sábado, 16 de julio de 2016

A lab founded by a tech billionaire just unveiled a major leap forward in cracking your brain's code

This is definitely not a scene from "A Clockwork Orange." Allen Brain Observatory



Bred for the lab, the mice were genetically modified so that specific cells in their brains would fluoresce when they became active. Researchers had installed the brain-windows surgically, slicing away tiny chunks of the rodents' skulls and replacing them with five-millimeter skylights.

  • Which cell lit up? 
  • Where in the brain? 
  • How long did it glow? 
  • What was the mouse doing at the time? 
  • What was on the screen?

"This is the first data set where we're watching large populations of neurons' activity in real time, at the cellular level," said Saskia de Vries, a scientist who worked on the project, at the private research center launched by Microsoft co-founder Paul Allen.

The problem the Brain Observatory wants to solve is straightforward. Science still does not understand the brain's underlying code very well, and individual studies may turn up odd results that are difficult to interpret in the context of the whole brain.

A decade ago, for example, a widely-reported study appeared to find a single neuron in a human brain that always — and only — winked on when presented with images of Halle Berry. Few scientists suggested that this single cell actually stored the subject's whole knowledge of Berry's face. But without more context about what the cells around it were doing, a more complete explanation remained out of reach.

"When you're listening to a cell with an electrode, all you're hearing is [its activity level] spiking," said Shawn Olsen, another researcher on the project. "And you don't know where exactly that cell is, you don't know its precise location, you don't know its shape, you don't know who it connects to."


To get beyond that kind of feeling around in the dark, the Allen Institute has taken what Olsen calls an "industrial" approach to mapping out the brain's activity.

"Our goal is to systematically march through the different cortical layers, and the different cell types, and the different areas of the cortex to produce a systematic, mostly comprehensive survey of the activity," Olsen explained. "It doesn't just describe how one cell type is responding or one particular area, but characterizes as much as we can a complete population of cells that will allow us to draw inferences that you couldn't describe if you were just looking at one cell at a time."


A visualization of cells examined in the project. Allen Brain Observatory





"If you're inserting an electrode you're going to keep advancing until you find a cell that kind of responds the way you want it to," he said. "By doing a survey like this we're going to see a lot of cells that don't respond to the stimuli in the way that we think they should. We're realizing that the cartoon model that we have of the cortex isn't completely accurate."

Olsen said they suspect a lot of that noise emerges from whatever the mouse is thinking about or doing that has nothing to do with what's on screen. They recorded videos of the mice during data collection to help researchers combing their data learn more about those effects.

The best evidence for this suspicion? When they showed the mice more interesting visuals, like pictures of animals or clips from the film "Touch of Evil," the neurons behaved much more consistently.

"We would present each [clip] ten different times," de Vries said. "And we can see from trial to trial many cells at certain times almost always respond — reliable, repeatable, robust responses."

In other words, it appears the mice were paying attention.

Allen Brain Observatory

But the project isn't over.


"Ultimately," Olson said,"we want to understand how this visual information in the mouse's brain gets used to guide behavior and memory and cognition."


So the underlying code of mouse — and human — brains remains largely a mystery, but the map that we'll need to unlock it grows richer by the day.

ORIGINAL: Tech Insider
Jul. 13, 2016

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