TY - JOUR
T1 - Transcranial magnetic stimulation in the rat
AU - Luft, A. R.
AU - Kaelin-Lang, A.
AU - Hauser, T. K.
AU - Cohen, L. G.
AU - Thakor, N. V.
AU - Hanley, D. F.
N1 - Funding Information:
Acknowledgement Andreas Luft was supported by a grant from the Deutsche Forschungsgemeinschaft (Lu748/2). Leonardo Cohen's work was partially supported by a grant from the Humboldt Foundation. The work was funded by grant RO1-NS24282 from the National Institutes of Health (Hanley, Thakor). We thank Marek Mirski, Department of Anesthesiology, Johns Hopkins University, for his support.
PY - 2001
Y1 - 2001
N2 - Transcranial magnetic stimulation (TMS) allows for quantification of motor system excitability. While routinely used in humans, application in other species is rare and little is known about the characteristics of animal TMS. The unique features of TMS, i.e., predominantly interneuronal stimulation at low intensity and non-invasiveness, are particularly useful in evaluating injury and recovery in animal models. This study was conducted to characterize the rodent motor evoked potential to TMS (MEPTMS) and to develop a methodology for reproducible assessment of motor excitability in the rat. MEPTMS were compared with responses evoked by electrical stimulation of cervical spinal cord (MEPCES) and peripheral nerve. MEP were recorded by subcutaneous electrodes implanted bilaterally over the calf. Animals remained under propofol infusion and restrained in a stereotactic frame while TMS followed by CES measurements were obtained before and after 2 h of idle time. TMS was applied using a 5-cm-diameter figure-of-eight coil. MEPTMS had onset latencies of 6.7±1.3 ms. Latencies decreased with higher stimulation intensity (r=-0.7, P<0.05). Two morphologies, MEPTMS, 1 and MEPTMS, 2, were distinguished by latency of the first negative peak (N1), overall shape, and amplitude. MEPTMS, 2 were more frequent at higher stimulation intensity. While recruitment curves for MEPTMS, 1 followed a sigmoid course, no supramaximal response was reached for MEPTMS, 2. Mid-cervical spinal transection completely abolished any response to TMS. MEPCES showed a significantly shorter latency (5.29±0.24, P<0.0001). Two types of MEPCES resembling MEPTMS, 1 and 2 were observed. Neither MEPTMS nor MEPCES changed on repeat assessment after 2 h. This study demonstrates the feasibility and reproducibility of TMS in the rat. Sigmoid recruitment curves for MEPTMS, 1 suggest input-output properties similar to those of the human corticospinal system. Latency differences between CES and TMS point to a supraspinal origin of the MEPTMS. The two morphologies likely reflect different cortical or subcortical origins of MEPTMS.
AB - Transcranial magnetic stimulation (TMS) allows for quantification of motor system excitability. While routinely used in humans, application in other species is rare and little is known about the characteristics of animal TMS. The unique features of TMS, i.e., predominantly interneuronal stimulation at low intensity and non-invasiveness, are particularly useful in evaluating injury and recovery in animal models. This study was conducted to characterize the rodent motor evoked potential to TMS (MEPTMS) and to develop a methodology for reproducible assessment of motor excitability in the rat. MEPTMS were compared with responses evoked by electrical stimulation of cervical spinal cord (MEPCES) and peripheral nerve. MEP were recorded by subcutaneous electrodes implanted bilaterally over the calf. Animals remained under propofol infusion and restrained in a stereotactic frame while TMS followed by CES measurements were obtained before and after 2 h of idle time. TMS was applied using a 5-cm-diameter figure-of-eight coil. MEPTMS had onset latencies of 6.7±1.3 ms. Latencies decreased with higher stimulation intensity (r=-0.7, P<0.05). Two morphologies, MEPTMS, 1 and MEPTMS, 2, were distinguished by latency of the first negative peak (N1), overall shape, and amplitude. MEPTMS, 2 were more frequent at higher stimulation intensity. While recruitment curves for MEPTMS, 1 followed a sigmoid course, no supramaximal response was reached for MEPTMS, 2. Mid-cervical spinal transection completely abolished any response to TMS. MEPCES showed a significantly shorter latency (5.29±0.24, P<0.0001). Two types of MEPCES resembling MEPTMS, 1 and 2 were observed. Neither MEPTMS nor MEPCES changed on repeat assessment after 2 h. This study demonstrates the feasibility and reproducibility of TMS in the rat. Sigmoid recruitment curves for MEPTMS, 1 suggest input-output properties similar to those of the human corticospinal system. Latency differences between CES and TMS point to a supraspinal origin of the MEPTMS. The two morphologies likely reflect different cortical or subcortical origins of MEPTMS.
KW - Corticospinal excitability
KW - Rat
KW - Transcranial magnetic stimulation
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U2 - 10.1007/s002210100805
DO - 10.1007/s002210100805
M3 - Article
C2 - 11500803
AN - SCOPUS:0034888454
SN - 0014-4819
VL - 140
SP - 112
EP - 121
JO - Experimental Brain Research
JF - Experimental Brain Research
IS - 1
ER -