Fish in the matrix: motor learning in a virtual world
Fish in the matrix: motor learning in a virtual world
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DOI：
10.3389/fncir.2012.00059
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发表时间：
2013-01-25
影响因子：
3.5
通讯作者：
Engert, Florian
中科院分区：
文献类型：
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作者：
Engert, Florian
运动方向的提取是由许多感觉系统执行的重要计算，并且特别地，视网膜中的方向选择性视网膜神经节细胞（DS-RGCs）获得其选择特性的机制已经被广泛研究。然而，DS-RGC是否只是将此信息传递到下游区域，或者在这些受体结构中是否发生额外的和潜在的从头加工，这是一个非常有趣的问题。在斑马鱼幼体顶盖，在这种动物中最大的视网膜沉淀区的神经元，显示方向选择性（DS）的反应，移动的视觉刺激，但这些属性是如何获得的仍然是未知的。为了研究这一点，我们首先使用双光子钙成像来分类顶盖细胞对以不同速度和不同方向移动的条的群体反应。随后，我们对这些DS顶盖神经元进行了体内全细胞电生理学研究，发现它们的抑制性输入强烈偏向运动的零方向，而兴奋性输入几乎没有表现出选择性。此外，我们发现，兴奋性电流引起的刺激在首选方向移动发生在抑制性电流之前，而刺激在零方向移动引起的电流在相反的时间顺序。由这些电流引起的膜电位调制通过尖峰产生机制增强，以在尖峰输出中产生放大的方向选择性。因此，我们的研究结果涉及一个本地的抑制电路在产生方向选择性在顶盖neurons.One的斑马鱼神经科学领域的大剩余的挑战是建立的技术和制剂，允许记录和扰动的神经活动的动物，可以有意义地与环境相互作用。由于在自由行为的斑马鱼中很难做到这一点，我在这里描述了两种通过拴系制剂实现这一目标的替代方法。第一种方法是将头部固定在琼脂糖中，并结合在线成像和尾部运动分析。在第二种方法中，麻痹的鱼被悬浮在中层水中，神经根记录作为预期运动的指标。在这两种情况下，鱼可以沉浸在虚拟环境中，并允许通过真实的或虚构的尾巴运动与这个虚拟世界互动。在这篇评论中给出的具体例子主要集中在视觉反馈的作用上，但一般原则肯定延伸到其他形式，包括本体感觉，听觉，平衡和体感。
The extraction of the direction of motion is an important computation performed by many sensory systems and in particular, the mechanism by which direction-selective retinal ganglion cells (DS-RGCs) in the retina acquire their selective properties, has been studied extensively. However, whether DS-RGCs simply relay this information to downstream areas or whether additional and potentially de novo processing occurs in these recipient structures is a matter of great interest. Neurons in the larval zebrafish tectum, the largest retino-recipent area in this animal, show direction-selective (DS) responses to moving visual stimuli but how these properties are acquired is still unknown. In order to study this, we first used two-photon calcium imaging to classify the population responses of tectal cells to bars moving at different speeds and in different directions. Subsequently, we performed in vivo whole cell electrophysiology on these DS tectal neurons and we found that their inhibitory inputs were strongly biased toward the null direction of motion, whereas the excitatory inputs showed little selectivity. In addition, we found that excitatory currents evoked by a stimulus moving in the preferred direction occurred before the inhibitory currents whereas a stimulus moving in the null direction evoked currents in the reverse temporal order. The membrane potential modulations resulting from these currents were enhanced by the spike generation mechanism to generate amplified direction selectivity in the spike output. Thus, our results implicate a local inhibitory circuit in generating direction selectivity in tectal neurons.One of the large remaining challenges in the field of zebrafish neuroscience is the establishment of techniques and preparations that permit the recording and perturbation of neural activity in animals that can interact meaningfully with the environment. Since it is very difficult to do this in freely behaving zebrafish, I describe here two alternative approaches that meet this goal via tethered preparations. The first uses head-fixation in agarose in combination with online imaging and analysis of tail motion. In the second method, paralyzed fish are suspended with suction pipettes in mid-water and nerve root recordings serve as indicators for intended locomotion. In both cases, fish can be immersed into a virtual environment and allowed to interact with this virtual world via real or fictive tail motions. The specific examples given in this review focus primarily on the role of visual feedback - but the general principles certainly extend to other modalities, including proprioception, hearing, balance, and somatosensation.