Nature：死无对证的时代终结

日前，冷泉港实验室（CSHL）研究团队在Nature上发表关于大脑切片的研究报道，称通过大脑切片可以准确地判断大鼠生前所接受的行为训练。这项研究为人们进一步理解大脑的学习和记忆编码机制提供了新的角度。

感觉的决定是基于感觉皮层神经元的活动，但是生物体如何学习将这种活动转化为合适的行为仍然有待摸索。研究人员在大鼠中研究声音线索转化为行动的过程。首先，对大鼠进行训练，使其对特定的声音与奖励建立条件反射。大鼠会根据声音的改变，在盒子里寻找奖励物品。并在大鼠接受训练的时候，检测神经连接的强度。发现对应的动物接受训练的情况，听觉纹状体会出现一个活性梯度。

研究人员推测，在此基础上或许能够通过死后的大脑切片来判断大鼠经历过什么样的训练。进一步的实验验证这种推断是完全正确的，这也标志着新的记忆编码的密码被破解，代表特定记忆的突触能被精确定位。

研究人员表示他们迫不及待地要将这种方法应用到向视觉这种更为复杂的学习形式和感觉系统中去。如果能够在不同的感觉系统中成果应用，这就意味着那些死无对证的时代即将终结。类似这种解读大脑的信息的实验并非由此开创，Mary Lou Jepsen是数字显示领域内的顶级专家，她研究如何将人类最具创造力的想法显示到屏幕上。在她令人大开眼界的演讲中，她将数字和大脑这两方面的爱好结合于两项尖端的脑研究项目中，它们可能为我们理解人类如何思考以及在思考什么指明新的方向。

生物谷推荐阅读英文原文：

selecive corticostriatal plasticity during acquisition of an auditory discrimination task

Perceptual decisions are based on the activity of sensory cortical neurons， but how organisms learn to transform this activity into appropriate actions remains unknown. Projections from the auditory cortex to the auditory striatum carry information that drives decisions in an auditory frequency discrimination task1. To assess the role of these projections in learning， we developed a channelrhodopsin-2-based assay to probe selecively for synaptic plasticity associated with corticostriatal neurons representing different frequencies. Here we report that learning this auditory discrimination preferentially potentiates corticostriatal synapses from neurons representing either high or low frequencies， depending on reward contingencies. We observe frequency-dependent corticostriatal potentiation in vivo over the course of training， and in vitro in striatal brain slices. Our findings suggest a model in which the corticostriatal synapses made by neurons tuned to different features of the sound are selectively potentiated to enable the learned transformation of sound into action.