Intrinsic Physiological Properties of RGC Subtypes.

<p>Intrinsic Physiological Properties of RGC Subtypes.</p

The effect of soma size on the frequency response of retinal ganglion cells.

<p>Panels (A–D) show the mean frequency response of A2, C2, D1 and D2 RGC types, respectively. Within each RGC type, cells are grouped and their frequency responses averaged according to their soma diameter. Within each RGC type, cells with the largest soma diameters are shown in black and those with the smallest soma diameters are shown in grey. For comparison, the frequency response, averaged over all cells of a given type, irrespective of soma diameter, is shown by the dashed line. Panels (E–H) show distributions of soma diameter for each of the A2, C2, D1 and D2 RGC types, respectively.</p

Long-term sensorimotor adaptation in the ocular following system of primates

<div><p>The sudden movement of a wide-field image leads to a reflexive eye tracking response referred to as short-latency ocular following. If the image motion occurs soon after a saccade the initial speed of the ocular following is enhanced, a phenomenon known as post-saccadic enhancement. We show in macaque monkeys that repeated exposure to the same stimulus regime over a period of months leads to progressive increases in the initial speeds of ocular following. The improvement in tracking speed occurs for ocular following with and without a prior saccade. As a result of the improvement in ocular following speeds, the influence of post-saccadic enhancement wanes with increasing levels of training. The improvement in ocular following speed following repeated exposure to the same oculomotor task represents a novel form of sensori-motor learning in the context of a reflexive movement.</p></div

Initial eye speeds of the two monkeys over sessions.

<p><b>A</b>,<b>B</b>. Mean ocular following eye speed for monkey 1 for rightward (<b>A</b>) and leftward (<b>B</b>) image motion plotted against binned sessions following saccades to the center of the screen at short (circles) and long (squares) delays. Error bars represent 95% confidence intervals. <b>D</b>,<b>E</b>. The same plots for monkey 2. <b>C</b>,<b>F</b>. The ratio of ocular following speed for the short-delay versus the long-delay conditions (Enhancement, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189030#pone.0189030.e001" target="_blank">Eq 1</a>) for rightward and leftward motion in monkey 1 (<b>C</b>) and monkey 2 (<b>F</b>). In general, ocular following eye speed was faster in the short-delay condition. Over time, initial ocular following eye speed increased such that this post-saccadic enhancement of the ocular following response was completely (monkey 1) or partly (monkey 2) abolished.</p

Analysis of ocular following speed following saccades at 0, 90 and 180 degrees.

<p>Comparison of the ocular following speed for Monkey 1 (A-C) and Monkey 2 (D-F). Each plot: 1) shows the saccade direction across a stationary vertical grating (abscissa) plotted against the ocular following eye speed (ordinate); 2) Open circles show the responses at short delay (50ms) conditions, while the x’s show the responses at the long delay (300ms) conditions; 3) Solid and dashed lines indicate that the background motion driving the ocular following response was rightward (0deg) or leftward (180deg) respectively. Monkey 1 shows a tendency for ocular following responses to be reduced when the background motion during ocular following is in the opposite direction to the preceding saccade, compared to the same or vertical conditions. This effect is strongest and equal for short delay conditions (circles) in the first 7 sessions (A). Monkey 2 shows a tendency for ocular following responses to increase when background motion is in the same direction as the preceding saccade, compared to the opposite and vertical directions. This effect is strongest for the short delay conditions (circles 50ms) and is consistently strong across sessions (D-F).</p

Visual stimuli, task and sample eye traces.

<p><b>A</b>. Visual stimuli and task. Monkeys viewed vertical cosine gratings and were required to fixate a small target (red). The fixation target was initially presented 10° either to the left, to the right or below the center of the screen. This peripheral target was then removed and replaced with a central target that the monkeys were required to saccade to and fixate for either 50 ms (short-delay condition) or 300 ms (long-delay condition). At the end of this delay the grating began moving either to the left or to the right. This motion elicited robust ocular following eye movements. <b>B</b>. Sample eye traces. Example vertical (top) and horizontal (middle) eye position, and horizontal eye speed (bottom) traces from one monkey for both the short- and long-delay conditions. Eye traces for all trials (gray) were aligned at the start of the motion. Red and blue traces show mean eye position and speed signals for the long- and short-delay conditions respectively. The rectangular box on the horizontal eye speed trace indicates the analysis window for calculation of initial ocular following eye speeds.</p

Dendritic and electrical receptive fields.

<p>a-b) Sample cells depicting the stimulating array (large black discs) and the patch-clamp recording electrode (denoted by a *). Overlaid on the images are the morphological reconstructions of the cells. The sample cell in (a) is also shown in (c) 16. The sample cell in (b) is also shown in (c) 20. Note that the stimulating electrodes appear large, but the exposed area is only 400 μm. Also visible are the lycra threads used to keep the retina affixed and the stimulating electrode tracks. c) The electrical receptive fields shown together with the dendritic receptive field estimates. The electrodes with stars above them show the approximate location of the optic disc for each preparation.</p

Electrical receptive field properties.

<p>A) Proportions of cells with up to three excitatory components. B) Proportions of cells with up to three suppressive components. C). The temporal windows over which suppressive and excitatory ERFs affected cell responses, thus indicating duration of stimulus integration time. Excitatory ERFs tended to occur within a short latency from the response (blue circles). Suppressive ERFs tended to extend over a long duration, which was variable from cell to cell (orange circles). The squares represent the means for all cells. D) RGC preference to cathodic-first or anodic-first stimulation. Squares represent means and lines indicate ±1 standard deviation. Stars denote significant differences (<i>p</i> < 0.05).</p