Sagdullaev Botir T, McCall Maureen A
Department of Psychological and Brain Sciences, University of Louisville, Louisville, KY 40292, USA.
Vis Neurosci. 2005 Sep-Oct;22(5):649-59. doi: 10.1017/S0952523805225142.
The receptive field (RF) of most retinal ganglion cells (RGCs) is comprised of an excitatory center and an antagonistic surround. Interactions between these RF elements shape most of the visual responses of RGCs. To begin to investigate center-surround interactions of mouse RGCs quantitatively, we characterized their responses in an in vivo preparation to a variety of spot and full-field stimuli. When RGCs were stimulated with a spot that matched the cell's RF center diameter (optimal spot), all RGCs could be categorized as either ON- or OFF-center. In all RGCs, full-field stimulation significantly reduced both the peak and the mean firing rates evoked with an optimal spot stimulus. Full-field stimulation revealed differences in other response properties between ON- and OFF-center RGCs. With a full-field stimulus, the duration of the OFF-center RGCs response was reduced making them more transient, while the duration of the ON-center RGCs increased making them more sustained. Of most interest, full-field stimulation altered the RF center response sign in approximately half of the OFF-center RGCs, which became either OFF/ON or ON only. In contrast, all ON-center and the other OFF-center cells conserved their RF response sign in the presence of the full-field stimulus. We propose that sign-altering OFF-center RGCs possess an additional RF surround mechanism that underlies this alteration in their response. Of general interest these results suggest that the sole use of full-field stimulation to categorize visual response properties of RGCs does not adequately reflect their RF organization and, therefore, is not an optimal strategy for their classification.
大多数视网膜神经节细胞（RGCs）的感受野（RF）由一个兴奋性中心和一个拮抗性外周组成。这些感受野元件之间的相互作用塑造了RGCs的大多数视觉反应。为了开始定量研究小鼠RGCs的中心-外周相互作用，我们在体内制备中表征了它们对各种点状和全视野刺激的反应。当用与细胞的RF中心直径匹配的点状刺激（最佳点）刺激RGCs时，所有RGCs可分为ON中心或OFF中心。在所有RGCs中，全视野刺激显著降低了最佳点刺激诱发的峰值和平均放电率。全视野刺激揭示了ON中心和OFF中心RGCs在其他反应特性上的差异。在全视野刺激下，OFF中心RGCs反应的持续时间缩短，使其更具瞬态性，而ON中心RGCs的持续时间增加，使其更具持续性。最有趣的是，全视野刺激在大约一半的OFF中心RGCs中改变了RF中心反应的符号，这些细胞变成了OFF/ON或仅ON。相比之下，所有ON中心和其他OFF中心细胞在全视野刺激下保持其RF反应符号。我们提出，符号改变的OFF中心RGCs拥有一种额外的RF外周机制，这是其反应改变的基础。这些结果普遍表明，仅使用全视野刺激来分类RGCs的视觉反应特性并不能充分反映其RF组织，因此，这不是对它们进行分类的最佳策略。
