טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentStatman Adiel
SubjectA Population Approach to Synaptic Size Distribution
DepartmentDepartment of Chemical Engineering
Supervisor Professor Naama Brenner
Full Thesis textFull thesis text - English Version


Abstract

Measurements based on recently-developed imaging methodologies have provided the time-course of individual synaptic size over time for large populations of synapses. These measurements have revealed that synapses are dynamic and change over time scales of minutes to weeks; they provide an opportunity to study the population dynamics of synapses and uncover principles that govern these dynamics and their relationships with physiological stimuli. Here I describe my study of synaptic population dynamics based on a stochastic model known as the Kesten process.  Our underlying assumption is that the integrated outcome of the myriad of molecular processes that drive synaptic remodeling dynamics can be effectively described by a combination of two processes, multiplicative and additive. Both processes are stochastic and are taken from distributions parametrically affected by physiological signals. We have showed that this seemingly simple model can generate rich dynamics which are qualitatively similar to the dynamics of glutamatergic synapses recorded in long-term time-lapse experiments in ex-vivo cortical networks. We also showed that this model reproduces the distributions of synaptic sizes measured in these experiments, the long-term stability of such distributions, and their scaling in response to pharmacological manipulations. Furthermore, we show that the limit population distribution of such process is intensive to its underlying mathematical details. Finally, we show that the kinetics of new postsynaptic density formation are also faithfully captured by the same model.  These results show that a simple phenomenological stochastic model can provide a unifying framework to understand many aspects of synaptic population dynamics and statistics.