M-wave of proximal retina in cat.
M-wave of proximal retina in cat.
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猫近端视网膜的 M 波。
DOI：
10.1152/jn.1986.56.4.1039
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发表时间：
1986
影响因子：
2.5
通讯作者：
Steinberg,RH
中科院分区：
文献类型：
--
作者：
Sieving,PA;Frishman,LJ;Steinberg,RH
目前对哺乳动物近端视网膜电图（ERG）的反应知之甚少。最近，有证据表明，近端视网膜参与产生模式视网膜电图（PERG）。在目前的工作中，我们调查了近端视网膜活动在完整的猫眼在光适应。用微电极记录视网膜内不同深度的圆形光点在稳定背景下闪烁时诱发的细胞外电位。在近端视网膜中发现了显著的负反应，这可以被识别为以前仅在冷血视网膜中观察到的M波。就像冷血反应一样，猫的M波由刺激开始和结束时的负向电位组成，这些电位的振幅最大，有小斑点。通过类比冷血的数据，猫M波被假定为由Muller细胞对近端视网膜神经元释放的K+的反应所产生的细胞外电压。此外，猫M波只出现在视杆饱和度及以上的背景下，并且在刺激开始和偏移时具有短的潜伏期（30 ms），这表明它是一种锥驱动的反应。根据M波的形态、深度分布和刺激-反应特征，可以将M波与PII（b波和DC分量）明确区分开。例如，明视PII在55%视网膜深度处的远端视网膜中具有其最大电压，而M波在25%视网膜深度处的近端视网膜中最大。此外，PII只是增加了幅度作为刺激点扩大，而M波表现出空间调谐。在光适应条件下，在小光斑刺激下，M波是猫视网膜最大的细胞外电压。用玻璃体内的银丝为参照的微电极记录视网膜表面附近的玻璃体ERG，发现玻璃体内对小光点的M波总是负极性的。因此，与PII不同，M波在玻璃体-视网膜边界处不反转极性。然而，由于杂散光的影响，我们无法评估M波的振幅的视网膜电图与弥漫性视网膜照明的贡献。我们的结论是，M波是存在于猫作为一个突出的锥驱动响应的近端视网膜，是从b波分开，其意义视网膜电图记录仍有待确定。
There has been relatively little known about responses from proximal retina in mammals that could contribute to the electroretinogram (ERG). Recently, there has been evidence that the proximal retina is involved in generating the pattern electroretinogram (PERG). In the present work we investigated proximal retinal activity in the intact cat eye during light adaptation. Extracellular potentials evoked in response to circular spots of light, flashed on steady backgrounds, were recorded with microelectrodes placed intraretinally at different depths. Prominent negative responses were found in proximal retina that could be identified as the M-wave previously observed only in cold-blooded retinas. Like the cold-blooded responses, the cat's M-wave consisted of negative-going potentials at stimulus onset and offset that were maximum in amplitude with small spots. By analogy to the cold-blooded data, the cat M-wave is presumed to be the extracellular voltage arising from Muller cell responses to K+ released by proximal retinal neurons. In addition, the cat M-wave only appeared with backgrounds at and above rod saturation and had short latencies (30 ms) at stimulus onset and offset, indicating that it is a cone-driven response. The M-wave could be clearly distinguished from PII (b-wave and DC component) on the basis of its form, depth distribution, and stimulus-response characteristics. For example, photopic PII had its maximum voltage in the distal retinal at 55% retinal depth, whereas the M-wave was maximal in the proximal retina at 25% retinal depth. Also, PII simply increased in amplitude as stimulus spots were enlarged, whereas the M-wave exhibited spatial tuning. Under light-adapted conditions and with small-spot stimuli the M-wave is the largest extracellular voltage in cat retina. By recording the vitreal ERG near the retinal surface with the microelectrode referenced to a silver wire in the vitreous, we found that the M-wave in response to a small spot always had a negative polarity in the vitreous. Thus, unlike PII, the M-wave does not reverse polarity at the vitreo-retinal border. Because of stray-light effects, however, we were not able to assess the amplitude of the M-wave's contribution to the ERG obtained with diffuse retinal illumination. We conclude that the M-wave is present in the cat as a prominent cone-driven response of proximal retina that is separate from the b-wave, and whose significance for electroretinographic recordings remains to be determined.