Journal: Neuron

Article Title: A Distance-Dependent Distribution of Presynaptic Boutons Tunes Frequency-Dependent Dendritic Integration

doi: 10.1016/j.neuron.2018.06.015

Figure Lengend Snippet: Increases in Short-Term Facilitation with Distance along a Dendrite Boost Distal Synaptic Integration (A) Whole-cell patch-clamp technique was used to record synaptic currents and fill CA1 pyramidal cells with a fluorescent dye to image its structure. Two stimulating pipettes were placed in the proximal (red) and distal (blue) extracellular domains of the basal dendritic tree of pyramidal cells to stimulate the local fibers. (B) Single cell example of average EPSC responses (average of 20 individual sweeps) to trains of 5 pulses at 20 Hz delivered to the proximal region (red trace) and the distal region (blue trace). The distal response shows greater facilitation compared to the proximal one. (C) Normalized average peak EPSC amplitudes for distal and proximal responses show greater sustained facilitation during a 5 pulse train (20 Hz) for distal synapses, n = 35 cells, multiple t tests with p values adjusted with the Holm-Sidak method, p < 0.05. (D) Paired-pulse ratios (PPRs) for each individual cell recorded at distal and proximal synapses. The majority (29/35) of cells display greater facilitation in the distal domain, n = 35 cells, p = 0.0003 two-tailed paired t test. (E) Distal increase in PPR is not ascribable to postsynaptic AMPA receptor desensitization (prevented by CTZ application) or to AMPA receptor saturation (avoided with γDGG application). Distal PPR is greater than proximal PPR with CTZ (n = 9 cells, p = 0.01), and γDGG (n = 13 cells, p < 0.01), two-tailed paired t test. Two-way ANOVA to test PPRs in control (D), CTZ, and γDGG conditions together shows no significant interaction, p = 0.84, indicating that the drugs have no effect on STP properties. (F) Full Synaptotagmin7 KO eliminates facilitation and proximo-distal STP differences. Triangles in lighter colors are from Syt7KO mice, n = 9 cells, circles in darker colors are littermate wild-type mice, n = 12 cells. For WT mice, proximal facilitation is lower than distal, multiple t tests, p < 0.05. WT facilitation is greater than Syt7KO facilitation, p < 0.01 multiple t tests. (G–I) Distal synaptic EPSCs take longer to reach the soma. (G) Left panel: normalized trace for a proximal and distal EPSC response showing the delayed kinetics of the distal compared to the proximal synaptic current. Right panel: the rise time constant of the EPSCs was significantly higher in distally triggered events, n = 49 cells, p < 0.001 Wilcoxon signed rank test. (H) Longer rise times correlate with the amount of facilitation, Spearman’s correlation. (I) PPR is higher when the stimulation electrode is placed further away from the soma, measured as distance along the dendrite, Spearman’s correlation. (J) Proximal synapses display greater P r than distal synapses. After MK-801 bath application, the normalized amplitude of EPSCs from proximally stimulated synapses decay faster, following successive stimulations, than distal ones; n = 8 cells. Data points were fit with a double exponential function (filled lines). Insets are example traces of 7 successive NMDA mediated EPSCs. (K) Frequency tuning curve showing PPRs for all frequencies tested. Distal PPRs (second stimulus only) increase significantly in the 20 Hz (n = 35) same as (D), and 50 Hz range (n = 20), p < 0.05, multiple t tests with Holm-Sidak adjusted p values. 5 Hz (n = 13 cells), 10 Hz (n = 16), 80 Hz (n = 9). (L–M) Short-term facilitation contributes to dendritic non-linear events in distal domains. (L) Current-clamp example traces (red proximal, blue distal stimulation) in response to a paired pulse, of increasing stimulus intensity (lighter color shades represent lower intensity). (M) The proportion of supra-linear events (at least 2 mV above the expected response) for distal synapses is greatly increased for the second pulse (P2) following facilitation at 20 Hz (0 events in P1, 8 events in P2, n = 10), while supra-linear events were detected to the first pulse (P1) for proximal stimulations (n = 10, 4 in P1, 5 in P2). At 5 Hz, where STP is absent, distal synapses had fewer supra-linear events (n = 5, 0 in P1, 2 in P2). See also and . Data are represented as mean ± SEM.

Article Snippet: For the NMDAR depletion experiments the extracellular solution contained the AMPAR channel blocker NBQX 10 μM (Santa Cruz Biotechnology) instead of AP-5.

Techniques: Patch Clamp, Two Tailed Test, Control

Journal: Neuron

Article Title: A Distance-Dependent Distribution of Presynaptic Boutons Tunes Frequency-Dependent Dendritic Integration

doi: 10.1016/j.neuron.2018.06.015

Figure Lengend Snippet:

Article Snippet: For the NMDAR depletion experiments the extracellular solution contained the AMPAR channel blocker NBQX 10 μM (Santa Cruz Biotechnology) instead of AP-5.

Techniques: Recombinant, Software

Journal: Nature

Article Title: Sustained antidepressant effect of ketamine through NMDAR trapping in the LHb

doi: 10.1038/s41586-023-06624-1

Figure Lengend Snippet: a , Experimental paradigm for slice recording after intraperitoneal injection of ketamine (10 mg kg −1 ) in CRS mice. b , Schematic of whole-cell recording of evoked synaptic responses in sagittal LHb slices. c – n , Data from temporally isolated AMPAR-eEPSCs and NMDAR-eEPSCs. c , i , Example traces of evoked AMPAR-eEPSCs (–70 mV, measured at the peak) and NMDAR-eEPSCs (+40 mV, measured at 35 ms after stimulation, dotted line) in LHb neurons in the presence of picrotoxin (PTX) at 1 h ( c ) and 24 h ( i ) after intraperitoneal injection of saline or ketamine in CRS mice. d , j , Ratios of NMDAR-eEPSCs and AMPAR-eEPSCs (recorded at 1.5 mA stimulation intensity) at 1 h ( d ) and 24 h ( j ) after intraperitoneal injection of saline or ketamine in CRS mice. e , g , k , m , Stimulus–response (input–output) curves of NMDAR-eEPSCs ( e , k ) and AMPAR-eEPSCs ( g , m ) of LHb neurons at 1 h ( e , g ) and 24 h ( k , m ) after intraperitoneal injection of saline or ketamine in CRS mice. f , h , l , n , Bar graphs of NMDAR-eEPSCs ( f , l ) and AMPAR-eEPSCs ( h , n ) recorded at 1.5 mA stimulation intensity at 1 h ( f , h ) and 24 h ( l , n ) after injection of saline or ketamine in CRS mice. o – r , Data from pharmacologically isolated pure NMDAR-eEPSCs. o , q , Example traces of evoked NMDAR-eEPSCs (+40 mV, measured at the peak) of LHb neurons in the presence of picrotoxin and NBQX at 1 h ( o ) and 24 h ( q ) after injection of saline or ketamine. p , r , Stimulus–response (input–output) curves of NMDAR-eEPSCs (isolated by application of picrotoxin and NBQX under voltage clamp at +40 mV) of LHb neurons at 1 h ( p ) and 24 h ( r ) after injection of saline or ketamine. Error bars indicate the s.e.m. (see Supplementary Table for statistical analyses and n numbers).

Article Snippet: Then, 10 μM NBQX (an AMPAR blocker, Sigma) was perfused into the recording solution to block AMPAR currents.

Techniques: Injection, Isolation, Saline

Journal: Nature

Article Title: Sustained antidepressant effect of ketamine through NMDAR trapping in the LHb

doi: 10.1038/s41586-023-06624-1

Figure Lengend Snippet: a , Left: example traces of LHb eEPSCs evoked at +40 mV in presence of PTX (black), PTX + NBQX (blue) and PTX + NBQX + AP5 (red) in ACSF. Right: Amplitudes of eEPSCs measured at 35 ms after stimulation onset. Note that eEPSC amplitudes at 35 ms post stimulation are not significantly affected by NBQX blockade of AMPARs, but are greatly reduced by AP5 blockade of NMDARs, indicating that the major component at this time point is NMDAR-eEPSC. b , c , Bar graphs showing percentage of NMDAR-eEPSCs smaller or larger than 10 pA at 1 h ( b ) and 24 h ( c ) after saline or ketamine treatment. d - f , Bar graphs of ratios of NMDAR-eEPSCs and AMPAR-eEPSCs ( d ), NMDAR-eEPSCs ( e ) and AMPAR-eEPSCs ( f ) of LHb neurons at 1.5 mA stimulation intensity from brain slices prepared at 3 d after i.p. injection of saline or ketamine in CRS mice. g , Percentage of blockade of NMDAR-eEPSCs at each time point calculated as (saline value - ketamine value)/saline value. * P < 0.05; **** P < 0.0001; NS, not significant. Error bars indicate SEMs. (see Supplementary Table for statistical analyses and n numbers). This figure is related to Fig. .

Article Snippet: Then, 10 μM NBQX (an AMPAR blocker, Sigma) was perfused into the recording solution to block AMPAR currents.

Techniques: Saline, Injection