Computer simulations of voltage clamping retinal ganglion cells through whole-cell electrodes in the soma

1996 ◽  
Vol 75 (5) ◽  
pp. 2129-2143 ◽  
Author(s):  
T. J. Velte ◽  
R. F. Miller
Keyword(s):  
Voltage Clamp ◽  
Retinal Ganglion Cells ◽  
Computer Simulations ◽  
Ganglion Cells ◽  
Dendritic Tree ◽  
Large Field ◽  
Retinal Ganglion ◽  
Whole Cell ◽  
Voltage Clamping ◽  
Whole Cell Recordings

1. Computer simulations of voltage-clamp experiments in retinal ganglion cells were implemented to better understand the insights that can be obtained with this physiological approach. 2. Simulation studies of voltage clamping were based on the contemporary approach of using whole-cell recordings with low resistance electrodes attached to the soma. Realistic ganglion cell morphologies were provided by cell staining experiments in the mudpuppy retina; selected cells included small-, medium-, and large-field neurons whose morphologies were entered into a computer through a neuron tracing program. 3. Values for the specific membrane resistance (Rm) varied from 5,000 to 100,000 omega/cm2 to conform to the range of Rm values obtained with intracellular sharp electrodes and whole-cell recordings. 4. Synaptic input currents were simulated by injecting current with and without an underlying conductance change into different regions of the dendritic tree. The time-variant waveform of the current included a combined transient and sustained component similar to the waveform of ON-bipolar activation. 5. Simulations were base on 1) intact structures, which included the soma and the entire dendritic tree, and 2) a more limited cell geometry that included representation of the soma, but only part of the dendritic tree, to represent the restricted morphology that might be rendered after cutting the retina into 150-microns cross sections for retinal slice experiments. 6. The results of this study indicate that voltage clamping from the soma, with optimal, low resistance electrodes and series resistance compensation, provides an error-free voltage clamp for slow signals that are generated within a small electrotonic distance from the soma (approximately 0.1 lambda). 7. The ideal voltage-clamp conditions are optimized when synaptic conductances are small and nonlinear membrane elements are minimally activated: small-field neurons best approximate these conditions, but clamping errors are evident in these cells when more distal branches are activated. The degree of error in voltage clamping was much greater when medium-and large-field neurons were evaluated. 8. It was not possible to clamp action potentials (nonpropagating) even when they were generated near the soma in any of the three model cells examined. 9. Experimental paradigms were developed to demonstrate that inadequate voltage clamping can lead to errors in the interpretation of experimental data when relevant variables are not taken into consideration. Suggestions are made for determining and optimizing favorable clamp conditions.

Estimating the contributions of NMDA and non-NMDA currents to EPSPs in retinal ganglion cells

1997 ◽  
Vol 14 (6) ◽  
pp. 999-1014 ◽  
Author(s):  
T. J. Velte ◽  
W. Yu ◽  
R. F. Miller
Keyword(s):  
Ganglion Cell ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Ambystoma Tigrinum ◽  
Inner Plexiform Layer ◽  
Retinal Ganglion ◽  
Whole Cell ◽  
Nmda Current ◽  
Control Response ◽  
Whole Cell Recordings

AbstractWhole-cell recordings were obtained from retinal ganglion cells of the tiger salamander (Ambystoma tigrinum) in a superfused slice preparation to evaluate contributions of NMDA (N-methyl-D-aspartate) and KA/AMPA (kainate/α-amino-3-hydroxy-5-methyl-4-isoxalone propionic acid) receptors to excitatory postsynaptic potentials (EPSPs) of retinal ganglion cells. Synaptic activation of retinal ganglion cells was achieved through the use of a brief pressure pulse of hyperosmotic Ringer (Ringer + sucrose) delivered through a microelectrode visually placed in the inner plexiform layer while whole-cell recordings were obtained from adjacent cells in the ganglion cell layer. Separation of NMDA and KA/AMPA excitatory postsynaptic currents (EPSCs) was achieved through the application of the antagonists NBQX and D-AP7, while inhibitory currents were blocked by strychnine and picrotoxin. Simple addition of the two independent EPSCs showed, most often, that the sum of the KA/AMPA and NMDA currents was less than the control response, but in some cases the sum of the two currents exceeded the magnitude of the control response. Neither result was consistent with expectations based on voltage-clamp principles and the assumption that the two currents were independent; for this reason, we considered the possibility of nonlinear interactions between KA/AMPA and NMDA receptors. Computer simulations were carried out to evaluate the summation experiments. We used both an equivalent cylinder model and a more realistic, compartmental model of a ganglion cell constrained by a passive leakage conductance, a linear KA/AMPA synaptic current, and a nonlinear NMDA current based on the well-known, voltage-sensitive Mg2+ block. Computer simulation studies suggest that the hypo- and hyper-summation of NMDA and KA/AMPA currents, observed physiologically, can be accounted for by a failure to adequately space clamp the neuron. Clamp failure leads to enhanced NMDA currents as the ion channels are relieved of the Mg2+ block; their contribution is thus exaggerated depending on the magnitude of the conductance change and the spatial location of the synaptic input.

Action Potentials in the Dendrites of Retinal Ganglion Cells

1999 ◽  
Vol 81 (3) ◽  
pp. 1412-1417 ◽  
Author(s):  
Toby J. Velte ◽  
Richard H. Masland
Keyword(s):  
Retinal Ganglion Cells ◽  
Action Potentials ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Muller Glia ◽  
Müller Glia ◽  
Whole Cell ◽  
The Absolute ◽  
Somatic Action Potentials ◽  
Site Of Stimulation

Action potentials in the dendrites of retinal ganglion cells. The somas and dendrites of intact retinal ganglion cells were exposed by enzymatic removal of the overlying endfeet of the Müller glia. Simultaneous whole cell patch recordings were made from a ganglion cell’s dendrite and the cell’s soma. When a dendrite was stimulated with depolarizing current, impulses often propagated to the soma, where they appeared as a mixture of small depolarizations and action potentials. When the soma was stimulated, action potentials always propagated back through the dendrite. The site of initiation of action potentials, as judged by their timing, could be shifted between soma and dendrite by changing the site of stimulation. Applying QX-314 to the soma could eliminate somatic action potentials while leaving dendritic impulses intact. The absolute amplitudes of the dendritic action potentials varied somewhat at different distances from the soma, and it is not clear whether these variations are real or technical. Nonetheless, the qualitative experiments clearly suggest that the dendrites of retinal ganglion cells generate regenerative Na+ action potentials, at least in response to large direct depolarizations.

Whole-cell currents activated at nicotinic acetylcholine receptors on ganglion cells isolated from goldfish retina

1993 ◽  
Vol 10 (2) ◽  
pp. 353-361 ◽  
Author(s):  
Bruce Yazejian ◽  
Gordon L. Fain
Keyword(s):  
Retinal Ganglion Cells ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Ganglion Cells ◽  
Hill Coefficient ◽  
Retinal Ganglion ◽  
Whole Cell ◽  
Induced Currents ◽  
Inwardly Rectifying ◽  
Goldfish Retina

AbstractWe have recorded whole-cell membrane currents in response to exogenously applied acetylcholine (ACh), nicotine, and 1,1 dimethyl-4-phenyl piperazinium iodide on retinal ganglion cells enzymatically dissociated from goldfish retina. Agonist applications induced nicotinic-type responses in a majority of cells when cells were isolated under optimal conditions. Currents were reminiscent of nicotinic-type ganglionic responses. Dose-response measurements of ACh-induced currents indicated an EC50 of 52 μM and a Hill coefficient of 0.6. Currents were selective for Na+ over Cl− and were highly inwardly rectifying. Responses were blocked reversibly by d-tubocurarine, hexamethonium chloride, and N-methyl-D-glucamine. In 50% of the cases, α-bungarotoxin reversibly blocked the current induced by ACh application. The blocking action of mecamylamine was irreversible and independent of the presence of agonist but was more effective in the presence of ACh. We conclude that functional nicotinic ACh receptors exist on most goldfish retinal ganglion cells.

GABA-activated single channel currents in outside-out membrane patches from rat retinal ganglion cells

1989 ◽  
Vol 3 (3) ◽  
pp. 275-279 ◽  
Author(s):  
Stuart A. Lipton
Keyword(s):  
Retinal Ganglion Cells ◽  
Cortical Neurons ◽  
Single Channel ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Whole Cell ◽  
Cell Recording ◽  
Excised Patches ◽  
Patch Configuration ◽  
Single Channel Currents

Abstractγ-aminobutyric acid (GABA) evokes large whole-cell currents in solitary mammalian retinal ganglion cells studied by the patch-clamp method. This evidence suggests that GABA acts directly on the retinal ganglion cells as an inhibitory transmitter as it does elsewhere in the mammalian central nervous system. Here, single-channel recordings of the currents underlying the GABA-induced responses were studied in outside-out patches of cell membrane. In some other preparations, single GABAA channels recorded in the excised patch configuration have been shown to have altered properties in comparison to responses elicited during whole-cell recording. For example, in cortical neurons single GABA-activated channels in excised patches display accelerated desensitization kinetics as well as rapid rundown of the response. Therefore, in retinal ganglion cells, responses generated by GABA in cell-free patches were compared to whole-cell responses. After determining that the responses to GABA in acutely isolated outside-out patches were indeed similar to those of the whole-cell currents in retinal ganglion cells, the unitary conductances were studied. It was determined that these single-channel events resemble those reported in other nervous tissues with 4 elementary conductances of ~10 pS, 19–22 pS, 30–33 pS, and 45–50 pS at 33–35°C.

Investigation of the geometry of the dendritic tree of retinal ganglion cells

1974 ◽  
Vol 5 (3) ◽  
pp. 237-243
Author(s):  
M. I. Vanslauskas ◽  
A. I. Gutauskas
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Dendritic Tree ◽  
Retinal Ganglion

Ganglion cells of a short-wavelength-sensitive cone pathway in New World monkeys: Morphology and physiology

1999 ◽  
Vol 16 (2) ◽  
pp. 333-343 ◽  
Author(s):  
LUIZ CARLOS L. SILVEIRA ◽  
BARRY B. LEE ◽  
ELIZABETH S. YAMADA ◽  
JAN KREMERS ◽  
DAVID M. HUNT ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Short Wavelength ◽  
New World ◽  
Ganglion Cells ◽  
Dendritic Tree ◽  
New World Monkeys ◽  
Retinal Ganglion ◽  
Old World ◽  
Contrast Gain ◽  
Cone Pathway

We have studied the morphology and physiology of retinal ganglion cells of a short-wavelength-sensitive cone (SWS-cone) pathway in dichromatic and trichromatic New World anthropoids, the capuchin monkey (Cebus apella) and tufted-ear marmoset (Callithrix jacchus). In Old World anthropoids, in which males and females are both trichromats, blue-ON/yellow-OFF retinal ganglion cells have excitatory SWS-cone and inhibitory middle- and long-wavelength-sensitive (MWS- and LWS-) cone inputs, and have been anatomically identified as small-field bistratified ganglion cells (SB-cells) (Dacey & Lee, 1994). Among retinal ganglion cells of New World monkeys, we find SB-cells which have very similar morphology to such cells in macaque and human; for example, the inner dendritic tree is larger and denser than the outer dendritic tree. We also find blue-on retinal ganglion cells of the capuchin to have physiological responses strongly resembling such cells of the macaque monkey retina; for example, responses were more sustained, with a gentler low frequency roll-off than MC-cells, and no evidence of contrast gain control. There was no difference between dichromatic and trichromatic individuals. The results support the view that SWS-cone pathways are similarly organized in New and Old World primates, consistent with the hypothesis that these pathways form a phylogenetically ancient color system.

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