Parallel pathways for representing temporal sensory information

作为夜行动物，啮齿类动物在很大程度上依靠它们的胡须来感知环境的精确性质，而这个系统的分辨率令人印象深刻：一只被蒙住眼睛的老鼠可以用胡须来区分只有微米级表面纹理不同的物体。由于不同哺乳动物的不同感觉系统具有深刻的相似性，研究老鼠的胡须可以为有关大脑感觉机制的一般问题提供重要的见解。当老鼠在探索一个物体时，它会以每秒10次的速度在物体表面来回扫胡须。这就导致了晶须的振动。这些振动被称为“微运动”，它们很重要，因为不同的物体会引起不同的微运动，所以老鼠能够区分它们。一个关键的暗示是，大鼠大脑中神经元的一个关键功能是表征和处理胡须运动。但这是如何发生的还不完全清楚。在我的实验室里，我们最近在理解丘脑——所有感官的重要控制中心——如何代表胡须运动方面取得了进展。以前人们认为丘脑中的神经元对须状刺激的反应都是一样的，但我们意外地发现了多样性。这一新发现带来了许多新问题，包括：这种多样性起源于大脑的哪个部位？不同类型的神经元位于丘脑的不同部位吗？大脑皮层中有相应类型的神经元吗？大脑皮层是一个关键的大脑结构，在大脑的感觉回路中仅次于丘脑。在这个项目中，我们试图回答这些问题。这项研究更广泛的意义在于，它将为感官系统和感官信息的处理方式提供新的见解。

Being nocturnal, rodents rely to a large extent on their whiskers to sense the precise nature of the environment, and the resolution of the system is impressive: using its whiskers, a blind-folded rat can discriminate between objects that differ only in micron-scale surface texture. Since it is well-established that different sensory systems in different mammals have profound similarities, studying the rats whiskers can offer important insight into general questions about the mechanisms of sensation in the brain. When a rat is exploring an object, it sweeps its whiskers back and forth across the surface around 10 times per second. This causes the whiskers to vibrate. These vibrations are known as 'micromotions' and they are important, since it is because different objects evoke different micromotions that the rat is able to tell them apart. A key implication is that a critical function of neurons in the rat's brain is to represent and process whisker motion. But how this happens is not fully understood. In my laboratory, we have recently made progress in understanding how the thalamus - a vital control centre for all the senses - represents whisker motion. Whereas previously it was thought that neurons in the thalamus all respond in the same way to a whisker stimulus, we unexpectedly found diversity. This new discovery opens up many new questions, including: Where in the brain does this diversity originate? Are neurons of different types located in different parts of the thalamus? Are there corresponding types of neuron in the cerebral cortex - a key brain structure, which is the next level after the thalamus in the brain's sensory circuit. In this project, we seek to answer these questions. The wider significance of the research is that it will contribute new insight into sensory systems and how sensory information is processed.