3D Brain Imaging Technique Allows Scientists to Monitor Entire Nervous System
Researchers at MIT and the University of Vienna have created an imaging system that reveals neural activity throughout the brains of living animals. This technique, the first that can generate 3D movies of entire brains at the millisecond timescale, could help scientists discover how neuronal networks process sensory information and generate behavior. The team used the new system to simultaneously image the activity of every neuron in the worm Caenorhabditis elegans, as well as the entire brain of a zebrafish larva, offering a more complete picture of nervous system activity than has been previously possible. The new approach, which uses an optimized light-field microscope, could help neuroscientists learn more about the biological basis of brain disorders.
Transcript
00:00:05 The brain is made out of a huge number of neurons. In the human brain we have perhaps 100 billion neurons. Those neurons work together in complex networks in order to generate things like thoughts and feelings. Now, if we want to know where in this complex network something is happening we ideally could be able to see all the processing happening all at once. If we can't do that, and we can only see a part of the circuit as it processes information, we might not know exactly where the actually computations are happening.
00:00:31 For example imagine you are trying to figure out how your computer works and you look at the screen. You might conclude, by looking at the screen, that there's a lot of stuff happening in the screen. But as we know its not the screen that's actually doing the computing, there are chips in the computer elsewhere that are processing the information. Our group is interesting in understanding how the brain works. And the key components for doing that are the tools for controlling the brain and reading out from the brain.
00:00:55 One way to read out from the brain is to read out the activity optically. So, if we can convert the activity of the neurons into lights then we can literally see how the brain is actually computing. In this current study the goal is to try and figure out whether there are ways to record the neural activity of all the cells in an organism. For example there is a small worm, C. elegans, which has only 302 neurons. Those neurons mediate sensation, movement, decision making and so forth. If we can record the neural activity - the fast electrical pulses that these cells use to compute - throughout an entire nervous system, then
00:01:33 it might be possible to figure out how different parts of the brain work together in order to generate complex outputs. Up until now people were only able to record the signal only from the brain or head region of the worm because of the intrinsic tradeoff between the field of view and the speed that comes from scanning. In this work we don't rely on any scanning which now allows us to do high-speed 3-D imaging with a very large field of view. What we found was that indeed we could take simultaneous three-dimentional images throughout the entire body of an organism, and along the way we picked up the neural activity of
00:02:10 cells throughout the brain and the various ganglia that make up the nervous system. Now, because we can image the neural activity throughout an entire nervous system, we can avoid the problem of not knowing where a particular computation is happening. We can see everything that's going on and that allows us to pinpoint where information processing is occurring.