share interactive transcript request transcript/captions live captions
download
|
MyPlaylist
SPEAKER: This is a presentation by Human Development Outreach and Extension at Cornell University.
JAMES SWAIN: So it's a pleasure to talk to you about the work that we've been doing for the last, well, six, seven years, really looking at something of fundamental importance-- I'd like to think-- to all of us. And that is how it is that we get to be where we are in terms of that first attachment that we have. So-- and to actually look at some of the maybe brain underpinning neurophysiological mechanisms that allow for the bonding to take place. And then we're just starting to hint-- as I'll talk about at the end-- how some of those neurobiological mechanisms may relate to the psychology in the form of the attachment, and that may either confer risk in the case of some things like postpartum depression, or may allow for some protection in the case of people that really make it through some adversity.
So it's been with the help of many, many people that we have what we have. So I'm not going to even be able to mention everybody. But just quickly, on the left panel are the sort of professorial colleagues at Yale that have been wonderful. And Jim Leckman, really, who recruited me seven years ago to see what I can do in brain imaging and child psychiatry, and it was really just this sort of parent/infant thing that allowed me to develop sort of our paradigm and to be in a position to be before you.
So Linda Mayes is a parent/infant sort of researcher with special interest on the effects of substances, which is another branch of this. How do substances maybe used by parents affect fetal development and the bonding, or hijack it? Bob Schultz, who is a prominent imaging person in the area of autism was a key kind of big brother and a terrible loss a few years ago from the child study center, but has been at first, sort of the person that let me come into his lab and use his computers. And Ruth Feldman I'll mention as the other sort of really key faculty mentor who is a pioneer in the study of parent/infant interactions as potentially videotape naturalistically, and then measured in a moment by moment-- as well as global measures, but also the aspects of synchrony, which we're also just starting to relate to brain function.
And of course, Pilyoung came a couple of years ago and has been helping me measurably bring down our data and get it into sort of paper-sized chunks that we can publish and share and get to the next stages. But I've been fortunate to work with a number of people. Esra came and really pushed us with our sort of looking at one aspect of whether or not having a cesarean section versus a vaginal delivery affects brain physiology relating to parenting, which I'll talk about. And then Lizzie, Hannah, other colleagues that have been sort of research assistants or summer students that have helped along the way.
This is our imaging center. Todd is sort of the chief of it and has been sort of helpful in the background all the way along. And I should thank the funding organizations that helped us. This so-called institute for research and unlimited love is a real place that you can look up, unlimitedloveinstitute.org. And they really got us off the ground and allowed me to sort of branch off and develop this work. But since then, we've been funded by NARSAD and the Klingenstein Third Generation Foundation to start to get into more situations where there's depression in the parents, and in situations where the parents are adolescents themselves, not quite children, but young-- and other colleagues at the Child Study Center that I'm going to get to.
So this is a bit of an overview of the talk. I may, at times, speed up a little bit as I see how much time we've got. But I'd like to sort of give a little bit of a background on what we know about the brain science of parenting. A lot of it, the majority of it is really from animal literature, a vast animal literature. But you know, humans have the big cortex and they're unique in many ways, which we're starting to understand.
Then, talk about how we approach parenting and in humans to sort of put together psychology and brain physiology. And then at this stage, really, a series of-- there's so much data that we actually have. I'll present a series of sort of hypotheses and attempts to answer them with the data that we have from the imaging data, from the sort of interview data, because we also ask a lot of questions of our parents as to how they're interacting with their baby and try to measure those interactions. And then how now we're starting to combine brain activity with actual behavior. So far, largely, again, in normal samples. But we'll head to the future. I think some of us, anyway, will be focused on issues of mental health, and then how to sort of treat them and correct or ameliorate difficulties or other problems like poverty.
So there are many different ways to think about parenting, but here are a few of them to think about. Again, what is it that is allowing this parent to adapt to the early postpartum, to do all the necessary things to provide love however that may be defined, warmth, nutrition, hydration, safety, et cetera, all of these things. What are the processes that change that human, that parent, from a female-- and we're interested in fathers as well-- in the postpartum, to someone whose world is also reorganized around the safety and well-being of that infant? So we think of it as a bit of a reset button. And for that reason also, a special laboratory to study the development of an attachment between two human beings, but in this case, where it's a parent and infant.
One of the controversial areas that really, I've built on from colleagues at the Child Study Center, is the extent to which the early postpartum may be characterized by thoughts and behaviors that are like obsessions and compulsions. So that's one of the ideas we have, but it's not met with universal warm reception, but is supported by some data that I'll mention. As we've done our research and done more of our interviews, I think we're learning also to incorporate much more of this sort of besides the obsessive compulsive sort of brain circuits, the elements of empathy, elements of emotion, regulation, and control that allow us to interact with our infant optimally.
So that was the question six or seven years ago. Could we measure something in the brain? And of course, at the time, I was actually quite dubious. But colleagues said, of course you can. Not only-- I'm not a parent, but not only from watching, but from those parents that I've talked to, of course, everything is different when you have a baby. But also, that the animal literature is indicated in many, many different ways, the importance and the change that occurs in parents to appropriately parent.
That's a sort of vast literature. And I'll touch on a few things. But once we think of brain function as a result of a long evolution and the capacity of the parent to do what they need to do as a result of evolution, it's sort of a segue for a moment to talk about the animal literature.
So again, it's a vast literature. There are books and courses, really, on the nature of the parental brain and animals. What happens during pregnancy? What happens in the postpartum? How different brain circuits are reorganized, and I'm just going to mention a few things largely from these sort of the rat and the rat mother and pup model, but that we believe would extend to all animals and a lot of it to ourselves, which is what we're sort of trying to find.
Based largely on lesion studies, you can lesion an awful lot of parts of the brain. And mother animals will still do a lot of parenting things. But there are a few key structures which reliably disrupt parenting behavior. And some of these are listed here. This so-called medial preoptic area.
The bed nucleus of the stria terminalis, some of the deep brain structures that are a source of great interest in human research in emotional regulation as well, like the amygdala and the ventral tegmental area that supply the dopamine for so many different functions, but in parenting may be very important for driving the behavior and associating parenting behavior with some kinds of rewards, or so we conceptualize. Additionally, there are a number of hormones for which interruption or blockade of the hormone interferes with parenting behavior. Some of those sex hormones as well as dopamine signaling come up again and again in the animal literature.
The other piece, I suppose, that gave me some heart six or seven years ago that there would be interesting things to find in parenting and that it was really, really important was this sort of pioneering work that everyone probably knows about, but it's nice to pay homage to for a moment. And that is this aspect of plasticity that was the work of colleagues in Montreal. Again, the environment, in one case of measurement, of licking and grooming of the infant alters, in an almost too good to be true way and through an unknown mechanism, that licking and grooming may alter the expression of stress-related hormone receptors in specific brain structures and in such a way that alters later behavior. So that if a pup is licked and groomed a lot, they tend to grow up to be mother animals that lick and groom a lot.
So it's sort of the shocking-- when it first came out 10 or so years ago-- that the development of the brain was critically contingent upon the environment. Again, I think something that lots of people thought, of course, that would make sense. But to find some of the actual substrates was very, very exciting.
OK. So if one were to superimpose the brain areas from the animal literature which if lesioned interrupt parenting behavior, this might be a cartoon. So this is just an excuse to show you some of the areas that we might look for in humans to be sensitive to stimuli of the baby, since from the animal literature they seem to be really important.
So one set of circuits is sort of the cingulate and its connections to the thalamus. And this comes up through evolutionary work of Paul MacLean, who was really the driving force of the first person who did a brain-imaging experiment with parents, that since mammals breastfeed and breastfeeding may be something that the infant calls, and that mammals are sort of a step above in the evolutionary scale from reptiles, and that that evolutionary step involved the cingulate, that the cingulate might be something really important for mammals in responding to the call and to some kind of need to breastfeed.
So this has come up a lot, the sort of thalamal cingulate circuit. But as well, a number of these deep brain structures that I was mentioning before that supply dopamine, that regulate some of the sex hormones, and some of the other so-called affiliative hormones like oxytocin and vasopressin, as well some of the areas that are supplied by the ventral tegmental area that are related to reward. And I dare say, again, when we get into the striatum, we think anyway about areas that are important for habitual, repetitive behaviors of which one might describe some aspects of parenting as behaviors which, once learned, need to be sort of repeated.
So how will we approach this? We can't lesion human brains. Well, we had one clue. So this is a study from 1999 that colleagues at Yale had published that was very generative. And they measured a number of aspects of parenting.
And again, very little actually has been done in human parenting to measure what the thoughts and behaviors are, surprisingly little, especially at that time. And one of the variables that they measured, in line with their sort of theoretical construct that parenting in the early postpartum is characterized by worries, preoccupations, and almost compulsive-like need to check and check again and check again. So the level of preoccupations from measurements around late pregnancy, around eight months, increase, reach some peak in the early postpartum, and then decline.
And they found mothers had more such preoccupations than fathers. And really just measured to a few points forward in time. It's another interesting question-- what would happen further out there?
So what I thought about was if we were to sort of draw, again, on the x-axis, a time, before and after birth, that brain imaging before birth may be possible, but it's going to be difficult. But if we looked after birth and wondered, well, what kind of brain responses there might be, if we could measure brain activity, there would be a pattern kind of like this. The mothers, in general, would have more such brain activity in response to infant stimuli than fathers. That there might be a rise in the pre-partum, but we're not really going to measure that.
And that if we measured in a couple of postpartum time points, we would see some level of brain activity that would be sort of paralleling the level of preoccupations that parents display. And that it would change over time. It's an interesting question about what would change. But if it were the anxiety-related sort of brain activity that supports anxious thoughts about parenting or worries about the baby, then that it would likely decrease over time.
So what we did was, between zero and two weeks, go to postpartum wards at the Yale New Haven hospital, walk into mothers' and fathers' rooms, and when we weren't thrown out, talk to them about the study. And if they agreed-- and about probably 1 in 5 ultimately agreed-- lend them a digital camera and digital audio recorders so that we could record baby cries and pictures that we asked them to choose. So we got sort of a discomfort cry associated with a diaper change. Again, you could argue about all of these stimuli. And pictures that the mother and father chose to be most representative of their own experience as parents. So we wouldn't judge or say that's the cuter picture, or-- you know, leave it to them. Because we're interested in their brain activity.
So then we have sort of two time points that I'm going to talk about. A two-to-four week time 1, in which we went to their homes, asked them a lot of questions about how they're behaving and thinking, and what their mood is like, and what their anxiety is like, and so on. And then also had them come in to the scanner at the Yale MR Center and present them, more or less, a slideshow and a sound show while they're lying in a magnet to be able to compare times when they're looking or listening to a baby or their own baby versus control sounds. And I'll describe that in more detail.
And had them come back at a second time point to have it all done again. And also go to their homes. And also, by three to four months, you can start to measure, there's enough social behavior in a baby by three months to measure dyadic interaction, and contingent synchrony, and responsiveness, and such concepts as maternal sensitivity to see if any such constructs relate to brain function.
Then I'll mention that we have a time 3 point at 18 to 24 months that we essentially have not analyzed yet, which includes a video subsample. So you'll have to have me back in the future. And then now we're actually just planning a follow-up to see if any of those really early brain activity and assessments of parenting predict infant outcome and cognitive functioning.
So you might think, or I might ask you to wonder for a moment, what kind of baby stimuli do you think would be most evocative, most likely to grab those areas of the brain that we need to be parents? So one is pictures. So here are a number of examples. And so you might imagine, if you were in the experiment, that you would be looking at a series of pictures.
Let's say this is your baby. And you'd see a bunch of those pictures. And you'd gaze on those pictures. And then your brain would be responding in a certain way. And we'd be able to compare brain activity with areas looking at a similarly cute baby, but not your baby. As well as control objects. We had some houses and some other control objects.
The other stimuli we had-- so again, conceptually, parenting is a complicated set of responses and interactions. We thought that the pictures could activate anxiety circuits, and uh-oh, you know, is the baby OK? But given these stimuli, we're probably more likely activating areas related to empathy, thinking about the baby's mind and state, but also possibly reward. So in all of these experiments, there's sort of a profound difficulty actually in what the design is and then what the actual data then mean. But I'll try not to get off on that tangent too much.
So the second stimuli we chose I'm going to spend much of the rest of the talk talking about our baby cries. So here's an example, just for a few seconds.
[BABY CRYING]
So if you can imagine, I joke that I don't think we would have got this through our IRB if they'd actually heard these cries. Because I personally find that after-- and we had these in 30-second blocks. That was just 10 seconds. That by halfway through that, you are ready to get out. And if you had several blocks of that, you're kind of climbing the-- you know.
So, I mean, these also are uniquely powerful signals, also, we think, evolutionarily designed to optimally attract attention and balance that against hopefully not attracting anger and such, but that to protect, to feed, to do whatever we need to do to keep that baby from crying. So it actually also provides an interesting laboratory with respect to things like reward, or almost negative reinforcement, or how would one avoid that cry from continuing.
[WHITE NOISE]
Whoops, I should say.
So the next question is, what would be a control sound? So we have a control cry that's sort of similarly intense. We also have a control sound. And the control sound, again, one could debate about whether it ought to be an animal cry, or a baby laughing, or some other kind of sound, a siren. We chose a sort of a white noise, staticky sort of sound, which was matched to the sound envelope so that it varies up and down and with the same frequency as the baby cry. And that was what you just heard, which, just to give you an example, is--
[WHITE NOISE]
So that was our sort of control sound, matched to volume, pattern, but sounding nothing like a baby crying. So here's an example. I'm just going to start out with just a bit of the visual data. Although that's not the bulk of what we're sort of-- a lot of the last couple of years has been trying to decide what to publish and what to focus our attention on. And I have this slide to give really a taste, but just a taste. And then I'll shift back to the brain responses to baby crying.
So this is the actual sort of experimental paradigm. You have rest blocks of 10 seconds. And the actual experimental blocks are 30 seconds long. We show six pictures, each one up there for five seconds, ask each parent to press a button indicating the extent to which that picture is emotionally evocative to them, to make sure, really, that they were awake. And also to make sure that things are sort of standardized across all these blocks.
And we had blocks of own baby and other baby. And that's what I'll show you. We also had other objects, sort of emotionally laden, own baby versus non-emotionally laden objects to try to get it what it is for the brain to interpret something that's emotionally laden. But these are other analysis that we're going to do some time. And some other kinds of pictures.
Again, we conceptualize that seeing your baby maybe anxiety provoking. Seeing your baby with yourself or your spouse might be less anxiety provoking. But I mention this because we did all these. But we haven't analyzed them all.
So you might ask, then, what areas light up? So this is what we see. There's your own baby versus, let's say, another baby.
And we see a lot of areas that one might expect, and that really amazingly match on fairly well with the animal literature. We see sensory response areas in the visual cortex and specifically some of the face processing areas that have been written about so much in recent years. We see limbic structures that have to do with attention orienting and depending on the interpretation, anxiety, ascertaining salience, the hippocampus. Possibly also memory and emotional memory.
We see this so-called thalamal cingulate cortex, which partly replicates the one other study that was done with cry that I'll get back to. But the idea that there are these emotion regulation sensory loops that may be activated by sort of whatever is going on in parents' brains when they're looking at their own baby compared to another baby. And we see some deep brain structures that probably, or we hypothesize, are driving the rest of the brain, reward. And for basal ganglia, we often interpret as part of the sort of repetitive, habitual, obsessive-compulsive-like thoughts and behaviors. OK.
So now I'm going to switch back to the auditory part and spend much of the rest of the talk on auditory stimuli. There's our scanner. And this is the experiment for the auditory part of our data.
We have blocks of own baby cry. You heard 10 seconds of it. We have them in 30-second blocks with a beep-- to make sure they press a button, and that they're awake and paying attention-- at 10, 20, 30 seconds. We have own baby cry.
We had another baby cry, which everybody heard. It's sort of a standard, medium-intensity baby cry. And we had the control sounds, which are those staticky noises matched to the pattern of the own baby cry or the other control baby crying.
[BABY CRYING]
So I have those examples again--
[WHITE NOISE]
--which I'll skip over.
So I'm going to divide these up sort of into basic questions that I'll try to answer. One is, is there a basic parental baby cry response circuit? And so for that, we put all of our-- a large group of our mothers and fathers together. So in this case, we're putting together mothers, fathers, of variable experience, whether they're first time or experienced parents, to see across this large group and just look at the other baby cry compared to the control sound, is there a response circuit, just to any baby cry?
And we see-- so this is cry again, not picture. We see insula, a sort of a really centrally placed chunk of cortex between frontal areas and deep brain structure areas that's coming up again and again in a lot of literature that's integrating complicated stimuli like this. It also exists in the literature as one of the three, four, five structures that are important for obsessive-compulsive disorder.
So unfortunately, a lot of these blobs can be multiply interpreted. And I'll try to show it towards the end or later in the talk that some of these areas we're trying to plant flags in as being especially important for parenting when the activity within them not only is higher when you're listening to your own baby cry or a baby cry, let's say, but when it also varies in a linear manner with respect to a measure of parenting behaviors or thoughts. But for now, this is just, is there a response circuit?
We also see auditory cortex. And we also have some issues with interpreting, is this purely auditory cortex? Or could some of the superior temporal activations be related to the aspects of the social brain that come up in different literature that are important for interpreting social signals?
And cingulates. And we see a nice little spot of cingulate that is-- cingulate being a cognitive controlling processing area. More anterior, more emotional. More posterior, more sort of logic-based. But this one may be parenting-based.
SPEAKER 2: Did you have causal analyses of these putative circuits? [INAUDIBLE] Granger causality or something-- have you looked at that?
SPEAKER 1: That's a really good question. So Granger causality is possible in our software. It comes out of the EEG literature and allows one to-- looks at the time data. You give it a seed in your experiment. And it looks a little bit before to see what areas had a similar pattern a little bit before and what areas had a similar pattern a little bit afterwards.
And a couple of years ago, we did look. But we haven't really done this systematically. But if you put a seed in-- I tried this with a few different just interesting places. If you put a seed into cingulate, you tend to see sensory and deep brain structures a little bit before and then more frontal cortical processing associated areas active a little bit after.
So for this, I'm largely going to present the very kind of most simple contrasts. And we're going to get to that. But not in this talk yet. But we can talk about that some more.
So then the question is, what about-- so this was time 1, is two to four weeks postpartum. Is it stable? So this is time 2.
And incredibly-- so this is a huge sample. Three months different in time, but the same cries-- that other baby cry in contrast with the control sound-- and we see incredibly overlapping structures. The cingulate was 1 centimeter different. But otherwise, the other areas are so closely overlapping that that's what I did.
Oops. Did I do that? OK. I think I have that in the next slide.
So this is all parents. I think I might have a slide misplaced. But one of the questions that comes up again and again, and that is, is this unique to parents or is this just a human response to baby cry? And we have a bit of a signal of this.
This is a table at time 1 of some of the areas that are active in this parents compared to non-parents for that other baby cry. So it's the other baby cry, whether you're a parent or a non-parent. It's not your own baby. So we can do a contrast of parents to non-parents and show a number of cortical areas that are active at time 1 and fewer of them at time 2.
So again, it may be that some of the brain responses to baby are sort of primed or optimized in the early postpartum and that over time, one gradually starts to become more like a non-parent and there are fewer differences. And again, this is for other baby cry. So not own baby cry. It's interesting that for the other baby cry, there's not so much of the deep brain animal research indicating areas. OK.
So this is a repetition of that other baby cry at the second time point, so at three to four months postpartum. Just to remind you of those sort of three big areas, temporal cortex, cingulate, and insula. And this is to compare it with own baby cry.
So what do you think would be different? So this is other baby cry. And this is own baby cry.
So here we see, essentially, a lot of the same areas except they're more powerfully active or more dramatically different, the contrast. But additional thalamic areas, other kind of deep brain structures, the kind of areas that come up in the animal literature. So that it's not just that the other baby cry is potent, is powerful enough, and shows up across time, and in a huge sample. But the own baby cry is even more. It adds in brain stem areas and a number of other sort of frontal areas.
So this is-- so I'm flipping back and forth. So-- oops. uh-oh. OK. This happens every talk. Something happens funny with one slide.
OK. So then it's, is the own baby cry response stable as well? So this is that time 2 again, that I showed down here. So this is three to four months postpartum. But did this take three months to develop? Or was it there even earlier?
And this is the time 1. So essentially very, very, very similar. Those areas-- cingulate, insula, and temporal, superior temporal cortices, but also a number of deep brain structures.
So much so that if you do the overlap-- I thought I had it for the other baby cry. But for the own baby cry, you see overlap in orange. And you see substantial overlap in time between time one and time two. So from colleagues that do sort of cognitive neuroscience experiments and study people even a day apart have trouble, in a sample this size, finding areas that overlap. So this, to some colleagues, is very shocking that there are so many areas that overlap.
So that's what's the same. This is what's different. So this is a contrast of time 1 to time 2. So time 1 are the sort of red areas. Time 2 are blue areas.
So I think I lost a sign to the insula as well. But here are some of the regions that are more active at the early time point, which coincides with some of our thinking that the early time point is associated with greater anxiety, higher parental preoccupations, and perhaps more activity in-- if you interpret putamen as a basal ganglia that's important for obsessive-compulsive-type thoughts and behaviors. And its connections to orbital frontal cortex as one interpretation-- that that circuit is hyperactive in the early postpartum in response to own baby cry, along with some other areas that we really are at the tip of figuring out.
Whereas by time 2-- oh. Sorry. That's why I put that in. So here are the insula. The reason I left that out for now is that with a pretty good significance level, the activity in this area is also correlated with the level of anxious, intrusive thoughts and behaviors.
So this is something that we have now under-- almost ready for our re-submission. But that this area which is a central integrative piece of cortex but also shows up in the OCD literature, the activity in response to baby cry is related to a measure of parental preoccupations and anxious thoughts and compensatory, compulsive-like behaviors.
So what about time-- the [INAUDIBLE] the blue areas, the areas more active at time 2-- three or four months-- than they are, more active at time 2 than time 1, we see cingulates-- a certain part of the cingulate. So cingulate is a complicated area. And some places will be more active at one time and some other areas at another time.
But we also see hypothalamus, which is related to a number of those stress hormones and access as well as breastfeeding behaviors and an affiliate of peptide formation. As well as a striatum. So that by time two, a different area may be mediating some of these thoughts and behaviors.
Striatum is more related to reward. So that maybe then the cry-- again, this is a little bit of a handwaving at this point. But the cry goes from insula, which may be interpreted as it could be also sort of almost a painful experience or related to obsessive-compulsive thoughts and behaviors at three weeks postpartum, but shifts to an area that's correlated in an area of reward. So that maybe by three or four months postpartum, that baby cry and the brain response to it is more related to either reward or the anticipation of reward, when the parent has a reunion with the baby, and picks it up, and it stops crying, and all of that.
So I'm not going to get through all aspects of this talk, I think, at this point. But from our data set-- so we have this huge data set of 40 to 50 families, really, that we-- I've sort of shown you a group of them kind of lumped together to look at sort of basic brain circuits and some of the brain areas that we think may be important. But we're starting to look at it by these subtopics. And that's one of the things where [INAUDIBLE] has really been enormously helpful in the last couple of years to zero in on sub-parts and to help flesh out those data sets and bring the [INAUDIBLE] up and help with the analysis.
So there's the question of-- and I've shown you a bit of it-- of own-ness. So to what extent is the baby's stimulus from one's own baby special or different from that of any old baby? There's the question of how long the relationship has been happening. So what's different between three weeks and three or four months? And hopefully also at a later time points down the road.
There's a question of timing. This is a very huge anecdotal-- well, anecdotal from what I understand-- that one's experience of a second or later child is so much different from that experience of their first child. Then there's gender effects. So do mothers and fathers brains respond differently to infant stimuli?
And then there's all the correlations. So I'm probably going to whip through some of this a little bit quickly. But I want to show you what I can.
So what about moms versus dads? And this is the moms versus dads. This is sort of a small subset at some point, which we're in a re-submission also, looking at own cry versus other cry. So it's own cry-ness showing a number of activations in a smaller sort of subset. So this is just first-time mothers at two to four weeks postpartum. And we see areas that we interpret as related to an OCD circuit.
Oops. OK. Well, I can leave that up.
Areas related to emotion regulation anxiety predominantly, or so we would sort of point arrows at and begin to say. Whereas by time 2, which is three to four months postpartum, we don't see activity in those areas. Instead, it's shifted to frontal areas that are important for emotional regulation, some deep brain areas that may be related to stress response and reward and hormone regulation.
Another sort of-- one focus I was talking about with colleagues on the last day was, what if you look in one sort of area and test the hypothesis that with time, baby stimuli become more rewarding. So this is a reward center generally recognized as an area that responds to rewarding stimuli that is not active in the first-time mothers at the first time point. Whereas for veteran parents that have already had a baby, at both time points, there is activity. So possibly getting at a question around the effect of having a baby on our brains.
There's also-- it's a smaller effect. But there's an effect even over a few months of having had a baby in this area. But it's sort of sub-threshold for these statistical tests. So it appears that having had a baby affects a specific area related to reward.
OK. What about gender? So this is the 14 first-time mothers, where we think about-- I'm sorry. This was-- I've modified this slide-- 26 mothers combining first-time and veteran. And I'm going to compare that with fathers.
So some of those areas related to OCD and emotional regulation, whereas in fathers, it's not like there's no activity. But there's significantly less activity. So it's an excuse to put in the Homer slide. But this may not just be that fathers' brains are less responsive or there's something wrong with males. In fact--
AUDIENCE: Maybe they're just more responsive to the noise.
SPEAKER 1: Right. More interested in the noise. Right. So there's a train coming or something like that.
But with time-- so the one thing is that it could be that over time, so exposure-- an exposure effect. So that's why this longitudinal study allows us to really look at different time points. So that at the time 1, fathers had fewer activations, primarily sensory and a couple of other cortical areas. But that by time 2, it's different from mothers, but a number of other brain stem areas. Again, given sort of the data set and the gradual-- the amount of time it takes to do these analyses, we're behind where we'd like to be.
But there's also a hint that in the few fathers that were stay-at-home dads, that their brains looked more like mothers'. We just don't really have an N large enough to say that in published form. But it's possibly an exposure effect, rather than strictly a gendered difference.
And so if you actually look at veteran mothers and fathers-- so, mothers on the left and fathers on the right-- you see a lot of common areas. I've sort of made this slide a little bit fancy. But there is considerable overlap. So once you've had a baby, even at time one, there's a lot of overlap.
AUDIENCE: So these-- are the moms all with a partner? Are any of them single moms? Or are they all with a partner?
SPEAKER 1: These were all-- pretty much all with a partner. I'm pretty sure they were all with partner. Not all the partners participated. There were-- we lost-- some of the dads were busy and--
AUDIENCE: [INAUDIBLE] question about single moms versus partnered moms. But you don't have the data to really look at that [INAUDIBLE]
SPEAKER 1: No. So now I'm going to present some of what [INAUDIBLE] presented. She successfully defended her PhD yesterday. That is--
AUDIENCE: [INAUDIBLE] interrupt with applause, don't you think?
[APPLAUSE]
Enough.
SPEAKER 1: So another thing we can look at, besides functional activity in response to cry, is we can look at actual brain structures, almost as an add-on. Because we need to gather the brain structure to be able to map the functional data onto it. So one of the things that [INAUDIBLE] brought to our lab is to look at density of tissue comparing time 2 to time 1.
And showing-- and this is all mothers, first-time mothers-- that a number of brain structures that make sense again in the light of the animal literature are becoming more dense as a result of their time in their new status as parents. And there's lots of wonderful literature in the animal field showing certain structures that actually proliferate-- their cells proliferate and change. So this is really fantastic. We're looking forward to sort of confirming some of the animal work and building some of the cortical areas that make sense that really can't be studied in animals.
This is true in fathers as well. But this is another Homer sort of brain. There are just fewer areas that change between time 2 and time 1.
OK. So I've only got a few minutes left. And don't want to be too, too rushed. But we've managed to replicate, more or less, what was done in the '90s by Jim and Linda and colleagues before I went there, which was that in our postpartum period, there is this decrease in parental worries as it comes out-- as it's factor analyzed and comes out as anxious, intrusive thoughts or parental preoccupations. The mothers still have more than fathers and that there's less at time 2 than time 1.
But in our extensive interviews, it's not all a decline. Some things increase. And a few of the variables that increase among them are the sort of idealizing thoughts. So anxiety decreases. And idealization and positive thoughts about being a parent increase over time.
OK. So sorry for this busy slide. This is really just to say that one of the sort of four or five papers that we're juggling and are on the way to publication, all being well, is looking for areas that across mothers and fathers and across time two to four weeks and three to four months, we found two areas that actually overlap in their correlation between brain activity and this measure of anxious, intrusive thoughts and harm-avoidant responses, which is our sort of postpartum construct of parenting, almost compulsive-like, but repetitive parenting behaviors. So again, more evidence that insula is an important integrative area for parenting, but also that certain cortical areas that maybe regulate some of these thoughts are important for parenting. And again, across time and gender.
So the other thing that we were able to publish, actually, just several months ago, was a contrast of-- this always happens at one talk-- a contrast of mothers according to delivery mode. So within our sample, we had a small number of mothers who had a cesarean section, purely elective, so not for any kind of medical or other complicating or confounding reason, versus from our sample a matched group of mothers that delivered vaginally. And we essentially don't see deactivations.
So it fits possibly-- again, these are kind of-- there's some handwaving leaps here between what this contrast means and-- what we think it means and what it actually means. But a key difference between these two delivery modes is that during vaginal delivery, there are whopping amounts of oxytocin released into the mother's system. So we'd like-- we preliminarily interpret that this increased sensitivity to the baby cry in vaginally delivering mothers compared to cesarean section delivering mothers may relate to that sort of priming of the brain with all of that oxytocin around delivery.
It's quite a controversial finding. Because lots of women have cesarean sections for perfectly understandable, lifesaving, reasonable reasons. But it may have some early postpartum effects on the way the mother's brain responds and it may fit with a weak but present signal in the literature that cesarean section increases a risk of postpartum depression.
In fact, we looked around for correlations between brain activity in this whole sample and depression and found a frontal area. So it may be that there's some frontal areas that are slightly misregulated as a response to that difference that may be important for the depression. There's considerable complexity interpreting some of these things.
This also fits with a piece of the work that-- sorry. There's a Kim et al down there-- that [INAUDIBLE] presented as part of her thesis, which is another kind of modulation of many things, but one of which is oxytocin in the system of the mother, is whether breastfeeding or not. And again, we largely see more activity in the brains of mothers who are breastfeeding compared to those that are formula feeding in response to their own baby cry.
And we'd also look for correlations in these areas that are more active. And a couple of the interesting ones that we're defending are this level of maternal sensitivity or sensitive care and touch and voice and so on is correlated in one of these emotion regulation areas with the response to baby cry. It might also sort of make sense that in an area related to anxiety, that the greater one is worrying perhaps that the decrease in either surveillance or, again, the amygdala does so many different things. And we need to all get to sort of the next frontiers or designing more specific experiments to test all the hypotheses that we can generate from this data.
And so finally, this is the third part of [INAUDIBLE] defense, which, sorry, I won't linger too much on it. But we looked for some measure that might be a proxy for the Michael Meaney et al kind of licking and grooming behavior having long term effects on parenting behavior. And one of them is to ask those parents what their early parenting experience is like.
There is this so-called Parker parental bonding instrument, which we use to separate parents according to what they think their early life experience was like, how much they were given the equivalent of licking and grooming. And indeed, we see structural differences between those that were treated in a more caring way compared to a less caring way. And we see structural differences and functional differences. And there's overlap in a number of frontal areas.
So these are the kinds of the areas that we think-- some of these frontal areas-- that are important for-- well, that may mediate-- this is the big speculation-- that may mediate the early life events and carry through all the way, so that when one becomes a parent-- if it's believable-- but that the early environment of that mother, whether caring, and synchronous, and so on, versus not so synchronous, may alter the structure and the function in certain cortical areas. So that when those babies grow up to be parents and participate in our study, their brains look different in some of the densities and respond differently to their own baby cry.
And now this is a slide to remind everybody of how important postpartum depression is, how common it is, how devastating it is, just not to the mother but to the offspring as well. And that we still really don't know what's going on, what the mechanisms are. And it's still a case-by-case psychiatric dilemma exactly how to treat. Because not all the treatments are fully understood in their effects on the mother or, for that matter, on the infant.
But we have sort of a couple of signals. And this is studying a couple of these frontal areas in a sub-sample of first-time mothers. Again, we don't really have too many super-depressed mothers in our sample. But where there's response to own baby cry and the response that was correlated with depression.
Again, there are huge issues still in interpreting this. Because this is a sort of a normal sample that did not get depressed. This may be normal. And it may just be that we need to see that in the more depressed sample, this curve goes down or something else happens. But at least we're starting to see maybe areas of brain response to infant stimuli that co-vary with measures of depression.
So that the hope is that at some point in the next years, we could identify parents who are more at risk of developing postpartum depression and even direct a therapy that would be more likely to help them. I mean, I'm getting off into the general project of biological psychiatry these days. But in our postpartum depressed sort of sample, where we might be able to make contributions.
So, I'm sorry, I've run way over time. But without sounding too grandiose, we think that a parent-infant relationship may be a special laboratory in which we may understand something about all relationships and how people bond, become friends, make romantic connections, et cetera. And we're planning studies to really look at, really independently, if indeed what we're seeing in these brain areas is true of different samples and which variables co-vary and are the ones that are most likely to help us predict who's going to become depressed and which therapy.
Because even this phenomenon of depression, there may be sort of cortical depressions and deeper brain depressions. And they may respond to different kinds of therapies. And we wonder about questions like that in samples of depressed mothers.
So there are all kinds of things we can do. We're just starting, again. I mean, I speak as though we've already finished all of this. But we're still basically trying to come to grips with the functional and structural responses of parents and changes that occur with having a baby and how they fit with measures of behavior.
But it seems that it's feasible and that there's a lot still left to do with different kinds of stimuli, and to get to the kids. So how are different kinds of parenting environments influencing children? And ultimately, then, how can we help parents to provide the optimal environment?
This has been a presentation by Human Development Outreach and Extension at Cornell University.
Watch the full presentation with speaker footage and slides .
James Swain of the Child Study Center at Yale University discusses his research on the neurological underpinnings of parent-infant bonding and how they relate to the psychology of attachment.
