Ph.D Thesis

Ph.D StudentReinartz Sebastian
SubjectFluctuations in Single Neuron Responses to Synaptic Envelope
DepartmentDepartment of Medicine
Supervisor PROF. Shimon Marom
Full Thesis textFull thesis text - English Version


The firing rate of neuronal spiking in vitro and in vivo, significantly varies over extended time scales, characterized by long-memory processes and complex statistics and appears in spontaneous as well as evoked activity upon repeated stimulus presentation. This variability is attributed to inherent non-stationarity at either the network level and/or the machinery underlying single neuron excitability.

Here, we focus on the contribution of a third source to observed firing rate variability that is, the non-stationary efficacy of the ensemble of synapses, impinging onto the observed neuron, activated in response to a given stimulus. Being an interface layer between the network and single cell, this synaptic envelope of a neuron might act as a potential bottleneck and ultimately modulate the effects of both network and cellular excitability on firing rate variability over extended time scales.

We developed and validated a method that is tailored for a controlled specific long-term activation of a single cortical neuron in vitro through its synaptic envelope. Applying this method we show that, within the range of physiological activation frequencies, the synaptic envelope is a key contributor to response variability, long-memory processes and complex statistics observed in single neuron recording over extended time scales (up to many hours). Synaptic envelope impacts on response variability in stimulation rates that are substantially lower compared to stimulation rates that drive excitability resources to fluctuate. Additional means to extend these results to the system (network) were applied and will be described.