Imagine you're walking through the park,
and you see a bunch of birds hanging out in a tree.
One of them begins to sing.
And quickly you locate the bird that is singing and identify it
as a sparrow.
Have you ever stopped to wonder how you did that?
First, you heard a noise.
Then you used your eyes to locate
the source of that noise.
And then you identified the producer of the song
as a sparrow.
That interaction of sight and sound
is what my research focuses on.
We know that the eyes and the ears
send information to the brain in great detail.
But it's just as important to know
how the brain sends information from more than one sense, how
that information is joined together and interpreted
in the brain.
It turns out that there are cells
in the brain that do respond directly to information
from more than one sense.
We call these cells multi-sensory.
And I'm working on finding out how exactly they process
that sensory information.
Some multi-sensory cells have enhanced responses
to this multi-sensory information.
Some cells do not.
And I'm working on figuring out why.
This is a question broader than how
is multi-sensory information processed.
What I'm really interested in is how
do neural circuits develop and function.
And I'm using the tools of sensory processing
in tadpoles to figure this out.
Tadpoles have simpler brains than humans
and other vertebrates.
And that allows me to study their neural circuits
in great detail.
I'm using a really cool technique
to study these circuits.
And I'm actually watching a living neural circuit
by taking over 20 images a second of these cells.
These cells light up because I've
added a dye that lights up when calcium is present.
And calcium is very closely correlated
with neural activity, and therefore,
serves as a good proxy.
By quantifying this lighting up, I
can find out if the cells respond to information just
from the eyes, just from the ears, or both.
And if they respond to both, do they have enhanced responses
to multi-sensory stimuli?
So far, I have found that individual cells
have different responses to the same stimulus.
Previously, we had thought that multi-sensory properties arose
from responses to weaker and stronger stimuli
in the same cell.
But my research shows that this same multi-sensory property
holds true across a neural circuit for a single stimulus.
Right now, I am following up on what
sort of single cell properties could give rise to this network
and behavior level property.
In particular, we have found a single protein
that is required.
It is called the NMDA type glutamate receptor.
Well known for its role in learning and memory,
integrates information in neurons.
Therefore, our working hypothesis
is that the information from the eyes and the ears
is integrated in each neuron.
And that integrated signal adds up to more than the sum
of the parts in the network.
Then that large network signal is used by the tadpole
to generate behavior.
However, beyond this, my results have been somewhat ambiguous.
Thus, is the challenge of science--
to keep asking questions and doing experiments
until the answer becomes clear.
Some of you may feel a bit lost, and that's OK.
Scientific discovery is rarely linear,
hardly ever makes sense the first time,
and requires a lot of hard work.
This is often hidden by the summary that you see online
or in the newspaper.
My results, and this method of studying
living neural circuits, is part of a broader, larger line
of scientific inquiry called basic science.
Basic science results and innovations
underlie all translational experiments, all treatments
for human disease.
These basic science questions help
us to find out what the normally behaving animals
and neural circuits are doing.
Because we need to know what normal looks
like before we can begin to understand disease states.
Now, bring yourself back to the sensory experience
of the sparrow.
A question that seems simple, how
do we interpret the world using our senses,
seems much more complex now.
The neurons, the neural circuits,
and the methods of scientific inquiry
all go into figuring out what our brains are doing.
And while this may now seem like an insurmountable task,
with the hard work and collaboration of researchers
like me, we can do it.
Thank you.
[APPLAUSE]