The holy grail
“The fruit fly larva was great, but that's just one brain, right?” Barsotti smiles. “Now what we're doing is taking images of lots more brains, from animals that were raised under different conditions, to try to generate a general brain map across species.”
In starting with smaller brains, scientists hope that many findings can be applied to humans - much like how the pharmaceutical industry uses animal trials to make successful human therapies. But while smaller brains are a good place to start, they are still unfathomably complex.
“The fruit fly brain took ten years to image and analyse,” Barsotti says. “The lizard brain will take another decade just to image. How long it takes to analyse depends on the progress we’re able to make.
“The human brain is the holy grail, to understand on a cellular level what every single neuron and synapse does. But with our current technology, it would take more than 1,000 years to fully map one human brain.
“We’d like to understand, evolutionarily, what is conserved in different animal brains. How do different brain parts relate to your habitat or size? Or whether you’re predator or prey?
“In order to do this, we have to ask ourselves: what are the most ethical animals we can study to gain an understanding of the human brain?”
Even small animal brains are humbling in their complexity. These seemingly simple creatures harbour dense, interwoven and responsive networks in their heads. Consider how difficult it would be to fully map the connections in a single mouse brain. Barsotti estimates that the data storage infrastructure alone would cost over a billion pounds. Teams of engineers, developers and researchers would be needed to process the petabytes of data produced - all to map the brain of something Robert Burns described as a ‘poor beastie’.
When Barsotti was scouring those neuroscience textbooks, she came across explanations of the human brain that emphasised our unique cleverness. In her latest work, she’s not so sure.
“If you look at the fly brain in very high resolution, you see it has a lot of these recurrent connections - connections responsible for learning, memory and navigation - that we assumed were unique to humans. These creatures are actually very smart.”
In addition to these ethical complications, scientists have to deal with a thorny thicket of practicalities. When mapping takes such a long time, the risk of failure is extended and painful. Believe it or not, Cambridge researchers are human - they make mistakes. Blurred images or lost sections in a sample could make it impossible to complete a full map, but those mistakes could take 10 years to come to light. With so few labs currently doing this work, there’s no back up.
“I would love there to be 100 labs doing this work, not just 3!” Barsotti says.
