Antagonistic but Not Symmetric Regulation of Primary Motor Cortex by Basal Ganglia Direct and Indirect Pathways
基底神经节直接通路和间接通路对初级运动皮层的拮抗性而非对称性调节

Motor cortex, basal ganglia (BG), and thalamus are arranged in a recurrent loop whose activity guides motor actions. In the dominant model of the function of the BG and their role in Parkinson’s disease, direct (dSPNs) and indirect (iSPNs) striatal projection neurons are proposed to oppositely modulate cortical activity via BG outputs to thalamus. Here, we test this model by determining how striatal activity modulates primary motor cortex in awake head-restrained mice. We find that, within 200 ms , dSPN and iSPN activation exert robust and opposite effects on the majority of cortical neurons. However, these effects are heterogeneous, with certain cortical neurons biphasically modulated by iSPN stimulation. Moreover, these striatal effects are diminished when the animal performs a motor action. Thus, the effects of dSPN and iSPN activity on cortex are at times antagonistic, consistent with classic models, whereas in other contexts these effects can be occluded or coactive.
运动皮层、基底神经节 (BG) 和丘脑构成一个循环回路，其活动指导运动行为。在基底神经节功能及其在帕金森病中的作用的主导模型中，直接通路 (dSPNs) 和间接通路 (iSPNs) 的纹状体投射神经元被认为通过基底神经节输出到丘脑来相反地调节皮质活动。在这里，我们通过确定纹状体活动如何在清醒的头固定小鼠中调节初级运动皮层来测试该模型。我们发现，在 200 毫秒内，dSPN 和 iSPN 的激活对大多数皮质神经元产生强烈且相反的影响。然而，这些影响是异质性的，某些皮质神经元受到 iSPN 刺激的双相调节。此外，当动物执行运动行为时，这些纹状体效应会减弱。因此，dSPN 和 iSPN 活动对皮质的影响有时是拮抗的，这与经典模型一致，而在其他情况下，这些影响可能会被掩盖或共同激活。

The basal ganglia (BG) are an interconnected group of subcortical nuclei that regulate movements and whose dysfunction contributes to multiple disorders (Albin et al., 1989; DeLong, 1990; Graybiel et al., 1994). Classical models of the motor BG describe a looped architecture in which motor cortex sends glutamatergic inputs to the striatum, the input stage of the BG, and is in turn influenced by the BG through inhibitory output to thalamus. The two output pathways of the striatum, comprised of direct (dSPNs) and indirect (iSPNs) pathway striatal projection neurons, are thought to exert push-pull control over primary motor cortex (M1) by either increasing or reducing its activity to promote or suppress motor action. The anatomical substrates that mediate these antagonistic effects are thought to be the divergent GABAergic striatonigral and striatopallidal projections of dSPNs and iSPNs, respectively (Alexander and Crutcher, 1990; Deniau and Chevalier, 1985). The striatonigral projection inhibits the substantia nigra pars reticulata (SNr), whereas the striatopallidal projection inhibits the external segment of the globus pallidus (GPe). The GPe in turn inhibits
基底神经节 (BG) 是一个相互连接的皮质下核团，调节运动，其功能障碍会导致多种疾病 (Albin 等，1989；DeLong，1990；Graybiel 等，1994)。运动 BG 的经典模型描述了一种环状结构，其中运动皮层向纹状体（BG 的输入阶段）发送谷氨酸能输入，反过来又受到 BG 通过对丘脑的抑制性输出的影响。纹状体的两个输出通路，由直接 (dSPNs) 和间接 (iSPNs) 通路纹状体投射神经元组成，被认为通过增加或减少其活动来促进或抑制运动来对初级运动皮层 (M1) 施加推拉控制。被认为介导这些拮抗作用的解剖学基础是 dSPNs 和 iSPNs 分别发出的发散性 GABA 能纹状体黑质和纹状体苍白球投射 (Alexander 和 Crutcher，1990；Deniau 和 Chevalier，1985)。纹状体黑质投射抑制黑质致密部网状部 (SNr)，而纹状体苍白球投射抑制苍白球外段 (GPe)。GPe 反过来抑制

SNr, making the net effect of iSPN activity to SNr excitatory (Gerfen et al., 1990). SNr provides GABAergic innervation of the ventrolateral thalamus (VL), which closes the loop via glutamatergic projections to cortex. This anatomical model explains the contributions of the BG to motor control, as well as the mechanisms by which symptoms of Parkinson’s disease are ameliorated by deep brain stimulation (Da Cunha et al., 2015) and is supported by lesion and pharmacological (Mink, 1996) as well as genetic and optogenetic (Bateup et al., 2010; Kravitz et al., 2010) studies.
SNr，使 iSPN 活动对 SNr 产生兴奋性净效应（Gerfen 等，1990）。SNr 赋予腹外侧丘脑 (VL) GABA 能神经支配，该支配通过投射到皮质的谷氨酸能通路闭合回路。该解剖模型解释了 BG 对运动控制的贡献，以及深部脑刺激如何改善帕金森病症状的机制（Da Cunha 等，2015），并得到了损伤和药理学研究（Mink，1996）以及遗传学和光遗传学研究（Bateup 等，2010；Kravitz 等，2010）的支持。

Nevertheless, many features of this model have not been tested and are difficult to predict. The magnitude, kinetics, and homogeneity of a cortical response depend on many factors, including the fraction of cortical activity that is driven by stria-tum-regulated thalamic inputs, the degree of tonic inhibition in the thalamus from ongoing SNr activity, and the speed with which cascading inhibitory networks disinhibit the thalamus and cortex. Many of these anatomical and functional parameters have not been determined, leaving fundamental aspects of the classic model of BG/cortical interactions untested and unconstrained.
然而，该模型的许多特征尚未经过测试，难以预测。皮质反应的幅度、动力学和均匀性取决于许多因素，包括皮质活动中由纹状体调节的丘脑输入所驱动的比例，丘脑中来自持续 SNr 活动的强直性抑制程度，以及级联抑制网络去抑制丘脑和皮质的速度。许多这些解剖学和功能参数尚未确定，使得经典的 BG/皮质相互作用模型的基本方面未经检验且不受约束。

Here we examine the control of cortex by striatum in awake, head-restrained mice. The effects of optogenetic manipulations of dSPN or iSPN firing on primary motor cortex were evaluated as mice performed a simple cued lever-pressing task for water reward. At the level of populations of cortical neurons, our results generally support classic models of BG-cortical interactions. However, individual neurons can have heterogeneous, asymmetric, and context-dependent responses to manipulation of striatal activity, highlighting the existence of BG pathways by which dSPNs and iSPNs can have selective and non-antagonist effects on distinct cortical neurons.
我们在此研究清醒、头部固定的老鼠中纹状体对皮质的控制。评估了在老鼠执行简单的线索性杠杆按压任务以获取水奖励时，对 dSPN 或 iSPN 放电进行光遗传学操作对初级运动皮质的影响。在皮质神经元群体水平上，我们的结果总体上支持经典的 BG-皮质相互作用模型。然而，单个神经元对纹状体活动操纵的反应可能是异质的、不对称的和依赖于环境的，这突出了 BG 通路的存在，通过这些通路，dSPNs 和 iSPNs 可以对不同的皮质神经元产生选择性和非拮抗作用。

Studies of interactions between BG and cortex require analysis in awake animals as striatal activity is minimal under anesthesia (Mahon et al., 2006; Spampinato et al., 1986). Therefore, mice expressing Cre recombinase in either iSPNs (Adora-2A-Cre) or dSPNs (Drd1a-Cre) (Figures 1 and S1A) and injected with Credependent adeno-associated virus (AAV) encoding ChR2 were habituated to head restraint. Mice were trained on a cued lever-pressing task in which a motor action carried out shortly after an auditory cue led to a water reward (Figures 1A, S1B, and S1C; see Supplemental Experimental Procedures). In trained
BG 和皮层相互作用的研究需要在清醒动物中进行分析，因为麻醉状态下纹状体活动最小（Mahon 等，2006；Spampinato 等，1986）。因此，在 iSPNs（Adora-2A-Cre）或 dSPNs（Drd1a-Cre）中表达 Cre 重组酶的小鼠（图 1 和 S1A）并注射了编码 ChR2 的 Cre 依赖性腺相关病毒 (AAV) 后，使其适应头部约束。小鼠接受了条件性杠杆按压任务的训练，其中在听觉信号后不久执行的运动行为会导致水奖励（图 1A、S1B 和 S1C；见补充实验程序）。在训练

Figure 1. Channelrhodopsin-Mediated Modulation of Striatum
图 1. 通道视紫红质介导的纹状体调节
(A) Schematic of task design (top). A trial starts with an uncued 1.5- to 3-s withhold period (red). If the animal does not press the lever during this time, a $10-\mathrm{kHz}$$10-\mathrm{kHz}$10-kHz10-\mathrm{kHz} tone is presented (vertical black line), which is followed by 1.5 -s potential reward period (green). If the animal presses and releases the lever during this period, it receives a water reward (blue line). This is followed by inter-trial delay ( $3-8\mathrm{s}$$3-8\mathrm{s}$3-8s3-8 \mathrm{~s} ) during which presses are neither rewarded nor punished. (Bottom) Lever press rates during recording sessions ( $n=20$$n=20$n=20n=20, eight mice) for periods of 1.5 s without lever presses $(t=-1.5$$(t=-1.5$(t=-1.5(t=-1.5 to 0 s$)$$)$)) that ended ( $t=0$$t=0$t=0t=0 ) with (black) or without (orange) the cue. (Inset) Finer timescale analysis ( $10-\mathrm{ms}$$10-\mathrm{ms}$10-ms10-\mathrm{ms} bins) shows that press rates diverge across conditions after $\sim 50\mathrm{ms}$$\sim 50\mathrm{ms}$∼50ms\sim 50 \mathrm{~ms}.
(A) 任务设计示意图（顶部）。试验以 1.5 至 3 秒的无提示抑制期（红色）开始。如果动物在此期间不按杠杆，则呈现 $10-\mathrm{kHz}$$10-\mathrm{kHz}$10-kHz10-\mathrm{kHz} 音调（垂直黑线），随后是 1.5 秒的潜在奖励期（绿色）。如果动物在此期间按下并释放杠杆，则会获得水奖励（蓝线）。之后是试次间延迟（ $3-8\mathrm{s}$$3-8\mathrm{s}$3-8s3-8 \mathrm{~s} ），在此期间按下杠杆既不奖励也不惩罚。(底部) 记录期间（ $n=20$$n=20$n=20n=20 ，八只小鼠）杠杆按压率，持续时间为 1.5 秒，无杠杆按压 $(t=-1.5$$(t=-1.5$(t=-1.5(t=-1.5 至 0 秒 $)$$)$)) ，以（ $t=0$$t=0$t=0t=0 ）有（黑色）或无（橙色）提示结束。（插图）更精细的时间尺度分析（ $10-\mathrm{ms}$$10-\mathrm{ms}$10-ms10-\mathrm{ms} 个区间）显示，在 $\sim 50\mathrm{ms}$$\sim 50\mathrm{ms}$∼50ms\sim 50 \mathrm{~ms} 之后，不同条件下的按压率出现差异。
(B) Sagittal slices showing ChR2 expression (red) following injection of Cre-dependent ChR2-mCherry encoding AAV in mice that express Cre in iSPNs or dSPNs. © (Top/middle) Example raster plots and histograms of activity of highly modulated units from iSPN-ChR2 (left) and dSPN-ChR2 (right) animals. Blue $=473-\mathrm{nm}$$=473-\mathrm{nm}$=473-nm=473-\mathrm{nm} illumination. (Bottom) Histogram of IchR2 for recorded units. Red indicates statistically significantly modulated units ( $t$$t$tt test, p $<0.05$$<0.05$< 0.05<0.05, iSPN 35 of 76 units; dSPN 57 of 98 ). (D) Latency to modulation of striatal units. I ChR2 $>0.75$$>0.75$> 0.75>0.75 : iSPN $n=7$$n=7$n=7n=7 units; dSPN $n=8$$n=8$n=8n=8; $I_{\text{ChR2}}0.1-0.5$$I_{\text{ChR2 }}0.1-0.5$I_("ChR2 ")0.1-0.5I_{\text {ChR2 }} 0.1-0.5 : iSPN $106\pm 44\mathrm{ms},\mathrm{n}=8$$106\pm 44\mathrm{ms},\mathrm{n}=8$106+-44ms,n=8106 \pm 44 \mathrm{~ms}, \mathrm{n}=8; dSPN $125\pm 16\mathrm{ms},\mathrm{n}=49$$125\pm 16\mathrm{ms},\mathrm{n}=49$125+-16ms,n=49125 \pm 16 \mathrm{~ms}, \mathrm{n}=49; $I_{\text{ChR2}}<-0.1$$I_{\text{ChR2 }}<-0.1$I_("ChR2 ") < -0.1I_{\text {ChR2 }}<-0.1 : iSPN $144\pm 48\mathrm{ms},\mathrm{n}=9$$144\pm 48\mathrm{ms},\mathrm{n}=9$144+-48ms,n=9144 \pm 48 \mathrm{~ms}, \mathrm{n}=9; dSPN $250\pm 58\mathrm{ms},\mathrm{n}=3$$250\pm 58\mathrm{ms},\mathrm{n}=3$250+-58ms,n=3250 \pm 58 \mathrm{~ms}, \mathrm{n}=3. All units with latency $<500\mathrm{ms}$$<500\mathrm{ms}$< 500ms<500 \mathrm{~ms} are included. Error bars are $\pm$$\pm$+-\pm SEM.
(B) 矢状切面显示注射依赖于 Cre 的 ChR2-mCherry 编码 AAV 后 ChR2 表达（红色），该 AAV 注射到 iSPNs 或 dSPNs 中表达 Cre 的小鼠体内。© (顶部/中间) iSPN-ChR2 (左) 和 dSPN-ChR2 (右) 动物中高调控单元活动示例栅格图和直方图。蓝色 $=473-\mathrm{nm}$$=473-\mathrm{nm}$=473-nm=473-\mathrm{nm} 光照。(底部) 记录单元的 I_ChR2直方图。红色表示统计学上显著调控的单元 ( $t$$t$tt 检验，p $<0.05$$<0.05$< 0.05<0.05 ，iSPN 76 个单元中的 35 个；dSPN 98 个单元中的 57 个)。(D) 纹状体单元调控的潜伏期。I_ChR2 $>0.75$$>0.75$> 0.75>0.75 ：iSPN $n=7$$n=7$n=7n=7 个单元；dSPN $n=8$$n=8$n=8n=8 ； $I_{\text{ChR2}}0.1-0.5$$I_{\text{ChR2 }}0.1-0.5$I_("ChR2 ")0.1-0.5I_{\text {ChR2 }} 0.1-0.5 ：iSPN $106\pm 44\mathrm{ms},\mathrm{n}=8$$106\pm 44\mathrm{ms},\mathrm{n}=8$106+-44ms,n=8106 \pm 44 \mathrm{~ms}, \mathrm{n}=8 ；dSPN $125\pm 16\mathrm{ms},\mathrm{n}=49$$125\pm 16\mathrm{ms},\mathrm{n}=49$125+-16ms,n=49125 \pm 16 \mathrm{~ms}, \mathrm{n}=49 ； $I_{\text{ChR2}}<-0.1$$I_{\text{ChR2 }}<-0.1$I_("ChR2 ") < -0.1I_{\text {ChR2 }}<-0.1 ：iSPN $144\pm 48\mathrm{ms},\mathrm{n}=9$$144\pm 48\mathrm{ms},\mathrm{n}=9$144+-48ms,n=9144 \pm 48 \mathrm{~ms}, \mathrm{n}=9 ；dSPN $250\pm 58\mathrm{ms},\mathrm{n}=3$$250\pm 58\mathrm{ms},\mathrm{n}=3$250+-58ms,n=3250 \pm 58 \mathrm{~ms}, \mathrm{n}=3 。所有潜伏期 $<500\mathrm{ms}$$<500\mathrm{ms}$< 500ms<500 \mathrm{~ms} 的单元均包括在内。误差条为 $\pm$$\pm$+-\pm SEM。
(E) ChR2-induced changes in behavior for iSPN-ChR2 ( $n=7$$n=7$n=7n=7 ), dSPN-ChR2 $(n=8)$$(n=8)$(n=8)(n=8), or ChR2-negative control ( $n=3$$n=3$n=3n=3 ) mice. Relative lever press rates (left) and durations (right) are the ratios of each metric with and without stimulation ( ${}^{\ast }\mathrm{p}<0.05$${}^{\ast }\mathrm{p}<0.05$^(**)p < 0.05{ }^{*} \mathrm{p}<0.05, Wilcoxon signed rank).
(E) ChR2 诱导的 iSPN-ChR2 ( $n=7$$n=7$n=7n=7 )、dSPN-ChR2 ( $(n=8)$$(n=8)$(n=8)(n=8) )或 ChR2 阴性对照 ( $n=3$$n=3$n=3n=3 )小鼠行为变化。相对杠杆按压率（左）和持续时间（右）是刺激前后每个指标的比率 ( ${}^{\ast }\mathrm{p}<0.05$${}^{\ast }\mathrm{p}<0.05$^(**)p < 0.05{ }^{*} \mathrm{p}<0.05 ，Wilcoxon 符号秩和检验)。
mice, lever presses occurred preferentially after tones with press rate 2.75 -fold $\pm 0.53$$\pm 0.53$+-0.53\pm 0.53-fold higher in the reward period compared with similarly structured uncued periods (Figure 1A; p < 0.01 Wilcoxon signed rank).
小鼠在奖励期间，杠杆按压更倾向于在音调后发生，按压速率比结构相似的无提示期间高 2.75 倍 $\pm 0.53$$\pm 0.53$+-0.53\pm 0.53 倍 (图 1A；p < 0.01，Wilcoxon 符号秩检验)。

Mice that reached behavioral proficiency were implanted with a fiber optic, and analysis of the effects of ChR2 stimulation was examined on a recording rig. The stimulating laser was on or off continuously for each trial and switched to the opposite state such that transitions occurred in intervals well separated (3-8 $\mathrm{s})$$\mathrm{s})$s)\mathrm{s}) from the reward and at least 1.5 s before a tone. Multielectrode
达到行为熟练程度的小鼠植入光纤，并在记录装置上分析 ChR2 刺激的效果。每次试验中刺激激光器持续开启或关闭，并切换到相反的状态，使得转换发生在间隔良好的时间段（距奖励 3-8 $\mathrm{s})$$\mathrm{s})$s)\mathrm{s}) ，且至少在音调前 1.5 秒）。多电极
array recordings in striatum confirmed effective optogenetic manipulation (Figure 1C). The degree of modulation of each unit was calculated as follows:
纹状体阵列记录证实了有效的光遗传操作（图 1C）。每个单元的调制程度计算如下：

(Equation 1)  （公式 1）
with $f_{\text{on}}$$f_{\text{on }}$f_("on ")f_{\text {on }} and $f_{\text{off}}$$f_{\text{off }}$f_("off ")f_{\text {off }} corresponding to average firing rates with the laser on and off, respectively, during a $1.5-\mathrm{s}$$1.5-\mathrm{s}$1.5-s1.5-\mathrm{s} period prior to the delivery of the cue where the animal does not press the lever.
其中 $f_{\text{on}}$$f_{\text{on }}$f_("on ")f_{\text {on }} 和 $f_{\text{off}}$$f_{\text{off }}$f_("off ")f_{\text {off }} 分别对应于激光开启和关闭期间动物在提示音发出前的 $1.5-\mathrm{s}$$1.5-\mathrm{s}$1.5-s1.5-\mathrm{s} 时间段内平均放电率，在此期间动物不按杠杆。

Figure 2. Antagonistic Modulation of Primary Motor Cortex by Direct and Indirect Pathways
图 2. 直接通路和间接通路对初级运动皮层的拮抗调制
(A) Activation of iSPNs decreases (left) and dSPNs increases (right) firing rates in motor cortex. Example raster plots (top) and histograms (bottom) of activity of cortical units prior to and during optogenetic stimulation of striatum (blue).
(A) iSPNs 激活减少（左）和 dSPNs 激活增加（右）运动皮层放电率。 例如，光遗传刺激纹状体（蓝色）之前和期间皮层单元活动的簇状图（顶部）和直方图（底部）。
(B) I ChR2 of cortical unit modulation with iSPN or dSPN stimulation. Red indicates statistically significantly modulated units (iSPN 136/193, 4 mice; dSPN 103/136, 4 mice; $t$$t$tt test, $p<0.05$$p<0.05$p < 0.05p<0.05 ).
(B) 皮层单元调制中 I ChR2 结合 iSPN 或 dSPN 刺激。红色表示统计学上显著调制的单元 (iSPN 136/193, 4 只小鼠；dSPN 103/136, 4 只小鼠； $t$$t$tt 检验， $p<0.05$$p<0.05$p < 0.05p<0.05 )。
© Mean firing rate of cortical neurons at the start and end of ChR2-stimulation (blue) of iSPNs (left) and dSPNs (right). Gray is $\pm$$\pm$+-\pm SEM.
© ChR2 刺激 iSPNs (左) 和 dSPNs (右) 开始和结束时皮质神经元的平均放电频率（蓝色）。灰色为 $\pm$$\pm$+-\pm SEM。
(D) Pseudo-colored plots of firing of all units normalized to rates in baseline period and ordered by $I_{\text{ChR2}}$$I_{\text{ChR2 }}$I_("ChR2 ")I_{\text {ChR2 }} (low to high). Blue/purple and yellow/ red represent relatively decreased and increased rates.
(D) 所有单元放电情况的伪彩色图，已归一化为基线期内的速率，并按 $I_{\text{ChR2}}$$I_{\text{ChR2 }}$I_("ChR2 ")I_{\text {ChR2 }} (低到高) 排序。蓝色/紫色和黄色/红色分别代表相对降低和增加的速率。

Furthermore, stimulation of iSPNs and dSPNs bidirectionally modulated lever press frequency (ratio of frequency with light on versus off: iSPN $0.45\pm 0.09,n=$$0.45\pm 0.09,n=$0.45+-0.09,n=0.45 \pm 0.09, n= 7 mice, $\mathrm{p}<0.05$$\mathrm{p}<0.05$p < 0.05\mathrm{p}<0.05; dSPN $3.1\pm 0.66,n=8$$3.1\pm 0.66,n=8$3.1+-0.66,n=83.1 \pm 0.66, n=8, $p<0.05$$p<0.05$p < 0.05p<0.05; Wilcoxon signed rank), whereas control mice showed no significant modulation ( $1.1\pm 0.06,n=3$$1.1\pm 0.06,n=3$1.1+-0.06,n=31.1 \pm 0.06, n=3 ). The duration of lever presses increased with activation of iSPNs but not dSPNs (iSPN: $6.3\pm 2.9-$$6.3\pm 2.9-$6.3+-2.9-6.3 \pm 2.9- fold change, $p<0.05$$p<0.05$p < 0.05p<0.05; dSPN: $1.2\pm 0.27$$1.2\pm 0.27$1.2+-0.271.2 \pm 0.27, not significant; control: $0.93\pm 0.07$$0.93\pm 0.07$0.93+-0.070.93 \pm 0.07, notsignificant; Wilcoxon signed rank; Figure 1E).
此外，iSPNs 和 dSPNs 的刺激双向调节杠杆按压频率（光照下与光照关闭时的频率比：iSPN $0.45\pm 0.09,n=$$0.45\pm 0.09,n=$0.45+-0.09,n=0.45 \pm 0.09, n= 7 只小鼠， $\mathrm{p}<0.05$$\mathrm{p}<0.05$p < 0.05\mathrm{p}<0.05 ；dSPN $3.1\pm 0.66,n=8$$3.1\pm 0.66,n=8$3.1+-0.66,n=83.1 \pm 0.66, n=8 ， $p<0.05$$p<0.05$p < 0.05p<0.05 ；Wilcoxon 符号秩检验），而对照组小鼠则没有显示出显著的调节（ $1.1\pm 0.06,n=3$$1.1\pm 0.06,n=3$1.1+-0.06,n=31.1 \pm 0.06, n=3 ）。杠杆按压持续时间随着 iSPNs 的激活而增加，但 dSPNs 的激活则不然（iSPN： $6.3\pm 2.9-$$6.3\pm 2.9-$6.3+-2.9-6.3 \pm 2.9- 倍变化， $p<0.05$$p<0.05$p < 0.05p<0.05 ；dSPN： $1.2\pm 0.27$$1.2\pm 0.27$1.2+-0.271.2 \pm 0.27 ，无统计学意义；对照组： $0.93\pm 0.07$$0.93\pm 0.07$0.93+-0.070.93 \pm 0.07 ，无统计学意义；Wilcoxon 符号秩检验；图 1E）。

To determine the effects of striatal activity on cortex, we inserted multielec-
为了确定纹状体活动对皮质的影响，我们插入了多电极-

ChR2 stimulation modulated striatal neurons with IChR2 distributed over most of its -1 to 1 range. Optogenetic stimulation increased firing rates in $39\mathrm{\%}$$39\mathrm{\%}$39%39 \% (30/76) and $87\mathrm{\%}$$87\mathrm{\%}$87%87 \% ( $85/98$$85/98$85//9885 / 98 ) of units when activating iSPNs and dSPNs (Figure 1C), respectively, presumably through a combination of direct activation and network effects. In each condition, $\sim 10\mathrm{\%}$$\sim 10\mathrm{\%}$∼10%\sim 10 \% had IChR2 $>0.75$$>0.75$> 0.75>0.75 (iSPN experiments: seven units; dSPN: nine). These putative ChR2-expressing units had low basal firing rates and responded with short latency to light. Units with intermediate activation had higher basal firing rates and responded more slowly (Figures 1D, S1D, and S1E). Significant inhibition of SPNs was rare following activation of dSPNs (4 units) and more common following iSPN activation (27 units) (Figure 1C). Such inhibition could result from SPN to SPN GABAergic synapses as well as from longrange circuit effects (see below).
ChR2 刺激调节了纹状体神经元，其中大部分 IChR2 分布在 -1 至 1 范围内。光遗传刺激分别在激活 iSPNs 和 dSPNs 时，提高了 $39\mathrm{\%}$$39\mathrm{\%}$39%39 \% (30/76) 和 $87\mathrm{\%}$$87\mathrm{\%}$87%87 \% ( $85/98$$85/98$85//9885 / 98 ) 单位的发放率（图 1C），这可能是由于直接激活和网络效应的结合。在每种情况下， $\sim 10\mathrm{\%}$$\sim 10\mathrm{\%}$∼10%\sim 10 \% 均具有 IChR2 $>0.75$$>0.75$> 0.75>0.75 （iSPN 实验：七个单位；dSPN：九个）。这些推定的 ChR2 表达单位具有较低的基础放电率，并以短潜伏期响应光刺激。激活程度中等的神经元具有较高的基础放电率，反应更慢（图 1D、S1D 和 S1E）。激活 dSPNs 后，SPNs 的显着抑制很少见（4 个单位），而激活 iSPNs 后则更为常见（27 个单位）（图 1C）。这种抑制可能源于 SPN 至 SPN 的 GABA 能突触以及长程电路效应（见下文）。

SPN activity was modulated by the task. SPNs had high pressrelated modulation indices (I press ), calculated by comparing activity in $\pm 0.25\mathrm{s}$$\pm 0.25\mathrm{s}$+-0.25s\pm 0.25 \mathrm{~s} around a spontaneous lever press to non-press periods (iSPN experiments: I ${}_{\text{press}}=0.21\pm 0.04$${}_{\text{press }}=0.21\pm 0.04$_("press ")=0.21+-0.04{ }_{\text {press }}=0.21 \pm 0.04; dSPN: $0.26\pm 0.07$$0.26\pm 0.07$0.26+-0.070.26 \pm 0.07 ).
SPN 活性受任务调节。SPN 具有高血压相关调制指数（Ipress），通过比较自发杠杆按压周围的 $\pm 0.25\mathrm{s}$$\pm 0.25\mathrm{s}$+-0.25s\pm 0.25 \mathrm{~s} 活动与非按压期（iSPN 实验：I ${}_{\text{press}}=0.21\pm 0.04$${}_{\text{press }}=0.21\pm 0.04$_("press ")=0.21+-0.04{ }_{\text {press }}=0.21 \pm 0.04 ；dSPN： $0.26\pm 0.07$$0.26\pm 0.07$0.26+-0.070.26 \pm 0.07 ）计算得出。
trode arrays in the forepaw region of primary motor cortex (M1) contralateral to the lever and ipsilateral to the stimulated striatum (Figure S2A). The stereotaxic location of forepaw was confirmed via microstimulation in anesthetized mice (Figure S2B). Furthermore, activity in this area is necessary for the task as focal injection of GABA transiently impaired performance (Figure S2C) and is sufficient, using receiver-operator characteristic analyses, to predict the timing of spontaneous lever presses (area under curve $=0.86\pm 0.02,\mathrm{n}=8$$=0.86\pm 0.02,\mathrm{n}=8$=0.86+-0.02,n=8=0.86 \pm 0.02, \mathrm{n}=8 mice).
对侧操纵杆，同侧刺激纹状体（图 S2A）的初级运动皮层（M1）前爪区域的电极阵列。麻醉小鼠经微刺激证实前爪立体定位（图 S2B）。此外，该区域的活动对于任务是必需的，因为 GABA 局部注射暂时损害了性能（图 S2C），并且可以使用接收器工作特性分析来预测自发杠杆按压的时间（曲线下面积 $=0.86\pm 0.02,\mathrm{n}=8$$=0.86\pm 0.02,\mathrm{n}=8$=0.86+-0.02,n=8=0.86 \pm 0.02, \mathrm{n}=8 小鼠）。

Firing rates of M1 neurons were compared with and without optogenetic stimulation during a $1.5-\mathrm{s}$$1.5-\mathrm{s}$1.5-s1.5-\mathrm{s} “baseline” period that ended with the tone and lacked lever presses, auditory cues, and rewards. Consistent with classical models, activation of iSPNs reduced the firing rates of $\sim 70\mathrm{\%}$$\sim 70\mathrm{\%}$∼70%\sim 70 \% of units (Figures 2 A and S2D): of 193 units ( $\mathrm{n}=4$$\mathrm{n}=4$n=4\mathrm{n}=4 mice), the firing rates of 136 were significantly changed with 132 inhibited and 4 excited ( $p<$$p<$p <p< 0.05 , two-tailed t tests on alternating trials). The population firing rate was reduced with a modulation index (IChR2) of -0.31
M1 神经元的放电速率在 $1.5-\mathrm{s}$$1.5-\mathrm{s}$1.5-s1.5-\mathrm{s} “基线”期（以音调结束，且没有杠杆按压、听觉提示和奖励）进行光遗传学刺激和不进行光遗传学刺激时进行了比较。与经典模型一致，iSPNs 的激活降低了 $\sim 70\mathrm{\%}$$\sim 70\mathrm{\%}$∼70%\sim 70 \% 个单元的放电速率（图 2 A 和 S2D）：在 193 个单元（ $\mathrm{n}=4$$\mathrm{n}=4$n=4\mathrm{n}=4 只小鼠）中，136 个单元的放电速率发生了显著变化，其中 132 个被抑制，4 个被兴奋（ $p<$$p<$p <p< 0.05，两尾 t 检验，交替试验）。群体放电速率降低，调制指数(IChR2)为-0.31