2020's Biggest Breakthroughs in Biology

[Music] it can be tempting to think of the brain as a computer digital computers process information by harnessing a network of billions of on and off switches called transistors and for decades neuroscientists believed the brain functioned in much the same way with neurons playing the part of these simple switches in this understanding of the human brain neurons themselves weren't intelligent it was the entire network of 100 billion neurons that made the human brain the most advanced information processing machine in the known universe or so we thought in the 1980s a more complex picture began to emerge we learn that neurons aren't all the same when stimulated individual dendrites can express different voltages this was the first clue that dendrites could be processing information independently and that our biological computing system might be more powerful than we thought this is yota poirasi a paper she co-published this year reveals just how much we underestimated neurons and dendrites so when matthew larkum in his lab discovered the presence of some peculiar types of the druidic spikes he came to me and we discussed what could be the functional role of these spikes so the main difference of this type of spikes compared to the ones we know already is the stronger the stimulus the smaller the amplitude of the detritic spike that they discovered this is something that had not been seen before in other types of animals and we didn't know what could be their functionality poirazzi built a computational model of neurons as a two-layer network where dendrites functioned like processors within processors we designed the model so that it would reproduce this decreasing amplitude behavior what does this mean it means that as you give the model a stronger excitatory stimulus the output of the model should get smaller and we wonder what could be the computation that would benefit from such a feature and we thought of exclusive or the exclusive or function known as xor is a complex logic gate commonly seen in neural networks it yields a binary output of one if one but only one of the inputs is one in other words a signal is only passed on when it is graded with the right combination of inputs mathematical theorists thought an entire network of neurons would be required to compute the xor function and the main novelty of our work is this is no longer true if you have a neuron that implements this type of a specific transfer function that is produced by these detritic spikes then you can solve the exclusive oral problem without requiring a large network so while it may be tempting to think about the human brain as a computer it's maybe more accurate to think about it as a hundred billion tiny supercomputers our individual neurons are much more powerful than the other types of neurons we've seen before in other types of animals and this could in turn contribute to our increased cognitive abilities as humans where does one individual end and another begin on the surface this seems like a simple enough question but for biologists it's not so straightforward viruses need host cells to replicate slime mold amoebas spend part of their lives as a single cell and other parts as a massive colony that moves like a single organism why is the natural world clustered into little ordered patches that we call organisms why is that that's david krakauer he and his colleagues at the santa fe institute completely reimagined individuality their new theory called the information theory of individuality argues that individuals are best thought of not in spatial terms but in temporal terms we would argue that it's more general that it's actually more profitable to focus on how information flows forward in time than the particular matter that the information is carried by individuals are not a static thing they're actually processes right so an individual is a process and that's a very different way of thinking about fundamental units in evolutionary biology than than we've seen in the past the theory operates according to three principles [Music] individuals can exist at any level of biological organization from the subcellular to the social group individuality can be nested with one individual living inside another and it exists on a continuum which means that entities can have different degrees of individuality this is a kind of more fluid and continuous notion of individuality that encompasses potentially a broad range of phenomena from physical systems through the biological there are three kinds of individuals the first is shaped by environmental factors but contains most of its information internally this is what humans and mammals are the second is the colonial form which involves a more complicated relationship between internal and external factors the third type is driven almost entirely by the environment stanislav wrote a beautiful short novel called solaris that was made into a wonderful film by tcharkovsky and in that an entire planet is an individual the entire ocean is sentient and that's so counterintuitive to us we couldn't imagine something that vast and that fluid having this property but why not and i think these kinds of formalisms might allow us to detect individuals that are very distributed and don't conform to our expectations based on biology [Music] it may seem like a truism that sleep loss is bad for your health but we know surprisingly little about why scientists still don't know for example why animals who are completely deprived of sleep die even more quickly than when they're starved jurgana regula's lab at harvard university studies the effects of sleep deprivation we thought that if we deprive animals of sleep and if we see that there's an effect of survival and then we dig around the entire body in an unbiased manner there's a chance that we may uncover some kind of cellular dysfunction or damage that could explain why sleep is required for survival these are scans from the small intestines of flies that were kept awake for 10 days in regula's lab that neon buildup is a material called reactive oxygen species or ros so you could see that there is really extensive damage extensive oxidation of gut molecules that follows accumulation of reactive oxygen species so you can see damage to dna for example and you can see cells dying this thing that was happening in the gut immediately preceded the time when animals started dying so that was a pretty um strong indication to us that this might not be just the correlation but might be might be causative for the demise of animals that happens during sleep deprivation regula and her lab were able to replicate their findings in mice this suggests that a fundamental job of sleep is to regulate the ancient biochemical process of oxidation oxidative stress is a consequence of sleep deprivation and the gut is specifically impacted by sleep loss and then that makes you think in general about the god kind of it's very special role that it that it um probably plays in in our lives right now and also that it has played in shaping um animals throughout evolution you

Channel: Quanta Magazine

Views: 505,636

Rating: 4.9516554 out of 5

Keywords:

Id: YpDsA7SE-3c

Length: 8min 21sec (501 seconds)

Published: Wed Dec 23 2020

Reddit Comments

[u/incoherent1]

I'm surprised they didn't mention the AI that can predict how proteins will fold.

[u/HunterCased]

David Krakauer -- the scientist that talks about the theory of individuality in this video -- recently gave a 2-part interview (with his brother, a prominent neuroscientist) on the Brain Inspired podcast:

• Part 1
• Part 2

They talk about complexity science and intelligence.