Huber Daniel, Petreanu Leopoldo, Ghitani Nima, Ranade Sachin, Hromádka Tomás, Mainen Zach, Svoboda Karel
Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia 20147, USA.
Nature. 2008 Jan 3;451(7174):61-4. doi: 10.1038/nature06445.
Electrical microstimulation can establish causal links between the activity of groups of neurons and perceptual and cognitive functions. However, the number and identities of neurons microstimulated, as well as the number of action potentials evoked, are difficult to ascertain. To address these issues we introduced the light-gated algal channel channelrhodopsin-2 (ChR2) specifically into a small fraction of layer 2/3 neurons of the mouse primary somatosensory cortex. ChR2 photostimulation in vivo reliably generated stimulus-locked action potentials at frequencies up to 50 Hz. Here we show that naive mice readily learned to detect brief trains of action potentials (five light pulses, 1 ms, 20 Hz). After training, mice could detect a photostimulus firing a single action potential in approximately 300 neurons. Even fewer neurons (approximately 60) were required for longer stimuli (five action potentials, 250 ms). Our results show that perceptual decisions and learning can be driven by extremely brief epochs of cortical activity in a sparse subset of supragranular cortical pyramidal neurons.
电微刺激能够在神经元群的活动与感知及认知功能之间建立因果联系。然而，被微刺激的神经元的数量和身份，以及诱发的动作电位的数量，都很难确定。为了解决这些问题，我们将光门控藻类通道蛋白-2（ChR2）特异性地导入小鼠初级体感皮层第2/3层的一小部分神经元中。体内ChR2光刺激能够以高达50赫兹的频率可靠地产生与刺激锁定的动作电位。在此我们表明，未经训练的小鼠很容易学会检测短暂的动作电位序列（五个光脉冲，1毫秒，20赫兹）。经过训练后，小鼠能够检测到在大约300个神经元中激发单个动作电位的光刺激。对于更长的刺激（五个动作电位，250毫秒），所需的神经元甚至更少（大约60个）。我们的结果表明，感知决策和学习可以由颗粒上层皮质锥体神经元稀疏子集中极其短暂的皮质活动时期驱动。
