How to hijack a brain

Most of us saw Blue Planet Two and the impact that plastics in our oceans are having on the wildlife there. But it’s not just the obvious large-scale things, like plastic bags, that are causing most of the problems: it’s actually the microplastic particles that these form when they break down. These particles are invisible to the naked eye, but they are steadily working their way through all forms of life in the ocean and appear to be impacting the health and activity of at least some of them. Speaking to Chris Smith, Danni Green is from Anglia Ruskin University; she’s just published a study showing that plastic particles affect the ability of some shellfish to attach themselves to their surroundings...

Chris - So which shellfish have you been looking at?

Danni - So we looked at the blue mussel, Mytilus edulis. This is the mussel that you probably most commonly would eat, the mussel that you would see in on the shelves of supermarkets. Myself and my collaborators from Maynooth University, we wanted to understand how these mussels have been affected in terms of the health but also how they function as ecosystem engineers. These are really important organisms: they form quite complex reefs, and they support a lot of biodiversity of other animals.

Chris - How did you discover that they're struggling to cling on?

Danni - I set up an experiment using an outdoor laboratory system so it's kind of realistic without releasing microplastics into the environment, which would not be very popular with DEFRA, and we dose them with microplastics and run the experiment for quite a long time - 52 days - and after this time I tested their tenacity, which is their ability to hold on to the substrate and you measure the vertical force that is necessary to detach them. And I found that the control mussels that were not exposed to microplastics had double the strength than the ones exposed.

Chris - They make a sticky material that enables them to cling on don't they?

Danni - So they form what's called byssal threads, so it's little tiny threads; and you would have seen these on mussels either on the shore or on your plate and these actually attach onto the rock and allow them to stay in place. And the mussels that were exposed to microplastics, so, they had half the number that they actually produce - they produce less threads. Therefore the strength was reduced.

Chris - And the dose of microplastics that you're exposing them to, was that sort of ocean-realistic? In other words, if I were to go out into the field and take a sample of seawater where mussels would be eating and going about their business, I would probably see levels of plastic equivalent to your experiment or not? 

Danni - I hope not! At the current day! So, the amounts that were used is representative of what we might find in the future, in the next kind of 50 to 100 years depending on which sort of projection you use. But actually, our concentrations were one of the lowest used in experiments to date. So it is quite realistic. These effects aren't happening now and there's still time to prevent this happening. 

Chris - Which is good news isn't it? But how do you think the plastics are achieving this effect? What are they doing to the mussels to mean that the byssal threads are reduced by up to 50 per cent in the affected animals? 

Danni - So it's difficult to tell. It's either that they're making the animal feel full, and it's not getting the same nutritional value from its food because it feels like it's full. We did a technical shotgun proteomics, where you basically take a blood sample (in this case it's called haemolymph but it's the equivalent of blood in vertebrates), and we analysed all the proteins in the organism and found that a lot of immune response proteins were being expressed - stress response detoxification proteins, all these things that are indicating that this animal is trying to get something out of its system. And this was the same whether you had normal microplastics or biodegradable microplastics. So there's an effect from both of these types.

Chris - Do you think this is unique to mussels, or have you started to look at other shellfish that will also be exposed in the same way? They're filter feeders - they'll be drawing in water and therefore potentially bringing these things into their bodies in the same way that the mussels do...

Danni - So it's difficult to tell if the exact effects that we had were unique but from other studies that I've done I found that oysters have also been impacted: they've had alterations to their filtration rate, differences in their biomass, and other people have found that their reproductive output has also been reduced by microplastics. So there are definitely effects happening on other bivalves, not just mussels.

Chris - It's interesting you're seeing this effect with just - if you want - "naked microplastics", because one of the other things people talk about in this context is that these plastics tend to soak up a toxic cargo of other oil-loving chemicals in the sea. So it could be a double whammy for these animals then, because not only are they getting a direct impact physically from the plastic, they could then get the toxic burden that goes with it. So they could be impacted twice?

Danni - Yeah, exactly. So it could either be from the plasticisers that are on the plastic itself, or it could be from the persistent organic pollutants they absorbed from the water that they're in; it could also be biological - it could be microorganisms attaching to the microplastics and then having an effect. And in order to separate these, we would have to do some pretty complex experiments, which I know that these sort of things are being done to try to work out what is it really that's causing this effect.

Chris - And just finally, if this turns out to play out the way you think it is in your experiments, what would be the marine impact of this?

Danni - If mussels can't attach to the rock then they can't form complex reefs; they can live in really exposed environments where the waves are gonna wash them away. So there's a greater chance of them being dislodged and therefore unable to form these really important habitats, which support biodiversity. They're also economically important, and when we farm them as well they're often left out on these kind of pole and line sorts of systems, so they could be dislodged: you could be losing yield. There's economic and ecological consequences...

The Earth is, to put it lightly, a pretty important factor in humanity’s origin, for a start we live here. But the extent to which features of the planet like rivers, rock type and plate boundaries have shaped our evolution and human history, runs very deeply. It affects everything from our development of intelligence, right up to who you might vote for at the next election. Don't believe us, well Lewis Dartnell from the University of Westminster, has just written a book on the topic, it's called Origins: how the earth made us, and Georgia caught up with him to find out why we’ve been so shaped by our own planet…

Lewis - Humans are an animal species just like any other organism. We have been adapting to our environment, we've been influenced by our ecosystem, by an environment we've been growing up in. So in some sense it's not surprising that as a species we've been crafted by our natural world. And the reason that we evolve such high intelligence in East Africa is because the environment was exceedingly unstable and very quickly fluctuating, because of a combination between the plate tectonics and that interacting with climate cycles to do with Earth's wobbling orbit. So it was our environment that created us to be very intelligent.

Georgia - Why would a changing climate help us become super smart?

Lewis - Because if you have a relatively static environment, so say its environment that's always pretty dry, an animal can evolve a very good survival strategy to that like a camel, and it would store a lot of water in its body and recycle all of that water and have kind of humps to minimise its body fat. But if you've got an environment that is always changing, fluctuating back and forth, there's no no one body solution to that. And the best solution that evolution can come up with in that case is a behavioural solution, it makes complex adaptable behavior, it gave us intelligence.

Georgia - Right. So if we'd had it good and easy and everything stayed the same would have become simple camel type.

Lewis - We probably wouldn't be having a conversation on the technology, in fact we wouldn't have language or tool use had it not been for this wildly fluctuating environment in East Africa. 

Georgia - How about more recently, I say recently, like when humans started to start making civilisations.

Lewis - So we look at the first civilisation and I'm sure everyone is familiar with Mesopotamia. There's a very fertile region between the rivers Tigris and Euphrates and that's where the first large cities popped up. That's where the very beginnings of civilisation began. And again there's something really quirky about the plate tectonics in that region where humanity first built civilisations. And what's happening is the Arabian Peninsula is swinging away from Africa like this great big barn door of continental drift and it slammed into the southern margin of Eurasia, of the other continental plate, and crumpled up a range of mountains called the Zagros mountains. And when you've got a great big heavy mountain range it pushes down the crust, the earth's crust alongside it, and you get what's known as a foreland basin. And we often find rivers like the Tigris and Euphrates flowing through that foreland basin and they fill up with a very fine, very fertile river deposited soil. And so in a sense humans settled and built their first civilisations in the place was easiest to get settled with agriculture and build these big populations and these first cities. And it was plate tectonics again that created that environment for us to settle into.

Georgia - And what about us today just like day to day lives. Is there anything that we've been influenced by that we might not know?

Lewis - Another great example that really jumped out to me when I was writing Origins, was it's not just ancient history. We still bear this deep imprint of the earth and the kind of geology underlying our feet in something as current and free flowing as politics, and there's a couple of examples in Origins. There is a very very clear correlation between Labour-voting constituencies and rocks dating back to the carboniferous era. So looking as far back in Earth's history as 300 million years now, and again that deep link is actually profound it jumps out at you when you just look at the two maps that I put into Origins. And the explanation is is actually quite simple because carboniferous age rocks are where the coal deposits are, and coal is what powered us through the industrial evolution in Britain and it's been, and it still is, an incredibly important energy source in the modern world. And the reason that the Labour constituents map over where the coal deposits is that the Labour political party rose out of trade unions, so that the link there is relatively simple. But I still think is absolutely profound when you think about it that something like the political map of where people just happen to vote for different political parties correlates so strongly with the age of geological rocks that happen to lie beneath your feet.

Are you being manipulated without even realising it? Georgia Mills got the low down from Philipe Bujold, who studies decision making at Cambridge University...

Philipe - Yeah. So actually I thought I'd give you an example of how easy you are to manipulate. So I'll ask you a quick question which is a very famous question. Daniel Kahneman and Amos Tversky, who won the Nobel Prize in 2003 in economics, did this test and so I'll ask you two sets of questions. Let's say we have 600 people that are infected with a specific disease and I give you the choice of two programmes that you can apply to try and save a few people. So programme A you know for a fact that about 200 people will be saved. Programme B about one third probability everyone will survive, everyone will be saved but then two thirds probability no one will be saved. Which one would you pick? Programme A or programme B?

Georgia - A I think, yeah.

Philipe - Yes. So that's what most people would pick. So you pick the safe option so you try to save 200 people for sure. If I'd asked the question a bit differently and instead basically give you two programmes that are about dying instead of saving. So we say programme C 400 people will die for sure or programme D there is a one third probability that no one will die or two thirds probability that everyone will die.

Georgia - That's trickier, D sounds better in that one, but they're the same.

Philipe - So you follow basically the average. So most people if you present an option as a gain would go with the risk-less option so you go for it the certain the sure options or saving 200 people. But here 400 people will die for sure is considered a loss. And people tend to be a lot more risk seeking when it comes to losses. So you prefer testing tense and so you can imagine this kind of question when you ask this a million times to different people, people have different patterns but everyone seems to follow this type of behaviour.

Georgia - Does this mean governments can use this to try and change our behaviour?

Philipe - Yes so these kinds of tests have actually started a whole new subfield of science called behavioural sciences. Within this we have behavioural insights which are different choice biases that we can use to try and modify people's behaviour. And most of this is actually for good, so I don't want to scare everyone. It's also been happening most of your lives we're just aware of it now. But sometimes it's not as good. And so with the advent of data science there's a lot of different things you can do, and alot of corporations, shops, companies are using that to maximise profit. But then on the other hand you have governments that are really trying to use that, to try and make society better if you want, according to the government that is.

Georgia - Hit me hit me with some examples then.

Philipe - Some examples, well actually I was talking to a group in Canada, my home countries. So their behavioural insights group in British Columbia, were asking question recently which was, how do you reduce the rate of human caused wildfires? For example you've probably heard about California last year very difficult. So that's a really good question and you don't want to force people to stop making fires. You just want to try and nudge them, which we call to try and reduce this risk. So they were asking a bunch of different questions and it seems like low cost messaging which is just reminding people, texting people about it, seems to influence their decision. And so what you want to do is still leave the decision there for people, so they still have the same choices, but the way you asked the choice is basically biasing the choice one way or another. So that's a great example. Another one that we probably all experience is on Netflix, and when you're watching TV on any streaming device really, when they start playing the next episode automatically this is a huge framing effect because if you had to choose that's a little gain. So you're choosing to watch the next episode you're winning, but if you have to stop the next episode automatically that's a loss. So it's a lot harder for people and you just keep watching, you binge watch and that's a very good example of what's happening.

Georgia - And what about sort of out and about in the street. So there are things there that we might come across on a daily basis?

Philipe - Yes actually in London there's a very good example. And that would be the buttons you have to press to cross the intersection. A lot of these actually in a lot of major cities don't do anything. They give you the impression of control which gives people the idea that oh they've pressed so they will wait. But most of the time they don't actually do anything. Now in most villages or smaller towns they actually have some measure of importance. But you can try next time in London or in New York a lot of these things don't do anything.

Georgia - We've been tricked. So what does that mean, it makes us less likely to just run across the road?

Philipe - Exactly so it reduces jaywalking. And there's another great example that would target men specifically if you've been to a urinal recently where you saw a bee or a fly in the urinal, that's people taking advantage of your psyche really to make you aim there so that you don't have spillover.

Georgia - Making it fun I guess as well. Is there a way to you know, shield yourself from this kind of stuff.

Philipe -  So unfortunately like a lot of behavioural effects you can't really shield yourself. So this takes advantage of how our brain is wired and so we're very very efficient at being flexible. That's a key trait of humans, but all this flexibility comes at a price. And it's that we take a lot of shortcuts in our decision making and a lot of what we do is going to be subjective, so relative. So I was talking about gains and losses earlier, a lot of this will be based off what you're seeing in your direct environment. So what's considered a win right now might be a loss tomorrow. And so that's a key symptom if you want of our flexibility of our humanness, but unfortunately it also makes us very risk prone for these kinds of behaviours.

The technique called “optogenetics” involves adding a light-sensing gene to nerve cells. This makes the nerve cells become light-sensitive themselves, enabling scientists to switch on and off different brain areas by implanting a small light-source into the brain. Georgia Mills spoke to Kay Maxine Tye, who uses optogenetics at MIT to understand how the different parts of the nervous system contribute to brain function and the generation of complex behaviours. She first of all explained how you make nerve cells light-sensitive...

Kay - The first projects well that became really popular was channelrhodopsin and channelrhodopsin is an algal protein so it's found an algae pond scum. And somehow this single-celled organism 'knows' that it needs to swim towards light where, actually, how it does this is that there is a light-sensitive channel and when that light hits that channel it opens. That, in the case of an algae, makes a little flagellum flap so that the algae moves forward. In neurons, it would make the neuron fire an action potential which is the means by which neurons can communicate with each other.

Georgia - Right. So by putting this protein; making sure it's expressed in certain parts of the brain when light is present you can basically switch them on.

Kay - Exactly.

Georgia - How do you get the protein to express only in the neurons you're interested in? 

Kay - A common way is to use a viral vector. There are all different types of viruses and you can express any gene of interest in a virus. The virus infects the cell and then the cell starts producing whatever that gene codes for. So in the case of channelrhodopsin I can package it into a virus and then use the virus to infect certain cells. Based on the cell type we can control the expression of channelrhodopsin.

Georgia - So what kinds of things are people using optogenetics for?

Kay - It's a really powerful tool because it allows us to go in and, you know the brain is just this big grey ball of mush, and how do we know how it works? We can piece by piece test what happens to the rest of the brain as well as to the animal's behaviour when we manipulate the activity of select populations of neurons. We can define those populations of neurons by what they produce, what type of neuron they are, what their connections are, and that helps us sort of dissect the circuitry of the brain.

Georgia - Could you give me a couple of examples of what you've actually made animals do?

Kay - Yes. So in our group, we publish a paper in 2015 and found that if you activate GABAergic, these are inhibitory neurons that project from the lateral hypothalamus to the ventral tegmental area, which is where most dopamine neurons are found... If you activate these GABAergic neurons what you get is - you know, we place the animal in an empty chamber and you start stimulating these neurons and the animal will begin licking the floor and then it will shift its way and engage as if it's picking up food from the ground and eating it, except that there's no food it's an empty cage. So their paws are empty, yet they're sitting back holding it up to their face and engaging in what looks like feeding behaviour. Another result that we've seen is you stimulate certain populations of neurons, for example, in the brain stem and you'll get all sorts of really robust escape-related behaviour: animals leaping out of their cage, jumping off of apparatus. One of my students once called this the popcorn mouse we got popcorn mice because the mice are just leaping all over, and that suggests that we're tapping into an escape related circuit.

Georgia - It sounds like this is quite a young field but there's amazing things being done already. How far do you think this could go? Could we get to the stage where we have like remote controlled mice?

Kay - I don't think remote controlled mice is very far off at all, I mean, wireless stimulation devices exist. I mean, the hardest part would be like the battery life of the wireless control. I mean, that we basically have now. I think that if that doesn't exist now it's, you know, a few months away from making possible.

Georgia - Wow. So you're telling me you could get a mouse and sort of say: "forward, left, right". That kind of thing?

Kay - Yeah, yeah! I mean, we can control motor cortex, we can make mice run in a circle. If we had two different lights on the different sides you could make the mice run left or right, or forward or freeze. I think running backwards is a little bit trickier. I mean, to me, a remote control mouse feels very much within reach.

Georgia - Do you think it could ever be done in humans?

Kay - I think the biggest concern that I would have about using it in the brain for humans - although I believe optogenetics is already being used for retinal prosthetics for people who are blind and to help them see, and for bladder control. Things are on the periphery of cases in which function is already completely lost and so there's relatively little to risk. But I think in terms of using it in the brain we still are just beginning to understand brain function. And so I think that is still quite dangerous because the viral tools that we have for expressing these transgenes which will be the only way to get into a human would be potentially feasible if, and only if, they could become stable and safe. And I think that is a big 'if'. Currently all the viral vector tools that I'm aware of and familiar with and have used have some level of toxicity.

Georgia - All right. So you don't have to worry about being remote controlled humans just this minute?

Kay - No! I think there's all sorts of ethical concerns that I hope will prevent irresponsible exploration!