Reading memory traces in cultured neuronal networks by probabilistic analysis

by Ghazaleh Afshar
Doctoral thesis
Date of Examination:2014-01-10
Date of issue:2014-02-21
Advisor:Prof. Dr. Fred Wolf
Referee:Prof. Dr. Fred Wolf
Referee:Prof. Dr. Florentin Wörgötter
Persistent Address: http://dx.doi.org/10.53846/goediss-4375

 

 

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Abstract

English

In this thesis, I am studying the enhancement of the collective burst dynamics, burst activation and propagation in hippocampal neuronal networks in-vitro by using optogenetic techniques. Channelrhodopsin-2 transfected hippocampal neuronal cultures were grown on MEAs for simultaneous optical stimulation and electrical recording from neuronal networks. We found low frequency photo-stimulation protocols that are sufficient to induce potentiation of network bursting, modifying bursting dynamics and increasing interneuronal synchronization. This study shows that mild stimulation protocols that do not enforce particular activity patterns onto the network can be highly effective inducers of network-level plasticity. I also investigated how this network level plasticity can be indicated in the burst activation and propagation dynamics by looking at the leader-follower neuronal relationship. I found that low frequency photo-stimulation is able to modify the temporal relationship between follower and leader neurons. It is shown that, by using fade-in photo-stimulation, there is a significant shortening of intra-burst firing rate peak delay of follower electrodes after offset of the stimulation compared to unperturbed spontaneous activity. This study indicated that network level potentiation is associated with a tighter temporal relationship between leader and follower neurons.
Keywords: Optogenetics; Network-level plasticity; Bursting; Synchronization; Leader-follower neurons
 
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