is language now we linguists defined
languages a set of rules that governs
any communicated system whether that
system sign language or spoken language
now language is one of the most
quintessential qualities we have as
human beings this basically makes us who
we are yet we know very little about how
the brain processes this arguably
language is one of the most difficult
things to study in science for centuries
we try to understand how the brain
acquires and uses language yet we know
very little how this is done for me as a
child I grew up in a multilingual home
with friends and family I was just
fascinated by the fact that at one
language topic at one top of
conversation multiple languages can be
switched in and out it amazed me then I
go to college and someone tells me hey
Mike you know you could study that
phenomenon I was hooked
I knew that’s what I wanted to do with
my whole life study language so at this
point you’re probably asking yourself
great but rats don’t speak Mike and
you’re right they do whole talk but they
sing and they sing real well now what
you see here is a sonogram now this is a
pictorial representation of an acoustic
signal on the Left y-axis kilohertz and
frequency on the bottom x-axis time
milliseconds so what you see think of a
think of it as a heat map where warmer
colors such as red or indicated of more
acoustic power cooler colors such as
blue or indicated of soft acoustic power
now the radish is different than we are
it prefers to vocalize in an ultrasonic
range outside of our normal hearing so
what we have to do is we have to use
computer technology to convert that to
our normal hearing range and when we
convert that signal this is what a rat
that’s beautiful sound I listen to these
things on headphones and I’m glad you
work with the rat we now know that
there’s three large distinct
classifications in their communication
repertoire the first one is the 22
kilohertz vehicle ization now what’s
unique about this type of call is that
it’s indicative of the animal and it’s
not happy as you can see from the
sonogram it’s very long in duration
carries a lot of acoustic power and it
doesn’t have frequency modulation no
contours to its frequency so when we
hear a rat or we do something to a rat
now the second large class of
vocalizations to the 50 kilohertz now
these are different from the 22 and that
the 50 kilohertz are reflective of when
the rats happy the other thing you’ll
know about this is that they’re shorter
in duration compared to the 22 killer
her vocals ation and they have frequency
contours now there’s a lot of different
ways you can make a rat happy in the lab
what we do when we’re training them we
give them fruit loops
they love sugar just like any kid
another way that we reward our rats for
doing what we asked them to do is we’ll
roll them on their backs well took up
their little bellies when you tickle
that’s telling you the rats happy now
the third class of call is the 40
kilohertz ition now this is unique to
the baby rat or rat pups as we call them
now when a rats born its deaf-blind
and it doesn’t have first so it has
trouble regulating temperature so if it
wanders away from the nest it’s
developed a surefire mechanism that the
mother will understand and bring it back
to the safety of the nest and it sounds
it’s almost if that rat same mom mom mom
those of you out there with children
especially your mother’s know
immediately with response this gets now
we are just beginning to really
appreciate the communicative system of
these rats there’s several different
call types and we know they have meaning
and they use them interchangeably with
each other it will be long before we
have the rosetta stone and better
now for me I’m interested in human
language and so we know from humans that
there’s gender differences there’s
subtle to gender differences the way the
girls speak the way the boys speak men
and women so I was interested what the
question of do rats have these subtle
differences so going back to that forty
kill hurtle ization that mom call if you
will we just simply recorded rats and as
you can see from the sonogram rats the
male rats vocalize differently than
female rats so being a neuroscientist
it’s inevitable we’re gonna ask the
question is there a gene responsible for
this well I can tell you this there’s no
one single gene responsible for language
but there is a gene that’s really
important and that’s Fox p2 so what we
know if Fox p2 comes from a family in
England what’s interesting about this
family in England is that there are
certain members of this family to have a
mutation in their fox p2 that mutation
causes problems and those problems are
language deficits and cognate cognitive
deficits so I was interested to ask the
question well if you have a mutation in
fox p2 it impacts the vocalizations
speech in humans I wonder if we altered
fox p2 and the rats if we’d see the same
thing so we did just that we targeted
Fox p2 with altered Fox p2 in these male
and female rats and what we found as you
recall from that earlier sonogram is in
the normal developing case males
vocalize differently than females but
when we inhibited Fox p2 and gave it to
the males and females what we found is
we’re able to reverse that
difference in their vocal calls so we’re
able to make a male sound like a female
and a female sound like a male as I
mentioned to you before that mom that 40
kilohertz and the mother is very
powerful
it’s a communicative unit they’re
exchanging informations so what we asked
is does changing that vocal call by
altering fox p2 changed the message
that’s being delivered from those pups
to the mom thereby changing her behavior
and the way she interacts with these
pups so you’ll notice in this picture
here on the right hand side this is the
cage of the rat on the right hand side
is where she built her nest what we
simply did was remove the pups marked
him for identification and placed some
of the opposite into the cage and
recorded the order of retrieval of the
mother picking up the pups taking him
back to the nest that behavior looks
like this now the thing you’ll notice
other than its speed is the mother just
doesn’t pick up the first pup she comes
to there’s something drawing her
attention to prefer to pick up other
pups over other ones in fact she’ll step
over some pick up some and drop them to
go retrieve another pup what we found is
that in the normal condition the mother
would prefer to retrieve a male before a
female but when we altered fox p2 what
we found is that the female remember
that when we alter fox p2 or switch the
vocalizations so what we found in this
type of behavior is that the mother when
she retrieved the male who was given the
inhibitor to Fox p2 that mother treated
that male not like a normal developing
male but in fact like a female and
retrieved him no different likewise with
a female who was given the inhibitor to
Fox p2 who now sounds like a male that
female was retrieved no different from
the normal developing male so
effectively
altering fox p2 changed vocal repertoire
of these pups that changed the signal
from the pups to the mother therefore
changing the way she interacted with her
pups
changing the behavior as a thing you’ll
notice about all these disorders
is one they’re all neural developmental
in origin – they have a higher
prevalence rate to affect boys over
girls and three one of the core symptom
ologies of these disorders is a language
deficit so I’m the luckiest person in
the world I think I get to study at
Virginia Tech I’m part of a great
program I have great colleagues probably
the best program director you can
imagine they let me do this stuff they
motivate me I’m inspired I’m that goofy
little kid that still loves language and
it’s really amazing to me that I can
study this and my goal is to help
contribute to science so I can better
understand language contribute to
science thereby giving people with
language deficits a voice and with that
thank you for your time [Applause]