Dr. Jennifer Groh

And now our audience knows about how sound is localized.

We haven't talked that much about how visual information is localized.

I think mostly that's fairly obvious that your eye is kind of a little camera and light hits a particular location on the retina.

And that retinal location tells us what the location of the visual stimulus is.

But it tells us the location of the visual stimulus with respect to the direction the eyes are pointing.

But our sound localization cues are with respect to where's the sound with respect to the head.

So this finding that neurons were responsive to sound but cared very much about the position of the eyes was really, you know, a startling finding when it first came about.

When I set up my own lab, I basically set out to find out, well, where does this computation happen?

Where is the brain incorporating information about eye movements into the processing of

We knew from the literature was, okay, the superior colliculus is one of the places, but does it happen in the superior colliculus or does it happen in a different brain area?

And so we kind of marched along the auditory pathway in brain areas that I call them part of the auditory pathway because they're much more closely connected to the ear than to anything else.

And because at the time, nobody thought there were visual signals in these areas.

We thought it was just auditory.

That too turned out not to be true, but they're definitely much more auditory than visual.

And what we found was that in each of these areas, eye movements affect the auditory signals there too, even though they weren't in this convergent structure of the superior colliculus.

So we decided that it would take a long time to march through every brain area

and that it might be worth sort of jumping over a few brain areas and looking in the ear itself.

So I need to give the audience a little bit more information about what, you know, what is possible in the ear and why that seemed like a reasonable thing to do.

It has some little muscles in it.

There are two muscles that control the bones of the middle ear.