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1.
Figure 7

Figure 7. Individual inhibitory receptors differently regulate spontaneous events.. From: Correlated Spontaneous Activity Persists in Adult Retina and Is Suppressed by Inhibitory Inputs.

A: Representative sEPSCs from major classes of GCs at individual conditions. B: Distributions of interevent intervals for the traces shown in A. In this experiment, the dual blockade of inhibitory receptors paradigm is applied to reveal the contribution of an individual receptor types. GABACRs filter out slow events, allowing mostly high-frequency events (<103 ms) to pass. GlyRs filter out fast events, allowing mostly low-frequency events (>103 ms) to pass. Events do not occur when GABAARs are active.

Abduqodir H. Toychiev, et al. PLoS One. 2013;8(10):e77658.
2.
Figure 1

Figure 1. Synaptic inputs suppress regenerative activity in adult retinal bipolar cells.. From: Correlated Spontaneous Activity Persists in Adult Retina and Is Suppressed by Inhibitory Inputs.

A: Schematic of a basic retinal circuitry with fluorescence images of representative BCs in the retina (P35–65). Horizontal lines define retinal synaptic and nuclear layers. pr - photoreceptor, bc - bipolar, ac -amacrine and gc - ganglion cells. B: The membrane potentials of identified BCs at rest and after blockade of dendritic and axonal synaptic inputs (middle) and L-type VGCaC (right). C: The membrane potentials at rest and after blockade of axonal synaptic inputs (middle) and L-type VGCaC (right).

Abduqodir H. Toychiev, et al. PLoS One. 2013;8(10):e77658.
3.
Figure 8

Figure 8. Spontaneous regenerative bipolar cell activity persists through adulthood and is suppressed by inhibitory inputs.. From: Correlated Spontaneous Activity Persists in Adult Retina and Is Suppressed by Inhibitory Inputs.

A: Stage III developmental waves are similar to the pharmacologically-unveiled wave-like events in mature retina. During stage III waves, inhibitory inputs are not fully matured (orange arrows), and permit the generation of glutamatergic events. Inhibitory synaptic inputs silence these spontaneous glutamatergic events in mature retina (red arrows). Precise contributions of presynaptic and direct components of inhibitory network remain unclear. B: Schematic of inhibitory receptor contributions in modifying regenerative events. GABAARs are the main suppressor of oscillatory events and are proposed to act as gating mechanism. GABACRs act as a high-pass filter. GlyRs act as a low-pass filter. The diagram does not necessarily depict the sequence of processing events.

Abduqodir H. Toychiev, et al. PLoS One. 2013;8(10):e77658.
4.
Figure 6

Figure 6. Inhibitory network tunes the frequency of oscillatory activity.. From: Correlated Spontaneous Activity Persists in Adult Retina and Is Suppressed by Inhibitory Inputs.

A: sIPSCs and sEPSCs from GCs at different conditions. Gradual removal of distinct components of inhibitory network tunes the frequency of BC-driven oscillatory activity in GC. Blockade of glycine (strychnine) and GABAARs (SR-95531 or bicuculline) shaped the oscillatory activity into high-frequency and low-amplitude events. The removal of slow inhibitory inputs mediated by GABACRs (TPMPA) shaped the oscillator into low-frequency and high-amplitude mode. B: A representative whole-cell sEPSC recording from a GC showing a gradual transition during a blockade of ‘fast’ and ‘slow’ components of inhibitory inputs. C: Response spectrogram illustrating transition in power and frequency profiles of BC output FFT power for GC shown in B. Blue to red transition depicts increase in FFT power at specified frequency domain during different pharmacological conditions.

Abduqodir H. Toychiev, et al. PLoS One. 2013;8(10):e77658.
5.
Figure 5

Figure 5. Developmental changes in the effect of cholinergic, inhibitory and L-type voltage-gated calcium channel-dependent networks on spontaneous activity.. From: Correlated Spontaneous Activity Persists in Adult Retina and Is Suppressed by Inhibitory Inputs.

A: sEPSCs recorded from GCs at different ages in control and following the blockade of nicotinic AChRs, inhibitory transmission and L-type VGCaCs. B and C: Summary graphs of GC activity and the contribution of different receptors over age. Early in postnatal development (P5–6) the activity is mediated by AChRs and blocked by DHβE/curarine. At second postnatal week, the contribution of AChRs is reduced. In contrast, regenerative compound activity revealed by SST is more prominent with age, as BC axons and inhibitory inputs mature and spontaneous currents decrease (C, red and black traces). This transition is most prominent in late second postnatal week (see text and for details). All data are reported as means ± SEM.

Abduqodir H. Toychiev, et al. PLoS One. 2013;8(10):e77658.
6.
Figure 2

Figure 2. Large compound events are present in postsynaptic ganglion and amacrine cells and rely on inputs from BCs and L-type voltage gated calcium channels (VGCaCs).. From: Correlated Spontaneous Activity Persists in Adult Retina and Is Suppressed by Inhibitory Inputs.

A and B: Spiking activity and sEPSCs from (A) a G2 ganglion cell and (B) a starburst amacrine cell in P35 retina. Application of inhibitory receptor blockers strychnine, SR-95531 and TPMPA (SST) induced large-amplitude oscillatory activity, which could be eliminated by either blocking the excitatory inputs with CNQX and D-AP5 or VGCaCs with nifedipine. C: Distribution of interevent intervals shows no significant difference in frequency of oscillatory activity across different GC classes. D: Sensitivity profile of oscillatory activity to pharmacological blockers of various types of Ca2+-channels (see text for details). All data are reported as means ± SEM.

Abduqodir H. Toychiev, et al. PLoS One. 2013;8(10):e77658.
7.
Figure 4

Figure 4. Contribution of sodium channels, glutamate spillover and gap junctions to propagation of adult retinal waves.. From: Correlated Spontaneous Activity Persists in Adult Retina and Is Suppressed by Inhibitory Inputs.

A: ΔF/F pseudo colored time-lapse images showing 1 s of retinal activity under different pharmacological conditions, illustrating the contribution of voltage-gated sodium channels, glutamate transporters, and gap junctions, respectively, to SST-induced adult retinal waves. Size of the retinal region in each panel is 636×1130 µm. B: Compound sEPSCs recorded from GCs under different pharmacological conditions. In the top panel, the inset highlights the selective blockade of spiking activity following application of TTX. For illustrative purposes, these recordings were obtained using a recording pipette with higher input resistance, to reveal spiking activity along with currents. Compound sEPSCs persisted under TTX and TBOA, but were abolished under MFA. C: Cumulative histogram of wave velocities under SST (transparent bars, black outline), TBOA (black bars), and TTX (gray bars). Velocities following TBOA and TTX are significantly slower than under SST alone (ANOVA, Bonferroni post-hoc tests, p>0.0001 and p = 0.0067, respectively). D: Bar graph of interwave intervals under different pharmacological conditions. Intervals following TBOA and TTX are significantly longer than under SST alone (ANOVA, Bonferroni post-hoc tests, p = 0.0016 and p>0.0001, respectively). All data are reported as means ± SEM. See Supplementary -8 for ΔF/F pseudo color recordings of the effect of TTX, TBOA, and MFA on waves.

Abduqodir H. Toychiev, et al. PLoS One. 2013;8(10):e77658.
8.
Figure 3

Figure 3. Calcium imaging reveals wave-like activity in adult retina that is suppressed by an inhibitory network.. From: Correlated Spontaneous Activity Persists in Adult Retina and Is Suppressed by Inhibitory Inputs.

A: left panel, A fluorescence image showing loading of calcium indicator OGB-1-AM (green) with superimposed GC (red). Dashed lines indicate position of the recording pipette. Arrowhead points to GC axon. Dark shadow in the left is a blood vessel. Scale bar 80 µm. (A, middle panel) Simultaneous calcium imaging (top) and whole-cell sEPSC traces from GC (bottom). (A, right panel) Cross-correlations between ΔF/F and sEPSCs (right, n = 21) and randomized controls. Note inversed Y-axis to reflect the opposite directions for correlated events – each increase in intracellular calcium (positive) coincides with an inward current (negative). B: A sequence of ΔF/F pseudo color time-lapse images during 12 s of retinal activity viewed from GC side at P47. Blockade of inhibitory feedback reveals the wave-like propagating activity across the retina (middle). This activity is not evident in untreated control conditions (top) and eliminated by application of nifedipine (bottom), a selective antagonist of L-type VGCaCs. Size of the retinal region in each panel is 636× µm. C: Time course of the ΔF/F monitored over 120 s from retinal region marked by a white box in B at various conditions. D: Histogram of wave velocities under SST condition. Bin size is 100 µm/s, n = 130 of waves and n = 4 of retinas. See Supplementary – for calcium recordings during control, SST and nifedipine conditions in raw (, ) and ΔF/F pseudo color modes (, ) from P47 retinas.

Abduqodir H. Toychiev, et al. PLoS One. 2013;8(10):e77658.

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