Rabbit retinal ganglion cells

Summary The classification of concentrically organized receptive fields of rabbit retinal ganglion cells was extended along similar lines to that in the cat by distinguishing brisk and sluggish classes and then sustained and transient types of each. Quantitative measures of responsiveness to stationary and to moving stimuli revealed characteristic features which distinguished these classes. Brisk-transient and brisk-sustained classes are not as distinct from each other as in the cat: centre size distributions overlapped almost completely and there was also substantial overlap of axonal conduction properties whether expressed in terms of latency or conduction velocity between two central stimulus sites. Representatives of every class of rabbit ganglion cells sent axons to the superior colliculus.Supported by a Postdoctoral Fellowship of the US Public Health Service     

霍乱毒素及妊娠对金黄地鼠视网膜节细胞再生的作用

目的:观察霍乱毒素(CTx)及妊娠对成年金黄地鼠视神经扎断后视网膜节细胞(RGCs)轴突再生的促进作用.方法:确定成年金黄地鼠交配3d后,扎断视神经(ON)近端,玻璃体内注射CTx.动物随机分为实验组和对照组:对照组为单纯扎断ON为损伤组、损伤PBS组;实验组分为CTx组与妊娠后扎断ON妊娠损伤组与妊娠CTx组.术后动物存活3周.用荧光金逆行标记再生的视网膜节细胞( RGCs),在荧光镜下观察视网膜平铺片再生RGCs的数量变化,并比较实验组各组再生RGCs的周长.结果:CTx组、妊娠损伤组、妊娠CTx组视网膜再生RGCs平均数比损伤组及PBS组增加,差异具有统计学意义.妊娠CTx组比CTx组、妊娠损伤组视网膜再生RGCs平均数增加.实验组各组再生的RGCs周长相比差异无统计学意义.结论:妊娠及玻璃体注入CTx具有促进视神经扎断后视网膜节细胞轴突再生的作用,两者有协同作用,各组再生的RGCs大小无明显差别.     

Intrinsically photosensitive retinal ganglion cells

Life on earth is subject to alternating cycles of day and night imposed by the rotation of the earth. Consequently, living things have evolved photodetective systems to synchronize their physiology and behavior with the external light-dark cycle. This form of photodetection is unlike the familiar "image vision," in that the basic information is light or darkness over time, independent of spatial patterns. "Nonimage" vision is probably far more ancient than image vision and is widespread in living species. For mammals, it has long been assumed that the photoreceptors for nonimage vision are also the textbook rods and cones. However, recent years have witnessed the discovery of a small population of retinal ganglion cells in the mammalian eye that express a unique visual pigment called melanopsin. These ganglion cells are intrinsically photosensitive and drive a variety of nonimage visual functions. In addition to being photoreceptors themselves, they also constitute the major conduit for rod and cone signals to the brain for nonimage visual functions such as circadian photoentrainment and the pupillary light reflex. Here we review what is known about these novel mammalian photoreceptors.     

Peptides influence retinal ganglion cells

Neurotensin, substance P and (D-Ala2, Met5)-enkephalinamide were iontophoresed onto ganglion cells of the amphibian retina. Substance P and neurotensin were found to be excitatory while (D-Ala2, Met5)-enkephalinamide suppressed all types of ganglion cells. These findings are consistent with a functional role for peptides in the vertebrate retina.     

Classification of turtle retinal ganglion cells

1. Receptive fields of 78 retinal ganglion cells were analyzed for their responses to moving and stationary lights that were presented under a variety of stimulus conditions. All cells were sensitive to moving stimuli, and their receptive fields often comprised excitatory and inhibitory sub-regions. 2. Properties used in the classification included responses to stationary flashed stimuli, receptive-field organization, changes in stimulus wavelength and adaptation, movement velocity, and direction of stimulus movement. Eight functional cell classes were derived: simple, ON-sustained, annular, wavelength-sensitive, directionally selective, bar-shaped, large-field, and velocity. 3. Simple cells, representing 21% of the sample, had circular or oval receptive fields of 3-22 degrees that gave transient responses to stationary, flashed lights. Many of these cells, but not all, showed antagonistic center-surround organizations. ON-sustained cells responded for the duration of the stimulus flash or for the duration of a light flash moving through the receptive field. These units comprised 8% of the sample; they had small, circular, non-directional receptive fields and they were most sensitive to red light. Their field sizes did not vary with changes in adaptation level. 4. Annular cells (4% of the sample) gave no responses to any stimulation in the field center, but they responded strongly to stimulation in the surround area, especially to stimuli that moved very slowly through the region. Annular cells were nondirectional, with circular centers of 5-6 degrees diam and annular surround widths of 2-4 degrees. They responded best in light adaptation. 5. Wavelength-sensitive cells, similar to most of the cells sampled, were sensitive to red light when light-adapted. Some cells in addition showed input from rods under dark adaptation. Intensity-response curves for these latter cells showed clear changes from one input to the other as the cells' functional ranges were explored. Some cells responded best to short- or middle-wavelength light, but these were more rarely met. Where multiple receptor inputs could be identified, long-wavelength stimuli evoked transient responses, whereas short-wavelength stimuli favored more sustained spike trains. Wavelength-sensitive cells in this category comprised 5% of the sample.     

Selectivity for multiple stimulus features in retinal ganglion cells

Under normal viewing conditions, retinal ganglion cells transmit to the brain an encoded version of the visual world. The retina parcels the visual scene into an array of spatiotemporal features, and each ganglion cell conveys information about a small set of these features. We study the temporal features represented by salamander retinal ganglion cells by stimulating with dynamic spatially uniform flicker and recording responses using a multi-electrode array. While standard reverse correlation methods determine a single stimulus feature--the spike-triggered average--multiple features can be relevant to spike generation. We apply covariance analysis to determine the set of features to which each ganglion cell is sensitive. Using this approach, we found that salamander ganglion cells represent a rich vocabulary of different features of a temporally modulated visual stimulus. Individual ganglion cells were sensitive to at least two and sometimes as many as six features in the stimulus. While a fraction of the cells can be described by a filter-and-fire cascade model, many cells have feature selectivity that has not previously been reported. These reverse models were able to account for 80-100% of the information encoded by ganglion cells.     

Asymmetrical dendritic fields of retinal ganglion cells

Dendritic branches of retinal ganglion cells in cats and frogs were studied by Golgi's bichromate-silver impregnation method. Besides the well-known varieties of ganglion cells, asymmetrical neurons with a unilateral arrangement of their dendrites are also present. Substantial differences are found in the structure of these ganglion cells depending on the architectonics of the inner plexiform layer of the retina, which is narrow in the cat but wide and divided into sublayers in the frog.The possible role of neurons with a unilateral arrangement of their dendrites is discussed on the basis of previous electrophysiological investigations of receptive fields of retinal ganglion cells and also of the retinal detectors.     

Morphological features of chick retinal ganglion cells

On average, in chicks, the total number of retinal ganglion cells is 4.9 x 10(6) and the cell density is 10400 cells/mm2. Two high-density areas, namely the central area (CA) and the dorsal area (DA), are located in the central and dorsal retinas, respectively, in post-hatching day 8 (P8) chicks (19000 cells/mm2 in the CA; 12800 cells/mm2 in the DA). Thirty percent of total cells in the ganglion cell layer are resistant to axotomy of the optic nerve. The distribution of the axotomy resistant cells shows two high-density areas in the central and dorsal retinas, corresponding to the CA (5800 cells/mm2) and DA (3200 cells/mm2). The number of presumptive ganglion cells in P8 chicks is estimated to be 4 x 10(6) (8600 cells/mm2 on average) and the density is 13500 and 10200 cells/mm2 in the CA and DA, respectively, and 4300 cell/mm2 in the temporal periphery (TP). The somal area of presumptive ganglion cells is small in the CA and DA (mean (+/- SD) 35.7 +/- 9.1 and 40.0 +/- 11.3 microm2, respectively) and their size increases towards the periphery (63.4 +/- 29.7 microm2 in the TP), accompanied by a decrease in cell density. Chick ganglion cells are classified according to dendritic field, somal size and branching density of the dendrites as follows: group Ic, Is, IIc, IIs, Ills, IVc. The density of branching points of dendrites is approximately 10-fold higher in the complex type (c) than in the simple type (s) in each group. The chick inner plexiform layer is divided into eight sublayers according to the dendritic strata of retinal ganglion cells and 26 stratification patterns are discriminated.     

Spatiospectral properties of goldfish retinal ganglion cells

1. Responses of single ganglion cells from isolated goldfish retinas were recorded during presentation of various spatial and spectral stimuli. Each cell was classified along several spatial [spatial summation class, spatial contrast sensitivity function (CSF), and response to contrast] and spectral (Red-ON, Red-OFF or Red-ON/OFF, and spectral opponency/nonopponency) dimensions. 2. Linearity of spatial summation was determined from responses to contrast-reversal sinusoidal gratings positioned at various locations across the receptive field of the cell. CSFs were derived from responses to sinusoidal gratings of various spatial frequencies and contrasts, drifting across the cell's receptive field at a rate of 4 Hz. Response to contrast was determined from responses to variations in contrast of a sinusoidal grating of optimal spatial frequency. Spectral classifications were based on responses to monochromatic stimuli presented separately to the center and surround portions of the receptive field. 3. Linearity of spatial summation (X-, Y-, and W-like) was independent of the cell's spectral properties; for example, an X-like cell could be classified as either a Red-ON, Red-OFF, or Red-ON/OFF center cell and as spectrally opponent or nonopponent. 4. There were differences in response to contrast across spectral categories. Red-OFF center cells were very sensitive to contrast compared with Red-ON center cells. Spectrally nonopponent cells were more responsive to contrast than spectrally opponent cells. 5. There were dramatic differences across the spectral categories in relative sensitivity to low spatial frequency stimuli; however, the spatial resolution (i.e., sensitivity to high spatial frequencies) of each spectral classification appeared to be similar.(ABSTRACT TRUNCATED AT 250 WORDS)     

Morphological properties of mouse retinal ganglion cells

The mouse retina offers an increasingly valuable model for vision research given the possibilities for genetic manipulation. Here we assess how the structural properties of mouse retinal ganglion cells relate to the stratification pattern of the dendrites of these neurons within the inner plexiform layer. For this purpose, we used 14 morphological measures to classify mouse retinal ganglion cells parametrically into different clusters. Retinal ganglion cells were labeled in one of three ways: Lucifer Yellow injection, 'DiOlistics' or transgenic expression of yellow fluorescent protein. The resulting analysis of 182 cells revealed 10 clusters of monostratified cells, with dendrites confined to either On or Off sublaminae of the inner plexiform layer, and four clusters of bistratified cells, dendrites spanning the On and Off sublaminae. We also sought to establish how these parametrically identified retinal ganglion cell clusters relate to cell types identified previously on the basis of immunocytochemical staining and the expression of yellow fluorescent protein. Cells labeled with an antibody against melanopsin were found to be located within a single cluster, while those labeled with the SMI-32 antibody were in four different clusters. Yellow fluorescent protein expressing cells were distributed within 13 of the 14 clusters identified here, which demonstrates that yellow fluorescent protein expression is a useful method for labeling virtually the entire population of mouse retinal ganglion cells. Collectively, these findings provide a valuable baseline for future studies dealing with the effects of genetic mutations on the morphological development of these neurons.     

Contextual tuning of direction-selective retinal ganglion cells

A direction-selective (DS) retinal ganglion cell responds well to a small object moving within its receptive field center, but less well when there is also a moving stimulus in the surrounding area; this has been described as tuning for local motion. We show here an additional selectivity, such that the surround has less effect if there is a discontinuity--that is, a difference in spatial phase, spatial frequency or velocity--between the center stimulus and that present in the surround.     

Correlated firing in rabbit retinal ganglion cells

A ganglion cell's receptive field is defined as that region on the retinal surface in which a light stimulus will produce a response. While neighboring ganglion cells may respond to the same stimulus in a region where their receptive fields overlap, it generally has been assumed that each cell makes an independent decision about whether to fire. Recent recordings from cat and salamander retina using multiple electrodes have challenged this view of independent firing by showing that neighboring ganglion cells have an increased tendency to fire together within +/-5 ms. However, there is still uncertainty about which types of ganglion cells fire together, the mechanisms that produce coordinated spikes, and the overall function of coordinated firing. To address these issues, the responses of up to 80 rabbit retinal ganglion cells were recorded simultaneously using a multielectrode array. Of the 11 classes of rabbit ganglion cells previously identified, coordinated firing was observed in five. Plots of the spike train cross-correlation function suggested that coordinated firing occurred through two mechanisms. In the first mechanism, a spike in an interneuron diverged to produce simultaneous spikes in two ganglion cells. This mechanism predominated in four of the five classes including the ON brisk transient cells. In the second mechanism, ganglion cells appeared to activate each other reciprocally. This was the predominant pattern of correlated firing in OFF brisk transient cells. By comparing the receptive field profiles of ON and OFF brisk transient cells, a peripheral extension of the OFF brisk transient cell receptive field was identified that might be produced by lateral spike spread. Thus an individual OFF brisk transient cell can respond both to a light stimulus directed at the center of its receptive field and to stimuli that activate neighboring OFF brisk transient cells through their receptive field centers.     

青光眼视网膜节细胞病变中的自噬异常

<正>青光眼是以视网膜节细胞(retinal ganglion cells,RGCs)进行性死亡和轴突溃变为病理特征的不可逆的严重致盲性神经退行性病变~([1-2])。眼压升高是其主要的危险因素。RGCs是唯一能将视网膜处理后的视觉信息编码为神经冲动传输到脑的神经元,其损伤与死亡是青光眼视功能丧失的主要原因。因而,探讨青光眼病变中RGCs的死亡机制,保护和维持RGCs的存活以及增强其功能,对于青光眼的防治至关重要。自噬又称为Ⅱ型程序性细胞死亡,是细胞器和大分子物质     

Sophisticated temporal pattern recognition in retinal ganglion cells

Pattern recognition is one of the most important tasks of the visual system, and uncovering the neural mechanisms underlying recognition phenomena has been a focus of researchers for decades. Surprisingly, at the earliest stages of vision, the retina is capable of highly sophisticated temporal pattern recognition. We stimulated the retina of tiger salamander (Ambystoma tigrinum) with periodic dark flash sequences and found that retinal ganglion cells had a wide variety of different responses to a periodic flash sequence with many firing when a flash was omitted. The timing of the omitted stimulus response (OSR) depended on the period, with individual cells tracking the stimulus period down to increments of 5 ms. When flashes occurred earlier than expected, cells updated their expectation of the next flash time by as much as 50 ms. When flashes occurred later than expected, cells fired an OSR and reset their temporal expectation to the average time interval between flashes. Using pharmacology to investigate the retinal circuitry involved, we found that inhibitory transmission from amacrine cells was not required, but on bipolar cells were required. The results suggest a mechanism in which the intrinsic resonance of on bipolars leads to the OSR in ganglion cells. We discuss the implications of retinal pattern recognition on the neural code of the retina and visual processing in general.     

Information transmission rates of cat retinal ganglion cells

To assess the information encoded in retinal spike trains and how it might be decoded by recipient neurons in the brain, we recorded from individual cat X and Y ganglion cells and visually stimulated them with randomly modulated patterns of various contrast and spatial configuration. For each pattern, we estimated the information rate of the cells using linear or nonlinear algorithms and for some patterns by directly measuring response probability distributions. We show that ganglion cell spike trains contain information from the receptive field center and surround, that the center and surround have similar signaling capacity, that antagonism between the mechanisms reduces information transmission, and that the total information rate is limited. We also show that a linear decoding algorithm can capture all of the information available in retinal spike trains about weak inputs, but it misses a substantial amount about strong inputs. For the strongest stimulus we used, the information rate of the best linear decoder averaged 40-70 bits/s across ganglion cell types, while the directly measured rate was around 20-40 bits/s greater. This implies that under certain stimulus conditions, visual information is encoded in the temporal structure of retinal spike trains and that a nonlinear decoding algorithm is needed to extract the temporally coded information. Using simulated spike trains, we demonstrate that much of the temporal structure may be explained by the threshold for spike generation and is not necessarily indicative of a complex coding scheme.     

Adaptation and dynamics of cat retinal ganglion cells

1. The impulse/quantum (I/Q) ratio was measured as a function of background illumination for rod-dominated, pure central, linear square-wave responses of retinal ganglion cells in the cat.2. The I/Q ratio was constant at low backgrounds (dark adapted state) and inversely proportional to the 0.9 power of the background at high backgrounds (the light adapted state). There was an abrupt transition from the dark-adapted state to the light-adapted state.3. It was possible to define the adaptation level at a particular background as the ratio (I/Q ratio at that background)/(dark adapted I/Q ratio).4. The time course of the square-wave response was correlated with the adaptation level. The response was sustained in the dark-adapted state, partially transient at the transition level, and progressively more transient the lower the impulse/quantum ratio of the ganglion cell became. This was true both for on-centre and off-centre cells.5. The frequency response of the central response mechanism at different adaptation levels was measured. It was a low-pass characteristic in the dark-adapted state and became progressively more of a bandpass characteristic as the cell became more light-adapted.6. The rapidity of onset of adaptation was measured with a time-varying adapting light. The impulse/quantum ratio is reset within 100 msec of the onset of the conditioning light, and is kept at the new value throughout the time the conditioning light is on.7. These results can be explained by a nonlinear feedback model. In the model, it is postulated that the exponential function of the horizontal cell potential controls transmission from rods to bipolars. This model has an abrupt transition from dark- to light-adapted states, and its response dynamics are correlated with adaptation level.     

GABA-activated whole-cell currents in isolated retinal ganglion cells

1. We have begun to analyze neurotransmitter-activated conductances in retinal ganglion cells by measuring the response of single voltage-clamped adult goldfish ganglion cells to gamma-aminobutyric acid (GABA). Here we describe 1) our method of identifying ganglion cells in vitro after their dissociation from papain-treated retinas, and 2) the response of these cells to GABA in the tight-seal whole cell configuration of the patch-clamp method (cf. 41) after 1-4 days of primary cell culture. 2. Ganglion cell somata were backfilled in situ by injections of horseradish peroxidase (HRP) into the optic nerve. After dissociation of the retinas containing these cells, HRP reaction product was localized to cells that retained the size, shape, and an intracellular organelle characteristic of ganglion cells in situ. These features enabled us thereafter to identify ganglion cells in vitro without retrograde marker transport. 3. GABA (3-10 microM) elicited inward currents and substantial noise increases in almost all ganglion cells at negative holding potentials. Reversal potential measurements in salines containing different chloride concentrations indicated that GABA produces a chloride-selective conductance increase in ganglion cells. Bicuculline (10 microM) reversibly inhibited ganglion cell GABA responses. Baclofen (10 microM) alone elicited no responses in ganglion cells. 4. Noise analysis of GABA-activated whole cell currents yielded elementary conductance estimates of 16 pS, with a slow time constant of 30 ms plus a faster component of 1-2 ms. No significant voltage dependence of these values was observed between -20 and -80 mV. 5. We have thus devised a means of identifying ganglion cells dissociated from adult retinas, identified GABAA receptors (cf. 16) on these cells, and found that the responses mediated by these receptors resemble those found in other regions of central nervous system (CNS). These results are consistent with the notion that GABA may function as an inhibitory transmitter at synapses on ganglion cells.