Journal: The European Journal of Neuroscience

Article Title: Central amygdala‐to‐pre‐Bötzinger complex neurotransmission is direct and inhibitory

doi: 10.1111/ejn.16589

Figure Lengend Snippet: Neuroanatomical tracing of projections from central amygdala (CeA) to pre‐Bötzinger complex (preBötC). (a) Parasagittal view of mouse brain with an arrow indicating cholera toxin B (CTb)‐Alexa488 injection in the right preBötC. Dotted vertical lines show midbrain sections in the CeA where CTb‐labelled neurons are shown in (d). This experiment produced the data in (b–d). (b) Transverse section showing the preBötC site of injection. (c) Percentage of CTb‐labelled neurons in the CeA ( n = 3). (d) 10× magnification (left and upper panels) and 40× magnification (lower panels) confocal images of right CeA showing CTb‐Alexa488‐labelled neurons following preBötC injections. Images were converted into maximum intensity z‐projections, and their contrast was adjusted. Numerals 1–4 indicate corresponding sections at different levels of magnification. d1–d4 show no colocalization of CTb (cyan) and protein kinase C‐delta (PKCδ) (magenta) in CeA sections as indicated by distance from Bregma. (e) Parasagittal view of mouse brain with an arrow indicating the AAV‐ChR2(H134R)‐EYFP injection in the CeA. (f) Transverse section showing enhanced yellow fluorescent protein (EYFP) at the CeA injection site. (g) Recording site in the preBötC; ‘P’ refers to the patch‐recording pipette. (h) EYFP expression in the preBötC under high magnification. Dorsal and lateral directions are shown for orientation and those orientations apply to all images in the CeA and preBötC.

Article Snippet: We injected an adeno‐associated virus (AAV) (7 × 10 12 GC/mL) for cre‐dependent channelrhodopsin‐2 (ChR2) expression (AAV5‐EF1α‐DIO‐hChR2[H134R]‐EYFP; 20298‐AAV5; Addgene, Watertown, MA, USA) into the right CeA of Vgat‐ires‐cre mice.

Techniques: Injection, Produced, Transferring, Expressing

Journal: PLoS biology

Article Title: Non-associative potentiation of perisomatic inhibition alters the temporal coding of neocortical layer 5 pyramidal neurons.

doi: 10.1371/journal.pbio.1001903

Figure Lengend Snippet: Figure 3. LTPi is selectively expressed at perisomatic GABAergic synapses from PV cell. (A, Left) Micrograph showing recording and stimulating configurations. The dashed white line schematizes the cut by a fourth broken glass pipette. (A, Right Top) Representative current-clamp traces of distally evoked eIPSPs before, after AP bursts (5 APs at 100 Hz, repeated 156) and after cut. (A, Right Bottom) Representative traces of proximally evoked eIPSPs in the same conditions. (B) Plots of proximal (Left) and distal (Right) IPSP amplitudes in control versus 20 min after LTPi- inducing AP bursts. (C, Left) Schematic of simultaneous paired recordings from a presynaptic PV basket cell and a postsynaptic layer 5 pyramidal neuron. PV cells were identified as expressing EGFP in PV-Cre::RCE mice (see Materials and Methods) [18]. (C, Right) Action currents in voltage clamp (green) in the presynaptic interneuron (IN) trigger uIPSCs in the postsynaptic pyramidal neuron (PYR). Black trace, before the depolarizing steps; red trace, after induction of d-LTPi. (D) Time course of the cell of (C), showing a persistent increase of uIPSCs after postsynaptic depolarizing steps (grey area). (E) Population data of paired recordings, showing LTPi when the postsynaptic cell was depolarized (filled symbols) and absence of plasticity when pyramidal neurons were not depolarized. Data are single values and/or mean 6 SEM. *p,0.05. (F) Schematic of optogenetic activation of SST- positive interneurons. ChR2 was co-expressed with mCherry in SST-cre mice using viral vectors (see Materials and Methods) [20]. (F, Right) Brief (2 ms) flashes of 470 nm light (blue bars) induced a GABAergic current that was insensitive to LTPi-inducing protocols (black trace, control; red trace, after postsynaptic depolarizing steps). (G) Time course of the cell of (F), showing lack of persistent increase of SST-mediated population IPSCs after postsynaptic depolarizing steps (grey area). (H) Population data of SST-mediated population IPSCs, showing lack of LTPi when the postsynaptic cell was depolarized. Numbers (1 and 2) refer to times of trace illustration. doi:10.1371/journal.pbio.1001903.g003

Article Snippet: Data are represented as mean 6 SEM. (TIF) Figure S2 Characterization of photo-induced distal IPSCs. (A) Two-photon fluorescence images of parasagittal sections of layer V S1 of an SST-Cre mouse injected with the adeno-associated virus expressing floxed ChR2 (AAV9.EF1.dflox.hChR2(H134R)mCherry.WPRE.hGH; Addgene 20297).

Techniques: Transferring, Control, Expressing, Activation Assay

Journal: Cerebral cortex (New York, N.Y. : 1991)

Article Title: Short-Term Facilitation of Long-Range Corticocortical Synapses Revealed by Selective Optical Stimulation.

doi: 10.1093/cercor/bhab325

Figure Lengend Snippet: Figure 1. Optical stimulation of vS1 and vM1 CC projections evoked facilitating synaptic excitation in L2/3 neurons. (A, B) Left: schematic showing virus injected into vS1 (A) or vM1 (B) of mice in vivo. Middle: live slice (300 μm) image showing an overlay of EYFP with brightfield. Right: low- and high-magnification fluorescence image of a 60-μm-thick section from the same live slice. EYFP-labeled vS1 axons terminate densely in superficial layers of vM1 (A), whereas EYFP-labeled vM1 axons terminate densely in L1 and L5/6 of vS1 (B). Sections were counterstained with DAPI. (C) Left: recording schematic showing photostimulation of ChR2-expressing vS1 terminal arbors (green) and a whole-cell recording from an excitatory L2/3 cell in vM1. Responses of a nonexpressing L2/3 RS cell to intracellular current steps (scale bars, 40 mV/200 ms). Middle: vS1-vM1 EPSCs evoked in the same neuron (shown in C, left) by a pair of optical stimuli at 20 Hz (blue arrow, 0.5 ms) (average of 10 trials). Right: Population data showing the average peak paired-pulse ratio at different interstimulus intervals (t). (D) Left: vS1-vM1 EPSCs evoked in the same cell (shown in C) by a 20-Hz train of optical stimuli (average of 10 trials). EPSCs increased 60–70% from the first to the fourth pulse. Middle and Right: EPSC amplitudes plotted as a function of stimulus number within 20-Hz trains (normalized to first responses) and the peak responses to the tenth stimulus as a function of stimulus frequency (normalized to first responses). (E) Left: recording schematic for the vM1-vS1 CC pathway. Responses of a nonexpressing L2/3 RS cell to intracellular current steps (scale bars, 40 mV/200 ms). Middle: vM1-vS1 EPSCs evoked in the same neuron (shown in E, left) by a pair of optical stimuli at 20 Hz (blue arrows, 0.5 ms) (average of 16 trials). Right: population data showing the average peak paired-pulse ratio at different interstimulus intervals (t). (F) Left: vM1-vS1 EPSCs evoked in the same neuron (shown in E) by a 20-Hz train of optical stimuli (average of 17 trials). EPSCs nearly doubled from the first to the fourth pulse. Middle and Right: EPSC amplitudes plotted as a function of stimulus number within 20-Hz trains (normalized to first responses) and the peak responses to the tenth stimulus as a function of stimulus frequency (normalized to first responses). The light intensity for each cell was set to obtain an initial 200 pA EPSC when held near the inhibitory reversal potential (−94 mV, see Materials and Methods). Values are represented as mean ± SEM. See also Supplementary Figures 1–5 and Supplementary Table 1.

Article Snippet: Retrograde-Cre experiments were carried out similarly, with injections of AAVretroEf1a-mCherry-IRES-Cre (Addgene plasmid # 55632) into vS1 followed by an AAV injection in vM1 that drove Cre-dependent expression of ChR2 (pAAV1-hSyn-hChR2(H134R)-EYFP, Addgene plasmid # 26973).

Techniques: Virus, Injection, In Vivo, Fluorescence, Labeling, Expressing

Journal: Cerebral cortex (New York, N.Y. : 1991)

Article Title: Short-Term Facilitation of Long-Range Corticocortical Synapses Revealed by Selective Optical Stimulation.

doi: 10.1093/cercor/bhab325

Figure Lengend Snippet: Figure 2. Synaptic responses during repetitive activation are more sustained for long-range CC than other excitatory cortical connections. (A) Long-range excitatory-to- excitatory (E-to-E) connections. A comparison of the first and second EPSC amplitude evoked by a pair of optical stimuli (20 Hz) directed at long-range CC or TC axons in the cortex: vM1-vS1L2/3, vS1-vM1L2/3, and VPm-vS1L4/L6. (B) Local E-to-E connections. A comparison of the first and second EPSP/C amplitude evoked by a pair of stimuli for local excitatory connections in the cortex: pairs of excitatory cells (20–60 Hz), photostimulation of local excitatory neurons/axons that conditionally expressed ChR2 in Rbp4-Cre or Scnn1a-Cre-Tg3 mice (10–20 Hz), and photostimulation of L4 to L2/3 axons/terminals (without parent somata) that conditionally expressed ChR2 using Scnn1a-Cre-Tg3 mice (20 Hz). To isolate axons/terminals from parent somata, a cut was made between L4 and L2/3. (C) Left: summary graph of paired-pulse ratios for the long-range and local excitatory cortical connections. Paired-pulse ratios were significantly larger for both long-range CC connections than all other excitatory connections (P < 0.0001, one-way ANOVA with Bonferroni’s post hoc test). Right: summary graph shows EPSC amplitudes plotted as a function of stimulus number within 20 Hz trains. Synaptic dynamics were significantly different, with responses to long-range CC inputs exhibiting short-term facilitation (n = 38 cells, 13 mice), local connections displaying weak depression (n = 27 cells, seven mice), and long-range thalamocortical inputs showing strong depression (n = 16 cells, four mice) (P < 0.00001, two-way ANOVA, stim. 2–10). (D) Top: Schematic showing AAVretro-Cre injected into the vS1 and Cre-dependent AAV-DIO-ChR2 injected into ipsilateral vM1 of mice in vivo. Bottom: live slice (300 μm) image of vM1 showing EYFP fluorescence indicating the location of ChR2-EYFP. (E) Top: a comparison of the first and second EPSC amplitude evoked by a pair of optical stimuli (20 Hz) directed at ChR2-expressing vS1P cells in vM1 (P = 0.93, paired t-test). Bottom: summary graph shows EPSC amplitudes plotted as a function of stimulus number within 20 Hz trains for local and long-range targets of vS1P cells in vM1 (Local: n = 5 cells, two mice; long- range: 21 cells, seven mice; P < 0.00001, two-way ANOVA, stim. 2–10). Red triangles and lines represent means. Long-range CC data from Figure 1. Values are represented as mean ± SEM.

Article Snippet: Retrograde-Cre experiments were carried out similarly, with injections of AAVretroEf1a-mCherry-IRES-Cre (Addgene plasmid # 55632) into vS1 followed by an AAV injection in vM1 that drove Cre-dependent expression of ChR2 (pAAV1-hSyn-hChR2(H134R)-EYFP, Addgene plasmid # 26973).

Techniques: Activation Assay, Comparison, Injection, In Vivo, Fluorescence, Expressing

Journal: Cerebral cortex (New York, N.Y. : 1991)

Article Title: Short-Term Facilitation of Long-Range Corticocortical Synapses Revealed by Selective Optical Stimulation.

doi: 10.1093/cercor/bhab325

Figure Lengend Snippet: Figure 3. Comparison of ChR2-evoked CC responses across layers. (A) Left: Recording schematic for the vS1-vM1 pathway. We sequentially recorded an excitatory L2/3 cell and an excitatory neuron in a separate layer of the same column. Layers were determined using layer-specific Cre-driver mouse lines crossed with a tdTomato reporter (see Materials and Methods). Right: representative single EPSCs evoked optically for pairs of excitatory cells recorded in different layers of vM1 (average of 6–11 trials). (B, C) A comparison of the average vS1-vM1 optically evoked EPSC amplitude (left), paired-pulse ratio at 20 Hz (middle), and EPSC amplitudes plotted as a function of stimulus number within 20-Hz trains for each L2/3-L5 (B) and L2/3-L6 cell pair (C). Red triangles and squares represent means and median, respectively. n displayed on the plot. L5 and L6 responses were significantly lower (P < 0.01, Wilcoxon paired signed-rank test), displayed lower paired-pulse ratios (P < 0.0001, paired t-test), and underwent less facilitation during 20-Hz trains than those in L2/3 (P < 0.0001, two-way ANOVA, stim. 2–10). (D) Left: the same experimental approach described in (A) for the vM1-vS1 pathway. Right: representative single EPSCs evoked for pairs of excitatory cells in different layers of vS1 (average of 5–11 trials). (E, F) A comparison of the average vM1-vS1 optically evoked EPSC amplitude (left), paired-pulse ratio at 20 Hz (middle), and EPSC amplitudes plotted as a function of stimulus number within 20-Hz trains for each L2/3-L5 (E) and L2/3-L6 cell pair (F). Red triangles and squares represent means and median, respectively. n displayed on the plot. EPSCs were stronger in L6 (P < 0.01, paired t-test), weaker in L4 (n = 7 pairs, three mice, data not shown, P < 0.03, Wilcoxon paired signed-rank test), and similar in L5 as compared with those in L2/3 (P = 0.07, Wilcoxon paired signed-rank test). L5 responses underwent less facilitation than those in L2/3 (PPR: P < 0.01, Mann–Whitney U test; train: P < 0.0001, two-way ANOVA, stim. 2–10), whereas L6 responses displayed similar paired-pulse facilitation (P = 0.24, paired t-test) but facilitated less than L2/3 during 20 Hz trains (P < 0.01, two-way ANOVA, stim. 2–10). L4 responses were too weak to test dynamics. For single EPSCs, cells were tested at the light intensity needed to obtain an initial 200 pA EPSC in L2/3 in voltage-clamp at −94 mV, whereas short-term plasticity was tested at the cell’s own 200 pA intensity. Values are represented as mean ± SEM. See also Supplementary Figure 2, Supplementary Tables 1 and 2.

Article Snippet: Retrograde-Cre experiments were carried out similarly, with injections of AAVretroEf1a-mCherry-IRES-Cre (Addgene plasmid # 55632) into vS1 followed by an AAV injection in vM1 that drove Cre-dependent expression of ChR2 (pAAV1-hSyn-hChR2(H134R)-EYFP, Addgene plasmid # 26973).

Techniques: Comparison, MANN-WHITNEY

Journal: Cerebral cortex (New York, N.Y. : 1991)

Article Title: Short-Term Facilitation of Long-Range Corticocortical Synapses Revealed by Selective Optical Stimulation.

doi: 10.1093/cercor/bhab325

Figure Lengend Snippet: Figure 4. Comparison of ChR2-evoked CC responses across GABAergic interneurons in L2/3 of vM1 and vS1. (A) Left: Recording schematic for the vS1-vM1 pathway. We simultaneously recorded a specific L2/3 interneuron and a nearby excitatory neuron. Experiments utilized Cre-driver mice targeting three classes of GABAergic cells in the neocortex (see Materials and Methods). Right: representative single EPSCs evoked optically in interneuron-RS pairs (average of 7–10 trials). (B–D) A comparison of the average vS1-vM1 optically evoked EPSC amplitude (left), the paired-pulse ratio at 20 Hz (middle), and EPSC amplitudes plotted as a function of stimulus number within 20-Hz trains for PV-RS (B), SOM-RS (C), and VIP-RS pairs (D). Colored triangles and squares represent means and median, respectively. n displayed on the plot. EPSCs were stronger in PV (P < 0.01, Wilcoxon paired signed-rank test) but weaker in both SOM and VIP as compared with those in L2/3 RS cells (SOM: P < 0.0001, paired t-test; VIP: P < 0.02, Wilcoxon paired signed-rank test). Short-term dynamics of excitatory vS1-vM1 synapses onto L2/3 interneurons were significantly different during 20-Hz trains than RS cells (P < 0.05, two-way ANOVA, stim. 2–10). (E) Left: The same experimental approach described in (A) for the vM1-vS1 pathway. Right: Representative single EPSCs evoked optically in interneuron-RS pairs (average of 8–10 trials). (F–H) A comparison of the average vM1-vS1 optically evoked EPSC amplitude (left), the paired-pulse ratio at 20 Hz (middle), and EPSC amplitudes plotted as a function of stimulus number within 20-Hz trains for PV-RS (F), SOM-RS (G), and VIP-RS pairs (H). Colored triangles and squares represent means and median, respectively. n displayed on the plot. EPSCs were stronger in PV (P < 0.01, paired t-test), weaker in SOM (P < 0.01, paired t-test), and similar in VIP as compared with those in L2/3 RS cells (P = 0.126, paired t-test). Short-term dynamics of excitatory vS1-vM1 synapses onto L2/3 interneurons were significantly different during 20-Hz trains than RS cells (P < 0.0001, two-way ANOVA, stim. 2–10). For single EPSCs, we tested pairs at the light intensity needed to obtain an initial 200 pA EPSC in the L2/3 excitatory neuron when recorded in voltage-clamp at −94 mV. We tested short-term plasticity at an intensity that evoked a reliable EPSC (typically 50–300 pA) for each cell. Values are represented as mean ± SEM. See also Supplementary Figure 6.

Article Snippet: Retrograde-Cre experiments were carried out similarly, with injections of AAVretroEf1a-mCherry-IRES-Cre (Addgene plasmid # 55632) into vS1 followed by an AAV injection in vM1 that drove Cre-dependent expression of ChR2 (pAAV1-hSyn-hChR2(H134R)-EYFP, Addgene plasmid # 26973).

Techniques: Comparison

Journal: Cerebral cortex (New York, N.Y. : 1991)

Article Title: Short-Term Facilitation of Long-Range Corticocortical Synapses Revealed by Selective Optical Stimulation.

doi: 10.1093/cercor/bhab325

Figure Lengend Snippet: Figure 5. Effect of AAV serotype and ChR2 fusion protein on optically evoked facilitation at CC synapses. (A) For each serotype (AAV2, AAV1, AAV5, and AAV9), representative EPSCs evoked optically by 20-Hz trains for an excitatory L2/3 cell located in vM1 (left) or vS1 (right) (average of 3–17 trials). We used the same vector (AAV-hSyn-hChR2(H134R)-EFYP), titer (3.1 × 1012 viral genomes/mL), volume per injection site (∼0.15 μL), and transduction time (21 ± 1 days) for each serotype to keep expression levels similar. (B) Summary graphs show the average EPSC amplitudes plotted as a function of stimulus number within 20-Hz trains for each serotype tested in the vS1-vM1 (left) and vM1-vS1 pathway (right). Facilitation was significantly weaker than other serotypes when using AAV5 in the vS1- vM1 pathway (P < 0.0001) and AAV1 in the vM1-vS1 pathway (P < 0.0001, two- way ANOVA, stim. 2–10, with Bonferroni’s post hoc test) (vS1-vM1: AAV1, n = 18 cells, two mice; AAV5, n = 16 cells, three mice; AAV9, n = 8 cells, two mice) (vM1- vS1: AAV1, n = 8 cells, three mice; AAV5, n = 8 cells, three mice; AAV9, n = 21 cells, seven mice). AAV2 data same as shown in Figure 1D,F. (C) Left: representative EPSCs evoked optically by 20-Hz trains for excitatory L2/3 cells in vS1 when using AAV2 to drive ChR2-EYFP or ChR2-mCherry expression in vM1 axons (average of 10 and 8 trials). For these experiments, we used the same titer and expression time. Right: Summary graph shows the average EPSC amplitudes plotted as a function of the stimulus number within 20-Hz trains for each vector. Short-term facilitation was blunted when using AAV2-ChR2-mCherry (n = 18 cells, three mice for mCherry; P < 0.0001, two-way ANOVA, stim. 2–10). AAV2-ChR2-EYFP data same as shown in Figure 1F. Values are represented as mean ± SEM. See also Supplementary Figure 7.

Article Snippet: Retrograde-Cre experiments were carried out similarly, with injections of AAVretroEf1a-mCherry-IRES-Cre (Addgene plasmid # 55632) into vS1 followed by an AAV injection in vM1 that drove Cre-dependent expression of ChR2 (pAAV1-hSyn-hChR2(H134R)-EYFP, Addgene plasmid # 26973).

Techniques: Plasmid Preparation, Injection, Transduction, Expressing

Journal: Cerebral cortex (New York, N.Y. : 1991)

Article Title: Short-Term Facilitation of Long-Range Corticocortical Synapses Revealed by Selective Optical Stimulation.

doi: 10.1093/cercor/bhab325

Figure Lengend Snippet: Figure 6. Effect of overterminal stimulation and extracellular Ca2+ concentrations on optically evoked facilitation at CC synapses. (A) Recording schematic for (B, C) showing photostimulation of CC arbors using different light-spot sizes (blue circles). Restricting the excitation light to over the terminal ends of ChR2-expressing axons and keeping the total emitted light power the same will likely cause more terminal depolarization. (B) Representative EPSCs evoked by large- and small-field repetitive photostimulation at 20 Hz for an excitatory L2/3 cell in vM1 (left) or vS1 (right) (average of 5–11 trials). (C) Summary graphs show average EPSC amplitudes plotted as a function of stimulus number within 20-Hz trains for each condition. Restricting the excitation light significantly decreased the facilitation at both vS1-vM1 (P < 0.0001) and vM1-vS1 synapses (P < 0.0001, two-way ANOVA, stim. 2–10; Average Power densities: vS1-vM1 = 0.71 and 71 mW/mm2; vS1-vM1 = 2.34 and 234 mW/mm2). Adjusting the power of the small spot to obtain an initial 200 pA EPSC also decreased facilitation (Light blue traces: vS1-vM1, P < 0.006; vM1-vS1, P < 0.0001; two-way ANOVA, stim. 2–10; Average Power densities: vS1-vM1 = 21 mW/mm2; vS1-vM1 = 111 mW/mm2). (D) Representative EPSCs evoked optically by 20-Hz trains for an excitatory L2/3 cell located in vM1 (top) or vS1 (bottom) recorded in 1.2 and 2.0 mM external Ca2+ (average of 10–12 trials). (E) Summary graphs show average EPSC amplitudes plotted as a function of stimulus number within 20-Hz train for 1.2 and 2.0 mM external Ca2+. Raising Ca2+ significantly decreased facilitation at both vS1-vM1 (P < 0.0001) and vM1-vS1 synapses (P < 0.0001, two-way ANOVA, stim. 2–10). (F) Recording schematic for (G, H) showing the same photostimulation approach described in (A). Large-field photostimulation was done in 1.2 mM external Ca2+, whereas small-field photostimulation was done in 2.0 mM external Ca2+. (G) Representative EPSCs evoked by large- and small-field repetitive photostimulation at 20 Hz recorded in 1.2 and 2.0 mM external Ca2+, respectively, for an excitatory L2/3 cell located in vM1 (left) or vS1 (right) (average of 10–12 trials). (H) Summary graphs show average EPSC amplitudes plotted as a function of stimulus number within 20-Hz train for the two conditions. Restricting the excitation light while in 2.0 mM external Ca2+ changed facilitation to depression (vS1-vM1, P < 0.0001; vM1-vS1, P < 0.0001, two-way ANOVA, stim. 2–10). The light intensity was set to obtain an initial ∼200 pA EPSC for C (light blue), D, E, and F, G. Right: Values are represented as mean ± SEM. See also Supplementary Figure 8.

Article Snippet: Retrograde-Cre experiments were carried out similarly, with injections of AAVretroEf1a-mCherry-IRES-Cre (Addgene plasmid # 55632) into vS1 followed by an AAV injection in vM1 that drove Cre-dependent expression of ChR2 (pAAV1-hSyn-hChR2(H134R)-EYFP, Addgene plasmid # 26973).

Techniques: Expressing

Journal: Cerebral cortex (New York, N.Y. : 1991)

Article Title: Short-Term Facilitation of Long-Range Corticocortical Synapses Revealed by Selective Optical Stimulation.

doi: 10.1093/cercor/bhab325

Figure Lengend Snippet: Figure 9. vS1 synapses in vS2 have similar short-term dynamics as vS1-vM1 and vM1-vS1 synapses. (A) Right: injection schematic. AAV2-ChR2-EFYP was injected unilaterally into the right vS1. Left: epifluorescence image of a live coronal brain slice (300 μm) centered on vS2, from a P43 mouse injected in vS1 16 days prior with AAV2-ChR2-EYFP. (B) The recording schematic shows photostimulation of ChR2-expressing vS1 terminal arbors (green) and whole-cell recording from a nonexpressing L2/3 RS neuron. Middle: responses of a L2/3 RS cell in vS2 to intracellular current steps (scale bars 40 mV/200 ms). Right: vS1 excitatory synaptic current evoked in the same neuron (middle) by a pair of optical stimuli at 20 Hz (blue arrow, 0.5 ms) (average 13 sweeps). (C) Left: vS1 excitatory synaptic currents evoked in the same neuron (shown in B, middle) by a 20-Hz train of optical stimuli (average of 30 trials). Right: average short-term dynamics of EPSCs evoked in L2/3 RS cells of vS2 during 20-Hz trains (n = 11 cells from three mice). Overall, long-range vS1-vS2 (sensory–sensory) CC responses facilitate similar to those observed in the vS1-vM1 (sensory–motor).

Article Snippet: Retrograde-Cre experiments were carried out similarly, with injections of AAVretroEf1a-mCherry-IRES-Cre (Addgene plasmid # 55632) into vS1 followed by an AAV injection in vM1 that drove Cre-dependent expression of ChR2 (pAAV1-hSyn-hChR2(H134R)-EYFP, Addgene plasmid # 26973).

Techniques: Injection, Slice Preparation, Expressing