Journal: eNeuro

Article Title: Calcium Imaging of Parvalbumin Neurons in the Dorsal Root Ganglia

doi: 10.1523/ENEURO.0349-18.2019

Figure Lengend Snippet: Approach for calcium imaging of proprioceptors in the intact DRG. A , Schematic of the imaging preparation. Electrical stimulation of the sciatic nerve evoked action potentials in peripheral sensory neurons. Compound action potentials were recorded via a suction electrode on the proximal dorsal root. PV+ sensory neurons, consisting mainly of proprioceptors but also some mechanoreceptors, expressed GCaMP6s using a Cre- lox strategy. Two-photon calcium imaging data were acquired from single neurons in the intact lumbar 5 (L5) DRG. B , A representative image of a GCaMP6s-expressing DRG neuron responding to electrical stimulation. Yellow line indicates the region chosen for line scan analysis (at ∼700-Hz scanning rate). C , Heat map of the electrically evoked change in fluorescence across the line scan (oriented vertically) over time (horizontal axis). Optical recording begins 5 s before stimulus is delivered to establish pre-stimulus resting fluorescence. D , Compound action potentials recorded from the L5 dorsal root during the stimulus train. Action potentials are observed with every electrical pulse (0.1-ms pulses at 50 Hz for 0.5 s). Amplitude of the compound action potential remains stable throughout the stimulus. Area within dotted box is enlarged in the box on the upper right corner. E , Representative calcium transient evoked by electrical stimulation (box on gray bar). The average fluorescence across the length of the line scan at each time point composes the raw calcium transient. F , A smoothing algorithm removes high frequency signal fluctuations. Analysis scripts quantify four parameters of the transient: peak amplitude (peak), RT, decay constant (DT1), and recovery time (DT2). For descriptions of each parameter, see Results.

Article Snippet: Extracellular recordings of compound action potentials in the L5 dorsal root were made to confirm the consistency of the nerve stimulation (EX4-400 Quad differential amplifier, low cut filter: 2 Hz, high cut filter: 10 kHz, gain: 1000×; Dagan Corp.; digitized using Clampex, version 10.7; Fig. 1 D ).

Techniques: Imaging, Expressing, Fluorescence

Journal: eNeuro

Article Title: Calcium Imaging of Parvalbumin Neurons in the Dorsal Root Ganglia

doi: 10.1523/ENEURO.0349-18.2019

Figure Lengend Snippet: Calcium transients evoked by nerve stimulation at various frequencies. A , Example transients from one cell following stimulation for 0.5 s at frequencies from 1 to 300 Hz. For reference, the standard stimulation of 25 action potentials used elsewhere in this study is shown in yellow. B , Resting fluorescence measured in arbitrary units does not change with increasing stimulation frequencies. C–F , Plots of transient parameter changes with varying stimulation frequencies. Error bars indicate SEM for responses evoked by stimulation frequencies of 10 Hz and higher.

Article Snippet: Extracellular recordings of compound action potentials in the L5 dorsal root were made to confirm the consistency of the nerve stimulation (EX4-400 Quad differential amplifier, low cut filter: 2 Hz, high cut filter: 10 kHz, gain: 1000×; Dagan Corp.; digitized using Clampex, version 10.7; Fig. 1 D ).

Techniques: Fluorescence