Article Figures & Data
Figures
- Figure 1.
Identification of the joint relevant subspace across the retinothalamic synapse. A, “Cell-attached” recording from the LGN and the detected retinal (blue) and thalamic (red) spike trains. B, Clusters of sorted retinal and thalamic spikes are discrete from each other and noise. C, Schematic diagrams of separate linear-nonlinear-Poisson encoding models for RGC and LGN neurons. D, A diagram of the joint feature space of the retinal and thalamic neurons with presynaptic (solid blue), postsynaptic (solid red), gained (dashed red), and lost (dashed blue) features represented as vectors. E, A schematic diagram of the joint encoding model and its use of the joint relevant subspace of both RGC and LGN neurons. F, Joint feature space for an X-cell pair; the presynaptic and postsynaptic relevant subspaces are both one-dimensional. The raw (black), RGC-spike-triggered (blue), and LGN-spike-triggered (red) stimulus ensembles are illustrated as scatterplots and marginal histograms (above and right); the ovals and smooth lines represent the Gaussian approximations of the distributions. The luminance values are dimensionless, unity Gaussian distributions. Conventions here apply to all remaining figures.
- Figure 2.
Spatiotemporal analysis of the joint retinothalamic feature space. A, Two types of Gaussian white noise used in this study, checkerboards (2D) and concentric rings (1D). B, The presynaptic and gained stimulus features (receptive fields) for an X-cell; side and bottom plots show the factorized spatial and temporal profiles. C, Comparison of spatial and temporal components of the presynaptic and gained features. Error bars indicate SD. D, E, Cumulative energy of the presynaptic and gained features over space and time; the spatial and temporal scales of the presynaptic features are normalized to 1. F, G, Population comparison (26 RGC–LGN pairs) of the spatial and temporal scales of presynaptic and gained features; the shaded zone shows the mean and SD of the logarithm of gained to presynaptic ratio. The circle and squares indicate data obtained using the one-dimensional and two-dimensional stimuli, respectively.
- Figure 3.
Change of single-spike code across the retinothalamic synapse. A, Single-spike information across the retinothalamic synapse for the population (n = 26); error bars show SDs. B, The RGC–LGN joint feature space for the example X-cell pair in Figure 1F; each direction within the plane represents a distinct feature. Only temporal components (8 examples) are illustrated because spatial components are nearly unaltered. C, Information content about the joint feature space illustrated as polar plots. The angular coordinate corresponds to different features and the radial coordinate represents information in single spikes; the solid arrows mark the presynaptic and postsynaptic features, and the dashed arrows indicate the gained and lost features, according to the conventions in Figure 1. The information about particular features falls on the filled, dumbbell-shaped curves and is limited by the pale pink and blue circles, which mark the single-spike information about the total joint feature space. Last, the gray sectors indicate the subset of features about which a thalamic spike conveyed less information that a retinal one. D, Marginal distributions of the raw, RGC-spike-triggered and LGN-spike-triggered stimulus ensembles along the presynaptic, gained, postsynaptic, and lost features. E, The presynaptic, gained, postsynaptic, and lost temporal features. F, The presynaptic and postsynaptic single-spike information about the presynaptic, gained, postsynaptic, and lost features; the horizontal lines mark the information for the joint feature space.
- Figure 4.
Change of pairwise correlation code across the retinothalamic synapse. A, Percentage of pairwise synergy computed over the joint feature space for the X-cell pair. B, The synergy in LGN plotted against synergy in RGCs for all spike pairs (n = 26); interspike time is color coded. C, D, Plots of synergy as a function of interspike time for all individual RGCs (left) and relay cells (right) (gray lines); the population mean (thick colored line) and SD (shade) overlie the curves for individual cells; Gaussian approximations are shaded for clarity.
- Figure 5.
Transformation of retinal correlation code into thalamic single-spike code explains the changes in coding efficiency across the retinothalamic synapse. A, The pairwise synergy for three different features: presynaptic (left), gained (middle), and irrelevant, or control (right) for the population (n = 26); the shaded band represents the SD. B, Information conveyed by single spikes and spike pairs for the example X-cell pair. The horizontal gray lines mark twice the amount of information conveyed by a single spike (these cannot be seen in the middle and right panels because they coincide with the horizontal axes). The colored lines plot the information conveyed by spike pairs. The inset illustrates that the irrelevant feature is orthogonal to the relevant subspace. C, Marginal distributions of the raw, RGC-spike-triggered and LGN-spike-triggered stimulus ensembles along the three features for the example X-cell pair. D, Marginal distributions of the RGC-spike-pair-triggered stimulus ensembles along the three features, families of distributions shown according to the intervals between RGC spikes in a pair.
- Figure 6.
“Paired-spike enhancement” as a model of the retinothalamic transmission. A, Retinothalamic transmission illustrated as binary “editing” of the retinal spike train shown above a model of the process. B, Efficacy plotted as a function of interspike interval for the example X-cell pair. C, Rasters of 50 trials of the actual RGC spike train superimposed on the actual and modeled LGN spike trains. D, Instant firing rates of the RGC and the actual and modeled LGN cells. A Gaussian window of 5 ms was used to estimate the firing rates. E, Reconstructions of Figure 1F for the “null” and interspike interval models. F, Reconstructions of Figure 3C for the two models. G, Reconstructions of Figure 4A, bottom, for the two models.
- Figure 7.
Performance of the models of retinothalamic transmission. A, Reconstructions of Figure 3A for the “null” and interspike interval models. B–D, Model–data comparison of the LGN single-spike information content for the two models; the information contents are estimated with regard to the joint feature space (B), the presynaptic feature (C), and the gained feature (D). E, Reconstructions of Figure 4B for the “null” and interspike interval models. F, Reconstructions of Figure 4D for the two models.
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