A model of retinal ganglion cell processing under natural viewing conditions.
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1
BCCN München, Germany
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2
LMU München, Germany
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3
Georg-August-Universität Göttingen, Germany
The retina is an important first stage of visual processing and is intensively studied. Little is known, however, about the retinal responses under atural viewing conditions. In particular, it is interesting to consider whether standard receptive field (RF) models can capture important features of the retinal response to complex non-stationary stimuli. We present a conceptually simple model of the peripheral visual system and investigate its behaviour under simulated eye movements. Specifically, we identify possible retinal mechanisms for rapid post-saccadic signalling as observed in several experimental studies.
We model the retina as a simple photoreceptor grid which feeds forward to a retinal ganglion cell (RGC) layer consisting of numerous distinct RGC populations. We model four such populations: linear midget cells, both On-type and Off-type, and non-linear parasol cells, On-type and Off-type. Spatial receptive fields are given by a difference-of-Gaussians model. Temporal integration profiles for each population are described by the difference of two bi-phasic temporal filters which are combined with the spatial receptive field to form a rank-2 spatio-temporal filter. For midget RGCs, this filter is linearly convolved with the stimulus and rectified to generate a membrane potential. Neuronal spiking is simulated by a threshold function with non-linear feedback. Parasol cells implement a non-linear spatial integration, in which the receptive field is divided into sub-fields. Contributions from each sub-field are temporally integrated and rectified, before being summed to provide an estimate of the parasol cell membrane potential. The standard centre-surround RF can be recovered by combining sub-field RFs.
The model reproduces several salient features in the reported behaviour of mammalian retina, including spatial and temporal modulation transfer functions. In addition, numerous studies have reported rapid post-saccadic bursting in retinal sub-populations. This behaviour is reproduced in our model, which displays strong transient responses to simulated saccades on a 10-ms timescale. These responses are observed primarily within our Off-type parasol population, and are less pronounced in On-type parasol cells. Midget RGCs do not display post-saccadic bursts. These differences in populations arise as a result of differing spatial and temporal integration profiles and the parasol integration non-linearity. Such dynamics are also implicated in the generation of latency codes for rapid post-saccadic processing. Our model thus captures prominent features relevant for understanding retinal processing during natural vision.
Keywords:
Eye Movements,
retinal ganglion cell,
sensory processing,
Vision
Conference:
BC11 : Computational Neuroscience & Neurotechnology Bernstein Conference & Neurex Annual Meeting 2011, Freiburg, Germany, 4 Oct - 6 Oct, 2011.
Presentation Type:
Poster
Topic:
sensory processing (please use "sensory processing" as keyword)
Citation:
Greene
G,
Wachtler
T and
Gollisch
T
(2011). A model of retinal ganglion cell processing under natural viewing conditions..
Front. Comput. Neurosci.
Conference Abstract:
BC11 : Computational Neuroscience & Neurotechnology Bernstein Conference & Neurex Annual Meeting 2011.
doi: 10.3389/conf.fncom.2011.53.00224
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Received:
11 Aug 2011;
Published Online:
04 Oct 2011.
*
Correspondence:
Dr. Garrett Greene, BCCN München, München, Germany, greene@bio.lmu.de