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[project_photoreceptor] beter descriptions

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Jan Grewe 2019-01-10 17:56:59 +01:00
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projects/project_photoreceptor/photoreceptor.tex
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@ -11,11 +11,16 @@
%%%%%%%%%%%%%% Questions %%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%% Questions %%%%%%%%%%%%%%%%%%%%%%%%%
\section*{Analysis of insect photoreceptor data.} \section*{Light responses of an insect photoreceptor.}
In this project you will analyse data from intracellular recordings of In this project you will analyse data from intracellular recordings of
a fly R\.1--6 photoreceptor. The membrane potential of the a fly R\,1--6 photoreceptor. These cells show graded membrane
photoreceptor was recorded while the cell was stimulated with a potential changes in response to a light stimulus. The membrane
light stimulus. potential of the photoreceptor was recorded while the cell was
stimulated with a light stimulus. Intracellular recordings often
suffer from drifts in the resting potential. This leads to a large
variability in the responses which is technical and not a cellular
property. To compensate for such drifts trials are aligned to the
resting potential before stimulus onset.
\begin{questions} \begin{questions}
\question{} The accompanying dataset (photoreceptor\_data.zip) \question{} The accompanying dataset (photoreceptor\_data.zip)
@ -24,22 +29,28 @@ light stimulus.
\textit{voltage} a matrix with the recorded membrane potential from \textit{voltage} a matrix with the recorded membrane potential from
10 consecutive trials, (ii) \textit{time} a matrix with the 10 consecutive trials, (ii) \textit{time} a matrix with the
time-axis for each trial, and (iii) \textit{trace\_meta} a structure time-axis for each trial, and (iii) \textit{trace\_meta} a structure
that stores several metadata. This is the place where you find the that stores several metadata including the \emph{amplitude} value
\emph{amplitude}, that is the voltage that drives the light that is the voltage used to drive the light stimulus. (Note that
stimulus, i.e. the light-intensity. this voltage is only a proxy for the true light intensity. Twice the
voltage does not lead to twice the light intensity. Within this
project, however, you can treat it as if it was the intensity.)
\begin{parts} \begin{parts}
\part{} Create a plot of the raw data. Plot the average response as \part{} Create a plot of the raw data. For each light intensity plot the average response
a function of time. This plot should also show the as a function of time. This plot should also depict the across-trial
across-trial variability.\\[0.5ex] variability in an appropriate way.\\[0.5ex]
\part{} You will notice that the responses have three main parts, a \part{} You will notice that the responses have three main parts, a
pre-stimulus phase, the phase in which the light was on, and pre-stimulus phase, the phase in which the light was on, and
finally a post-stimulus phase. Create an characteristic curve that finally a post-stimulus phase. Create an characteristic curve that
plots the response strength as a function of the stimulus plots the response strength as a function of the stimulus
intensity for the ``onset'' and the ``steady state'' intensity for the ``onset'' and the ``steady state''
phases.\\[0.5ex] phases of the light response.\\[0.5ex]
\part{} The light switches on at time zero. Estimate the delay between stimulus.\\[0.5ex] \part{} The light switches on at time zero. Estimate the delay between stimulus and response.\\[0.5ex]
\part{} You may also decide to analyze the post-stimulus response in some \part{} Analyze the across trial variability in the ``onset'' and ``steady state''. Check for statistically significant differences.
\pate{} The membrane potential shows some fluctuations (noise)
compare the noise before stimulus onset and in the steady state
phase of the response.
\part{} (optional) You may also analyze the post-stimulus response in some
more detail. more detail.
\end{parts} \end{parts}
\end{questions} \end{questions}