Recent Comments
Category Archives: Calcium Imaging
The power of correlation functions
During my physics studies, I got to know several mathematical tools that turned out to be extremely useful to describe the world and to analyze data, for example vector calculus, fourier analysis or differential equations. Another tool that I find … Continue reading
Posted in Calcium Imaging, Data analysis, electrophysiology
Tagged Data analysis, electrophysiology, Matlab, Microscopy, Python
6 Comments
Annual report of my intuition about the brain
There are not many incentives for young neuroscientists to think aloud about big questions. Due to lack both of knowledge and authority, discussing very broad questions like how the brain works risks to be embarrassing at best. Still, I feel … Continue reading
Whole-cell patch clamp, part 4: look and feel
In previous blog posts, I have been discussing some aspects of whole-cell patch clamp recordings ([1], [2], [3], [4]). Today, I will show some instructive videos that I recorded during experiments. I’m hoping that they will convey the look and feel … Continue reading
Posted in Calcium Imaging, electrophysiology, Imaging, Microscopy, Neuronal activity, zebrafish
Tagged electrophysiology, Microscopy, photons, zebrafish
3 Comments
Precise synaptic balance of excitation and inhibition
The main paper of my PhD just got published: Rupprecht and Friedrich, Precise Synaptic Balance in the Zebrafish Homolog of Olfactory Cortex, Neuron (2018). (PDF) You might like it if you are also interested in Classical balanced networks Things you … Continue reading
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
All-optical entirely passive laser scanning with MHz rates
Is it possible to let a laser beam scan over an angle without moving any mechanical parts to deflect the beam? It is. One strategy is to use a very short-pulsed laser beam: A short pulse width means a finite … Continue reading
How deconvolution of calcium data degrades with noise
How does the noisiness of the recorded calcium data affect the performance of spiking-inferring deconvolution algorithms? I cannot offer a rigorous treatment of this question (Update August 2020: Now I have treated this question rigorously.) , but some intuitive examples. … Continue reading
A convolutional network to deconvolve calcium traces, living in an embedding space of statistical properties
As mentioned before (here and here), the spikefinder competition was set up earlier this year to compare algorithms that infer spiking probabilities from calcium imaging data. Together with Stephan Gerhard, a PostDoc in our lab, I submitted an algorithm based on convolutional networks. Looking … Continue reading
Spike detection competition
The main drawback of functional calcium imaging is its slow dynamics. This is not only due to limited frame rates, but also due to calcium dynamics, which are a slow transient readout of fast spiking activity. A perfect algorithm would infer the … Continue reading
Posted in Calcium Imaging, Data analysis, machine learning
Tagged Data analysis, machine learning, Matlab
2 Comments
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
10 Comments
A blog about neurophysiology 