1. Volume 20, Issue 8, Pages 1867-1880 (August 2017)
Synaptic Regulation of a Thalamocortical Circuit Controls Depression-Related Behavior 
Oliver H. Miller, Andreas Bruns, Imen Ben Ammar, Thomas Mueggler, Benjamin J. Hall 
Cell Reports 
Volume 20, Issue 8, Pages (August 2017)
DOI: /j.celrep
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2. Cell Reports 2017 20, 1867-1880DOI: (10.1016/j.celrep.2017.08.002)
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3. Figure 1
Deletion of GluN2B from mPFC Pyramidal Neurons Decreases Depression-like Behavior
(A and B) Conditional deletion of GluN2B from mPFC pyramidal neurons. Mice homozygous for an allele in which exon 5 of the Grin2b gene (GluN2B coding) is flanked by loxP sequences were injected with AAVs driving expression of GFP (control) or GFP-Cre recombinase (2BΔmPFC) under a CaMKIIα promotor.
(C) Homozygous GluN2Bfloxed mice were injected with control virus or Cre into the mPFC to delete GluN2B (2BΔmPFC mouse). Scale bar, 60 μM (inset, 20 μM).
(D) 2BΔmPFC mice displayed a phenotype of decreased despair-like behavior in the forced swim test (FST) and tail suspension test (TST) (FST: control, ± 10.18, n = 16; 2BΔmPFC, ± 17.12, n = 10, p < 0.05; TST: control, 186.0 ± 11.69, n = 17; 2BΔmPFC: ± 11.83, n = 11, p < 0.05).
(E) No alteration in locomotion behavior was observed in the open field test (OFT; control, 901.2 ± 84.52, n = 17; 2BΔmPFC, ± 116.2, n = 9, ns).
Error bars represent ±SEM. ∗p < 0.05.
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4. Figure 2
Layer 3 Pyramidal Neurons Lacking GluN2B Receive Enhanced Excitatory Synaptic Drive Contributing to Their Increased Excitability
(A) Whole-cell current-clamp recordings of control and 2BΔmPFC neurons assessing the frequency of spontaneous APs (scale bar, 20 mV/500 ms).
(B) 2BΔmPFC neurons fired APs more readily than control neurons (control, ± , n = 8; 2BΔmPFC, ± , n = 8, p < 0.01).
(C) Voltage-clamp recordings of excitatory and inhibitory synaptic inputs onto control and 2BΔmPFC neurons (scale bars, 20 pA/1 s).
(D) Analysis of sEPSC amplitudes revealed that 2BΔmPFC neurons receive enhanced excitatory input (control, ± , n = 15; 2BΔmPFC, ± , n = 15, p < 0.01), while analysis of EPSC frequency revealed no significant difference between 2BΔmPFC and control cells (control, 8.42 ± 1.93, n = 1;, 2BΔmPFC, 9.27 ± 1.75, n = 15, ns).
(E) No change in IPSC amplitude (control, ± 1.03pA, n = 6; 2BΔmPFC ± 1.24, n = 9, ns) or frequency (control, ± 4.4, n = 6; 2BΔmPFC, ± 1.96, n = 9, ns) was observed.
(F) Synaptic drive ratio (EPSC frequency × amplitude/IPSC frequency × amplitude) revealed increased excitatory synaptic drive in 2BΔmPFC neurons (control, ± 0.048, n = 7; 2BΔmPFC, ± 0.153, n = 8, p < 0.05).
Error bars represent ±SEM. ∗p < 0.05; ∗∗p < 0.01.
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5. Figure 3
Distinct Short-Term Plasticity of Glutamatergic and GABAergic Synaptic Inputs from the MDT and vHipp onto Layer 3 Pyramidal Neurons in the mPFC
(A and D) 10-Hz trains of 1-ms blue light pulses elicited robust postsynaptic EPSCs in layer 3 mPFC pyramidal neurons. (A) MDT inputs exhibited rapidly depressing kinetics, whereas (D) vHipp EPSCs facilitated (scale bars, 50 pA/200 ms).
(B and E) 10-Hz trains of 1-ms blue light pulses elicited robust postsynaptic IPSCs in layer 3 mPFC pyramidal neurons. Stimulation of both (B) MDT and (E) vHipp inputs elicited depressing IPSCs but with distinct kinetics (scale bar represents 200 pA/200 ms in B and 50 pA/200 ms in E).
(C and F) Summary data for short-term plasticity of (C) MDT or (F) vHipp synaptic inputs into the mPFC.
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6. Figure 4
MDT→mPFC Inputs Are Uniquely Modified by Deletion of GluN2B from Postsynaptic Pyramidal Neurons in the mPFC
(A and D) Chronos was injected into the (A) MDT or (D) vHipp, and the mPFC was injected with CaMKII-Cre to postsynaptically delete GluN2B from pyramidal neurons. Coronal sections of the PFC were prepared for whole-cell recording in the prelimbic mPFC and photostimulation of afferent fibers.
(B and E) Postsynaptic deletion of GluN2B amplifies the high probability of release, depressing phenotype of (B) MDT excitatory inputs into the mPFC (MDT control: n = 17, scale bar, 40 pA/200 ms; 2BΔmPFC: n = 7, scale bar, 100 pA/200 ms; two-way ANOVA F(1, 190) = 15.91, p < ). Conversely, postsynaptic deletion of GluN2B has no effect on the kinetics of (E) vHipp excitatory inputs into mPFC (vHipp control: n = 17, scale bar, 20 pA/200 ms; 2BΔmPFC: n = 6, scale bar, 20 pA/200 ms; two-way ANOVA F(1, 210) = 1.686, p = ).
(C and F) Postsynaptic deletion of GluN2B results in a sustained feed-forward inhibitory response throughout the stimulus train in (C) MDT inputs (MDT control: n = 17; 2BΔmPFC: n = 7; two-way ANOVA F(9, 110) = 16.57, p < 0.05). Conversely, postsynaptic deletion of GluN2B has no effect on the kinetics of (E) vHipp inhibitory inputs into the mPFC (vHipp control: n = 17; 2BΔmPFC: n = 6; two-way ANOVA F(1, 200) = , ns; scale bar represents 100 pA/200 ms in E and 50 pA/200 ms in F).
Error bars represent ±SEM. ∗p < 0.05; ∗∗∗∗p < ; ns, no significant change.
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7. Figure 5
GluN2B Deletion from mPFC Pyramidal Neurons Increases Synaptic Drive and Permits Synaptically Driven AP Generation after MDT Fiber Stimulation
(A) Sample traces of EPSCs after MDT fiber stimulation in control animals, Cre+ cells from 2BΔmPFC animals, and paired Cre− cells in 2BΔmPFC animals.
(B) Statistical comparison of paired control and 2BΔmPFC neurons demonstrates enhanced synaptic drive after GluN2B deletion (paired control: ± 35.3, n = 8; 2BΔmPFC: ± 72.57, n = 8, p < 0.01).
(C) Sample traces of voltage responses in mPFC pyramidal neurons to MDT fiber stimulation.
(D) Postsynaptic deletion of GluN2B alters pyramidal neuron response to MDT fiber activation such that trains of synaptic stimulation elicit AP neurons (0.0% of control cells, 71.4% of 2BΔmPFC cells, and 0.0% of paired control cells).
(E) Sample traces of EPSCs after vHipp fiber stimulation in control animals, Cre+ cells from 2BΔmPFC animals, and paired Cre− cells in 2BΔmPFC animals.
(F) Statistical comparison of paired control and 2BΔmPFC neurons demonstrates no change in synaptic drive after GluN2B deletion (paired control: ± 6.42, n = 3; 2BΔmPFC: ± 5.75, n = 3, ns).
(G) Sample traces of voltage responses in mPFC pyramidal neurons to vHipp fiber stimulation.
(H) Postsynaptic deletion of GluN2B does not alter firing drive of vHipp inputs (0.0% of control cells, 0.0% of 2BΔmPFC cells, and 0.0% of paired control cells).
Error bars represent ±SEM. ∗∗p < 0.01; ns, no significant change.
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8. Figure 6
Acute Activation of the MDT→mPFC Circuit Is Sufficient to Elicit a Decrease in Depression-like Behavior
(A) Schematic showing the intersectional viral manipulation. Virally encoded and Cre-dependent excitatory DREADD hM3Dq was injected into the MDT, while Cre-encoding CAV virus was injected into the mPFC. This induces expression of hM3Dq specifically in MDT neurons projecting to the mPFC.
(B) Left: fixed section containing the MDT demonstrating expression of hM3Dq-mCherry (pseudocolored green, with DAPI in magenta; scale bar, 200 μm). Right: current-clamp recording of an mCherry+ neuron in the MDT showing the effects of brief CNO application (1 μM) (scale bar, 20 mV/5 s).
(C) Left: image from a live section containing the mFPC and demonstrating hM3Dq-mCherry-containing fibers (pseudocolored green; scale bar, 75 μm). Right: voltage-clamp recording from an mPFC pyramidal neuron held at −70 mV. A brief application of CNO results in an increase in spontaneous EPSCs onto these neurons (scale bar, 20 pA/30 s).
(D) Activation of the MDT→mPFC circuit decreases despair-like behavior as measured in the FST (control: ± 11.22, n = 14; MDT→mPFChM3D: ± 10.53, n = 15, p < 0.05) and TST (control: ± 5.583, n = 14; MDT→mPFChM3D: ± 6.601, n = 15, p < 0.05).
(E) No change in locomotion was observed in the open field test (OFT; control: ± 60.62, n = 14; MDT→mPFChM3D: ± 68.24, n = 15, ns).
Error bars represent ±SEM. ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001; ∗∗∗∗p < ; ns, no significant change.
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9. Figure 7
GluN2B Contributes Strongly to Synaptic Current at MDT→mPFC Synapses
Pyramidal neurons current-clamped at +40 mV and recording monosynaptic glutamatergic optogenetically elicited excitatory post synaptic potentials (oEPCSs) (TTX, 4-AP, and picrotoxin in the bath) from MDT or vHipp inputs.
(A) Sample traces of NMDAR-mediated current from MDT→mPFC input basally, with ifenprodil and APV in the bath.
(B) Quantification reveals a significant proportion of the NMDAR-mediated current (34.9%, p < 0.01) is mediated by GluN2B-containing NMDARs.
(C) Sample traces of NMDAR-mediated current from vHipp→mPFC input basally, with ifenprodil and APV.
(D) Quantification reveals insignificant Glun2B-containing NMDAR-mediated current (12.52%, ns).
(E and F) Sample traces of AMPAR (measured at −70 mV) and NMDAR (measured at +40 mV and 50 ms after stimulus) currents driven by MDT and vHipp inputs.
(G) Quantification demonstrates that MDT inputs have a significantly lower AMPAR/NMDAR ratio.
Error bars represent ±SEM.
∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001; ∗∗∗∗p<0.0001; ns, no significant change.
Cell Reports  , DOI: ( /j.celrep )
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