Sparse recurrent excitatory connectivity in the microcircuit of the adult mouse and human cortex
- Allen Institute for Brain Science, United States
- Regional Epilepsy Center at Harborview Medical Center, United States
- University of Washington School of Medicine, United States
- Swedish Neuroscience Institute, United States
Figures
Figure 1 with 1 supplement
Electrophysiological recordings of evoked excitatory synaptic responses between individual cortical pyramidal neurons in mouse primary visual cortex.
(A) Cartoon illustrating color, Cre-line, and cortical layer mapping in slice recording region (V1). Example maximum intensity projection images of biocytin-filled pyramidal neurons for L2/3 and …
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Figure 1—source data 1
Electrophysiological recordings of evoked excitatory synaptic responses between individual cortical pyramidal neurons in mouse primary visual cortex.
- https://doi.org/10.7554/eLife.37349.006
Figure 1—figure supplement 1
Experiment methodology and analysis workflow.
(A) Example connected pair showing the stimulation pulses (top) and action potentials (middle) in the presynaptic cell; monosynaptically evoked EPSPs (bottom) in the postsynaptic cell. Traces …
Figure 2
Electrophysiological recordings of evoked excitatory synaptic responses between individual human cortical pyramidal neurons.
(A) Cartoon illustrating color and cortical layer mapping in slice recording region (temporal or frontal cortex). Example maximum intensity projection images of biocytin-filled pyramidal neurons for …
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Figure 2—source data 1
Electrophysiological recordings of evoked excitatory synaptic responses between individual human cortical pyramidal neurons.
- https://doi.org/10.7554/eLife.37349.009
Figure 3
Characterization of synapse detection limits.
(A) Scatter plot showing measured EPSP amplitude versus minimum detectable amplitude for each tested pair. Detected synapses (manually annotated) are shown as blue diamonds; pairs with no detected …
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Figure 3—source data 1
Characterization of synapse detection limits.
- https://doi.org/10.7554/eLife.37349.012
Figure 4 with 3 supplements
Distance dependent connectivity profiles of mouse and human E-E connections.
(A) Recurrent connection probability and distribution of connections for mouse -linesand layer 2/3. Mean connection probability (filled circles) and 95% confidence intervals (bars) for connections …
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Figure 4—source data 1
Distance dependent connectivity profiles of mouse and human E-E connections.
- https://doi.org/10.7554/eLife.37349.017
Figure 4—figure supplement 1
Intralaminar connectivity rates were unaffected by recording depth and medial-lateral position in V1.
(A) Connectivity rate was assessed as a function of slice number, spanning a total sampled region across experiments of 3.5 mm of cortex (350 µm per slice). (B) The observed synaptic connectivity …
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Figure 4—figure supplement 1—source data 1
Intralaminar connectivity rates were unaffected by recording depth and medial-lateral position in V1.
- https://doi.org/10.7554/eLife.37349.018
Figure 4—figure supplement 2
Characterization of two-photon photostimulation.
(A) Cartoon illustrating loose-seal recording configuration utilized to test photostimulation parameters. Example recording of repeated photostimulation or a ReaChR-positive cell. (B) Cumulative …
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Figure 4—figure supplement 2—source data 1
Characterization of two-photon photostimulation.
- https://doi.org/10.7554/eLife.37349.019
Figure 4—figure supplement 3
Two-photon optogenetic mapping details.
(A) Maximum intensity projection of Tlx3-Cre:Ai136 slice and a recorded neuron. Blue circle denotes location of stimulated presynaptic neuron. (B) Top: Electrophysiological recording of postsynaptic …
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Figure 4—figure supplement 3—source data 1
Two-photon optogenetic mapping details.
- https://doi.org/10.7554/eLife.37349.020
Figure 5 with 1 supplement
Short-term dynamics of mouse recurrent connections by Cre-line and layer (n in Table 1 ‘STP’).
(A) Schematic of STP and STP recovery stimuli. (B) Sim1-Cre EPSPs in response to a 50 Hz stimulus train (top; eight induction pulses and four recovery pulses delayed 250 ms; individual connection: …
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Figure 5—source data 1
Influence of internal EGTA on short-term dynamics.
- https://doi.org/10.7554/eLife.37349.023
Figure 5—figure supplement 1
Influence of internal EGTA on short-term dynamics.
(A) Normalized response amplitude during a 50 Hz train in Tlx3 (cyan) and Sim1 (blue) connections with 0.3 mM EGTA present in the internal solution (filled) and in the absence of EGTA (open). Data …
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Figure 5—figure supplement 1—source data 1
Influence of internal EGTA on short-term dynamics.
- https://doi.org/10.7554/eLife.37349.024
Figure 6
Modeling of short-term depression in recurrent Rorb, Sim1, and Tlx3 connections (n in Table 1 ‘STP’).
(A) Sim1 average dynamic response; Same data as in Figure 5C, top plotted on a log-X time scale with modeling fits overlaid. (B) Results of model for parameters P0 and 𝜏r0. Values are means with …
Tables
Table 1
The number of connections probed and the number of connections used in subsequent analyses per the analysis flow diagram in Figure 1—figure supplement 1C–G.
For each column, the Figure 1—figure supplement 1 letter indicates the end level in the analysis flow diagram while the main figure reference indicates n connections included in that figure. For …
| Layer/Cell Type | Total probed (Figure 1—figure supplement 1C) | Total connected (Figure 1—figure supplement 1C) | Total connection probability (%) | Strength (Figure 1—figure supplement 1E, Figure 1F) | Kinetics (Figure 1—figure supplement 1F, Figure 1F) | Connection probability (%) w/in 100 µm (Connected/probed, Figure 1—figure supplement 1D, Figure 4A,C) | STP (Figure 1—figure supplement 1G, Figures 5 and 6) |
|---|---|---|---|---|---|---|---|
| Mouse L2/3 | 180 | 15 | 8.3 | 12 | 9 | 13/130 (10.0) | 9 |
| Rorb | 315 | 20 | 6.3 | 13 | 13 | 18/247 (7.3) | 9 |
| Tlx3 | 1108 | 39 | 3.5 | 17 | 14 | 36/746 (4.8) | 5 |
| Sim1 | 783 | 55 | 7.0 | 18 | 18 | 41/527 (7.8) | 7 |
| Ntsr1 | 450 | 2 | 0.4 | 2 | 2 | 0/313 (0.0) | N/A |
| Human L2 | 132 | 22 | 16.7 | 18 | 18 | 13/69 (18.8) | N/A |
| Human L3 | 249 | 37 | 14.9 | 33 | 29 | 20/106 (18.9) | N/A |
| Human L4 | 123 | 4 | 3.3 | 2 | 2 | 1/51 (2.0) | N/A |
| Human L5 | 112 | 13 | 11.6 | 6 | 6 | 6/49 (12.2) | N/A |
Table 2
Properties of mouse EPSPs.
Median, mean, and standard deviation of EPSP properties plotted in Figure 1F for each layer and Cre-type. Number of connections used in the amplitude and CV analysis are found in Table 1 ‘Strength’, …
| Amp median (mV) | Amp mean (mV) | Amp SD (mV) | Latency median (ms) | Latency mean (ms) | Latency SD (ms) | Rise Time median (ms) | Rise Time mean (ms) | Rise Time SD (ms) | CV median | CV mean | CV SD | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| L2/3 | 0.26 | 0.34 | ±0.32 | 1.48 | 1.87 | ±1.0 | 1.24 | 1.45 | ±0.57 | 0.55 | 0.56 | ±0.15 |
| Rorb | 0.31 | 0.54 | ±0.49 | 1.31 | 1.50 | ±0.6 | 1.32 | 1.63 | ±0.94 | 0.59 | 0.55 | ±0.24 |
| Sim1 | 0.33 | 0.52 | ±0.51 | 1.86 | 2.05 | ±0.82 | 1.91 | 1.86 | ±1.1 | 0.36 | 0.43 | ±0.2 |
| Tlx3 | 0.14 | 0.24 | ±0.24 | 1.81 | 2.07 | ±0.74 | 1.44 | 1.35 | ±1.1 | 0.51 | 0.51 | ±0.18 |
Table 3
Properties of human EPSPs.
Median, mean, and standard deviation of EPSP properties plotted in Figure 1F for each layer and Cre-line. Number of connections used in the amplitude and CV analysis are found in Table 1 ‘Strength’, …
| Amp median (mV) | Amp mean (mV) | Amp SD (mV) | Latency median (ms) | Latency mean (ms) | Latency SD (ms) | Rise time median (ms) | Rise time mean (ms) | Rise time SD (ms) | CV median | CV mean | CV sd | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| L2 | 0.22 | 0.30 | ±0.22 | 1.84 | 1.79 | ±0.78 | 1.47 | 1.53 | ±0.59 | 0.80 | 0.64 | ±0.29 |
| L3 | 0.34 | 0.54 | ±0.68 | 1.57 | 1.58 | ±0.97 | 1.60 | 2.07 | ±1.36 | 0.39 | 0.44 | ±0.23 |
| L4 | 0.97 | 0.97 | ±1.05 | 2.70 | 2.70 | ±1.80 | 2.02 | 2.02 | ±0.47 | 0.37 | 0.37 | ±0.20 |
| L5 | 0.62 | 0.80 | ±0.69 | 1.64 | 1.75 | ±0.59 | 1.16 | 1.23 | ±0.46 | 0.29 | 0.34 | ±0.10 |
Table 4
Mean and standard deviation of 8:1 ratio at 50 Hz and 9:1 ratio at 50 Hz and 250 ms delay for individual synapses.
Unless noted, EGTA was 0.3 mM and n’s are listed in Table 1, STP.
| 8:1 pulse ratio (50 Hz) mean ± SD | Recovery (9:1) ratio (250 ms) mean ± SD | Paired-pulse ratio (50 Hz) mean ± SD | |
|---|---|---|---|
| L2/3 | 0.92 ± 0.57 | 0.76 ± 0.48 | 1.14 ± 0.63 |
| Rorb | 0.39 ± 0.14 | 0.55 ± 0.26 | 0.66 ± 0.13 |
| Sim1 | 0.37 ± 0.18 | 0.46 ± 0.26 | 0.73 ± 0.17 |
| Tlx3 | 0.48 ± 0.32 | 0.72 ± 0.24 | 0.8 ± 0.15 |
| Sim1 (0 EGTA), n = 6 | 0.27 ± 0.17 | N/A | 0.68 ± 0.22 |
| Tlx3 (0 EGTA), n = 2 | 0.51 ± 0.12 | N/A | 1.15 ± 0.03 |
Table 5
Model parameter values and statistics for Rorb, Sim1, and Tlx3 recurrent connections.
Parameter values are from the model performed on the grand mean for each connection type with the standard error of the covariance matrix. The Z-score was computed following Equation 6; the Z-score …
| Connection type/Model Parameter | 𝜏r0 (sec ± SE) | P0 (±SE) | 𝜏FDR (ms ± SE) | αFDR (±SE) | r2 | Rorb Z-score | Sim1 Z-score | Tlx3 Z-score |
|---|---|---|---|---|---|---|---|---|
| Rorb | 1.26 ± 0.29 | 0.30 ± 0.03 | 130.6 ± 56.8 | 0.85 ± 0.09 | 0.836 | N/A | P0 = 2.02 | P0 = 3.55 |
| Sim1 | 3.55 ± 0.93 | 0.22 ± 0.02 | 269.4 ± 128.2 | 0.77 ± 0.12 | 0.836 | 𝜏r0 = 2.31 | N/A | P0 = 2.12 |
| Tlx3 | 1.20 ± 0.62 | 0.16 ± 0.02 | 276.3 ± 213.2 | 0.47 ± 0.09 | 0.737 | 𝜏r0 = 1.12 | 𝜏r0 = 2.79 | N/A |
Additional files
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Supplementary file 1
Description of features extracted from raw data to use in synapse classifier.
- https://doi.org/10.7554/eLife.37349.028
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Transparent reporting form
- https://doi.org/10.7554/eLife.37349.029
