71 lines
2.8 KiB
TeX
71 lines
2.8 KiB
TeX
\documentclass[a4paper,12pt,pdftex]{exam}
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\newcommand{\ptitle}{Interspike-intervall correlations}
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\input{../header.tex}
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\firstpagefooter{Supervisor: Jan Benda}{phone: 29 74573}%
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{email: jan.benda@uni-tuebingen.de}
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\begin{document}
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\input{../instructions.tex}
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%%%%%%%%%%%%%% Questions %%%%%%%%%%%%%%%%%%%%%%%%%
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\begin{questions}
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\question You are recording the activity of a neuron in response to
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constant stimuli of intensity $I$ (think of that, for example,
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of sound waves with intensities $I$). The neuron has an adaptatation
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current that adapts the firing rate with a slow time constant down.
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Explore the dependence of interspike interval correlations on the firing rate,
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adaptation time constant and noise level.
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The neuron is a neuron with an adaptation current.
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It is implemented in the file \texttt{lifadaptspikes.m}. Call it
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with the following parameters:
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\begin{lstlisting}
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trials = 10;
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tmax = 50.0;
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input = 10.0; % the input I
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Dnoise = 1e-2; % noise strength
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adapttau = 0.1; % adaptation time constant in seconds
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adaptincr = 0.5; % adaptation strength
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spikes = lifadaptspikes( trials, input, tmax, Dnoise, adapttau, adaptincr );
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\end{lstlisting}
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The returned \texttt{spikes} is a cell array with \texttt{trials} elements, each being a vector
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of spike times (in seconds) computed for a duration of \texttt{tmax} seconds.
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The input is set via the \texttt{input} variable, the noise strength via \texttt{Dnoise},
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and the adaptation time constant via \texttt{adapttau}.
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\begin{parts}
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\part Measure the intensity-response curve of the neuron, that is the mean firing rate
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as a function of the input for a range of inputs from 0 to 120.
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\part Compute the correlations between each interspike interval $T_i$ and the next one $T_{i+1}$
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(serial interspike interval correlation at lag 1). Plot this correlation as a function of the
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firing rate by varying the input as in (a).
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\part How does this dependence change for different values of the adaptation
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time constant \texttt{adapttau}? Use values between 10\,ms and
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1\,s for \texttt{adapttau}.
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\part Determine the firing rate at which the minimum interspike interval correlation
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occurs. How does the minimum correlation and this firing rate
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depend on the adaptation time constant \texttt{adapttau}?
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\part How do the results change if the level of the intrinsic noise \texttt{Dnoise} is modified?
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Use values of 1e-4, 1e-3, 1e-2, 1e-1, and 1 for \texttt{Dnoise}.
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\uplevel{If you still have time you can continue with the following question:}
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\part How do the interspike interval distributions look like for the different noise levels
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at some example values for the input and the adaptation time constant?
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\end{parts}
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\end{questions}
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\end{document}
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