Journal: Journal of Neurophysiology

Article Title: Spatiotemporal Dynamics of Rhythmic Spinal Interneurons Measured With Two-Photon Calcium Imaging and Coherence Analysis

doi: 10.1152/jn.00679.2010

Figure Lengend Snippet: Two-photon calcium imaging of ventral spinal interneurons during fictive locomotion. A: experimental setup (MPM, multiphoton microscope; iVR/cVR, ipsilateral/contralateral ventral root extracellular recordings in the upper lumbar spinal cord, from T13 to L2). B: visualization of Hb9-GFP interneurons that showed GFP expression when excited at 900 nm. C: ventromedial spinal interneurons loaded with Fluo-3 AM and imaged at 800 nm. D: cell bodies were manually selected as regions of interest and calcium signals summed from the individual regions of interest. E: time-lapse fluorescence of 35 ventromedial spinal interneurons recorded simultaneously in a single trial. Using multitaper coherence analysis on 3 repeated trials, the rhythmic activity of the cells was classified as coherent if |C| ≥ |C|P = 0.05 (green) or not coherent if |C| < |C|P = 0.05 (black) with the ipsilateral ventral root motor output (bottom). Cells 22, 23, and 25 were Hb9 interneurons confirmed by GFP fluorescence and post hoc X-gal staining for LacZ expression.

Article Snippet: The analysis was implemented in 64-bit MATLAB with the multitaper spectral analysis package Chronux ( www.chronux.org ) ( Mitra and Bokil 2008 ).

Techniques: Imaging, Microscopy, Expressing, Fluorescence, Activity Assay, Staining

Journal: Journal of Neurophysiology

Article Title: Spatiotemporal Dynamics of Rhythmic Spinal Interneurons Measured With Two-Photon Calcium Imaging and Coherence Analysis

doi: 10.1152/jn.00679.2010

Figure Lengend Snippet: Multitaper coherence analysis of simulated and experimental calcium imaging data. A: a model neuron fires once at the peak of the neural circuit's output. The circuit output was a sine function and fluorescence was the spike pattern convolved with an exponentially decaying function. B: the power spectra of the simulated fluorescence and the circuit output. The peak of the circuit output power spectra, the circuit output frequency, is indicated by a gray triangle. C: multitaper coherence analysis showed that at the circuit output frequency (gray triangle), the simulated fluorescence trace was highly rhythmic (coherence magnitude, |C| = 1) and lagged the circuit output with a fixed phase of 1.14 caused by the calcium dynamics. The |C|P = 0.05 value is indicated by a gray line. D–F: the same analysis applied to a model neuron that fires as a Poisson process with a sinusoidal firing rate. The average firing rate is ∼2 Hz. The same simulated circuit output was used to calculate coherence. G–I: the same analysis was applied to experimental data from the fluorescence of a ventromedial spinal interneuron and the extracellular recording of an ipsilateral ventral root. Three trials were acquired consecutively, and the raw data were plotted for 1 of the trials. The trial-averaged power spectra were calculated for the fluorescence and the rectified root trace. Coherence was calculated for each of the 3 trials (thin lines) and trial-averaged (thick line).

Article Snippet: The analysis was implemented in 64-bit MATLAB with the multitaper spectral analysis package Chronux ( www.chronux.org ) ( Mitra and Bokil 2008 ).

Techniques: Imaging, Fluorescence