Neural Underpinnings of Individual Recognition in the Brain

Part 1: Isabella Catalano Interview

Duration: 00:07:10
Transcript

00:00:05:19 - Hi I'm Thi Nguyen with the Science Communication Lab
00:00:08:08 and I'm excited to talk to scientists
00:00:10:04 who presented with the Share Your Research Competition.
00:00:12:18 Today I'm talking to Isabella.
00:00:14:06 Isabella would you like to introduce yourself?
00:00:16:08 - Hi I'm Isabella.
00:00:17:13 I'm a PhD student in the Integrated Program
00:00:20:01 in Neuroscience at McGill University in Montreal Canada.
00:00:23:08 - And tell me
00:00:24:07 what research questions are you curious about?
00:00:27:05 - I'm really curious about how you as an individual
00:00:31:22 interact with other individuals
00:00:34:04 and specifically what's going on in your brain
00:00:37:05 when that's happening that kind of lets you
00:00:39:18 know who you're talking to.
00:00:41:12 - And what motivated you
00:00:42:17 to get into this particular science field?
00:00:45:08 - So as a kid I was always really interested
00:00:47:17 in like the animal kingdom
00:00:49:01 and how different animals interact with each other.
00:00:51:15 And especially growing up like one of the easiest things
00:00:54:15 to look for is you know
00:00:55:21 you have a little bird feeder in your yard
00:00:57:12 so you can see all the birds interacting.
00:00:59:15 And you really start to notice after a while
00:01:02:10 that they kind of seem to know
00:01:04:18 who they're interacting with
00:01:06:11 and all sorts of things like that.
00:01:09:15 And that kind of just always fascinated me
00:01:11:14 just how did they know who
00:01:14:16 they all look identical to me right?
00:01:16:07 So how were they able to tell?
00:01:19:01 And then as I got older I got really interested
00:01:21:01 into neuroscience as well because all of the behaviors
00:01:24:03 that you do all kind of stem from what's going on
00:01:27:14 in your brain and what's driving your body
00:01:29:18 and all of your behaviors forward.
00:01:32:05 And so the kind of research that I do now
00:01:33:16 is kind of the synthesis of those two interests
00:01:37:23 where I really get to look at what's going on in the brain
00:01:42:00 when animals are recognizing each other
00:01:43:22 and interacting with each other.
00:01:46:21 - So observation as like a key thing
00:01:51:05 that fuels your curiosity?
00:01:53:21 - Definitely definitely I think so.
00:01:56:15 - As we talked about your as I heard about your research
00:01:59:13 as you talked about it you also one key part
00:02:02:03 is sort of the sound.
00:02:04:03 And have bird sounds and bird calls been influential
00:02:09:12 for you growing up too?
00:02:10:20 - Just going outside and listening to all of them for sure.
00:02:13:12 I think as I've grown older
00:02:15:17 I've definitely come to appreciate it more.
00:02:18:00 And especially now that I live in a bigger city
00:02:19:22 where there's not quite as much bird population around
00:02:24:13 I definitely miss hearing as much bird song as I used to
00:02:27:17 for sure.
00:02:29:00 - And what's one thing about being a scientist
00:02:32:13 that you wish other people knew?
00:02:34:15 - I really wish people understood
00:02:38:07 or understood more that science is really a process
00:02:41:01 and not just a single hard truth.
00:02:45:15 I think especially in the way
00:02:47:19 that science sometimes gets reported
00:02:49:22 and sometimes gets communicated
00:02:51:11 there's this impression
00:02:53:02 that it's like you do all this research
00:02:55:03 and you find this immutable truth about the world
00:02:58:01 and that's never going to change
00:02:59:12 when really science is such a process of building
00:03:03:09 upon what other people have discovered
00:03:05:12 and building upon knowledge that we already know
00:03:08:01 to discover new things.
00:03:09:21 And I think understanding that this is something mutable
00:03:12:16 that can change is really important.
00:03:15:15 - And in working in science you know
00:03:17:09 you're talking about some of the discoveries and curiosities
00:03:20:07 that people make if you were to talk to a young person
00:03:22:19 who's interested in going into science
00:03:24:12 what are some of the great things about doing research
00:03:27:08 and what are some of the most challenging things?
00:03:29:05 - I'll start with the most challenging things first.
00:03:31:08 I think it takes a lot of hard work
00:03:33:22 and it takes a lot of persistence.
00:03:36:19 And you do kind of have to be prepared
00:03:39:18 to just commit to doing a lot of work
00:03:41:17 before you see a lot of the payoff.
00:03:43:23 But I think the great part about that
00:03:47:01 is once you have committed you're not alone first off.
00:03:50:07 Like you have a whole lab working with you
00:03:53:05 like it's such a collaborative process
00:03:55:04 and getting to interact with so many other people
00:03:57:22 from so many walks of life is really a rewarding experience.
00:04:03:11 And when you do end up when you've done all the work
00:04:06:23 and you do end up with this like new thing in your hand
00:04:10:10 and you're the first person to see this new data
00:04:12:15 and how it all comes together
00:04:14:10 that's just a really incredible feeling.
00:04:17:01 - What is one of your first science memories?
00:04:21:02 - One of my first science memories is probably
00:04:27:12 I guess I have kind of two-fold story for this.
00:04:30:01 One is more naturalistic.
00:04:31:18 So I remember being I think I must have been
00:04:35:04 like eight or nine or something
00:04:38:07 and I'd seen some robins building a nest in a tree
00:04:42:10 and then we had a big storm and the next day
00:04:44:06 obviously the nest was on the ground
00:04:45:18 and it was kind of like broken up.
00:04:47:16 So I spent the whole rest of the day
00:04:49:22 like digging out mud putting it back together.
00:04:52:14 And then I set it all nicely
00:04:54:00 into a little bush and I tried to dig up worms
00:04:58:05 and put them in the nest for the robins to come back.
00:05:00:23 And I just spent hour
00:05:01:21 like just looking through the tree leaves
00:05:04:21 to see if they were coming back or not.
00:05:06:08 And obviously they weren't going to
00:05:08:09 but that was really fun for me.
00:05:14:04 Additionally also my grandmother used to work in
00:05:16:22 she used to teach biochemistry.
00:05:18:16 And so when she was taking care of me
00:05:20:13 she would take me to sit in her lab
00:05:22:03 and she would set me up in the back of her lab
00:05:24:04 with a Bunsen burner and just little jars
00:05:27:05 of like flammable chemicals.
00:05:29:10 And I would just sit there for hours with a little stick
00:05:32:12 dipping them into the chemicals
00:05:34:18 and putting them over the fire
00:05:35:21 and seeing what colors they went.
00:05:38:01 And I figured out the whole firework color scheme.
00:05:40:18 And it was really fun.
00:05:42:05 - Actually my one last last question.
00:05:45:17 What do you love about the brain?
00:05:47:04 - How complex it is.
00:05:48:23 I think it's like the basic workings of it are so simple
00:05:54:09 that we've known about them for a really long time.
00:05:56:18 Like you know action potentials and the neurons fire
00:05:59:09 and the electricity is what carries information.
00:06:03:08 And yet we're still discovering
00:06:05:03 all of these new like nuances to that.
00:06:07:21 And then not only on the cellular level
00:06:10:10 but when you zoom out and focus on the circuit level
00:06:12:23 or even on the brain level
00:06:15:01 you get all sorts of emergent properties
00:06:16:22 and the complex ways that it all interacts with itself.
00:06:21:12 Like I just think it's fascinating
00:06:24:16 to be able to think about untangling
00:06:27:01 even just a small part of that.
00:06:29:06 - It's been such a pleasure to talk to you
00:06:31:13 and I hope you at home
00:06:33:02 will check out Isabella's research talk
00:06:35:13 and how she untangles the neural underpinnings
00:06:40:15 of individual recognition in the brain.
00:06:42:09 Thank you so much Isabella.
00:06:44:12 - Thank you.

Part 2: Individual Recognition in Zebra Finch

Duration: 00:22:20
Transcript

00:00:00:00 (bright gentle music)
00:00:12:14 - Picture this:
00:00:13:17 You're in a coffee shop
00:00:14:19 you're waiting in line to get your coffee
00:00:16:16 and you hear someone calling your name.
00:00:18:15 So you turn and look and someone's coming towards you.
00:00:20:23 And they're super excited like
00:00:22:12 " ""Oh my gosh it's been so long."
00:00:24:02 What have you been up to?
00:00:24:23 How have you been doing?
00:00:26:03 " We really need to catch up sometime."""
00:00:28:11 And meanwhile you're just standing there wondering
00:00:31:22 where in the world are you supposed
00:00:33:14 to remember this person from?
00:00:36:06 If this has ever happened to you like it's happened to me
00:00:38:17 this is a great example of just how important the ability
00:00:41:20 to recognize another individual is
00:00:43:18 even just in our day-to-day lives.
00:00:46:01 It's also a great reminder of what happens
00:00:49:00 when you don't recognize another individual.
00:00:51:12 So now that you've got your coffee
00:00:53:08 you're walking down the street
00:00:54:18 and you hear some chirping in the bushes.
00:00:57:21 You turn and look
00:00:58:23 and there's a whole flock of sparrows just sitting
00:01:01:11 in the bushes there.
00:01:02:13 Some of them are chirping some of them are singing
00:01:05:02 and others are chasing each other around.
00:01:07:20 Now as a kid and even now as an adult
00:01:10:22 I've always been fascinated by the animal kingdom.
00:01:14:11 And one of the things that you start
00:01:16:13 to notice when you spend a whole lot
00:01:18:00 of time looking at birds on bird feeders is
00:01:20:16 that there's a whole web
00:01:21:23 of really complex social activity going on.
00:01:24:14 Some birds will let others sit next to them.
00:01:26:21 Some will chase the others away.
00:01:29:07 And there's just a lot going on.
00:01:31:01 And one of the questions that I had was always
00:01:33:23 how do the birds know who they're supposed
00:01:36:13 to be chasing away from the feeder
00:01:38:06 or who they're allowing to sit next to them?
00:01:41:01 And this question is something
00:01:43:03 that informs my current PhD research.
00:01:45:23 Hi I'm Isabella.
00:01:47:02 I'm in the Integrated Program in Neuroscience
00:01:49:09 at McGill University
00:01:50:23 and my guiding research question is
00:01:53:12 how does individual recognition work in your brain?
00:01:57:02 In particular I'm interested in the neural circuits
00:01:59:16 that let you take sensory information
00:02:01:09 such as someone calling your name
00:02:03:05 or a specific pattern of feathers
00:02:05:12 and turn that into the recognition of an individual.
00:02:09:18 To study this I use zebra finches as a model animal.
00:02:13:22 And zebra finches are a gregarious songbird species.
00:02:17:15 And in the wild they live in flocks
00:02:19:05 of up to hundreds of individuals.
00:02:21:12 Additionally zebra finches mate for life.
00:02:24:02 And this means that they have to be really good
00:02:25:21 at picking out one specific individual
00:02:28:11 from the crowd again and again.
00:02:30:22 So they have a really robust system
00:02:32:20 of recognizing other individuals
00:02:34:21 and this is something that makes them really good
00:02:37:06 for my type of research.
00:02:39:17 Additionally zebra finches have a couple
00:02:41:16 of other unique traits.
00:02:44:13 So this here is a picture of a pair of zebra finches.
00:02:47:12 They are sitting really close together
00:02:49:14 in this behavior called clumping.
00:02:51:11 It's kind of the equivalent of a human cuddle
00:02:54:08 and it's something that they do with a mated pair.
00:02:57:12 And right away you can can see
00:02:59:01 that there's some very distinctive visual cues here.
00:03:02:07 So the male on the left has
00:03:03:22 these bright orange cheek patches.
00:03:05:22 He also has these nice zebra stripes on his chest.
00:03:08:18 And these are both visual cues that he can use
00:03:10:20 to signal his identity.
00:03:12:16 Additionally zebra finches are songbirds
00:03:16:02 which means that they also have song.
00:03:18:01 And the song sounds something like this.
00:03:19:22 (zebra finch singing)
00:03:23:21 And we know that song is also used by zebra finches
00:03:27:16 to identify other individuals
00:03:30:08 because female zebra finches consistently prefer
00:03:33:13 to hear their mate's song over a strangers.
00:03:36:13 So the way that you would test this
00:03:38:09 is you build a really long cage
00:03:40:05 and you have a speaker on either end.
00:03:42:16 And one speaker is going to be playing the mate's song
00:03:45:13 and another speaker is going
00:03:46:20 to be playing a random bird's song.
00:03:48:14 So an unfamiliar song.
00:03:49:22 And then you put the female bird in the center
00:03:52:19 and you let her choose where she wants
00:03:54:16 to spend the most amount of time.
00:03:57:02 You can think of this in human terms
00:03:59:00 as if you're in a club and each floor of the club
00:04:02:02 is playing a different style of music.
00:04:03:17 You're going to spend the most time
00:04:05:04 on the floor that's playing the kind of music that you like.
00:04:07:20 And this is exactly what we see with the finches.
00:04:10:07 So if you look at the mean percentage
00:04:12:11 of time spent on one side or the other
00:04:15:03 you see that overwhelmingly
00:04:16:17 the zebra finches choose to spend time listening
00:04:19:06 to their mate's song.
00:04:21:19 Additionally zebra finches
00:04:23:01 also have some other unique attributes.
00:04:25:22 So when the males are learning to sing
00:04:28:06 they are learning to sing based on being taught
00:04:30:23 from an older male.
00:04:32:07 And if there's no older males present
00:04:33:23 then the juveniles never quite figure out
00:04:37:05 how to sing properly.
00:04:39:07 Now this is from males.
00:04:40:06 And for females they don't really sing at all.
00:04:43:16 However we do find that female finches
00:04:46:22 who are raised without song actually have
00:04:49:01 an impaired ability to discriminate between frequencies.
00:04:52:04 So you can think of this
00:04:53:01 as they can't quite tell the difference
00:04:55:01 between an A and an A sharp for example.
00:04:58:19 Now in one study
00:05:00:04 what the authors did was they trained zebra finches
00:05:02:14 to break a beam in response
00:05:04:06 an infrared beam in response to some frequencies
00:05:06:22 and to not break the infrared beam
00:05:08:17 in response to other frequencies.
00:05:10:08 And then they tested female finches
00:05:12:21 who were raised with song and raised without song.
00:05:15:20 So the finches who were raised
00:05:16:22 with song learned this task really well.
00:05:20:16 and they were able to do this
00:05:23:11 after a couple of days of training
00:05:24:18 at about 90% accuracy all of the time.
00:05:27:18 However female zebra finches
00:05:29:08 who were raised without song never learned
00:05:32:02 the task quite as well
00:05:33:02 and they weren't able to do it
00:05:34:11 with the same level of accuracy.
00:05:37:11 And this kind of impairment also carries over
00:05:40:05 to more ecologically relevant aspects
00:05:42:19 of zebra finch life.
00:05:45:08 So zebra finch males can sing two kinds of song.
00:05:48:10 And one is a very high quality courtship song
00:05:51:13 and this is meant to impress females
00:05:53:16 and show them what a great guy the male is.
00:05:57:01 And this is really intended to court and woo the females.
00:06:00:22 So if we look on this graph
00:06:02:12 where a one is a preference for a courtship song
00:06:05:04 and a zero is a preference for a different song
00:06:07:08 and 0.5 is about a chance level
00:06:09:18 so no preference at all
00:06:11:09 what we see is that normally reared females really prefer
00:06:14:06 the courtship song.
00:06:15:08 And this makes sense.
00:06:16:14 Again the males are using this courtship song
00:06:19:13 to attract females and show them that they're great
00:06:22:22 so it makes sense evolutionarily speaking
00:06:25:00 that normally reared females
00:06:27:09 who are raised in the same conditions
00:06:28:19 as they would be in the wild really prefer
00:06:30:22 this really attractive song.
00:06:32:20 However what we see with song-naive females
00:06:35:11 so the females who are raised without song
00:06:38:02 is that they are hovering around the chance line.
00:06:41:01 So they don't have a strong preference either way.
00:06:45:06 And this is very atypical for a species who
00:06:48:11 again use song as a method of courtship.
00:06:52:02 What is really interesting about this however
00:06:55:00 is that song-naive females still form preferences
00:06:58:06 for their mate's song.
00:07:00:01 So previously I talked to you about
00:07:01:23 how zebra finch females preferred
00:07:03:05 to hear their mate's song
00:07:04:08 and that was with females who were raised normally.
00:07:06:22 So they were raised with exposure to song.
00:07:09:07 But what we find is that the song-naive females
00:07:12:09 the ones who are raised without exposure to song
00:07:14:23 even though they have this impaired ability
00:07:17:05 to distinguish sounds and they don't seem
00:07:19:16 to show the same species-typical preferences
00:07:21:19 for courtship song as normally reared females do
00:07:24:06 they still prefer to hear their mate's song.
00:07:27:09 So in my research
00:07:28:17 I want to use both normally reared and song-naive females
00:07:31:20 to be able to see whether the ability
00:07:34:12 to recognize a mate acoustically
00:07:36:14 is really based on brain circuits
00:07:38:16 that are taking place in areas involved
00:07:41:04 with auditory processing
00:07:42:20 or if it lies elsewhere in the brain
00:07:44:13 and there's something else going on here.
00:07:46:22 Again I'm really interested in the neural circuits
00:07:49:05 so a lot of what I'm gonna talk about
00:07:50:16 is all stuff that's going to take place
00:07:52:18 on a cellular level within the brain.
00:07:55:09 And in order to study this
00:07:57:09 we built an apartment complex.
00:07:59:15 Okay not really.
00:08:01:03 But we did have a whole setup where
00:08:04:11 here we're going to have our first floor
00:08:07:01 of an apartment building for example.
00:08:09:21 And all of these females are going to be raised normally.
00:08:13:20 So these are all females who are raised
00:08:15:06 with exposure to song.
00:08:17:06 And the first two females here are nextdoor neighbors
00:08:21:16 in the apartment building.
00:08:22:20 And unfortunately the walls here are extremely thin.
00:08:26:05 So everything that's going on
00:08:27:15 in the first female's cage is going
00:08:29:20 to be heard by the second female and vice versa.
00:08:33:06 There's not a lot of privacy here.
00:08:36:07 Next these last two females
00:08:38:07 they are living on the complete opposite end of the hallway.
00:08:41:18 So they have never seen the first two birds.
00:08:44:21 They've never heard the first two birds.
00:08:46:22 They might even think that those apartments are vacant.
00:08:49:23 But importantly for my study is
00:08:51:17 that they've never heard these first two birds.
00:08:54:22 Now I mentioned previously that what I'm looking
00:08:57:23 for is neuronal activation.
00:08:59:22 And in order to look at differences in this
00:09:02:08 I'm going to be creating different stimulus conditions.
00:09:05:11 So the first stimulus condition is going
00:09:08:07 to be the mate song condition.
00:09:09:23 And this is going to be the red female listening
00:09:12:16 to her own mate song.
00:09:14:08 So this is a song that she's heard a lot
00:09:15:19 because he's going to sing to try and impress her.
00:09:18:05 This is her mate
00:09:19:14 and so this is something that's really relevant to her.
00:09:23:15 Next we're going to have familiar song.
00:09:27:04 So this is the green bird hearing the red bird's mate.
00:09:30:14 So again the walls here are very thin
00:09:33:08 so the green bird has heard the red bird's mate
00:09:35:20 just as much as the red bird has heard her own mate.
00:09:39:01 The difference here is that the green bird
00:09:40:20 is not mated to this guy.
00:09:42:11 She is just very familiar with his song.
00:09:45:14 Next we're going to have the stranger song condition.
00:09:49:04 And the stranger song condition
00:09:50:21 is the blue bird here hearing the red bird's mate.
00:09:54:04 And the first time that the blue bird
00:09:55:19 is ever going to hear this song is during this experiment.
00:09:58:17 So she's never heard it before.
00:10:00:00 This is a complete stranger to her.
00:10:03:02 And finally we're going to have the silence condition.
00:10:05:23 And the silent control is really important for my study
00:10:09:03 because it's going to let us have a background level
00:10:11:15 of neural activation that we can base most
00:10:14:01 of our analyses on.
00:10:16:08 So once we have this whole floor set up
00:10:19:13 what we do is we replicate it just a couple floors down.
00:10:24:04 And everything is the same.
00:10:25:10 The apartment layout is the same.
00:10:27:00 The stimulus conditions are the same.
00:10:28:21 The only difference is that the females in this portion
00:10:31:22 in this floor are raised song-naive.
00:10:35:22 So they are raised without song.
00:10:38:09 And this is going to let us compare
00:10:40:04 between the normally reared females
00:10:42:00 and the song-naive females.
00:10:44:02 So once we have all of our stimuli set up
00:10:47:10 then we get to decide where
00:10:49:06 in the brain we're going to look.
00:10:50:15 So this is an image of a zebra finch brain.
00:10:53:07 The front is the right side
00:10:55:05 and the back is the left side.
00:10:56:21 And you can kind of already see just with your eyes
00:10:59:09 that there are certain boundaries here
00:11:02:10 and different regions
00:11:03:12 and we have to decide where we're going to start.
00:11:05:17 Luckily for me there's been a lot of previous research
00:11:07:21 that points to this particular area.
00:11:10:13 This is called the caudal medial nidopallium or the NCM
00:11:14:04 and this is a secondary auditory processing region.
00:11:16:21 And it's very heavily involved in song learning
00:11:20:11 and song recognition.
00:11:23:08 What we see is that for example
00:11:24:21 when a male is singing
00:11:26:21 or when a female is listening to another bird singing
00:11:29:23 we see a lot of neural activity going on in the NCM.
00:11:33:16 So we really wanted to start here
00:11:34:23 because this seems like a good candidate region
00:11:37:11 and maybe we can see if there's differences
00:11:39:05 between the mate versus a familiar
00:11:40:23 or other conditions that we have.
00:11:43:07 So we take all of our brain slices
00:11:44:16 we go to the microscope room
00:11:46:02 we take a lot of images.
00:11:48:22 And I mean a lot of images.
00:11:51:22 And then we get to look at them.
00:11:54:05 So we're going to start
00:11:55:01 with the normal silence condition here.
00:11:57:09 And this is a blank screen.
00:12:00:12 And this kind of makes sense.
00:12:01:23 So we're looking in the NCM
00:12:03:22 which is an auditory processing region
00:12:06:03 and we're not actually having any auditory input
00:12:09:04 for the moment.
00:12:10:07 And so you wouldn't expect to see any activity here.
00:12:13:04 So that's great.
00:12:15:02 Then we're going to move on to the stranger song condition.
00:12:18:05 And here we actually start to see some activity.
00:12:21:06 So the red stain that we're seeing here
00:12:23:01 is a stain for pS6
00:12:25:01 which is the phosphorylated version
00:12:26:18 of the S6 ribosomal protein.
00:12:29:03 And this protein phosphorylates when the neuron is active.
00:12:32:08 So every cell that you're going to see in this bright red
00:12:35:04 that is a cell that was active during the stimulus playback.
00:12:38:08 And so we see a couple of these
00:12:39:18 in the stranger song condition.
00:12:42:02 In the familiar song condition
00:12:43:19 we also see a couple of active cells.
00:12:46:09 And finally in the mate song condition
00:12:48:05 we see a whole bunch of active cells.
00:12:51:14 And you can think of this as existing on a gradient.
00:12:55:09 So the silence condition
00:12:56:22 we don't have a lot of activity at all.
00:12:59:00 The mate song condition
00:13:00:01 we have a whole bunch of activity.
00:13:01:16 And then we have stranger song
00:13:03:06 and familiar song kind of mixed in the middle there.
00:13:07:02 And intuitively we think this might make sense.
00:13:10:00 So the mate's song is a really important song.
00:13:12:08 We know that behaviorally
00:13:14:01 these birds prefer the mate's song
00:13:15:21 so you can kind of guess that it would make sense
00:13:18:05 that there's a lot of activity in the mate song condition.
00:13:21:19 But now we have to look at the song-naive birds.
00:13:25:19 So starting off with the silence condition
00:13:28:09 we see that this is exactly what we're seeing
00:13:30:19 in the normally reared birds.
00:13:32:12 So they start off with no activity at all. This is great.
00:13:36:14 And then we get to the stranger song condition.
00:13:40:11 And here you can almost immediately tell
00:13:43:10 that there's a big visual difference
00:13:44:20 between how much activity is going on
00:13:46:17 in the song-naive birds' brains
00:13:48:07 and how much is going on
00:13:49:14 in the normally reared birds' brains.
00:13:52:01 And in fact if we look at all of our other conditions
00:13:56:00 we see that the pattern that we saw during
00:13:58:12 the normally reared bird stimuli
00:14:01:14 is not being replicated
00:14:04:22 in the song-naive bird stimuli.
00:14:07:18 So now we have to quantify all of this.
00:14:10:02 And the quantification means going
00:14:11:20 through every single image that I took
00:14:13:12 and counting every single cell in every single image.
00:14:16:02 So shout-out to my lab mates for helping me with that.
00:14:19:18 But once we have that done we can build a graph.
00:14:22:10 So on this y-axis
00:14:23:18 we see the average number of pS6 cells.
00:14:26:18 So the average number of active cells.
00:14:29:04 And we've broken down the rest of the graph
00:14:30:20 by rearing and by stimulus.
00:14:33:13 So starting with the normally reared females
00:14:37:03 what we see is that the normally reared females show
00:14:39:08 the greatest brain activation
00:14:40:23 when they're hearing their mate's song.
00:14:42:23 So the silence condition is very low activation
00:14:46:23 and the mate song condition is much higher activation
00:14:49:19 and then you have unfamiliar
00:14:51:08 and familiar kind of in the middle there.
00:14:54:12 And this mirrors what we saw in the images
00:14:57:12 where the silence condition had the least
00:15:01:05 and the mate had the most.
00:15:03:17 Now moving on to the song-naive females
00:15:06:14 what we see is that they actually show
00:15:08:11 the greatest activation in response to an unfamiliar song
00:15:11:22 whereas the mate condition is kind of middling for them.
00:15:16:04 And this really begs two questions:
00:15:19:05 First why this difference in activity?
00:15:23:00 And second if the activity is different
00:15:25:13 then how come the birds can still recognize their mates?
00:15:28:20 So we talked about how the NCM
00:15:30:22 is involved in song learning and recognition
00:15:34:08 but we also talked about
00:15:35:19 how the birds will prefer to hear their mate's song.
00:15:39:16 And what we see is that the neural activation patterns
00:15:43:13 that we're looking at
00:15:44:13 especially in the song-naive females
00:15:46:11 aren't matching the behavior that we're seeing.
00:15:49:00 So we're going to look elsewhere in the brain.
00:15:51:15 And in order to decide where to look
00:15:53:13 we were thinking of looking at areas
00:15:55:19 that might be connected to the NCM in some way.
00:15:58:11 And in order to find the places
00:15:59:23 that are connected to the NCM
00:16:01:11 a team used a tracer.
00:16:03:01 And a tracer is basically a dye
00:16:05:01 that you can inject into one part of the brain
00:16:07:05 and it'll spread a long axonal
00:16:09:03 and neuronal connections to other regions of the brain
00:16:11:11 that are connected to the area where you did the injection.
00:16:15:14 So in this case our tracer is a bright pink
00:16:18:07 and so any neurons that are connected
00:16:20:08 to the NCM are going to show up
00:16:22:10 as having these bright pink dots in the neuron itself.
00:16:26:09 So using that
00:16:27:05 we're able to identify different regions
00:16:28:18 that could have this tracer.
00:16:31:04 Now this tracer was a retrograde tracer
00:16:33:20 meaning that it goes against the current of information.
00:16:36:14 So you can think of it as swimming upstream
00:16:39:06 against the electrical impulses.
00:16:41:04 So if the tracer is going this way
00:16:44:22 then the information is actually flowing this way.
00:16:48:20 And while there were a number of areas
00:16:50:23 that had tracer in it from the NCM
00:16:53:13 we decided to focus on just this one first.
00:16:58:04 And this area is a region called the VTA.
00:17:00:04 This is a very old region evolutionarily speaking.
00:17:04:10 So humans also have a VTA.
00:17:06:16 And it's an area that produces a lot of dopamine
00:17:09:05 and it's heavily involved in reward.
00:17:12:05 Additionally according to previous research
00:17:14:05 we split the VTA into two areas for analysis:
00:17:17:01 the rostral part and the caudal part.
00:17:19:14 And spoiler alert
00:17:21:01 we didn't find any significant differences
00:17:22:20 in the rostral part
00:17:23:21 but I will tell you about the caudal part
00:17:26:07 as we continue now.
00:17:28:01 So we went back to the microscope room
00:17:29:10 we took a bunch more images
00:17:30:14 we got those quantified
00:17:32:15 and now I get another graph.
00:17:34:05 And here we're actually looking at the percent
00:17:36:14 of dopaminergic neurons that are active.
00:17:39:14 And the first thing that you might notice
00:17:42:03 is that there is no difference based on rearing.
00:17:45:00 So the normally reared females in the blue circles
00:17:47:19 and the song-naive females in the red squares
00:17:50:19 they are mixed together.
00:17:53:06 So there's no difference based on
00:17:55:07 whether they're raised with or without song.
00:17:57:22 Next you might notice this trend
00:18:01:02 that seems to imitate what we saw
00:18:03:16 in the normally reared NCM.
00:18:06:01 And for this we're seeing that
00:18:07:20 in all birds in this caudal VTA
00:18:10:16 they're showing greater activity upon hearing
00:18:13:12 their mate's song.
00:18:15:11 And this is really interesting
00:18:16:22 because it is mimicking the behavior that we see.
00:18:20:02 So to summarize this whole presentation for you
00:18:23:13 first regardless of how they're raised
00:18:26:06 we see that we see a similar brain activity
00:18:28:17 in the caudal VTA.
00:18:30:14 And this is a parallel
00:18:33:05 to the behavior that we're seeing
00:18:34:15 where again regardless of how they're raised
00:18:36:18 with song or without song
00:18:38:13 we see these birds prefer to listen to their mate.
00:18:42:04 And to me this is particularly interesting
00:18:45:04 because this is not the pattern
00:18:48:11 that we see in the NCM.
00:18:49:22 So in the NCM
00:18:50:21 we see two very different patterns of behavior
00:18:54:04 in response to the mate's song
00:18:55:12 versus other conditions based on how these birds are raised.
00:18:59:23 However in the VTA
00:19:02:04 we see this trend of activity
00:19:03:19 that really mimics the behavior that we see.
00:19:06:22 And on the one hand
00:19:08:19 this is really cool for me as a scientist
00:19:10:08 to finally have something
00:19:11:10 that looks like it's imitating the behavior
00:19:13:23 but it also seems to imply
00:19:15:13 that maybe the locus
00:19:18:12 of individual recognition isn't actually
00:19:20:23 in the places where sound
00:19:24:02 or sensory processing is happening
00:19:26:01 but might be in other areas of the brain
00:19:28:21 such as the more reward focused VTA.
00:19:32:00 However this comes with a caveat
00:19:34:07 that future research is still needed.
00:19:36:04 So I've talked to you about two different brain regions
00:19:38:14 but there's still the whole rest of the brain
00:19:40:16 that needs to be looked at.
00:19:42:00 And this is actually the work
00:19:43:02 that I'm currently continuing to do.
00:19:45:15 Additionally there are
00:19:46:19 also other sensory modalities to investigate.
00:19:49:19 I mentioned in the beginning that zebra finches
00:19:52:08 also have this very distinctive plumage
00:19:55:05 and that this is a visual cue that they can use.
00:19:57:12 So it would be interesting to investigate
00:19:59:19 whether or not these same patterns hold true
00:20:04:02 for the visual sensory modality
00:20:05:20 or if it's just the auditory.
00:20:07:23 And additionally we can also combine this
00:20:10:21 and create multimodal presentations.
00:20:13:12 So if a bird is both seeing and hearing their mate
00:20:17:09 do we see again similar or different patterns
00:20:20:03 of activity in the brain?
00:20:21:15 And how does that relate to the behavioral output
00:20:24:04 that we get?
00:20:26:10 Finally while my main interest in this research is
00:20:30:02 because I'm very interested in how animals work
00:20:32:15 and how communication and individual recognition works
00:20:35:12 in the animals themselves
00:20:37:06 there is also something to be said
00:20:39:06 for the translational impact of how understanding
00:20:42:14 how individual recognition works
00:20:43:20 in birds could actually inform our understanding
00:20:46:03 of human recognition.
00:20:48:00 So there are certain diseases where
00:20:50:09 as the disease progresses
00:20:51:14 people start to lose the ability to recognize others.
00:20:54:15 And even more devastating
00:20:56:10 they start to lose the ability
00:20:57:10 to recognize their loved ones.
00:20:59:07 And if we understand how individual recognition works
00:21:03:03 on a cellular level
00:21:05:01 so how do these sensory inputs get taken
00:21:07:15 and what circuits process that into the ability
00:21:10:13 to recognize someone else
00:21:12:05 this could open up the path
00:21:13:12 for developing therapeutic drugs
00:21:15:23 or other methods of ameliorating these symptoms.
00:21:20:23 So in conclusion
00:21:22:07 next time that you're out getting coffee with a friend
00:21:24:13 and you hear some sparrows chirping in the bushes
00:21:27:07 spare a thought for the complex web
00:21:30:02 of neural activity that's going on
00:21:32:08 that lets them know who they're talking to
00:21:35:02 and who they're chasing around.
00:21:37:00 And on the same token
00:21:38:22 spare a thought for the complex web of activity
00:21:41:11 that's going on in your own brain
00:21:43:03 that lets you recognize other individuals.
00:21:45:23 With that I'd like to thank my lab
00:21:47:22 and our funding and all of you for watching.
00:21:51:08 Thank you.
00:22:02:22 (bright gentle music)

Videos in this Talk

Part 1: Isabella Catalano Interview
Audience:
- Student
- Researcher
- Educators
- Educators of Adv. Undergrad / Grad
Part 2: Individual Recognition in Zebra Finch
Audience:
- Student
- Researcher
- Educators
- Educators of Adv. Undergrad / Grad

Speaker: Isabella Catalano

Total Duration: 0:29:30

Recorded: May 2022

All Talks in Neuroscience

Talk Overview

Do birds know who they are talking to? How do we know who we are talking to? In this 2022 Share Your Research Talk, Isabella Catalano untangles the use of auditory and visual modalities to answer the questions behind what happens in the brain to make recognition possible. Her thesis research uses zebra finches as a model system to study individual recognition in the brain. She has looked at different brain regions, including areas for learning and memory and reward, in zebra finches in response to their mate’s call, and found differing levels of cell activity in certain regions when hearing a mate versus silence. She is still doing more work in this area, but this research has implications for diseases in which we lose the ability to recognize individuals, even those close to us.

Speaker Bio

Isabella Catalano

Isabella Catalano is a PhD candidate at McGill University, in the laboratory of Dr. Sarah C. Woolley, where she studies individual recognition in zebra finches. Isabella seeks to become a research professor. Continue Reading