A critical role for NMDA receptors in parvalbumin interneurons for gamma rhythm induction and behavior methods
Aim. Evidence-backed execution summary for A critical role for NMDA receptors in parvalbumin interneurons for gamma rhythm induction and behavior methods from A critical role for NMDA receptors in parvalbumin interneurons for gamma rhythm induction and behavior.
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mouse
Subject model for the experiment.
- Use
- confirm full cohort details in the source paper
Immunohistochemistry
reagent used in the protocol.
- Use
- Free-floating sections (30 µm) were prepared and immunostained. The following primary antibodies were used: PV PVG-214 (Swant, Bellinzona, Switzerland; 1:2000), enhanced yellow fluorescent protein (EYFP) (GFP-1020 Aves, Tigard, OR, USA; 1:500). Antibody staining was revealed using species-specific fluorop...
Slice electrophysiology
AAV DIO channelrhodopsin-2 (ChR2)-mCherry was injected into hippocampus of 5- to 7-week-old PV-Cre and PV-Cre/NR1f/f mice. At 7-10 days after viral transduction, transverse hippocampal slices (400 µ m thickness) were prepared as described., The tungsten bipolar electrode (FHC, Bowdoin, ME, USA) wa...
- Use
- AAV DIO channelrhodopsin-2 (ChR2)-mCherry was injected into hippocampus of 5- to 7-week-old PV-Cre and PV-Cre/NR1f/f mice. At 7-10 days after viral transduction, transverse hippocampal slices (400 µ m thickness) were prepared as described., The tungsten bipolar electrode (FHC, Bowdoin, ME, USA) wa...
Anesthetized electrophysiology
AAV DIO ChR2-mCherry was injected into barrel cortex of adult (8-12 weeks old) PV-Cre or PV-Cre/NR1f/f mice as described earlier. Electrophysiological in vivo recordings were performed 1-3 weeks after viral injections. Extracellular single-unit and local field potential (LFP) recordings were made with te...
- Use
- AAV DIO ChR2-mCherry was injected into barrel cortex of adult (8-12 weeks old) PV-Cre or PV-Cre/NR1f/f mice as described earlier. Electrophysiological in vivo recordings were performed 1-3 weeks after viral injections. Extracellular single-unit and local field potential (LFP) recordings were made with te...
Anesthetized electrophysiology
Light stimulation was generated by a 473 nm laser and light pulses were given via a 200 µ m diameter, unjacketed optical fiber at the cortical surface 75-200 µ m from the recording electrodes.
- Use
- Light stimulation was generated by a 473 nm laser and light pulses were given via a 200 µ m diameter, unjacketed optical fiber at the cortical surface 75-200 µ m from the recording electrodes.
Anesthetized electrophysiology
Unit and local field potential analysis used software custom written in Igor Pro (Wavemetrics, Portland, OR, USA) by JAC. Spontaneous anesthetized LFP measurements were made during periods with no light stimulation. For each light stimulation frequency, we measured relative power,, in an 8 Hz band centered o...
- Use
- Unit and local field potential analysis used software custom written in Igor Pro (Wavemetrics, Portland, OR, USA) by JAC. Spontaneous anesthetized LFP measurements were made during periods with no light stimulation. For each light stimulation frequency, we measured relative power,, in an 8 Hz band centered o...
Awake electrophysiology
Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) were implanted: two electrodes were placed bilaterally in primary somatosensory (barrel) cortices 1.5 mm posterior to bregma and 3.5R...
- Use
- Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) were implanted: two electrodes were placed bilaterally in primary somatosensory (barrel) cortices 1.5 mm posterior to bregma and 3.5R...
Open field analysis
Activity in a novel open field was measured in monitors with sets of 16 light beam arrays. During 60 min the hardware detected beams broken by the animal, with the software determining the location and activity of the animal. For the pharmacological treatment, one set of mice was first monitored in the open fi...
- Use
- Activity in a novel open field was measured in monitors with sets of 16 light beam arrays. During 60 min the hardware detected beams broken by the animal, with the software determining the location and activity of the animal. For the pharmacological treatment, one set of mice was first monitored in the open fi...
Acoustic startle and prepulse inhibition
For testing of sensorimotor gating, startle response and prepulse inhibition (PPI) were determined using the Startle Monitor System (SM100; Hamilton Kinder, San Diego, CA, USA). The animals were habituated to the experimental equipment for two days. Day 3, the PPI testing day, each animal was exposed to 65 dB...
- Use
- For testing of sensorimotor gating, startle response and prepulse inhibition (PPI) were determined using the Startle Monitor System (SM100; Hamilton Kinder, San Diego, CA, USA). The animals were habituated to the experimental equipment for two days. Day 3, the PPI testing day, each animal was exposed to 65 dB...
T-maze test
For testing of working memory, a modified T-maze, the discrete paired-trial variable-delay alternation task, was used.
- Use
- For testing of working memory, a modified T-maze, the discrete paired-trial variable-delay alternation task, was used.
Awake electrophysiology
Software used for acquisition, scoring, statistics, or reporting.
- Use
- Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) were implanted: two electrodes were placed bilaterally in primary somatosensory (barrel) cortices 1.5 mm posterior to bregma and 3.5R...
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Slice electrophysiology
AAV DIO channelrhodopsin-2 (ChR2)-mCherry was injected into hippocampus of 5- to 7-week-old PV-Cre and PV-Cre/NR1f/f mice. At 7-10 days after viral transduction, transverse hippocampal slices (400 µ m thickness) were prepared as described., The tungsten bipolar electrode (FHC, Bowdoin, ME, USA) was placed in the stratum radiatum or oriens and the Schaffer collateral/commissural fibers were stimulated at 0.1 Hz. Picrotoxin (0.15 m M, Sigma, St Louis, MO, USA) was dissolved in artificial cerebrospinal fluid (aCSF) to block GABA A receptor-mediated synaptic transmission for whole-cell patch clamp recordings. α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated excitatory postsynaptic current (EPSCs) were recorded at -70 mV and NMDAR-mediated EPSCs were recorded at +40 mV with the same stimulus strength in the presen...
Anesthetized electrophysiology
AAV DIO ChR2-mCherry was injected into barrel cortex of adult (8-12 weeks old) PV-Cre or PV-Cre/NR1f/f mice as described earlier. Electrophysiological in vivo recordings were performed 1-3 weeks after viral injections. Extracellular single-unit and local field potential (LFP) recordings were made with tetrodes or stereotrodes. Stimulus control and data acquisition was performed using software custom written in LabView (National Instruments, Austin, TX, USA) and Matlab (The Mathworks, Natick, MA, USA) by Ulf Knoblich.
Awake electrophysiology
Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) were implanted: two electrodes were placed bilaterally in primary somatosensory (barrel) cortices 1.5 mm posterior to bregma and 3.5 mm from the midline. In each hemisphere, a signal electrode was implanted 0.5 mm below the cortical surface and a reference electrode was implanted 1.75 mm below the cortical surface. A stainless steel screw over right posterior parietal cortex served as ground. Recording sessions took place in an empty box to which animals had not been previously exposed. After a 5-10-min habituation period, 20 min of baseline data were recorded for each animal. After the baseline period, four NR1f/f control and four PV-Cre/NR1f/f mice were injected intraperitone...
Characterization of PV-Cre/NR1f/f mice
PV-Cre/NR1f/f mice were viable, developed normally and did not exhibit growth abnormalities or other gross anatomical changes (data not shown). Cre-dependent recombination from the PV locus was specific to PV-expressing cells and followed the postnatal onset of PV expression ( ). PV-Cre-driven recombination in somatosensory cortex and hippocampus was detected at postnatal day 13 (P13) with increased recombination at 29 days (P29) and almost complete recombination at 8 weeks (, ). Whole-cell recordings in hippocampal slices in vitro confirmed the functional loss of NMDAR currents in PV cells in PV-Cre/NR1f/f mice (five cells in four PV-Cre/NR1f/f mice, seven cells in five control mice, P =0.03, unpaired t -test; ). We found the cortical architecture (layers and barrels in somatosensory cortex), migration and differentiation of PV interneurons to be normal in PV-Cre/NR1f/f mice (; P =...
Spontaneous and induced gamma oscillations are altered in PV-Cre/NR1f/f mice
To explore the role of NMDAR in PV interneurons on evoked gamma activity in the awake state, we challenged PV-Cre/NR1f/f mice with an acute administration of the non-competitive NMDAR antagonist MK-801 (0.5 mg kg -1; intraperitoneal; ) or saline (data not shown). In agreement with previous findings, control mice acutely displayed a significant increase in LFP in the 30-50 Hz gamma range (post1, 5-15 min after MK-801 administration; P <0.05, Wilcoxon signed-rank test; ). PV-Cre/NR1f/f mice, in contrast, displayed a significant reduction in gamma-band activity after NMDAR antagonist treatment ( ). Control mice and PV-Cre/NR1f/f mice displayed a significant induction in the 6-10 Hz frequency band relative power at later time points (post2, 25-35 min after MK-801 administration; ). In the 12-24 Hz band, the rel...
Behavioral effects of NMDAR deletion in PV cells
We characterized the PV-Cre/NR1f/f mice in a series of paradigms to assess general locomotor and exploratory behaviors as well as cognitive tasks evaluating learning and memory. The PV-Cre/NR1f/f mice and their littermate controls (NR1f/f) were introduced into an automated novel open field environment at an age of 7 weeks ( n =11 per genotype). We did not observe any consistent behavioral differences between PV-Cre/NR1f/f and control mice over the entire 60 min trial or in any 5 min block after analysis of 18 different parameters, including total distance ( ), locomotion, stereotypy and center/margin time (data not shown).
Behavioral effects of NMDAR deletion in PV cells
We questioned whether PV-Cre/NR1f/f mice at later stages develop behavioral abnormalities in the open field and therefore assessed mice of 11-12 weeks of age ( n =9 per genotype). We found a nonsignificant trend toward a decrease in total distance traveled over the 60-min period for PV-Cre/NR1f/f mice compared with control mice ( P >0.05; Mann-Whitney test; ). Analysis of time spent in the center ( ) or margin of the open field, vertical movements (data not shown) or stereotypy counts ( ) did not reveal differences between the genotypes over the 60-min period.
Behavioral effects of NMDAR deletion in PV cells
Our electrophysiological findings indicate that the PV-Cre/NR1f/f mice have a selective deficit in gamma emergence following optogenetic drive of FS-PV interneurons or pharmacological NMDAR inhibition. To investigate potential behavioral differences in response to acute NMDAR inhibition, we exposed naïve PV-Cre/NR1f/f and control mice ( n =11 per genotype) to the open field for 30 min and then challenged them with administration of the NMDAR antagonist MK-801 at a low dose (0.3 mg kg -1 ) followed by continued exposure to the open field for 60 min. Control mice responded over time to MK-801 administration with increased horizontal activity and induction of stereotypies as previously reported ( ). In contrast, PV-Cre/NR1f/f mice showed a markedly reduced sensitivity to MK801 ( ), consistent with our electrophysiological findings that PV interneu...
Measurement outputs
What raw and processed outputs should exist?
All behavioral tests were performed blind for the genotype of the mice. Male PV-Cre/NR1f/f mice and littermate male controls (NR1f/f) were used for all behavioral tests. Behavio...
- Raw artifact
- Per-sample or per-animal endpoint measurements collected during the experiment
- Processed artifact
- Structured table with cleaned measurements ready for comparison
- Reported as
- Summary statistics and between-group or across-timepoint comparisons
All procedures were conducted in accordance with the National Institutes of Health guidelines and with the approval of the Committee on Animal Care at MIT, Cambridge, MA, USA. W...
- Raw artifact
- Per-sample or per-animal endpoint measurements collected during the experiment
- Processed artifact
- Structured table with cleaned measurements ready for comparison
- Reported as
- Summary statistics and between-group or across-timepoint comparisons
Unit and local field potential analysis used software custom written in Igor Pro (Wavemetrics, Portland, OR, USA) by JAC. Spontaneous anesthetized LFP measurements were made dur...
- Raw artifact
- Per-sample or per-animal endpoint measurements collected during the experiment
- Processed artifact
- Structured table with cleaned measurements ready for comparison
- Reported as
- Summary statistics and between-group or across-timepoint comparisons
Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) we...
- Raw artifact
- Per-sample or per-animal endpoint measurements collected during the experiment
- Processed artifact
- Structured table with cleaned measurements ready for comparison
- Reported as
- Summary statistics and between-group or across-timepoint comparisons
Analysis plan
How should the outputs become interpretable results?
Acquisition
Collect raw experimental outputs with enough metadata to preserve sample identity, condition, and timing.
inferred from protocolPreprocessing / cleaning
All behavioral tests were performed blind for the genotype of the mice.
from paperScoring or quantification
Quantify the primary readouts for this experiment: All behavioral tests were performed blind for the genotype of the mice. Male PV-Cre/NR1f/f mice and littermate male controls (NR1f/f) were used for all behavioral tests. Behavio...; All procedures were conducted in accordance with the National Institutes of Health guidelines and with the approval of the Committee on Animal Care at MIT, Cambridge, MA, USA. W...; Unit and local field potential analysis used software custom written in Igor Pro (Wavemetrics, Portland, OR, USA) by JAC. Spontaneous anesthetized LFP measurements were made dur...; Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) we....
from paperStatistical comparison
All behavioral tests were performed blind for the genotype of the mice. Male PV-Cre/NR1f/f mice and littermate male controls (NR1f/f) were used for all behavioral tests. Behavio...; Spike waveforms of regular spiking (RS) and FS cells were characterized. In each case, FS measurements were made from cells expressing ChR2 and driven by light pulses and RS mea...; Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) we...; PV-Cre/NR1f/f mice were viable, developed normally and did not exhibit growth abnormalities or other gross anatomical changes (data not shown). Cre-dependent recombination from...
from paperReporting output
Report representative outputs alongside summary comparisons for All behavioral tests were performed blind for the genotype of the mice. Male PV-Cre/NR1f/f mice and littermate male controls (NR1f/f) were used for all behavioral tests. Behavio..., All procedures were conducted in accordance with the National Institutes of Health guidelines and with the approval of the Committee on Animal Care at MIT, Cambridge, MA, USA. W..., Unit and local field potential analysis used software custom written in Igor Pro (Wavemetrics, Portland, OR, USA) by JAC. Spontaneous anesthetized LFP measurements were made dur..., Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) we....
inferred from protocolStructured statistical methods
All behavioral tests were performed blind for the genotype of the mice. Male PV-Cre/NR1f/f mice and littermate male controls (NR1f/f) were used for all behavioral tests. Behavio...; Spike waveforms of regular spiking (RS) and FS cells were characterized. In each case, FS measurements were made from cells expressing ChR2 and driven by light pulses and RS mea...; Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) we...; PV-Cre/NR1f/f mice were viable, developed normally and did not exhibit growth abnormalities or other gross anatomical changes (data not shown). Cre-dependent recombination from...
source structuredSource and audit
What supports the facts on this page?
Evidence quotes (8)
AAV DIO channelrhodopsin-2 (ChR2)-mCherry was injected into hippocampus of 5- to 7-week-old PV-Cre and PV-Cre/NR1f/f mice. At 7-10 days after viral transduction, transverse hippocampal slices (400 µ m thickness) were prepared as described., The tungsten bipolar electrode (FHC, Bowdoin, ME, USA) was placed in the stratum radiatum or oriens and the Schaffer collateral/commissural fibers were stimulated at 0.1 Hz. Picrotoxin (0.15 m M, Sigma, St Louis, MO, USA) was dissolved in artificial cerebrospinal fluid (aCSF) to block GABA A receptor-mediated synaptic transmission for whole-cell patch clamp recordings. α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated excitatory postsynaptic current (EPSCs) were recorded at -70 mV and NMDAR-mediated EPSCs were recorded at +40 mV with the same stimulus strength in the presence of NBQX (0.005 m M, Tocris, Ellisville, MO, USA).
AAV DIO ChR2-mCherry was injected into barrel cortex of adult (8-12 weeks old) PV-Cre or PV-Cre/NR1f/f mice as described earlier. Electrophysiological in vivo recordings were performed 1-3 weeks after viral injections. Extracellular single-unit and local field potential (LFP) recordings were made with tetrodes or stereotrodes. Stimulus control and data acquisition was performed using software custom written in LabView (National Instruments, Austin, TX, USA) and Matlab (The Mathworks, Natick, MA, USA) by Ulf Knoblich.
Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) were implanted: two electrodes were placed bilaterally in primary somatosensory (barrel) cortices 1.5 mm posterior to bregma and 3.5 mm from the midline. In each hemisphere, a signal electrode was implanted 0.5 mm below the cortical surface and a reference electrode was implanted 1.75 mm below the cortical surface. A stainless steel screw over right posterior parietal cortex served as ground. Recording sessions took place in an empty box to which animals had not been previously exposed. After a 5-10-min habituation period, 20 min of baseline data were recorded for each animal. After the baseline period, four NR1f/f control and four PV-Cre/NR1f/f mice were injected intraperitoneally with 0.5 mg kg -1 of MK-801 and four NR1f/f control and four PV-Cre/NR1f/f mice were injected intraperitoneally with saline and another 40 min of data were recorded. The behavioral state of all animals was scored by an observer blind to the genotype, and the sessions for...
PV-Cre/NR1f/f mice were viable, developed normally and did not exhibit growth abnormalities or other gross anatomical changes (data not shown). Cre-dependent recombination from the PV locus was specific to PV-expressing cells and followed the postnatal onset of PV expression ( ). PV-Cre-driven recombination in somatosensory cortex and hippocampus was detected at postnatal day 13 (P13) with increased recombination at 29 days (P29) and almost complete recombination at 8 weeks (, ). Whole-cell recordings in hippocampal slices in vitro confirmed the functional loss of NMDAR currents in PV cells in PV-Cre/NR1f/f mice (five cells in four PV-Cre/NR1f/f mice, seven cells in five control mice, P =0.03, unpaired t -test; ). We found the cortical architecture (layers and barrels in somatosensory cortex), migration and differentiation of PV interneurons to be normal in PV-Cre/NR1f/f mice (; P =0.65 for layers 2/3 and P =0.53 for layers 4-6, two-tailed unpaired t -test; n =3 per genotype).
To explore the role of NMDAR in PV interneurons on evoked gamma activity in the awake state, we challenged PV-Cre/NR1f/f mice with an acute administration of the non-competitive NMDAR antagonist MK-801 (0.5 mg kg -1; intraperitoneal; ) or saline (data not shown). In agreement with previous findings, control mice acutely displayed a significant increase in LFP in the 30-50 Hz gamma range (post1, 5-15 min after MK-801 administration; P <0.05, Wilcoxon signed-rank test; ). PV-Cre/NR1f/f mice, in contrast, displayed a significant reduction in gamma-band activity after NMDAR antagonist treatment ( ). Control mice and PV-Cre/NR1f/f mice displayed a significant induction in the 6-10 Hz frequency band relative power at later time points (post2, 25-35 min after MK-801 administration; ). In the 12-24 Hz band, the relative power remained unchanged in control animals during the same time frame, but was significantly reduced in PV-Cre/NR1f/f animals ( ). Saline treatment did not induce any significant changes in locomotor behavior or relative power in any frequency band between genotypes throughout the duration of...
We characterized the PV-Cre/NR1f/f mice in a series of paradigms to assess general locomotor and exploratory behaviors as well as cognitive tasks evaluating learning and memory. The PV-Cre/NR1f/f mice and their littermate controls (NR1f/f) were introduced into an automated novel open field environment at an age of 7 weeks ( n =11 per genotype). We did not observe any consistent behavioral differences between PV-Cre/NR1f/f and control mice over the entire 60 min trial or in any 5 min block after analysis of 18 different parameters, including total distance ( ), locomotion, stereotypy and center/margin time (data not shown).
We questioned whether PV-Cre/NR1f/f mice at later stages develop behavioral abnormalities in the open field and therefore assessed mice of 11-12 weeks of age ( n =9 per genotype). We found a nonsignificant trend toward a decrease in total distance traveled over the 60-min period for PV-Cre/NR1f/f mice compared with control mice ( P >0.05; Mann-Whitney test; ). Analysis of time spent in the center ( ) or margin of the open field, vertical movements (data not shown) or stereotypy counts ( ) did not reveal differences between the genotypes over the 60-min period.
Our electrophysiological findings indicate that the PV-Cre/NR1f/f mice have a selective deficit in gamma emergence following optogenetic drive of FS-PV interneurons or pharmacological NMDAR inhibition. To investigate potential behavioral differences in response to acute NMDAR inhibition, we exposed naïve PV-Cre/NR1f/f and control mice ( n =11 per genotype) to the open field for 30 min and then challenged them with administration of the NMDAR antagonist MK-801 at a low dose (0.3 mg kg -1 ) followed by continued exposure to the open field for 60 min. Control mice responded over time to MK-801 administration with increased horizontal activity and induction of stereotypies as previously reported ( ). In contrast, PV-Cre/NR1f/f mice showed a markedly reduced sensitivity to MK801 ( ), consistent with our electrophysiological findings that PV interneurons are an important target for the non-competitive NMDAR antagonists.
Machine-readable layer
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"name": "A critical role for NMDA receptors in parvalbumin interneurons for gamma rhythm induction and behavior methods",
"description": "Evidence-backed execution summary for A critical role for NMDA receptors in parvalbumin interneurons for gamma rhythm induction and behavior methods from A critical role for NMDA receptors in parvalbumin interneurons for gamma rhythm induction and behavior.",
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"text": "AAV DIO channelrhodopsin-2 (ChR2)-mCherry was injected into hippocampus of 5- to 7-week-old PV-Cre and PV-Cre/NR1f/f mice. At 7-10 days after viral transduction, transverse hippocampal slices (400 µ m thickness) were prepared as described., The tungsten bipolar electrode (FHC, Bowdoin, ME, USA) was placed in the stratum radiatum or oriens and the Schaffer collateral/commissural fibers were stimulated at 0.1 Hz. Picrotoxin (0.15 m M, Sigma, St Louis, MO, USA) was dissolved in artificial cerebrospinal fluid (aCSF) to block GABA A receptor-mediated synaptic transmission for whole-cell patch clamp recordings. α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated excitatory postsynaptic current (EPSCs) were recorded at -70 mV and NMDAR-mediated EPSCs were recorded at +40 mV with the same stimulus strength in the presen..."
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"name": "Anesthetized electrophysiology",
"text": "AAV DIO ChR2-mCherry was injected into barrel cortex of adult (8-12 weeks old) PV-Cre or PV-Cre/NR1f/f mice as described earlier. Electrophysiological in vivo recordings were performed 1-3 weeks after viral injections. Extracellular single-unit and local field potential (LFP) recordings were made with tetrodes or stereotrodes. Stimulus control and data acquisition was performed using software custom written in LabView (National Instruments, Austin, TX, USA) and Matlab (The Mathworks, Natick, MA, USA) by Ulf Knoblich."
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"text": "Eight NR1f/f control and eight PV-Cre/NR1f/f mice (8-10 weeks) were used for awake electrophysiology. Teflon-coated tungsten electrodes (impedance of 100 kΩ) were implanted: two electrodes were placed bilaterally in primary somatosensory (barrel) cortices 1.5 mm posterior to bregma and 3.5 mm from the midline. In each hemisphere, a signal electrode was implanted 0.5 mm below the cortical surface and a reference electrode was implanted 1.75 mm below the cortical surface. A stainless steel screw over right posterior parietal cortex served as ground. Recording sessions took place in an empty box to which animals had not been previously exposed. After a 5-10-min habituation period, 20 min of baseline data were recorded for each animal. After the baseline period, four NR1f/f control and four PV-Cre/NR1f/f mice were injected intraperitone..."
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"name": "Characterization of PV-Cre/NR1f/f mice",
"text": "PV-Cre/NR1f/f mice were viable, developed normally and did not exhibit growth abnormalities or other gross anatomical changes (data not shown). Cre-dependent recombination from the PV locus was specific to PV-expressing cells and followed the postnatal onset of PV expression ( ). PV-Cre-driven recombination in somatosensory cortex and hippocampus was detected at postnatal day 13 (P13) with increased recombination at 29 days (P29) and almost complete recombination at 8 weeks (, ). Whole-cell recordings in hippocampal slices in vitro confirmed the functional loss of NMDAR currents in PV cells in PV-Cre/NR1f/f mice (five cells in four PV-Cre/NR1f/f mice, seven cells in five control mice, P =0.03, unpaired t -test; ). We found the cortical architecture (layers and barrels in somatosensory cortex), migration and differentiation of PV interneurons to be normal in PV-Cre/NR1f/f mice (; P =..."
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"name": "Spontaneous and induced gamma oscillations are altered in PV-Cre/NR1f/f mice",
"text": "To explore the role of NMDAR in PV interneurons on evoked gamma activity in the awake state, we challenged PV-Cre/NR1f/f mice with an acute administration of the non-competitive NMDAR antagonist MK-801 (0.5 mg kg -1; intraperitoneal; ) or saline (data not shown). In agreement with previous findings, control mice acutely displayed a significant increase in LFP in the 30-50 Hz gamma range (post1, 5-15 min after MK-801 administration; P <0.05, Wilcoxon signed-rank test; ). PV-Cre/NR1f/f mice, in contrast, displayed a significant reduction in gamma-band activity after NMDAR antagonist treatment ( ). Control mice and PV-Cre/NR1f/f mice displayed a significant induction in the 6-10 Hz frequency band relative power at later time points (post2, 25-35 min after MK-801 administration; ). In the 12-24 Hz band, the rel..."
},
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"name": "Behavioral effects of NMDAR deletion in PV cells",
"text": "We characterized the PV-Cre/NR1f/f mice in a series of paradigms to assess general locomotor and exploratory behaviors as well as cognitive tasks evaluating learning and memory. The PV-Cre/NR1f/f mice and their littermate controls (NR1f/f) were introduced into an automated novel open field environment at an age of 7 weeks ( n =11 per genotype). We did not observe any consistent behavioral differences between PV-Cre/NR1f/f and control mice over the entire 60 min trial or in any 5 min block after analysis of 18 different parameters, including total distance ( ), locomotion, stereotypy and center/margin time (data not shown)."
},
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"@type": "HowToStep",
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"name": "Behavioral effects of NMDAR deletion in PV cells",
"text": "We questioned whether PV-Cre/NR1f/f mice at later stages develop behavioral abnormalities in the open field and therefore assessed mice of 11-12 weeks of age ( n =9 per genotype). We found a nonsignificant trend toward a decrease in total distance traveled over the 60-min period for PV-Cre/NR1f/f mice compared with control mice ( P >0.05; Mann-Whitney test; ). Analysis of time spent in the center ( ) or margin of the open field, vertical movements (data not shown) or stereotypy counts ( ) did not reveal differences between the genotypes over the 60-min period."
},
{
"@type": "HowToStep",
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"name": "Behavioral effects of NMDAR deletion in PV cells",
"text": "Our electrophysiological findings indicate that the PV-Cre/NR1f/f mice have a selective deficit in gamma emergence following optogenetic drive of FS-PV interneurons or pharmacological NMDAR inhibition. To investigate potential behavioral differences in response to acute NMDAR inhibition, we exposed naïve PV-Cre/NR1f/f and control mice ( n =11 per genotype) to the open field for 30 min and then challenged them with administration of the NMDAR antagonist MK-801 at a low dose (0.3 mg kg -1 ) followed by continued exposure to the open field for 60 min. Control mice responded over time to MK-801 administration with increased horizontal activity and induction of stereotypies as previously reported ( ). In contrast, PV-Cre/NR1f/f mice showed a markedly reduced sensitivity to MK801 ( ), consistent with our electrophysiological findings that PV interneu..."
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