Rivera-Alvidrez Zuley, Lin Ichi, Higgins Charles M
Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721, USA.
Vis Neurosci. 2011 Sep;28(5):419-31. doi: 10.1017/S095252381100023X. Epub 2011 Aug 22.
Motion-sensitive neurons in the visual systems of many species, including humans, exhibit a depression of motion responses immediately after being exposed to rapidly moving images. This motion adaptation has been extensively studied in flies, but a neuronal mechanism that explains the most prominent component of adaptation, which occurs regardless of the direction of motion of the visual stimulus, has yet to be proposed. We identify a neuronal mechanism, namely frequency-dependent synaptic depression, which explains a number of the features of adaptation in mammalian motion-sensitive neurons and use it to model fly motion adaptation. While synaptic depression has been studied mainly in spiking cells, we use the same principles to develop a simple model for depression in a graded synapse. By incorporating this synaptic model into a neuronally based model for elementary motion detection, along with the implementation of a center-surround spatial band-pass filtering stage that mimics the interactions among a subset of visual neurons, we show that we can predict with remarkable success most of the qualitative features of adaptation observed in electrophysiological experiments. Our results support the idea that diverse species share common computational principles for processing visual motion and suggest that such principles could be neuronally implemented in very similar ways.
包括人类在内的许多物种的视觉系统中的运动敏感神经元，在暴露于快速移动的图像后，会立即表现出运动反应的抑制。这种运动适应在果蝇中已得到广泛研究，但尚未提出一种能解释适应最显著成分的神经元机制，该成分的出现与视觉刺激的运动方向无关。我们确定了一种神经元机制，即频率依赖性突触抑制，它解释了哺乳动物运动敏感神经元适应的许多特征，并用于模拟果蝇的运动适应。虽然突触抑制主要在发放脉冲的细胞中进行了研究，但我们使用相同的原理为分级突触中的抑制建立了一个简单模型。通过将此突触模型纳入基于神经元的基本运动检测模型，并实施一个模拟视觉神经元子集间相互作用的中心 - 外周空间带通滤波阶段，我们表明能够非常成功地预测在电生理实验中观察到的适应的大多数定性特征。我们的结果支持这样一种观点，即不同物种在处理视觉运动方面共享共同的计算原理，并表明这些原理可能以非常相似的方式在神经元中得以实现。
