Luminance and contrast adaptation of the inner retina

Adaptation is a common feature of sensory systems, matching neural
activity to the range of inputs from the environment. In the visual system this
is of great importance because visual stimulus can change across 9 orders of
magnitude. In this context the visual system attempts to match both the
magnitude and variance of the input to the range of neural activity of its
component neurons. This adaptation to the environment begins during the
first stage of visual computations of vision, in the retina. In this thesis I have
focused on how circuit mechanisms of adaptive processes are computed in
the retina. There are ~20 different circuits and each circuit extracts an
individual feature of the visual stream. Specific mechanisms of adaptation
were isolated in some of these neuronal circuits. First I studied how ganglion
cells adapt to different light intensities, and identified a circuit responsible for a
switch-like component between two distinct states that implements distinct
perceptual regimes at different light levels. In the second part I investigated
how identified neuronal circuits respond to contrast adaptation, showing that
different ganglion cells respond differently to changes in contrast. I was able
to show that identified ON cell types adapt to changes in contrast, while and
OFF cells do not. In the third part of my thesis I was involved in the
development of a tool that allows cell type specific manipulation of circuits
called Transcription Devices Dependent on GFP (T-DDOG) based on camelid
antibodies. I demonstrated its relevance by using it to express optogenetic
tools to drive a light response in a specific cell class of the retina, bipolar cells.