Fig 1.
Reduced motor evoked potentials induced by transcranial magnetic stimulation in Thy1-ChR2 transgenic mice.
A. Representative traces showing bilateral TMS-evoked motor evoked potentials (MEPs) in a wild type C57 Black mouse (WT; black) and a Thy1-ChR2 transgenic mouse (blue). The black arrows indicate times of transcranial magnetic stimulation (TMS). B-D. The amplitudes of bilateral TMS-evoked MEPs were dramatically decreased in the ChR2 mice compared with WT mice (B); the latencies of bilateral TMS-evoked MEPs were significantly increased in the ChR2 mice (C), and the percentage of mice in which MEPs were induced by TMS was greatly reduced in the ChR2 mice (D) (***: p<0.001, Student t-test).
Fig 2.
Reduced MEPs evoked by transcranial electrical stimulation in Thy1-ChR2 transgenic mice.
A. Representative traces showing electrically evoked motor evoked potentials (MEPs) in a wild type C57 Black mouse (WT). The asterisk indicates a response evoked with an electrical pulse at the threshold level (4 mA). B. The threshold for electrically evoking MEPs was significantly higher in Thy1-ChR2 mice than in WT mice (**: p < 0.01, n = 8–9 mice in each group). C. Representative traces showing similar latency, amplitudes, and waveform of maximally evoked MEPs in WT (black) and ChR2 (blue) mice. The arrows indicate times of electrical stimulation. D-E. The amplitudes (D) and latency (E) of MEPs evoked at maximal electrical stimulation were similar between the WT and Thy1-ChR2 mice (p > 0.05).
Fig 3.
No significant change in MEPs induced by electrical stimulation of motor cortex in ChR2 transgenic mice.
A. Representative traces showing similar long-latency motor evoked potentials (MEPs) in wild type (WT; black) and ChR2 (blue) mice. B-C. There were no significant differences in stimulating thresholds (B) and time to peak amplitude of MEP (C) between WT and ChR2 mice.
Fig 4.
Similar intrinsic properties of layer V pyramidal neurons in WT and Thy1-ChR2 mice.
A. Representative traces of action potential (AP) firing of layer V pyramidal neurons of wild type (WT; black) and ChR2 (blue) mice in response to current injections. B. Similar I-F slope in ChR2 mice: Spike frequencies to step current injections in ChR2 mice were similar to those of the WT mice (p > 0.05, one-way ANOVA). C-D. AP thresholds (C) and input resistances were similar between WT and ChR2 mice.
Table 1.
Electrophysiological properties of membrane and action potential.
Fig 5.
No significant change in motor function in Thy1-ChR2 transgenic mice.
A. Basso Mouse Scale (BMS) locomotor scores were not different between wild type (WT) and ChR2 transgenic mice. B. Grid-walking test showed no significant differences in paw drop ratios of both left and right hindlimbs between WT and ChR2 mice. C-D. Rotarod test showed that there were no significant differences in the latency to fall at the speeds of 18 rpm (C) and 30 rpm (D) between WT and ChR2 mice.