2021's Breakthroughs in Neuroscience and Other Biology

For centuries, doctors and scientists have tried to unlock the mysteries of the human brain. How is it organized? Which areas control different mental functions, and how is it all wired together to generate our subjective psychological experience? For the past 100 years, neuroscientists have approached the brain like map-makers, charting its features and activities within well-defined boundaries. The prefrontal cortex is celebrated as the seat of rationality. The motor cortex plans and coordinat

es movement. The somatosensory cortex and parietal lobes control our perception of the physical world. The temporal lobes process memories, language, and emotion. The occipital lobe processes and integrates visual information. And the cerebellum helps execute our body’s motor commands. Scientists have looked at the brain through the lens of our beliefs about what it means to be human. So when we're looking at parts of the brain, trying to figure out what they do, scientists are usually using the

ir beliefs about what makes a human mind, and some of those ideas you can trace all the way back to Plato. Recent studies of traditional categories of cognitive brain functions, like memory, show surprising amounts of activity that overlap different parts of the brain – so much that the simple map and its strict categories lose their meaning. The way that we've been conceptualizing the mind doesn't map very well at all to the functions of different systems in the brain. These kinds of distinctio

ns are very subjective and it's probably better to try to look at the brain and figure out what its organizational properties are without appealing to these culturally ladened categories, which aren't respected by the brain. Russell Poldrack is doing just that. At his lab at Stanford University, he’s taking a computational approach to understanding the organizing features of our mind. If you have people perform a bunch of different psychological tasks that vary in the psychological functions tha

t we think they engage, let's collect a bunch of data on a bunch of different tasks and ask the data what kind of structure there is. Poldrack's lab used machine learning to try to isolate neural activity related to memory recall. But rather than simply mapping into memory centers, the data correlated with more general constructs of activity — ones for which we don't yet have names. What that has shown us in some cases is that things that we might've thought were measuring the same thing really

don't seem to be measuring the same thing at all. I think we need to fundamentally rethink how we conceptualize the functions of the brain. Within neuroscience, there's a broad agreement that the brain is a computational machine and we need to understand what the computations are that it's doing, and that we should be able to ultimately understand psychological function in terms of those computations. Part of the challenge is that we don’t have a great language for describing those computations

other than math. So it raises essentially a question of whether we're going to end up with models of the brain that are really good at predicting the activity of the brain, but that we can't sort of give human understandable explanations to. Deep in the jungles of Southeast Asia lives the world’s strangest flower. This is Rafflesia arnoldii. It’s affectionately known as the “corpse flower” because it smells like rotting meat to attract pollinating flies. It’s the largest flower in the world, wit

h the size and weight of a small child. But the weirdness doesn’t end there. Rafflesia is not just a flower—it’s a parasite. They require part or all of their nutrients and water from another plant. As a result, we often find alien genetic material in the genome of a parasitic plant—many times from the host. One of the hypotheses is that parasitic plants steal from the host as a weapon to make them a better parasite. Liming Cai is the latest of a long line of biologists to attempt to sequence Ra

fflesia’s notoriously unwieldy genome. Biologists struggled because the Rafflesia genome features highly repetitive elements called transposons, known as jumping genes for their ability to cut and paste themselves at repeating intervals. Most organisms silence these elements, but Rafflesia is not most organisms. These highly repeated elements [are] causing a lot of problems for a scientist trying to assemble genomes because it's basically like putting a jigsaw puzzle, but every piece is identica

l. This year, with the help of a bioinformatics team, Cai successfully created a draft genome for a species of Rafflesia. Her findings were even more shocking than biologists had expected. There are a couple of things going on here that really sort of blew my mind in the first place and really make us rethink what defines a plant. So all plants have a similar set of genes. In Rafflesia, what we found is that it has lost nearly half of the conserved plant genes, which is really a record-breaking

finding. Cai also found that 90% of Rafflesia’s genome consists of repeating DNA, like transposons. That’s highly unusual. No one knows why, but the answer may transform our understanding of parasite genomics. With the advances of genome sequencing technology, we can explore all the weird branches of the tree of life—how rules can be bent by all sorts of really creative strategies. Life is really diverse and nature often surprises. In the early 20th century, sleep became a popular topic for rese

archers. The weapon of choice was the newly invented electroencephalograph, or EEG, a machine measuring electrical activity in the brain. This approach produced many insights, but it also set up a bias in the studies: that sleep is a neurological phenomenon, and its purpose and structure is located in the brain. Everybody has thought that sleep is of the brain, by the brain, for the brain. This is a famous quote by Alan Hobson, who's a brilliant sleep scientist that made some huge contributions

to the field. But it really overlooks the fact that, in fact, we're not brains. We’re organisms, we’re integrated. Everything we do is integrated with everything else. The first cracks in this brain-centric view started to show when the Swiss scientist Irene Tobler noticed that cockroaches sleep. Since then, we’ve learned that simpler creatures, with less and less brain, also sleep. And recently, a new discovery has changed the narrative entirely. This is a hydra. It’s one of the simplest forms

of animal life. Instead of a brain, hydras have nerve nets, the most basic nervous systems in nature. This year, a group of Japanese scientists demonstrated that hydras sleep. These tiny fresh-water organisms are living proof that sleep evolved before brains. But if sleep didn’t evolve in and for the brain, what is it for? More and more scientists are really looking in peripheral tissues and asking how the body can impact the brain and how the brain can impact the body specifically with respect

to sleep regulation. In my lab, the current hypothesis is that there are some situations that the brain can't fix itself. And in association with whatever damage has taken place, sleep can lower the activation energy to have these circuits begin to find that solution. So the idea then is that when you're asleep, you're using less energy, but the energy that you are using, you're using in a different way that you're supporting functions that you would not be able to otherwise support if you were

awake. The research on hydras is the latest in a growing body of evidence that sleep first evolved to help regulate metabolism and enhance repair, and only later took on brain-related functions. I really do believe that sleep and metabolism are intertwined. So that's going to be the future.