RF dynamics of a lagged on-center X-neuron.

<p>Similar plots as for the Y-neuron in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024523#pone-0024523-g001" target="_blank">Fig. 1</a>. In (A), notice the initial suppression of the response. Number of presentations of each spot 70.</p

Fits to time-resolved DOG functions for example on-center Y and X neurons in <b>Figs. 1</b> and <b>2</b>.

<p><b>A</b>, Experimental Y-neuron response data. <b>B</b>, Best fit to time-resolved DOG model in Eq. (4). <b>C</b>, Deviation between experimental results (A) and model results in (B). Error <i>ε</i> (cf. Eq. 1) is 0.016. <b>D</b>, Fitted values of weight parameters <i>A</i>(<i>t_i</i>) and <i>B</i>(<i>t_i</i>) for Y neuron. <b>E</b>, Fitted values of width parameters <i>a</i>(<i>t_i</i>) and <i>b</i>(<i>t_i</i>) for Y neuron. <b>F</b>, Time-resolved error <i>ε_t</i> (cf. Eq. 2) for Y neuron. <b>G–L</b>, Same as (A)–(F) for the X-neuron response data. The deviation between experimental results (G) and model results (H) corresponds to an error <i>ε</i> = 0.012. Note that the almost vertical lines in panels (D) and (J) signal a rapid growth of the fitted value of the weight parameter <i>B</i> to values beyond the maximum values of the y-axes. The almost vertical lines in panels (E) and (K) correspondingly signal a rapid growth of the width parameter <i>b</i>.</p

RF dynamics for an on-center X-neuron.

<p>Similar plots as for the Y-neuron in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024523#pone-0024523-g001" target="_blank">Fig. 1</a>. Number of presentations of each spot 125.</p

Best-fit parameters from fitting the transient-sustained (TS) model in Eq. (14) to response data for example Y and X cells, cf. Fig. 10.

<p>The number marked with asterisks are not fitted: <i>R_bkg</i> is found by averaging the background response prior to the stimulus-evoked response, and <i>t_s</i> is fixed at 62.5 ms (see main text). Fitting errors (Eq. 1) for both the TS-model and the CS-model (center-surround model, Eq. 6) are also listed.</p

Predicted ‘one-dimensional impulse response’, i.e., impulse response for long and thin bars, for the transient-sustained (TS) model for example on-center Y and X neurons in <b>Figs. 1</b> and <b>2</b>.

<p>This impulse-response function of the form given in Eq. (16), but with the spatial functions <i>g_m</i>(<i>r</i>) replaced by the function <i>g_bar,m</i>(<i>x</i>) listed in Eq. (21). The test bar in the example has a length <i>L</i> = 10 deg. All model parameters correspond to the fit depicted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024523#pone-0024523-g010" target="_blank">Fig. 10</a> and are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024523#pone-0024523-t001" target="_blank">Table 1</a>. <b>A.</b> Predicted receptive-field function for full TS-model for Y neuron. <b>B.</b> Contribution from transient part (<i>f_t1</i>(<i>t</i>) <i>g_bar,t1</i>(<i>x</i>)+<i>f_t2</i>(<i>t</i>) <i>g_bar,t2</i>(<i>x</i>)). <b>C.</b> Contribution from sustained part (<i>f_s</i>(<i>t</i>) <i>g_bar,s</i>(<i>x</i>)). <b>D</b>–<b>F. </b><b>S</b>ame as (A)–(C) for the X-neuron. Notice that (i) the color scale in C and F differ from the scale in the other corresponding color maps and (ii) that the negative response for the Y-neuron has been truncated at the numerical value −100 spikes/s/deg in panels A and B.</p

RF dynamically changes during brief stimulus presentation.

<p>Data from an on-center Y-neuron. <b><i>A</i></b>, Colormap image of response (z-axis) to a series of spots (n = 25) of different diameters (y-axis) at different time after spot onset (x-axis). Spots were centered on the RF. <b><i>B</i></b>, Center-width as function of time after spot onset. Center-width was determined by spot diameter giving maximal response. The RF-center shrank from initially 8 deg to a minimum of 0.5 deg and then increased to a stable width of 2 deg at ∼100 ms. <b><i>C</i></b>: Spot width tuning curves for a selected number of time-slices. Notice the truncated x-axis. The time-slice for the spatial summation curve at 52.5 ms is marked by the vertical dashed line in (A), and the first and last data point in this curve are marked by white crosses in (A). Notice the shoulder or bimodal appearance of the curves in the range of 72.5 and 107.5 ms. Single (Eq. 4) and double (Eq. 5) DOG-functions were fitted to the data. Continuous curves show the best-fitting 2-DOG function (linearly interpolated between the spot sizes corresponding to experimental data points). Cases in which the 2-DOG gave statistically better fit than the best-fitting single DOG are marked with asterisk. <b><i>D</i></b>, Replot of data in (B) where center width of the transient (red curve) and sustained component (green curve) are separated based on the estimated start of the sustained component, and the end of the first component. <b><i>E</i></b>, Development of center-surround antagonism. Notice that 100% antagonism was reached within the first 70 ms. <b><i>F</i></b>, Development of the firing rate to the spot that just filled the RF-center. <b><i>G</i></b>, Data from (F) separated for the transient (red) and sustained (green) components. Error bars are ±SE. Number of presentations of each spot, 200.</p

Principal components analysis (PCA) of early part of response data (t<100 ms) for example on-center Y and X neurons in <b>Figs. 1</b> and <b>2</b>.

<p><b>A</b>,<b>B</b>, 1^st and 2^nd principal components, respectively, for the Y-neuron response data, i.e., contributions from terms with <i>n = 1</i> and <i>n = 2</i> in Eq. (3). <b>C</b>, Sum of contributions from two first principal components (and background activity) for Y neuron. <b>D</b>, Deviation between experimental results for Y neuron and PCA results in (C). Error <i>ε</i> (cf. Eq. 1) is 0.044. <b>E</b>, Fitted transient temporal function <i>F_t1</i>(<i>t</i>) (Eq. 11, blue dashed line) to 1^st temporal PCA component (blue solid line), and fitted transient temporal function <i>F_t2</i>(<i>t</i>) (Eq. 12, green dashed line) to 2^nd temporal PCA component (green solid line) for early part ( t<97.5 ms) of Y-neuron data. <b>F</b>, Blue dashed line: Fitted DOG spatial functions (Eq. 10) to 1^st spatial PCA component of early part (t<97.5 ms) of Y-neuron data (blue solid line). Green dashed line: Corresponding DOG function fit to the 2^nd spatial PCA component (green solid line). The best fit of a DOG function (red dashed line) to the 1^st spatial PCA component of the <i>last</i> part of the Y-neuron data is also shown (red line). <b>G–L</b>, Same as (A)–(F) for X-neuron response data. The deviation between experimental results and PCA results (I) corresponds to an error <i>ε</i> = 0.021.</p

RF dynamics of an off-center Y-neuron.

<p>Similar plots as for the Y-neuron in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024523#pone-0024523-g001" target="_blank">Fig. 1</a>. Number of presentations of each spot 115.</p

Predicted spatiotemporal impulse-response function <i>D_TS</i>(<i>t,r</i>), cf. <b>Eq.(16)</b>, for the transient-sustained (TS) model for example on-center Y and X neurons in <b>Figs. 1</b> and <b>2</b>.

<p>All model parameters correspond to the fit depicted in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024523#pone-0024523-g010" target="_blank">Fig. 10</a> and are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024523#pone-0024523-t001" target="_blank">Table 1</a>. <b>A.</b> Predicted impulse-response function for full TS-model for Y neuron. <b>B.</b> Contribution from transient part (<i>f_t1</i>(<i>t</i>) <i>g_t1</i>(<i>r</i>)+<i>f_t2</i>(<i>t</i>) <i>g_t2</i>(<i>r</i>)). <b>C.</b> Contribution from sustained part (<i>f_s</i>(<i>t</i>) <i>g_s</i>(<i>r</i>)). <b>D</b>–<b>F.</b> Same as (A)–(C) for the X-neuron. Notice that (i) the color scale in C and F differ from the scale in the other corresponding color maps and (ii) that the negative response for the Y-neuron has been truncated at the value −50 spikes/s/deg² in panels A and B.</p

Fits to spatial part of sustained component of TS model for example on-center Y and X neurons in <b>Figs. 1</b> and <b>2</b>.

<p><b>A</b>, Last part (t>125 ms) of experimental Y-neuron response data used in fit. <b>B</b>, Best fit to DOG model in Eq. (10) representing the spatial part of the sustained component in the TS-model. <b>C</b>, Deviation between experimental results (A) and model results in (B). Error <i>ε</i> (cf. Eq. 1) is 0.053. <b>D–F</b>, Same as (A)–(C) for the X-neuron. The deviation between experimental results (D) and model results (E) corresponds to an error <i>ε</i> = 0.019. The fitted parameter values (<i>A_s</i>, <i>B_s</i>, <i>a_s</i>, <i>b_s</i>) from both fits are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024523#pone-0024523-t001" target="_blank">Table 1</a>.</p