[project_vectorstrength] text improvements

projects/project_vector_strength/vector_strength.tex

@@ -11,9 +11,16 @@
 
 %%%%%%%%%%%%%% Questions %%%%%%%%%%%%%%%%%%%%%%%%%
 \section*{Quantifying the coupling of action potentials to the EOD.}
-P-unit electroreceptors are driven by the fish's self-generated field,
-the EOD. In this project you have to quantify the strength of this
-coulpling using the \textbf{vector strength}:
+Phase coupling of neuronal activity is observed in several
+system. This means that the action potentials fired by a neuron occur
+with specific phase relation to the driving periodic signal. For example sensory
+neurons in the auditory system and the electrosensory system fire in
+close phase relation to the stimulus frequncy.  P-type electroreceptor
+afferents (P-units) of the weakly electric fish \emph{Apteronotus
+  leptorhynchus} are driven by the fish's self-generated field, the
+EOD and fire action potentials phase locked to it. In this project you
+have to quantify the strength of this coulpling using the
+\textbf{vector strength}:
 \begin{equation}
  VS = \sqrt{\left(\frac{1}{n}\sum_{i=1}^{n}\cos
  \alpha_i\right)^2 + \left(\frac{1}{n}\sum_{i = 1}^{n} \sin \alpha_i
@@ -26,20 +33,22 @@ locking, respectively.
 
 \begin{questions}
   \question In the accompanying datasets you find recordings of the
-  ``baseline'' activity of P-unit electroreceptors of different weakly
-  electric fish of the species \textit{Apteronotus leptorhynchus}.
-  The files further contain respective recordings of the \textit{eod},
-  i.e. the fish's field The data is sampled with 20\,kHz and the spike
-  times are given in seconds.
+  ``baseline'' activity of P-unit electroreceptors (in the absence of
+  an external stimulus) of different weakly electric fish of the
+  species \textit{Apteronotus leptorhynchus}.  The files further
+  contain respective recordings of the \textit{eod}, i.e. the fish's
+  electric field. The data is sampled with 20\,kHz and the spike times
+  are given in seconds.
   \begin{parts}
-    \part Plot the average EOD waveform of each fish together with an respective PSTH.
+    \part Illustrate the phase locking by plotting the PSTH within the EOD cycle.
     \part Implement a function that estimates the vector strength
-    between the \textit{eod} and the spikes.
+    between the \textit{EOD} and the spikes.
     \part Create a polar plot that shows the timing of the spikes 
     relatve to the EOD.
-    \part Analyze the baseline responses of each fish and extrace measures as were introduced in chapter 8 of the script. Plot the results
+    \part Apply an appropriate statistical test to check whether locking is statistically significant.
+    \part Analyze the baseline responses of each fish and extract measures as were introduced in chapter 10 of the script. Plot the results
     appropriately.
-    \part Does the vector strength correlate with the EOD frequency? 
+    \part Does the vector strength correlate with the EOD frequency or the reponse variability (CV)?
   \end{parts}
 \end{questions}