Johnston Jamie, Lagnado Leon
School of Life Sciences, University of Sussex, Brighton, United Kingdom.
Elife. 2015 Mar 18;4:e06250. doi: 10.7554/eLife.06250.
Motion anticipation allows the visual system to compensate for the slow speed of phototransduction so that a moving object can be accurately located. This correction is already present in the signal that ganglion cells send from the retina but the biophysical mechanisms underlying this computation are not known. Here we demonstrate that motion anticipation is computed autonomously within the dendritic tree of each ganglion cell and relies on feedforward inhibition. The passive and non-linear interaction of excitatory and inhibitory synapses enables the somatic voltage to encode the actual position of a moving object instead of its delayed representation. General rather than specific features of the retinal connectome govern this computation: an excess of inhibitory inputs over excitatory, with both being randomly distributed, allows tracking of all directions of motion, while the average distance between inputs determines the object velocities that can be compensated for.
运动预期使视觉系统能够补偿光转导的缓慢速度,从而精确确定移动物体的位置。这种校正已经存在于神经节细胞从视网膜发出的信号中,但这种计算背后的生物物理机制尚不清楚。在这里,我们证明运动预期是在每个神经节细胞的树突状树突内自主计算的,并且依赖于前馈抑制。兴奋性和抑制性突触的被动和非线性相互作用使体细胞电压能够编码移动物体的实际位置,而不是其延迟表示。视网膜连接组的一般而非特定特征支配着这种计算:抑制性输入超过兴奋性输入,且两者随机分布,允许跟踪所有运动方向,而输入之间的平均距离决定了可以补偿的物体速度。