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Relative spike time coding and STDP-based orientation selectivity in the early visual system in natural continuous and saccadic vision: a computational model

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Abstract

We have built a phenomenological spiking model of the cat early visual system comprising the retina, the Lateral Geniculate Nucleus (LGN) and V1’s layer 4, and established four main results (1) When exposed to videos that reproduce with high fidelity what a cat experiences under natural conditions, adjacent Retinal Ganglion Cells (RGCs) have spike-time correlations at a short timescale (~30 ms), despite neuronal noise and possible jitter accumulation. (2) In accordance with recent experimental findings, the LGN filters out some noise. It thus increases the spike reliability and temporal precision, the sparsity, and, importantly, further decreases down to ~15 ms adjacent cells’ correlation timescale. (3) Downstream simple cells in V1’s layer 4, if equipped with Spike Timing-Dependent Plasticity (STDP), may detect these fine-scale cross-correlations, and thus connect principally to ON- and OFF-centre cells with Receptive Fields (RF) aligned in the visual space, and thereby become orientation selective, in accordance with Hubel and Wiesel (Journal of Physiology 160:106–154, 1962) classic model. Up to this point we dealt with continuous vision, and there was no absolute time reference such as a stimulus onset, yet information was encoded and decoded in the relative spike times. (4) We then simulated saccades to a static image and benchmarked relative spike time coding and time-to-first spike coding w.r.t. to saccade landing in the context of orientation representation. In both the retina and the LGN, relative spike times are more precise, less affected by pre-landing history and global contrast than absolute ones, and lead to robust contrast invariant orientation representations in V1.

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Abbreviations

CGC:

Contrast Gain Control

DoG:

Difference-of-Gaussian

EPSP:

Excitatory Post-Synaptic Potential

IPL:

Inner Plexiform Layer

IPSP:

Inhibitory Post-Synaptic Potential

LGN:

Lateral Geniculate Nucleus

LTD:

Long Term Depression

LTP:

Long Term Potentiation

OPL:

Outer Plexiform Layer

PSTH:

Post-Stimulus Time Histogram

RF:

Receptive Field

RGC:

Retinal Ganglion Cell

SRM:

Spike Response Model

STDP:

Spike Timing-Dependent Plasticity

V1:

primary visual cortex (a.k.a. area 17).

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Acknowledgements

This research was supported by the Fyssen Foundation and the FP7 European Project Coronet. We thank Adrien Wohrer for having developed the Virtual Retina simulator (Wohrer and Kornprobst 2009), both user-friendly and highly configurable, and for the quality of his support. We also thank Wolfgang Einhäuser for kindly providing the videos used in (Betsch et al. 2004), and Mario Pannunzi for the numerous insightful brainstorms we had.

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    Timothée Masquelier

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Masquelier, T. Relative spike time coding and STDP-based orientation selectivity in the early visual system in natural continuous and saccadic vision: a computational model. J Comput Neurosci 32, 425–441 (2012). https://doi.org/10.1007/s10827-011-0361-9

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