scholarly journals Simple Model for Encoding Natural Images by Retinal Ganglion Cells with Nonlinear Spatial Integration

2021 ◽  
Author(s):  
Jian K. Liu ◽  
Tim Gollisch

A central goal in sensory neuroscience is to understand the neuronal signal processing involved in the encoding of natural stimuli. A critical step towards this goal is the development of successful computational models of this encoding. For ganglion cells in the vertebrate retina, the development of satisfactory models for responses to natural visual scenes is an ongoing challenge. Standard models typically apply linear integration of visual stimuli over space, yet many ganglion cells are known to show nonlinear spatial integration in natural stimulus contexts. We here study the encoding of natural images by retinal ganglion cells, using multielectrode-array recordings from isolated salamander retinas. We assess how responses to natural and blurred images depend on first- and second-order statistics of spatial patterns inside the receptive field. This leads us to a simple extension of current standard ganglion cell models, which are based on linear spatial integration. We show that taking not only the weighted average of light intensity inside the receptive field into account but also its variance over space yields substantially improved response predictions of responses to novel images. Finally, we demonstrate how this model framework can be used to assess the spatial scale of nonlinear spatial integration. Our results underscore the importance of nonlinear spatial stimulus integration in the retina in responses to natural images. Furthermore, the introduced model framework provides a simple, yet powerful extension of standard models and may serve as a benchmark for the development of more detailed models of the nonlinear structure of receptive fields.

2011 ◽  
Vol 28 (5) ◽  
pp. 403-417 ◽  
Author(s):  
WALTER F. HEINE ◽  
CHRISTOPHER L. PASSAGLIA

AbstractThe rat is a popular animal model for vision research, yet there is little quantitative information about the physiological properties of the cells that provide its brain with visual input, the retinal ganglion cells. It is not clear whether rats even possess the full complement of ganglion cell types found in other mammals. Since such information is important for evaluating rodent models of visual disease and elucidating the function of homologous and heterologous cells in different animals, we recorded from rat ganglion cells in vivo and systematically measured their spatial receptive field (RF) properties using spot, annulus, and grating patterns. Most of the recorded cells bore likeness to cat X and Y cells, exhibiting brisk responses, center-surround RFs, and linear or nonlinear spatial summation. The others resembled various types of mammalian W cell, including local-edge-detector cells, suppressed-by-contrast cells, and an unusual type with an ON–OFF surround. They generally exhibited sluggish responses, larger RFs, and lower responsiveness. The peak responsivity of brisk-nonlinear (Y-type) cells was around twice that of brisk-linear (X-type) cells and several fold that of sluggish cells. The RF size of brisk-linear and brisk-nonlinear cells was indistinguishable, with average center and surround diameters of 5.6 ± 1.3 and 26.4 ± 11.3 deg, respectively. In contrast, the center diameter of recorded sluggish cells averaged 12.8 ± 7.9 deg. The homogeneous RF size of rat brisk cells is unlike that of cat X and Y cells, and its implication regarding the putative roles of these two ganglion cell types in visual signaling is discussed.


Author(s):  
S. Molotchnikoff

SUMMARY:The relationships between the center and the surround of the receptive field of the rabbit retinal ganglion cell were investigated. This was done by coupling localized light spots and electrical activation of the retina and by analyzing the time of the excitatory and inhibitory periods. The responsiveness to the electrical transretinal pulse revealed a) that ON stimulation in OFF-center cells and OFF stimulation in ON-center cells, elicited a primary period of inhibition with a short latency; b) the long latency response of surround stimulation was not preceded by an inhibitory period unless the center was simultaneously stimulated in the same direction; c) a transient response to a stationary spot of light is followed by a period of inhibition. These results are discussed in relation to the known cellular retinal networks.


1997 ◽  
Vol 78 (2) ◽  
pp. 614-627 ◽  
Author(s):  
Naoki Kogo ◽  
Michael Ariel

Kogo, Naoki and Michael Ariel. Membrane properties and monosynaptic retinal excitation of neurons in the turtle accessory optic system. J. Neurophysiol. 78: 614–627, 1997. Using an eye-attached isolated brain stem preparation of a turtle, Pseudemys scripta elegans, in conjunction with whole cell patch techniques, we recorded intracellular activity of accessory optic system neurons in the basal optic nucleus (BON). This technique offered long-lasting stable recordings of individual synaptic events. In the reduced preparation (most of the dorsal structures were removed), large spontaneous excitatory synaptic inputs [excitatory postsynaptic potentials (EPSPs)] were frequently recorded. Spontaneous inhibitory postsynaptic potentials were rarely observed except in few cases. Most EPSPs disappeared after injection of lidocaine into the retina. A few EPSPs of small size remained, suggesting that these EPSPs either were from intracranial sources or may have been miniature spontaneous synaptic potentials from retinal ganglion cell axon terminals. Population EPSPs were synchronously evoked by electrical stimulation of the contralateral optic nerve. Their constant onset latency and their ability to follow short-interval paired stimulation indicated that much of the population EPSP's response was monosynaptic. Visually evoked BON spikes and EPSP inputs to BON showed direction sensitivity when a moving pattern was projected onto the entire contralateral retina. With the use of smaller moving patterns, the receptive field of an individual BON cell was identified. A small spot of light, projected within the receptive field, guided the placement of a bipolar stimulation electrode to activate retinal ganglion cells that provided input to that BON cell. EPSPs evoked by this retinal microstimulation showed features of unitary EPSPs. Those EPSPs had distinct low current thresholds. Recruitment of other inputs was only evident when the stimulation level was increased substantially above threshold. The average size of evoked unitary EPSPs was 7.8 mV, confirming the large size of synaptic inputs of this system relative to nonsynaptic noise. EPSP shape was plotted (rise time vs. amplitude), with the use of either evoked unitary EPSPs or spontaneous EPSPs. Unlike samples of spontaneous EPSPs, data from many unitary EPSPs formed distinct clusters in these scatterplots, indicating that these EPSPs had a unique shape among the whole population of EPSPs. In most BON cells studied, hyperpolarization-activated channels caused a slow depolarization sag that reached a plateau within 0.5–1 s. This property suggests that BON cells may be more complicated than a simple site for convergence of direction-sensitive retinal ganglion cells to form a central retinal slip signal for control of oculomotor reflexes.


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