Selective responses to faces, scenes, and bodies in the ventral visual pathway of infants [video]
November 15, 2021
November 9, 2021
Heather L Kosakowski
All Captioned Videos Publication Releases
MIT graduate student Heather Kosakowski and MIT Prof. Rebecca Saxe discuss their latest paper in Current Biology where they show that 2- to 9-month-old human infants have face-, scene- and body- selective responses in FFA, PPA, and EBA, respectively, constraining theories of cortical development.
[MUSIC PLAYING] REBECCA SAXE: fMRI is an amazing tool for studying how brains work because, unlike almost any other tool that we have, you can do it in a perfectly healthy, fully functioning human baby. You don't have to wait for any kind of injury or illness. But at the same time, you can see the whole brain. So other tools that we have that involve measuring from the skull, you can only see the parts of the brain that are near the skull. And there are many things we want to know about brain development that happen in the deep parts of your brain.
HEATHER KOSAKOWSKI: When I joined Rebecca Saxe's lab as a lab manager, she and Ben Deen had just published a really exciting study in Nature Communications where they had found face and scene responses in infant brains using functional Magnetic Resonance Imaging, or fMRI. I thought that was super exciting. And my foster sister was having a baby. So I said, Becca! Please let me scan my sister's baby. And she said, OK. My sister let me scan her baby too.
And so I started scanning babies, which was really exciting. But as I learned how to scan babies, I also started noticing ways we could improve scanning methods. We started a collaboration of Rebecca Saxe, me, Nancy Kanwisher, Boris Keil, Atsushi Takahashi to design a new coil. Boris had helped design the previous coil. And so this team had all worked together before. I was the newbie.
But I had some very specific ideas for how I thought it could be more comfortable with babies. And also, I wanted to be able to use headphones so we could attenuate scanner noise and hopefully get better data. And so we designed a new coil that flexible and adaptable in the way it came around infants heads, but also enabled us to use headphones, so we could use a higher resolution acquisition sequence.
And so that was super exciting. One of the reasons it was so exciting is because it minimized the susceptibility artifact in the ventral temporal cortex, which was region of the brain I was especially interested in, especially for this study, where we were looking for responses in the fusiform face area, the parahippocampal place area, and the extrastriate body area.
REBECCA SAXE: Heather's key results in this paper is that she could find all three of those brain areas in babies who are two to nine months old, so babies who have had very little visual experience with the world. And each one of them is in the spatial location that you would predict from where it will be when that baby's an adult. And also is already sensitive to the exact category that it will be when that baby becomes an adult.
So the face area already responds just to faces; the body area, just the bodies; and the scene area, just to scenes. So that tells you even these tiny babies with so little visual experience, they already organize their visual world in approximately the way we do. The big parts of a visual system are there in a very young baby.
HEATHER KOSAKOWSKI: So this was a really cool, novel, exciting finding that is going to be something for the field to contend with. Because many of the theories of cortical development right now don't expect that babies will have category-selective responses in the VTC. And so it's really exciting to see how the field moves forward in trying to understand cortical development from here. I'm currently working on a project looking at speech and music responses in infants' brains too. And also looking at face responses across the infant cortex. So hopefully you'll be hearing more about that stuff soon.
A lot of parents ask if there are any safety concerns about scanning their babies. And so what we use to take the pictures of the babies' brains is a big magnet. And so the big magnet means that pieces of metal can be a hazard. So if you bring in a pen or something, it might fly towards the magnet. And so we make sure all parents and babies don't have any metal.
The other safety concern with scanning is that the scanner makes a lot of noise. And so we make sure infants have plenty of hearing protection so we don't have to worry about harming their hearing. And we give parents hearing protection too. But other than that, it's completely safe for babies. They can participate while they're awake or they're asleep. And they can have pacifiers and bottles and cry when they want to get out. [LAUGHS] And so it's totally safe and fine.
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