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[Steve] When we're looking at animal
behavior we're really ultimately
reading out functions of the nervous
system.
[soft music]
How the nervous system works
is one of the big mysteries in
biology and neuroscience.
And I think that that's a place
where the worm can step in and be
really powerful, because
given that it's transparent and so
easy to work with experimentally it
has only 302 neurons.
That lets us really powerfully go in
and assign the sort of neural
substrates for these different
aspects of animal behavior that we
study.
So one behavior that the community's
been really interested in is the
ability of worms to detect and avoid
bright, ultraviolet or blue light.
And so that makes
sense in terms of the worm's natural
behavior because the worm's
transparent. So if the worm
ever went into direct sunlight it
would begin to run the risk of
damaging its DNA.
What was harder to understand is
that worms don't have eyes.
So how
are the worms detecting the light
anatomically and also molecularly?
How do they do it?
Earlier work by other groups in the
field found a protein called
lite-1 that seems to be required for
the worm to run away from bright
light. And something was really
surprising is that unlike other
genes to detect light, lite-1
looks a lot like a taste receptor.
So this was sort of odd.
We got involved in this
a little bit later when we
found that shining this bright light
onto a worm also inhibited
their feeding behaviors.
And so we wondered whether maybe the
light could be producing noxious
tastes and then the worm is tasting
them. So maybe it's able to
taste light via these
products that light produces.
And sure enough we found that one
of these chemicals, hydrogen
peroxide, if you give the worm
hydrogen peroxide they'll stop
eating and start to spit. And that
inhibition of eating depends on
these same genes that control the
responses to light.
And so we found a
neuron that directly controls the
muscles that produce spitting.
I found three neurons which
are able to function upstream of
this neuron to make the worm spit.
And something that has been unexpected
and interesting about that is that
we found that these neurons that
produce spitting are also involved
in inhibiting the muscles of the
mouth to make the worm stop eating.
We think that really the worm is
sort of like balancing these two
competing needs to 1)
stop eating so that you stop
ingesting this bad thing, and 2)
to be able to eject the bad thing
that is in your mouth out of the
mouth.
I think that what we're doing is
important because the worm community
is having a lot of firsts in being
able to connect the behavior of
animals to the structure of their
nervous system and their genetics.
We're going to learn more and more
about ourselves and our nervous
systems and that has implications
not only for our health and
well-being but also what our place
in the world is.