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Tag Archives: Calcium Imaging
How well do CNNs for spike detection generalize to unseen datasets?
Some time ago, Stephan Gerhard and I have used a convolutional neural network (CNN) to detect neuronal spikes from calcium imaging data. (I have mentioned this before, here, here, and on Github.) This method is covered by the spikefinder paper … Continue reading
Preamplifier bandwidth & two ways of counting photons
For two-photon point scanning microscopy, the excitation laser is typically pulsing at a repetition rate of 80 MHz, that is one pulse each 12.5 ns. To avoid aliasing, it was suggested to synchronize the sampling clock to laser pulses. For this, it is important … Continue reading
Posted in Calcium Imaging, Imaging, Microscopy
Tagged Calcium Imaging, laser scanning microscopy, Microscopy, Scanning
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Whole-cell patch clamp, part 1: introductory reading
Ever since I my interested in neuroscience become more serious, I was fascinated by the patch clamp technique, especially applied for the whole cell. Calcium imaging or multi-channel electrophysiology (recent review) is the way to go in order to get an idea what … Continue reading
Posted in electrophysiology, Microscopy, zebrafish
Tagged Calcium Imaging, electrophysiology, patch clamp, zebrafish
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The larval zebrafish, and the adult zebrafish
Zebrafish are often used as a model organism for in vivo brain imaging, because they are transparent. Or at least that is what many people think who do not work with zebrafish. In reality, most people use zebrafish larvae for in vivo … Continue reading
Posted in Calcium Imaging, Neuronal activity, zebrafish
Tagged Calcium Imaging, zebrafish
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Large field of view microscopes for mouse brain imaging
For typical confocal or two-photon microscopes that maintain (sub)cellular resolution, a high-magnification objective is needed (typically 16x, 20x or 25x). This in turn limits the field of view (FOV) to ⌀ 1.0-1.5 mm. For imaging in the mouse brain cortex, which is … Continue reading
Posted in Calcium Imaging, Imaging, Microscopy
Tagged Calcium Imaging, laser scanning microscopy, Microscopy
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Spatial visualization of temporal components for neuronal activity imaging
The standard analysis workflow for neuronal activity imaging based on calcium signals is to 1) draw ROIs around putative neurons, 2) extract the average fluorescence time trace of this ROI, 3) work with this timetrace for subsequent analysis (principal components, … Continue reading
Posted in Calcium Imaging, Data analysis, Imaging, Neuronal activity
Tagged Calcium Imaging, zebrafish
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Fast z-scanning using a voice coil motor
We just published a paper on fast remote z-scanning using a voice coil motor. For 2P calcium imaging. It’s a nice paper with some interesting technical details. The starting point was the remote z-scanning scheme used by Botcherby et al. (2012) from … Continue reading
Posted in Calcium Imaging, Imaging, Microscopy, Neuronal activity
Tagged Calcium Imaging, laser scanning microscopy, Microscopy, Scanning
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Modulating laser intensity on multiple timescales (x, y and z)
In point-scanning microscopy and especially when using resonant scanners, the intensity of the beam is typically modulated using a Pockels cell. For resonant scanning, the dwell time per micrometer is not constant along the scanned line, and one wants either to … Continue reading
Posted in Calcium Imaging, Imaging, Microscopy
Tagged Calcium Imaging, laser scanning microscopy, Microscopy, Scanning
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Undistort/unwarp images for resonant scanning microscopy
For image acquisition using a resonant scanning microscope, one of the image axes is scanned non-linearly, following the natural sinusoidal movements of the resonant scanner. This leads to a distortion of the acquired images, unless a online correction algorithm or … Continue reading
Posted in Calcium Imaging, Microscopy
Tagged Calcium Imaging, laser scanning microscopy, Microscopy, Scanning, zebrafish
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Point spread functions
One way to characterize the quality of one’s microscope is to measure the point spread function (PSF), that is the image that is created by a point source (which can be a fluorescent bead smaller than the expected size of the … Continue reading
A blog about neurophysiology 