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Ryan S Phillips

Ian Rosner

Aryn H Gittis

Jonathan E Rubin

(2020)
The effects of chloride dynamics on substantia nigra pars reticulata responses to pallidal and striatal inputs

eLife 9:e55592.

https://doi.org/10.7554/eLife.55592
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Figures
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Additional files

14 figures, 1 table and 1 additional file

Figures

Figure 1

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Two-compartment SNr model neuron includes currents that affect ${[C l^{-}]}_{i}$ and produces appropriate dynamics.

(A) Schematic diagram of the model. (B) Tonic spiking voltage traces for both compartments, with minimum voltages labeled. (C) Model f-I curve. (D) Phase plot of the rate of change of the membrane …

Figure 2

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Simulated short-term synaptic depression and facilitation of GABAergic synapses originating from GPe neurons of the indirect pathway (A and B) and Str neurons of the direct pathway (C and D) under voltage clamp.

For the GPe and Str simulations, the left traces (A and C) show current and right panels (B and D) show the pared pulse ratios (PPR) resulting from repeated synaptic stimulation at different …

Figure 3

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Figure 4 with 1 supplement

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Tonic chloride conductance and extrusion capacity determine somatic $E_{G A B A}$ and SNr responses to simulated 40 Hz GPe stimulation.

(A) Dependence of somatic $E_{G A B A}$ on the tonic chloride conductance ( $g_{G A B A}^{T o n i c}$ ) and the potassium-chloride co-transporter KCC2 extrusion capacity ( $g_{K C C 2}$ ). (**B–E**) Examples of SNr responses to simulated indirect …

Figure 4—figure supplement 1

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Biphasic SNr response to longer simulated GPe stimulation.

(A) Dependence of somatic $E_{G A B A}$ on the tonic chloride conductance ( $g_{G A B A}^{T o n i c}$ ) and the potassium-chloride co-transporter KCC2 extrusion capacity ( $g_{K C C 2}$ ) as previously shown in Figure 4A. (B) Example of ‘Partial …

Figure 5

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Tonic chloride conductance and extrusion capacity determine dendritic $E_{G A B A}$ and SNr responses to 20 Hz Str stimulation.

(A) Dependence of somatic $E_{G A B A}$ on the tonic chloride conductance ( $g_{G A B A}^{T o n i c}$ ) and the potassium-chloride co-transporter KCC2 extrusion capacity ( $g_{K C C 2}$ ). (**B–F**) Examples of SNr responses to simulated indirect …

Figure 6 with 2 supplements

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Characterization of experimentally observed SNr responses to optogenetic stimulation of (top) GPe and (bottom) Str projections to SNr in vitro.

(A1 and B1) Examples of response types observed for 10 s stimulation of GPe or Str projections. (A2 and B2) Quantification types of SNr response to optogenetic stimulation at varying frequencies …

Figure 6—figure supplement 1

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Summary of SNr responses to optogenetic stimulation of GPe synaptic terminals.

(**A1–A4**) Raster plots of spiking sorted by the duration of the pause in spiking at the start of the stimulation period for all SNr neurons tested. (**B1–B4**) Effect of GPe stimulation on the firing rate …

Figure 6—figure supplement 2

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Summary of SNr responses to optogenetic stimulation of Str synaptic terminals.

(**A1–A4**) Raster plots of spiking sorted by the duration of the pause in spiking at the start of the stimulation period for all SNr neurons tested. (**B1–B4**) Effect of Str stimulation on the firing rate …

Figure 7

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Phase response curves (PRCs) of the model SNr neuron depend on $E_{G A B A}$ .

(A and B) Example traces illustrating the effect of a single GABAergic synaptic input on the phase of spiking in a simulated SNr neuron for hyperpolarized and depolarized $E_{G A B A}$ , respectively. (C) For …

Figure 8 with 1 supplement

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Effect of $E_{G A B A}$ on SNr synchrony in a unidirectional (left) and bidirectional (right) synaptically connected two-neuron network.

(A1-A3 and B1-B3) (Top) Identification of PRC fixed points and (Bottom) histogram of the timing of synaptic inputs in the phase of neuron 2 (Input Phase) as a function of $E_{G A B A}$ . Recall that positive …

Figure 8—figure supplement 1

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Schematic illustration of the convergence toward anti-phase locking in a birectionally coupled pair of SNr neurons.

Each vertical, deeply colored bar denotes a spike time of the cell with that color (red or blue). Following the spike time of each cell, the PRC for that cell is shown (the PRCs for $E_{G A B A} = - 60 m V$ are used). …

Figure 9

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Characterization of phase slipping oscillations in the unidirectionally connected two-neuron network.

(A) Illustration of the phase of the postsynaptic neuron at the moment when it receives each input from the presynaptic neuron (input phase) for the unidirectionally connected two neuron network as …

Figure 10 with 7 supplements

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Effects of changing the presynaptic firing rate on synchrony and postsynaptic oscillations in a feed-forward SNr neuron pair.

(A) Tuning curve for presynaptic firing rate (FR) versus applied current, $I_{A P P}$ . Dashed line indicates the baseline firing rate (10.5 Hz) with no applied current. (B) Histograms of the input phase in …

Figure 10—figure supplement 1

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The relationship between $E_{G A B A}$ and phase locking and the emergence of slow oscillations are maintained at least up to in vivo SNr firing rates.

(A) Relationship between applied current ( $I_{A P P}$ ) and the firing rate of an isolated SNr model neuron. (B) Example voltage trace for a simulated neuron firing at 33.0 Hz with $I A P P = 0.8 p A / p F$ . (C) Histograms of input …

Figure 10—figure supplement 2

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Effect of increasing noise on SNr phase relationships as a function of $E_{G A B A}$ .

(A) Dependence of CV (blue) and firing rate (red) of model SNr neuron on applied noise amplitude. (B) Example voltage trace at the highest level of added Gaussian noise ( $0.6 p A / p F$ ) and $C V = 0.1$ . (C) …

Figure 10—figure supplement 3

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Effect of synaptic delay on the relationship between $E_{G A B A}$ and presynaptic/postsynaptic phase locking.

(**A–C**) Examples of synaptic delays of increasing magnitude: 0 mS, 1.6 mS, and 8.6 mS, respectively. (D) Histogram of input phase in the postsynaptic neuron as a function of $E_{G A B A}$ and varying delay …

Figure 10—figure supplement 4

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Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between two presynaptic neurons.

(A) Characterization of the varying degrees of presynaptic synchrony defined by the parameter presynaptic offset. The presynaptic offset is the phase difference between the first (red) and second …

Figure 10—figure supplement 5

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Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between three presynaptic neurons.

(A) Characterization of the varying degrees of presynaptic synchrony defined by the parameter presynaptic offset. The presynaptic offset is the phase difference between the first (red),second …

Figure 10—figure supplement 6

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Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between four presynaptic neurons.

(A) Characterization of the varying degrees of presynaptic synchrony defined by the parameter presynaptic offset. The presynaptic offset is the phase difference between the first (red),second …

Figure 10—figure supplement 7

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Effects of varying $E_{G A B A}$ on post synaptic dynamics in the three-neuron motif where neuron 1 projects to neuron 2 and neuron 3 and neuron 2 projects to neuron 3 (motif number 10 from Song et al., 2005).

(A) Phase difference between the two presynaptic neurons (cell 1 and cell 2) as a function of $E_{G A B A}$ . (B) Firing rate and coefficient of variation (CV) in the postsynaptic neuron (cell 3) as a function …

Figure 11

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Effect of varying $E_{G A B A}$ in a network of 100 model SNr neurons with random, sparse connectivity.

(A) Histogram showing the number of neurons receiving zero to eight synaptic inputs. (B) Mean network firing rate as a function of $E_{G A B A}$ . (C) Mean network CV as a function of $E_{G A B A}$ . Shaded regions in B …

Figure 12

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Slow oscillations in the SNr seen under dopamine depleted conditions in vivo are suppressed by channelrhodopsin-2 optogenetic stimulation of GABAergic GPe terminals in the SNr.

(**A–B**) Example (A) raster plot and (B) power spectrum of a single spiking unit in SNr without (blue) and with (red) optogenetic stimulation of GPe terminals over multiple trials. (C) Frequencies of …

Figure 13 with 2 supplements

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Tonic somatic $C l^{-}$ conductance affects somatic and dendritic $E_{G A B A}$ and tunes SNr responses to Str inputs.

(A) Raster plot of spikes in the simulation of an SNr network model containing 50 simulated neurons that receive tonic somatic inhibition from GPe projections. (B) Integrated SNr population activity …

Figure 13—figure supplement 1

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Switching from a single dendrite to multiple thin dendrites increases rate but not magnitude of $C l^{-}$ accumulation and subsequent depolarization of $E_{G A B A}$ in response to simulated $40 H z$ Str stimulation.

Neuronal response (blue) and $E_{G A B A}$ dynamics (red) in a neuron with (**A,C**) two or (**B,D**) four thin dendrites. For comparison $E_{G A B A}$ dynamics in a neuron with a single dendrite is shown in gray in all panels. …

Figure 13—figure supplement 2

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Increasing the number of dendrites has no qualitative effect on the the time it takes to generate a pause in SNr activity in response to ramping Str activity.

Relationship between the tonic $C l^{-}$ conductance and $T_{p a u s e}$ for (A) one dendrite, (B) two (B1) or four (B2) dendrites with total surface area and capacitance matched to the single dendrite, and (C) two (C1)…

Figure 14

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Summary figure/cartoon - GPe output provides tonic Cl load tuning SNr synchrony and the strength of Str inhibition.

Tables

Table 1

Ionic channel parameters.

Channel	Parameters
$I_{N a}$	$g_{N a} = 35 n S / p F$	$E_{N a} = 50.0 m V$
	$m_{1 / 2} = - 30.2 m V$	$k_{m} = 6.2 m V$
	$τ_{m}^{0} = 0.05 m s$	$τ_{m}^{1} = 0.05 m s$	$τ_{1 / 2}^{m} = 1 m V$
	$σ_{m}^{0} = 1 m V$	$σ_{m}^{1} = 1 m V$
	$h_{1 / 2} = - 63.3 m V$	$k_{h} = - 8.1 m V$
	$τ_{h}^{0} = 0.59 m s$	$τ_{h}^{1} = 35.1 m s$	$τ_{1 / 2}^{h} = - 43.0 m V$
	$σ_{h}^{0} = 10 m V$	$σ_{h}^{1} = - 5 m V$
	$s_{1 / 2} = - 30.0 m V$	$k_{s} = - 0.4 m V$
	$τ_{s}^{0} = 10 m s$	$τ_{s}^{1} = 50 m s$	$τ_{1 / 2}^{s} = - 40 m V$
	$σ_{s}^{0} = 18.3 m V$	$σ_{s}^{1} = - 10 m V$	$s_{m i n} = 0.15$
$I_{N a P}$	$g_{N a P} = 0.175 n S / p F$
	$m_{1 / 2} = - 50.0 m V$	$k_{m} = 3.0 m V$
	$τ_{m}^{0} = 0.03 m s$	$τ_{m}^{1} = 0.146 m s$	$τ_{1 / 2}^{m} = - 42.6 m V$
	$σ_{m}^{0} = 14.4 m V$	$σ_{m}^{1} = - 14.4 m V$	$m_{m i n} = 0.0$
	$h_{1 / 2} = - 57.0 m V$	$k_{h} = - 4.0 m V$
	$τ_{h}^{0} = 10.0 m s$	$τ_{h}^{1} = 17.0 m s$	$τ_{1 / 2}^{h} = - 34.0 m V$
	$σ_{h}^{0} = 26.0 m V$	$σ_{h}^{1} = - 31.9 m V$	$h_{m i n} = 0.154$
I_K	$g_{K} = 50 n S / p F$	$E_{K} = - 90.0 m V$
	$m_{1 / 2} = - 26 m V$	$k_{m} = 7.8 m V$
	$τ_{m}^{0} = 0.1 m s$	$τ_{m}^{1} = 14.0 m s$	$τ_{1 / 2}^{m} = - 26.0 m V$
	$σ_{m}^{0} = 13.0 m V$	$σ_{m}^{1} = - 12.0 m V$
	$h_{1 / 2} = - 20.0 m V$	$h_{m} = - 10.0 m V$
	$τ_{h}^{0} = 5.0 m s$	$τ_{h}^{1} = 20.0 m s$	$τ_{1 / 2}^{h} = 0.0 m V$
	$σ_{h}^{0} = 10.0 m V$	$σ_{h}^{1} = - 10.0 m V$	$h_{m i n} = 0.6$
$I_{C a}$	$g_{C a} = 0.7 n S / p F$	$E_{C a} = 13.27 \cdot l n (C a_{o u t} / C a_{i n})$
	$C a_{o u t} = 4.0 m M$	$C a_{i n}$ , see Equation 18
	$m_{1 / 2} = - 27.5 m V$	$k_{m} = 3.0 m V$	$τ_{m} = 0.5 m s$
	$h_{1 / 2} = - 52.5 m V$	$k_{h} = - 5.2 m V$	$τ_{h} = 18.0 m s$
$I_{S K}$	$k_{S K} = 0.4 m M$	$n_{S K} = 4$	$τ_{s k} = 0.1 m S$
$I_{L e a k}$	$g_{L e a k} = 0.04 n S / p F$	$E_{L e a k} = - 60 m V$
$I_{G A B A}^{S}$	$W_{G A B A}^{G P e} = 0.2 n S / p F$	$E_{G A B A}^{S}$ , see Equation 23	$τ_{S y n E} = 3.0 m s$
	$D_{0} = 1.0$	$α_{D} = 0.565$	$τ_{D} = 1000 m s$
	$D_{m i n} = 0.67$	$W_{G A B A}^{S N r} = 0.1 n S / p F$
$I_{S D}$ , $I_{D S}$	$g_{C} = 26.5 n S$
$I_{T R P C 3}$	$g_{T R P C 3} = 0.1 n S / p F$	$E_{T R P C 3} = - 37.0 m V$
$I_{G A B A}^{D}$	$W_{G A B A}^{S t r} = 0.4 n S / p F$	$E_{G A B A}^{D}$ , see Equation 23	$τ_{G A B A}^{D} = 7.2 m s$
	$F_{0} = 0.145$	$α_{F} = 0.125$	$τ_{F} = 1000 m s$

Additional files

Transparent reporting form: https://cdn.elifesciences.org/articles/55592/elife-55592-transrepform-v1.pdf
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Figures

Two-compartment SNr model neuron includes currents that affect ${[C l^{-}]}_{i}$ and produces appropriate dynamics.

Simulated short-term synaptic depression and facilitation of GABAergic synapses originating from GPe neurons of the indirect pathway (A and B) and Str neurons of the direct pathway (C and D) under voltage clamp.

Simulated short-term synaptic depression and facilitation of GABAergic synapses originating from GPe neurons of the indirect pathway (A and B) and Str neurons of the direct pathway (C and D) under current clamp.

Tonic chloride conductance and extrusion capacity determine somatic $E_{G A B A}$ and SNr responses to simulated 40 Hz GPe stimulation.

Biphasic SNr response to longer simulated GPe stimulation.

Tonic chloride conductance and extrusion capacity determine dendritic $E_{G A B A}$ and SNr responses to 20 Hz Str stimulation.

Characterization of experimentally observed SNr responses to optogenetic stimulation of (top) GPe and (bottom) Str projections to SNr in vitro.

Summary of SNr responses to optogenetic stimulation of GPe synaptic terminals.

Summary of SNr responses to optogenetic stimulation of Str synaptic terminals.

Phase response curves (PRCs) of the model SNr neuron depend on $E_{G A B A}$ .

Effect of $E_{G A B A}$ on SNr synchrony in a unidirectional (left) and bidirectional (right) synaptically connected two-neuron network.

Schematic illustration of the convergence toward anti-phase locking in a birectionally coupled pair of SNr neurons.

Characterization of phase slipping oscillations in the unidirectionally connected two-neuron network.

Effects of changing the presynaptic firing rate on synchrony and postsynaptic oscillations in a feed-forward SNr neuron pair.

The relationship between $E_{G A B A}$ and phase locking and the emergence of slow oscillations are maintained at least up to in vivo SNr firing rates.

Effect of increasing noise on SNr phase relationships as a function of $E_{G A B A}$ .

Effect of synaptic delay on the relationship between $E_{G A B A}$ and presynaptic/postsynaptic phase locking.

Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between two presynaptic neurons.

Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between three presynaptic neurons.

Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between four presynaptic neurons.

Effects of varying $E_{G A B A}$ on post synaptic dynamics in the three-neuron motif where neuron 1 projects to neuron 2 and neuron 3 and neuron 2 projects to neuron 3 (motif number 10 from Song et al., 2005).

Effect of varying $E_{G A B A}$ in a network of 100 model SNr neurons with random, sparse connectivity.

Slow oscillations in the SNr seen under dopamine depleted conditions in vivo are suppressed by channelrhodopsin-2 optogenetic stimulation of GABAergic GPe terminals in the SNr.

Tonic somatic $C l^{-}$ conductance affects somatic and dendritic $E_{G A B A}$ and tunes SNr responses to Str inputs.

Switching from a single dendrite to multiple thin dendrites increases rate but not magnitude of $C l^{-}$ accumulation and subsequent depolarization of $E_{G A B A}$ in response to simulated $40 H z$ Str stimulation.

Increasing the number of dendrites has no qualitative effect on the the time it takes to generate a pause in SNr activity in response to ramping Str activity.

Summary figure/cartoon - GPe output provides tonic Cl load tuning SNr synchrony and the strength of Str inhibition.

Tables

Ionic channel parameters.

Additional files

Transparent reporting form

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Cite this article

Two-compartment SNr model neuron includes currents that affect [C⁢l-]i<math id="inf9"><msub><mrow><mo stretchy="false">[</mo><mrow><mi>C</mi><mo>⁢</mo><msup><mi>l</mi><mo>-</mo></msup></mrow><mo stretchy="false">]</mo></mrow><mi>i</mi></msub></math> and produces appropriate dynamics.

Simulated short-term synaptic depression and facilitation of GABAergic synapses originating from GPe neurons of the indirect pathway (A and B) and Str neurons of the direct pathway (C and D) under voltage clamp.

Simulated short-term synaptic depression and facilitation of GABAergic synapses originating from GPe neurons of the indirect pathway (A and B) and Str neurons of the direct pathway (C and D) under current clamp.

Tonic chloride conductance and extrusion capacity determine somatic EG⁢A⁢B⁢A<math id="inf42"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> and SNr responses to simulated 40 Hz GPe stimulation.

Biphasic SNr response to longer simulated GPe stimulation.

Tonic chloride conductance and extrusion capacity determine dendritic EG⁢A⁢B⁢A<math id="inf74"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> and SNr responses to 20 Hz Str stimulation.

Characterization of experimentally observed SNr responses to optogenetic stimulation of (top) GPe and (bottom) Str projections to SNr in vitro.

Summary of SNr responses to optogenetic stimulation of GPe synaptic terminals.

Summary of SNr responses to optogenetic stimulation of Str synaptic terminals.

Phase response curves (PRCs) of the model SNr neuron depend on EG⁢A⁢B⁢A<math id="inf109"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math>.

Effect of EG⁢A⁢B⁢A<math id="inf120"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> on SNr synchrony in a unidirectional (left) and bidirectional (right) synaptically connected two-neuron network.

Schematic illustration of the convergence toward anti-phase locking in a birectionally coupled pair of SNr neurons.

Characterization of phase slipping oscillations in the unidirectionally connected two-neuron network.

Effects of changing the presynaptic firing rate on synchrony and postsynaptic oscillations in a feed-forward SNr neuron pair.

The relationship between EG⁢A⁢B⁢A<math id="inf160"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> and phase locking and the emergence of slow oscillations are maintained at least up to in vivo SNr firing rates.

Effect of increasing noise on SNr phase relationships as a function of EG⁢A⁢B⁢A<math id="inf167"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math>.

Effect of synaptic delay on the relationship between EG⁢A⁢B⁢A<math id="inf178"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> and presynaptic/postsynaptic phase locking.

Relationship between postsynaptic firing properties as a function of EG⁢A⁢B⁢A<math id="inf180"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> and varying degrees of synchrony between two presynaptic neurons.

Relationship between postsynaptic firing properties as a function of EG⁢A⁢B⁢A<math id="inf183"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> and varying degrees of synchrony between three presynaptic neurons.

Relationship between postsynaptic firing properties as a function of EG⁢A⁢B⁢A<math id="inf186"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> and varying degrees of synchrony between four presynaptic neurons.

Effect of varying EG⁢A⁢B⁢A<math id="inf201"><msub><mi>E</mi><mrow><mi>G</mi><mo>⁢</mo><mi>A</mi><mo>⁢</mo><mi>B</mi><mo>⁢</mo><mi>A</mi></mrow></msub></math> in a network of 100 model SNr neurons with random, sparse connectivity.

Slow oscillations in the SNr seen under dopamine depleted conditions in vivo are suppressed by channelrhodopsin-2 optogenetic stimulation of GABAergic GPe terminals in the SNr.

Increasing the number of dendrites has no qualitative effect on the the time it takes to generate a pause in SNr activity in response to ramping Str activity.

Summary figure/cartoon - GPe output provides tonic Cl load tuning SNr synchrony and the strength of Str inhibition.

Ionic channel parameters.

Transparent reporting form

Two-compartment SNr model neuron includes currents that affect ${[C l^{-}]}_{i}$ and produces appropriate dynamics.

Tonic chloride conductance and extrusion capacity determine somatic $E_{G A B A}$ and SNr responses to simulated 40 Hz GPe stimulation.

Tonic chloride conductance and extrusion capacity determine dendritic $E_{G A B A}$ and SNr responses to 20 Hz Str stimulation.

Phase response curves (PRCs) of the model SNr neuron depend on $E_{G A B A}$ .

Effect of $E_{G A B A}$ on SNr synchrony in a unidirectional (left) and bidirectional (right) synaptically connected two-neuron network.

The relationship between $E_{G A B A}$ and phase locking and the emergence of slow oscillations are maintained at least up to in vivo SNr firing rates.

Effect of increasing noise on SNr phase relationships as a function of $E_{G A B A}$ .

Effect of synaptic delay on the relationship between $E_{G A B A}$ and presynaptic/postsynaptic phase locking.

Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between two presynaptic neurons.

Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between three presynaptic neurons.

Relationship between postsynaptic firing properties as a function of $E_{G A B A}$ and varying degrees of synchrony between four presynaptic neurons.

Effect of varying $E_{G A B A}$ in a network of 100 model SNr neurons with random, sparse connectivity.