Margot edited MethodsThe_Hindmarsh_Rose_ModelThe_Hindmarsh__.html  over 8 years ago

Commit id: 523fa4bc16a18dca897c00957cce10e26cb76d3a

deletions | additions      

       

replacing the applied current, I, with an estimated response function,



x=y-ax^3+bx^2-z+\hat{r}(t)

\hat{r}(t) = h(t) \star s(t)

where  h(t) is a linear filter, s(t) is the stimulus, and $\star$ is   convolution. This adjustment allows us to fit the HR model to in vivo   neuron recording data.



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Genetic class="ltx_title_subsection">


Genetic  Algorithm


Mathematical  models such as the HR-neuron provide researchers a framework to understand and  predict qualities of a given system of interest. Researchers have developed 

processing environment. Rather than having one chain randomly sampling   the posterior distribution, the ensemble sampler has hundreds of small   chains sampling at once. These features should allow the sampler to   converge on good parameter estimations more quickly than standard MCMC algorithms.


Evaluating Fitness

We evaluated the fitness of our models by using the SPIKE synchronization metric (Kruez et al, 2015). This metric calculates time similarity between spike trains by counting up the number of coincidences between.  The metric is calculated,



SYNC = \frac{1}{M}\sum_{k=1}^{M}C_k

\[C_i^{(n,m)} = \left \{\begin{matrix}
1 if min_j(|t_i^m-t_j^m)|) <\tau_{i,j}& \\

0 > otherwise &

\end{matrix}\]

where M is number of possible coincidences, C is the coincidence factor  for pairs of spikes, and $\tau$ is the coincidence window.

This metric provides some advantages over other commonly used spike-train similarity metrics, such as van-Rossum distance (van Rossum, 2001). It is time-scale independent, requires no parameter optimization, and very computationally efficient because it requires no convolutions.


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Method class="ltx_title_subsection">


Method  Validation - Twin Data Analysis


We demonstrate the effectiveness of both MCMC and genetic algorithms for solving DSTRF HR-neuron  models by means of “twin data” analysis (Toth et al., 2011). We set the  parameters of an HR-neuron model to known fixed values and integrated across 

the same manner from MCMC and genetic algorithm estimates of the DSTRF model.  When an MCMC or genetic algorithm generated spike train bests matches our original  spike train based on some fitness function, we inspect and compare parameter  estimates.



 estimates.