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. 2018 Sep 6;7:e38841. doi: 10.7554/eLife.38841

Figure 3. The RF surround regulates nonlinear spatial integration in the RF center.

(A) Left column: Example Off parasol RGC spike response to an isolated split-field grating stimulus in the RF center. Rows of each raster correspond to repeated presentations of the same stimulus for the example cell. There is no linear equivalent stimulus in this case since the grating has a mean of zero. Center column: when the center stimulus is paired with a bright surround, the grating and the surround alone produce very similar spike responses. Right column: a dark surround suppresses the response in both cases, and the grating is unable to elicit a strong response. (B) For the example cell in (A), we tested sensitivity to the center grating stimulus with a range of contrasts presented to the surround. Negative contrast surrounds (hyperpolarizing for Off bipolar cells) decrease the response. Positive contrast surrounds (depolarizing for Off bipolar cells) sum sub-linearly with the grating stimulus such that for the brightest surrounds, the addition of the grating only mildly enhances the cell’s response. Points show mean ( ± S.E.M.) spike count. (C) We measured the response difference between the grating stimulus and the surround-alone stimulus across a range of surround contrasts (horizontal axis) and for four different central grating contrasts (different lines). For each grating contrast, addition of either a bright or dark surround decreased sensitivity to the added grating. Points are population means ( ± S.E.M.) (n = 5 Off parasol RGCs). (D–F) same as (A–C) for excitatory synaptic current responses of an Off parasol RGC. Points represent mean ( ± S.E.M.) excitatory charge transfer for the example cell in (E) and population mean ( ± S.E.M.) (n = 7 Off parasol RGCs) in (F).

Figure 3—source data 1. Included is a .mat file containing a data structure for the data in Figure 3A–C.
Off parasol RGC spike responses are included as raw traces and binary vectors of spike times for a range of central grating contrasts and surround contrasts. For all responses, data are sampled at 10 Khz, and both center and surround stimuli appear after 200 ms and persist for 200 ms.
elife-38841-fig3-data1.mat (34.7MB, mat)
DOI: 10.7554/eLife.38841.008
Figure 3—source data 2. Included is a .mat file containing a data structure for the data in Figure 3D–F.
Off parasol RGC excitatory current responses (in units of pA) have been baseline-subtracted. For all responses, data are sampled at 10 Khz, and both center and surround stimuli appear after 200 ms and persist for 200 ms.
elife-38841-fig3-data2.mat (34.2MB, mat)
DOI: 10.7554/eLife.38841.009
Figure 3—source data 3. Included is a .mat file containing a data structure for the data in Figure 3—figure supplement 1.
On parasol RGC excitatory current responses (in units of pA) and have been baseline-subtracted. For all responses, data are sampled at 10 Khz, and both center and surround stimuli appear after 200 msec and persist for 200 ms.
elife-38841-fig3-data3.mat (26MB, mat)
DOI: 10.7554/eLife.38841.010

Figure 3.

Figure 3—figure supplement 1. Regulation of spatial integration by the RF surround of On parasol RGCs.

Figure 3—figure supplement 1.

Compare to Figure 3A–C. (A) Left: On parasol RGC excitatory current response to a split-field grating stimulus in the RF center. Right: when the center stimulus is paired with a dark surround (depolarizing for this On-center RGC), the grating and the linear equivalent stimulus produce very similar excitatory current responses. (B) For the example cell in (A), we tested sensitivity to the center grating stimulus with a range of contrasts presented to the surround. Positive contrast surrounds (hyperpolarizing) decrease the response. Negative contrast surrounds (depolarizing) sum sub-linearly with the grating stimulus such that for thedarkest surrounds, the addition of the grating only mildly enhances the cells response. Points show mean ± S.E.M. excitatory charge transfer. (C) We measured the response difference between the grating stimulus and the surround-alone stimulus across a range of surround contrasts (horizontal axis) and for four different central grating contrasts (different lines). For each grating contrast, addition of either a bright or dark surround decreased sensitivity to the added grating. Points are population means ( ± S.E.M.) (n = 6 On parasol RGCs).