
引用
收藏
页码:313 / 321
页数:9
相关论文
共 44 条
[1]  
BARKER AT, 1991, ELECTROEN CLIN NEURO, P227
[2]   Enhanced excitability of the human visual cortex induced by short-term light deprivation [J].
Boroojerdi, B ;
Bushara, KO ;
Corwell, B ;
Immisch, I ;
Battaglia, F ;
Muellbacher, W ;
Cohen, LG .
CEREBRAL CORTEX, 2000, 10 (05) :529-534
[3]   OPTIMAL FOCAL TRANSCRANIAL MAGNETIC ACTIVATION OF THE HUMAN MOTOR CORTEX - EFFECTS OF COIL ORIENTATION, SHAPE OF THE INDUCED CURRENT PULSE, AND STIMULUS-INTENSITY [J].
BRASILNETO, JP ;
COHEN, LG ;
PANIZZA, M ;
NILSSON, J ;
ROTH, BJ ;
HALLETT, M .
JOURNAL OF CLINICAL NEUROPHYSIOLOGY, 1992, 9 (01) :132-136
[4]   Local lateral connectivity of inhibitory clutch cells in layer 4 of cat visual cortex (area 17) [J].
Budd, JML ;
Kisvárday, ZF .
EXPERIMENTAL BRAIN RESEARCH, 2001, 140 (02) :245-250
[5]   THE INFLUENCE OF STIMULUS TYPE ON THE MAGNETIC EXCITATION OF NERVE STRUCTURES [J].
CLAUS, D ;
MURRAY, NMF ;
SPITZER, A ;
FLUGEL, D .
ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY, 1990, 75 (04) :342-349
[6]   Transcranial magnetic stimulation - Which part of the current waveform causes the stimulation? [J].
Corthout, E ;
Barker, AT ;
Cowey, A .
EXPERIMENTAL BRAIN RESEARCH, 2001, 141 (01) :128-132
[7]   Magnetic stimulation coil and circuit design [J].
Davey, K ;
Epstein, CM .
IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, 2000, 47 (11) :1493-1499
[8]   ELECTRIC AND MAGNETIC STIMULATION OF HUMAN MOTOR CORTEX - SURFACE EMG AND SINGLE MOTOR UNIT RESPONSES [J].
DAY, BL ;
DRESSLER, D ;
DENOORDHOUT, AM ;
MARSDEN, CD ;
NAKASHIMA, K ;
ROTHWELL, JC ;
THOMPSON, PD .
JOURNAL OF PHYSIOLOGY-LONDON, 1989, 412 :449-473
[9]   The physiological basis of transcranial motor cortex stimulation in conscious humans [J].
Di Lazzaro, V ;
Oliviero, A ;
Pilato, F ;
Saturno, E ;
Dileone, M ;
Mazzone, P ;
Insola, A ;
Tonali, PA ;
Rothwell, JC .
CLINICAL NEUROPHYSIOLOGY, 2004, 115 (02) :255-266
[10]  
Di Lazzaro V, 2001, EXP BRAIN RES, V138, P268