Strategies to encode information with glutamate release in synapses of the Danio Rerio visual system

Darnet, Lea (2019) Strategies to encode information with glutamate release in synapses of the Danio Rerio visual system. Doctoral thesis (PhD), University of Sussex.

[img] PDF - Published Version
Download (27MB)

Abstract

I have used the fluorescent reporter iGlusnFR to observe glutamate release from bipolar cell (BC) terminals onto retinal ganglion cells (RGCs) dendrites and from RGCs outputs in live zebrafish using multiphoton microscopy.
Most neurons in the brain represent information using a digital code: temporal sequences of spikes of fixed amplitude that trigger the quantized release of neurotransmitter. The amplitude distribution of BCs events demonstrated clear quantization, showing that bipolar cells generate multivesicular events in vivo to encode visual information. I showed then that the vesicles constituting the events were released in a coordinated fashion and was not described by a Poisson process. It was then possible to understand for the first time how visual information was encoded with a vesicle code. Coding with amplitude was more prevalent in OFF cells than ON cells. Multivesicular events encoded higher contrasts with elevated temporal precision, achieving an accuracy comparable to spikes leaving the retina (about 3 ms). Ribbon synapses therefore discretize their outputs into sequences of numbers ranging from zero up to ~11 enhancing the dynamic range and the temporal accuracy of the vesicle code.
Further, when observing iGluSnFR signals on the dendrites of individual RGCs, multiple individual inputs could be distinguished with varying sensitivity to tuning to spatial orientation. Thus, I used iGluSnFR to understand how visual information was transmitted onto RGCs by comparing inputs from BCs into single RGCs and outputs from the same RGCs in the optic tectum. I used this optical approach to study retinal computations such as dynamic predictive coding. Dynamic predictive coding is computed by RGCs of zebrafish. A combination of excitatory inputs from BCs and inhibitory inputs generate this phenomenon.

Item Type: Thesis (Doctoral)
Schools and Departments: Brighton and Sussex Medical School > Neuroscience
Subjects: Q Science > QP Physiology > QP0351 Neurophysiology and neuropsychology > QP0361 Nervous system > QP0364.5 Neural transmission
Q Science > QP Physiology > QP0351 Neurophysiology and neuropsychology > QP0431 Senses > QP0448 Special senses > QP0474 Vision. Physiological optics
Depositing User: Library Cataloguing
Date Deposited: 21 May 2019 15:51
Last Modified: 21 May 2019 15:51
URI: http://sro.sussex.ac.uk/id/eprint/83902

View download statistics for this item

📧 Request an update