84 lines
3.0 KiB
TeX
84 lines
3.0 KiB
TeX
\documentclass[a4paper,12pt,pdftex]{exam}
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\newcommand{\ptitle}{Serial ISI correlations}
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\input{../header.tex}
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\firstpagefooter{Supervisor: Jan Benda}{}{email: jan.benda@uni-tuebingen.de}
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\begin{document}
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\input{../instructions.tex}
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The gymnotiform weakly electric fish \textit{Apteronotus
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leptorhynchus} has an active electrosensory system. An electric
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organ generates an electric field surrounding the
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fish. Electroreceptive organs distributed over the whole body of the
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fish sense minute perturbations of the electric field caused by
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objects close to the fish. P-unit electroreceptor afferents send
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information from the electroreceptive organs to the brain. They are
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spontaneously active when the fish is not electrically stimulated,
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that is when the electroreceptors are only stimulated by the fish's
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own unperturbed electric field.
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In this project we want to analyze how the baseline firing rates and
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the serial correlations of the interspike intervals vary between
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different P-units.
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In the file \texttt{baselinespikes.mat} you find two variables:
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\texttt{cells} is a cell-array with the names of the recorded cells
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and \texttt{spikes} is a cell array containing the spike times in
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seconds of recorded spontaneous activity for each of these cells.
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\begin{questions}
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\question Baseline firing properties
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\begin{parts}
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\part Load the data! How many cells are contained in the file?
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\part Plot the spike rasters of a few cells.
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For the presentation, choose a few cells based on the results of
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this project.
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By just looking on the spike rasters, what are the differences
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between the cells?
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\part Compute the firing rate of each cell, i.e. number of spikes per time.
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Illustrate the results by means of a histogram and/or box whisker plot.
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\part Compute interspike-interval histograms and the
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coefficient-of-variation of the interspike intervals, $C_{ISI}$,
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for each of the cells.
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\end{parts}
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\question Serial correlations
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\begin{parts}
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\part Compute and plot the serial correlations between interspike
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intervals up to lag 10.
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What do you observe? In what way are the interspike-interval
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correlations similar betwen the cells? How do they differ?
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\part Illustrate relevant serial correlations with a return
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map. How is the return map related to what you see in the
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corresponding raster plot? How is it related to the corresponding
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serial correlation?
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\part Implement a permutation test for computing the significance
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at an appropriate significance level of the serial
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correlations. Keep in mind that you test the correlations at 10
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different lags. At which lags are the serial correlations
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statistically significant?
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\part Are the serial correlations somehow dependent on the firing rate?
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Plot the significant correlations against the firing rate. Do you
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observe any dependence?
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Use an appropriate statistical test to support your observation.
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\end{parts}
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\end{questions}
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\end{document}
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