Micro Wave: Spreading Warm Bread With Socks : Short Wave It's another Micro Wave! Today, what happens in your brain when you notice a semantic or grammatical mistake ... according to neuroscience. Sarah Phillips, a neurolinguist, tells us all about the N400 and the P600 responses.

Plus, we dive into some listener mail — which you can send to us by emailing shortwave@npr.org.

Micro Wave: Spreading Warm Bread With Socks

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(SOUNDBITE OF MICROWAVE RUNNING)

MADDIE SOFIA, HOST:

Heyo. Maddie Sofia here with the indomitable Emily Kwong.

EMILY KWONG, HOST:

Oh, why, thank you. Hey, everybody. We are here with another Micro Wave - the series, not the kitchen tool.

SOFIA: Correct, yes. Micro Waves are what we're calling these mini little episodes with a few quick science facts and some listener mail, which you people seemed to love last time. So here we are, giving the people what they want.

KWONG: And this time, we've got some neuroscience, right?

SOFIA: Yes, the one true love of our producer Rebecca Ramirez.

KWONG: Indeed.

SOFIA: So today, we are talking boxing about some cool effects that happen in your brain.

KWONG: Wait. Sorry. Did you just say talking boxing?

SOFIA: (Laughter) Your little brain picked up on that, didn't it?

KWONG: Yeah. Is this a neuroscience episode about words or something?

(LAUGHTER)

KWONG: What's going on?

SOFIA: You're onto me, Kwong. So last week...

KWONG: You people...

SOFIA: ...Was #BlackInNeuroWeek, a week celebrating black excellence in neuroscience-related fields. And one scientist, Sarah Phillips, is a neurolinguist. She studies - yes. She studies how the brain processes language. So today on the show, what happens in the brain when we notice a grammatical mistake, according to neuroscience?

KWONG: In less than 10 minutes.

SOFIA: Just get out.

KWONG: Boopity bop (laughter).

SOFIA: Boopity bop.

(SOUNDBITE OF MUSIC)

SOFIA: OK. So earlier, I did this thing that probably sounded weird to you, Emily.

KWONG: Yeah. Your sentence - it didn't make any sense. But, you know, another day, another dollar.

SOFIA: (Laughter) All right. OK. Well - wow.

KWONG: (Laughter).

SOFIA: So when someone does something unexpected like that when they're talking to you or - get this - even when you're reading something that doesn't follow these standard conventions of the language, something kind of cool happens in your brain.

KWONG: Oh, so they can actually measure this.

SOFIA: Right.

SARAH PHILLIPS: So when we study the brain, one of the ways that we can study brain activity is by measuring electrical current that is flowing through your cortex, right? So the surface of your brain - for the cells to talk to each other, they release electrical current.

SOFIA: This is Sarah Phillips, our expert I mentioned earlier.

PHILLIPS: I am a rising fourth-year Ph.D. student in the Linguistics Department at New York University. And I'm also a member of the NYU Neurolinguistics Lab.

KWONG: Very cool.

SOFIA: She studies bilingualism and code switching, which we will touch on in a future episode because it is objectively awesome. But for today, she's helping me out as I explain these two things called N400 and P600.

KWONG: OK.

SOFIA: These are measurable responses that happen in your brain as you process language.

KWONG: OK. So, like, the little electrical signals that your brain is always giving off.

SOFIA: Right. But these are different from your normal brain buzzing that would happen if you were listening to, like, a, quote, normal sentence.

KWONG: Got it.

SOFIA: Basically, these phenomena are your brain saying, like, hey, hold up. Something weird's happening here.

KWONG: OK. So, like, when I peanut jam your brain...

(LAUGHTER)

KWONG: Is that an example of one? Did that...

SOFIA: Yes.

KWONG: ...Spark some neurochemistry for you?

SOFIA: Yeah, yeah. It felt wrong in a lot of ways.

KWONG: (Laughter).

SOFIA: Yeah. So as I peanut jam your brain - that's a good one. Anyways, yes. In 1982, psychologists Marta Kutas and Steven Hillyard published a paper showing that among these electrical signals, there was this big response about 400 milliseconds after a person reading a sentence came across a word that was, like, semantically confusing, or the meaning was wrong.

KWONG: OK. So it's, like, a linguistic oddball sentence is thrown your way. Your brain will produce a N400 response - or 400 milliseconds after you heard peanut jam in that sentence.

SOFIA: (Laughter).

KWONG: I peanut jam your brain. Your brain was, like, what's that? That didn't make any sense.

SOFIA: Exactly, yeah. And your brain does this, Kwong, in less than half a second, which is wild. So Sarah Phillips, art linguist from earlier, explained it also happens in other scenarios like garden-path sentences.

PHILLIPS: So you start to hear a sentence, and you think you know what's going to happen next. But then something kind of goes wrong.

SOFIA: OK.

PHILLIPS: And so when something goes wrong your brain has to go, wait. What? I don't think I interpreted this how it was supposed to be. So now I've got to restart.

SOFIA: Which Sarah says can happen with a sentence as simple as, he spread the warm bread with socks.

KWONG: Yummy (laughter). This is fun. I like this. OK. So how does this compare to the P600 you were mentioning earlier? Is that different than N400?

PHILLIPS: The big difference is just that they go in opposite directions, and they happen at different time points.

SOFIA: So when she says opposite direction, she's talking about how they kind of show up on these, you know, science graphs. You've heard of them.

KWONG: Sure.

SOFIA: So one shows up in the positive, and the other shows up as negative - N and P.

KWONG: Ah, OK.

SOFIA: But for me, the easiest thing to hang onto is that they happen at different times. So the N400 happens 400 milliseconds after the whoopsie. The P600 the brain gives off slightly later. That response peaks roughly 600 milliseconds after the whoopsie.

PHILLIPS: That's really it. And we're trying to then understand, when we see this type of effect, what could this effect represent? What is this effect characterizing what's happening in the brain?

SOFIA: And, initially, researchers thought that the answers to these questions was that the N400 was happening because of semantic errors.

KWONG: So involving the meaning of words.

SOFIA: Right. And that the P600 was showing up because of grammatical errors, which, not to brag - but (singing) I make all the time.

KWONG: And we love you for that.

SOFIA: Yeah. Yeah. Sure, OK. But it turns out, as research into all this has gone on, these effects might be more generalized kind of than researchers previously thought. It might just have to do with how your brain processes complex language.

PHILLIPS: And this just shows that when we think about language and how we process language, there are actually a lot of steps involved, starting from recognizing that the sound that you hear is a sound of the language that you speak and how those sounds then combine to form subparts of words.

KWONG: The brain is a magical creature, you know?

SOFIA: (Laughter).

KWONG: What a nice, little jaunt through the fields of neuroscience. Thank you, Maddie Sofia.

SOFIA: Well, don't thank me. Thank Sarah Phillips.

KWONG: Oh, thank you, Sarah Phillips.

SOFIA: And Rebecca - it was kind of her idea - this whole show.

KWONG: OK. Rebecca gets a lot of credit all the time. All right.

SOFIA: And now thank me. And now thank me.

KWONG: Let's move on, people.

SOFIA: OK, fair enough. Fair enough. All right. Listener mail time?

KWONG: Listener mail time. OK. First up is an email from Dean (ph). He says, hi, Maddie. I want you to know that I really like the way you thank or address all of the guests at the end of your show. I've listened to them all. I especially like how you say, quote, "I appreciate you." Initially, I thought it was tacky or excessive. But then I...

SOFIA: OK, fair but hurtful, fair but hurtful. OK.

KWONG: He's not done. He's not done. But then I thought about how you say it, and it seems like you really mean it. I can sense the passion in how you present the show, the guests and yourself when it comes to science. I think we need more of this sense of appreciation in the world. I'm a high school science teacher, and I try so hard to express passion for learning and science to my students. I gain inspiration from you and scientists and reporters on your show. And I've used some of your episodes for some of my classes. Maddie, I appreciate you - exclamation point, exclamation point, exclamation point. Dean.

SOFIA: Oh, my God, Dean. Well, I'll tell you what, bud. I appreciate you right back. And also, feel free to use all of our episodes for lesson plans. I'm very here for that. You know what I'm saying, Kwong?

KWONG: We love hearing about that. It's true.

SOFIA: Yeah.

KWONG: And, Maddie, Dean is completely right. You have made me far more enthusiastic about science than I already was.

SOFIA: (Laughter).

KWONG: So thank you for it.

SOFIA: Oh, my gosh. Emily, guess what? I really appreciate that.

KWONG: OK. I think we have another one, yeah?

SOFIA: Yes. This one is from Jen (ph). I like it for its ingenuity. OK. Just heard you on Sam Sanders' podcast.

KWONG: It's Been A Minute.

SOFIA: Amazing show. And here is what I do for outdoor exercising. I wear a face shield while out, plus a mask in more populated places. Love that. It at least protects me from flying sweat, snot, droplets from passing folks - parentheses - I also modded my bike helmet, adding a shop-type face shield.

KWONG: Whoa.

SOFIA: Easy to see through, plus still keeps the bugs out of my eyeballs - end parentheses very smart. Plus, it gives some protection to others, should I be spewing virions myself. Anyway, it is a better-than-nothing mitigation that lets people see you smile. Jen. And you know what?

KWONG: What?

SOFIA: I appreciate Jen.

KWONG: OK. You're an appreciation monster.

(LAUGHTER)

SOFIA: It's true. I'm not getting out of control. It is real, though, everybody. It is real. OK. So...

KWONG: Maddie's just a walking heart with arms. All right. So thanks for listening to this Micro Wave episode.

SOFIA: If you have a science question for us or you just want to say hey, as always, you can email us.

KWONG: We're at shortwave@npr.org.

SOFIA: This episode was produced by Rebecca Ramirez. And Viet Le edited it.

KWONG: And Yowei Shaw and I checked the facts.

SOFIA: I am still Maddie Sofia.

KWONG: And I'm, hopefully, still Emily Kwong. Thanks for listening to SHORT WAVE from NPR. Bye.

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