Welcome to Sensitive With an Edge for highly sensitive people who embrace their intensity, uniqueness, and value in this world. Join us on the exploration of relationships,
complex trauma recovery, non -conventional mindsets, neurodiversity, and themes that involve healing, growth, and empowerment. So welcome,
today you're going to hear about some fascinating information that you can put to use about your brain from healing to aging. We are legitimately talking with an expert on the human brain,
absolute renowned brain specialist Dr. Sarah McKay. She's an Oxford University -educated neuroscientist, author, speaker, and the director of the Neuroscience Academy,
which offers professional development training in applied neuroscience and brain health. She is also the author of two books, the Women's Brain Book, the Neuroscience of Health,
Hormones, and Happiness. Sounds good. You have to get it. And the baby brain, her most recent one, the surprising neuroscience of how pregnancy and motherhood sculpt our brains and change our minds for the better.
So we love that. Some may have seen her on her TED Talk or various other international appearances in the media. Her website is drsarahmcki .com and you can follow her on Instagram @drsarahmcki as well.
Dr. Sarah, thank you so much for being here. It's just absolute pleasure to have you here. Oh, Thank you for the invitation, Chris. It's always nice to, as I said before, we kicked off to have some conversations and some chats instead of being in my own head doing my work.
- Absolutely, well, we appreciate it for sure. So I'd like to start off with something pretty fascinating. I've heard you explain this. I'm actually one of your students. And I just really recommend that people take your courses,
they're amazing, love it. And you've talked about a basic model for how we considered the brain, can you walk us through this a little bit to start with? Yeah, it's interesting because this sort of came about a few years ago when I found that people were often asking me questions that were too big and impossible to answer like how does the brain work and how does the brain feel anxiety or what happens to the brain
and insomnia and or you know what foods can I nourish the brain with. A lot of the questions I felt needed an answer that was, for want of a better word,
holistic, or at least I recognized that there were always numerous factors and kind of inputs to the brain. And I was like, I need a framework.
I need a way of helping people to understand the complexity of the brain, but in a simple way. And so the model I came up with was loosely related to the biopsychosocial framework which people may or may not be familiar with,
which is a way of considering kind of health and well -being from the perspective of biology, psychology and sociology. So it's loosely inspired by that, but it sort of puts the brain in the middle and enables you to think about all of the various influences or factors or inputs to the brain from your sort of bottom -up biology,
so I call it bottom -up biology, the outside -in world, so the world out there comes into our brain and our nervous system through our senses. And then also there is this aspect of sort of top -down whether that be the workings of the mind,
psychology, thoughts, kind of expectations, beliefs. And so this framework gives me a way of using neuroscience that is well established,
that is evidence -based to kind of approach really complex problems. And so I often say there's all of these inputs coming into the brain from our body and the brain is having a conversation back with our body.
So this is kind of infernal, eternal sort of feedback loop or multiple many hundreds and thousands of feedback loops to be honest. Some of the signals coming from your body up to your brain,
you're unaware of, you wouldn't have a clue about like the pH of your gut or a particular level of a hormone, for example, you know, what's happening in your bone density, which is signaling through to your brain and vice versa.
But some signals from your body coming up to your brain, you are consciously aware of or you may be able to tune into them. So, you know, if you've got an aching back or if you're hungry, you've got a full bladder,
You know, you're pregnant, you can feel a baby kicking. There's a lot of signals which you are aware of and we call this particular sense interception. So that's like you've got a sense of your interior.
And a lot of these signals are a strong component of the emotions that we experience. And there are also signals about a sort of a homeostasis like what kind of status is our body in that our brain is able to monitor and make meaning of and then regulate but we've also got all this information streaming from the outside world via our sensors it doesn't kind of make its way in via magic or ESP it comes in through
what we see a large component of our brain this processing is made up of processing visual information also what we hear and if something is close enough to us you know we can touch it or smell it or taste it and even ingest it.
So the food we eat is kind of a signal about this sort of the status of the environment around us. And the environment around us includes, you know, the people that we interact with every day,
you know, the rising and setting of the sun, the built environment we live in, and rather unfortunately, what streams in via this device, which now streams everything that's happening in the world,
even the most dreadful, awful things that you could imagine, or perhaps you should never see, that's right there in front of you. Our brain doesn't know that it's actually happening on the other side of the planet. It thinks it's happening in the here and now.
So this has ruined a lot of things, I think. That's a lot taken a lot. And then we've finally got this sort of top down meaning that we make of our bottom up body and relationship to the outside and world by our top down sort of thoughts or feelings or expectations and beliefs.
And so this is this framework that I like to teach up front whenever I talk or teach my courses or programs, because then that enables us to go ahead and answer other questions that we might have about what's happening in the brain when,
right, right. I like that structure and people can look at it in those two different ways and then kind of determine what's going on from there. - Yeah, it's very visual.
It's very visual. And I get people to draw, I mean, I know this isn't a visual medium, but I often get people to draw it out on pen and paper. And teachers have used it in classrooms with kids.
They will divide the playground and to bottom up outside and top down, "Hey kids, what can we do to have a healthy brain today?" And the kids can run around each of those segments and act out things. So it's very visual and kind of a great simple framework for then incorporating lots of complexity.
Wow. So now you educate how we have neuroplasticity for that brain that's processing all of this. And of course, for some that don't know, it's our ability to reorganize our structure,
function or connections in the brain throughout our lives. How would you explain to someone how this works? And then as well, how can they optimize this through their life? I heard from you that we can have this throughout our lives and that was a surprise.
That's a surprise for a lot of people. I think if you aren't familiar with the neurobiological mechanisms underlying neuroplasticity, it seems like it's this one thing.
The brain can change and now that we know that it makes it easy to change or it's possible when we've got that knowledge and that's not necessarily what it means. Neuroplasticity from you know the perspective of a neuroscientist and I like to be kind of let's be precise about this is sort of an umbrella term which encompasses a whole lot of mechanisms by which the brain learns or grows or changes or responds to the
environment. That simply means those neurons or those sinuses are responding to changes that they are experiencing And that happens throughout the lifespan because essentially that's what learning and memory is.
That's why you can remember what you had for breakfast this morning, or you would pick up a book that you read in bed every night and you can remember what you'd read the day before because your brain has the capacity to learn and remember.
And that falls under that umbrella of plasticity. So we can still learn and remember throughout our lifespan. However, there are other points in the lifespan where we see more broad scale or sort of larger structural changes in the brain,
and these are more likely to happen within particular windows or sensitive periods of development. Sometimes they get called critical periods of development, sensitive periods, sometimes that's used interchangeably.
Sometimes we require specific experiences during these very plastic times. So we've got different sort of types of plasticity.
We've got critical period plasticity. We have this, this sort of very sensitive phase of brain development and plasticity through adolescence. So puberty kind of starts the, the brain,
the, the brain going through this, this period of plasticity and adolescence. And then we have other times in life when the brain is more malleable and responds to particular experiences,
different types of plasticity. it's not one thing. And there's kind of more or less easy or harder to learn different skills at different points in the lifespan based on this particular type of plasticity which is enabled.
Right. Is there anything that someone can do? Let's say they're going through middle age. Is there anything they can do to optimize our neural plasticity at that point? Hmm. Well, at this point, the thing is is has kind of mandated or selected for I should say that the brain and during infancy and childhood and then again in adolescence is exceptionally plastic and is open to learning by experience and then it kind of
shuts down and so we believe there must be a reason for that. So the types of plasticity that we want to tap into in middle age we don't want to just be changed by everything in the environment as we are in infancy.
At adulthood, we then want to be going right, "Am I learning a new skill or a new task?" We need to be very precise and very focused to figure out what is this thing I'm wanting to learn and how can I maximize my opportunities here.
We're not going to just simply learn it because we've tapped into plasticity. We've got to go outside and top down and go, "What are the ways to learn this skill. So say you want to learn a new musical instrument,
you've never played music before, it's going to be a whole lot harder than it was if you started playing, say the violin at eight, you decide at 48, you're going to learn to play the violin. Well, I have this other model where I kind of talk about,
you know, refire to rewire. So you've got to have your reason. Okay, I'm going to learn a musical instrument, very precise here, I'm going to learn how to play the violin. And then you're going to need to learn from someone because you probably won't learn just by picking it up and mucking about,
you know, have a clue. You'll need to sort of engage someone to teach you. You would go and learn from a skilled person who will give you feedback and correct your mistakes. You'll need to kind of get yourself in a kind of an emotional arousal state for learning.
And we know brains don't learn when they're like, meh, bored, meh. And they also don't learn when they're like super stressed and freaked out. But you need some kind of degree of arousal. You need that sweet spot where you're open and willing to learn and you're kind of alert and paying attention.
So you need some kind of degree of arousal. And then you've got to do all of the really boring things. Well, you need a bit of the grit and resilience. You've got to practice, practice, practice, practice. Repeat, repeat, repeat, repeat. You can use your kind of imagination.
You can use your mental rehearsal skills to kind of practice when you're not literally there and then we also know there's a few psychological tricks you can do whereby you could talk to yourself as if I am a violinist rather than I am learning to play the violin and we know this comes about from health psychology and behaviour change whereby we might say instead of saying oh I'm training to run a 10k say I am a
runner and that kind of your mind set around to make that learning process, you know, you kind of become a bit more forgiving of yourself as well of making mistakes. So they're the kind of things you've got to do.
And then of course, factor in all of the basics, sleep, you know, rest, you've got to have gaps between your learning or, you know, the healthy nutrition,
the lifestyley well -being tips that most of us are familiar with, but not everyone. Yeah, Yeah, that's healthcare. Now, what about pruning, pruning of our neural connections? How helpful is that?
Yeah, well, that's essentially one of the things that happens under this big umbrella of plasticity. So I was talking before about synapses, which are the point -to -point connections between two neurons.
So a single neuron will have like an axon, which is kind of like the output to the next sort of neuron in the chain. and then it will also be receiving inputs from maybe one or maybe thousands of other neurons and it receives inputs on its dendrites.
So it looks like branches of the tree and on the branches of the tree on the dendrites are these little things called spines which look like buds on the branch of a tree like what you would see in spring when it's first starting to kind of flourish and these little buds are kind of like these little synaptic points these point to point connections.
And what we see is one type of plasticity is either the kind of the flourishing or the pruning away of those little buds or of those synapses. And some types of learning,
particularly when you go through a learning process, you might make more synaptic connections. And then perhaps as you develop your skill, you might kind of prune away the ones you don't need.
And what we see particularly during childhood development, heading into adolescence, we see this flourishing and growth of more and more synaptic connections. And then during adolescence,
when we go through this next sensitive phase of neurological development, we see the pruning away of connections that aren't needed. We often see that as we go through learning processes,
we might see flourishing and pruning, but it doesn't always kind of go in the direction you might predict. It can be quite surprising to learn that when we prune away the unwanted connections we don't need and consolidate the ones we do,
that's kind of the brain's streamlining and refining itself. But what the pruning away can kind of add up to overtime or subtract away from over time,
I should say, is perhaps like loss of brain volume. You might get like a thinner cortex in the region where the pruning has happened. And we think, well,
that sounds like degeneration because you don't want your brain to shrink. But what that is is the brain kind of streamlining and refining itself, because essentially it's driven towards efficiency. It doesn't want to have more neural connections to support than it So it's like,
well, I don't need them or consolidate and focus in on these ones. So often you might see cortical volume loss during periods of great plasticity,
or you might see the cortex or parts of the brain becoming less active. As you get better at a particular task or a skill, the learning process requires a lot of energy and activation and a lot of neurons working together.
And then as you get better at that skill, refine that task, the brain gets much more efficient, much less neurons are activated and you'll see less overall neural neural activation. So the brain's quite smart in that way.
And that it's trying to be quite efficient. We like, we don't need all of that. We'll prune it away. It's like a, a gardener and a garden kind of pruning away at a bush. We're only going to keep the, the kind of the branches and leaves that we need to keep this,
this plant alive. We're going to get rid of all of the the extras. Right. Right. So it's all a good thing. Now, in the women's brain book, you discussed the facts that women's hormones have on the brain.
And I'd love to hear more about that. I know my audience would. Goodness me. Well, that's a huge question. We've got a lot of hormones in our body. Some of the more famous ones in the last kind of year or so have been around those hormones that we release in our gut when we're full or not and We've got,
you know, these new drugs in our Zenpik, I think is the brand name, reducing, you know, was used for diabetes and our people are losing loads of weight because we're kind of, you know, inhibiting this release of this hormone.
So everyone thinks that they're not hungry, so they don't eat and so they lose weight. We're only just sort of learning about the effects that's also having within the brain because most hormones that we release within our body make their way into our brains,
not all, but many do. In vice versa, we have neurotransmitters and hormones which were released from our brains, which can make their way into our bloodstream and throughout the rest of our body.
So there's always these kind of constant conversations going forward to focus on kind of women's health. People are always really interested in estrogen, which is released from our ovaries,
particularly during our reproductive years between puberty and menopause. With usually, Unless you're on the pill, you'll have higher levels of synthetic estrogen all the time.
When you're naturally cycling on your menstrual cycle, it'll be kind of fluctuating up and down every month or so. And then when you go through pregnancy, you'll get the high level of estrogen. In fact, in one pregnancy,
you'll get a greater dose of estrogen than you'll receive during the entire rest of your lifespan combined. And when estrogen is being released from the ovaries all from the placenta or whatever if you're pregnant.
It makes its way all throughout our body and we know that estrogen makes its way throughout our body during puberty because we get the development of secondary sex characteristics. We go breasts and kind of become a wee bit fatter etc.
But the signalling of estrogen is also picked up by our brain and that is because throughout our brain and throughout the rest of our body we have what are called estrogen receptors And you don't get any molecule or neurotransmitter or hormone working just randomly throughout the body as if you kind of die through the body and it just permeates everywhere.
It's always a specific action and mechanism. So we've always got a hormone. So we've got estrogen. Estrogen can only act via an estrogen receptor. And it's often referred to as like a key going into a lock and it doesn't necessarily open a door it's more like putting a key like into your when we used to put keys into cars we don't do that so much you push a button you know you put your key into car and you turn
on the machine and then there would be this kind of mechanism and that's what estrogen does it kind of locks into its kind of mechanism it turns it on and there's various processes which will happen within that particular cell it could be a cell within your breast,
it could be a neuron within your brain, it could be within your hair follicles. We know that it acts within the brain because we have this brain ovarian conversation, that's what's otherwise known as your hypophilamic pituitary ovarian axis,
the HPO axis, and sometimes you might have seen that in the science textbook or something at high school, so we've got the ovarian that the ovaries releasing estrogen, chatting to neurons in the hypothalamus,
neurons in the hypothalamus, chapter, neurons in the pituitary gland, those neurons release hormones, which make their way through the bloodstream back to the ovaries. So you've got this little cyclical conversation.
And that regulates your menstrual cycle and your fertility. But there's other parts of the brain, which also have receptors for estrogen. And we're only just talking about one hormone here, kind of the the sort of the classic now in the textbook study of the active estrogen on neurons within a specific part of the brain,
hippocampus, which is involved with kind of memory and sort of spatial navigation, was first kind of described in the late 90s where, remember I described dendrites before,
which are like branches on a tree and we've got the little buds, which are the little spines and they kind of flourish and grow and it turns out there's certain neurons within that a certain part of the hippocampus that kind of ebb and flow or grow sort of flourish their little spines and then prune their little spines and flourish their little spines as estrogen levels kind of go up and down.
So we know estrogen modulates the kind of the flourishing and removal of their spines every month. So we know that there's certain ways in which the brain is responding to levels of estrogen.
Now whether that be as I said you perhaps you're on the pill and you take that continuously for 20 years which many women do very safely you're going to have the high levels of estrogen all of that time or perhaps you've just got your big giant peak of estrogen and pregnancy or you've kind of got it ticking away during your menstrual cycle and then you've got some of the brain and body effects that we see when
estrogen sort of starts dialing down through perimenopause and menopause. The question then is, well, how much is estrogen having an impact on what we think and how we feel and how we behave?
'Cause they're all related but slightly different. And in the women's brain book, and I say I wrote the women's brain book during sort of 2017, 2016, 2017. And we've just agreed with the publisher to do an update for 2025,
which I'm very excited about. So I'm looking forward to updating a lot of my knowledge in some of the areas I'm a little less up to date on. But in the women's brain, because like, well, does does these levels,
changing levels of history and change how we think? Like, does it impact cognition? Are we like, more cognitively able at different points of time in our menstrual cycle? And the data on that's pretty unclear and that there doesn't seem to be a lot of evidence that you're more cognitively fit and able when your estrogen levels are higher versus lower throughout the course of the menstrual cycle.
There is some data looking at women who've been long -term oral contraceptive pill users so that estrogen levels, synthetic estrogen, but it's acting the same way at quite high and those women do appear to score slightly higher on some tests of cognition And that's hard to surprise because we know that estrogen is a cognitive enhancer broadly speaking overall.
I hope you found our interview with Dr. Sarah McKay helpful so far. Make sure that you catch part two when she shares eye -opening information on estrogen in the body and how depression and anxiety can be caused by perimenopause and menopause.
What to do about this and how to approach aging in a healthy way. We release a new episode every other Friday. So remember to subscribe, rate, and share this to help us continue,
and to get Sensitive with an Edge out to more people. Also, if it's time for you to take care of yourself, let me help you get unstuck, and join the empowered Sensitive membership in the links below.
Thank you so much for listening. Sensitive With an Edge is a podcast created by Chris M. Lyon for highly sensitive people seeking relatable and practical insights. While the content is designed to be informative and supportive,
it is not intended as medical or clinical advice. Listeners are encouraged to determine their own sensitivity level and consult with a healthcare professional if needed. Use and opinions expressed in this podcast are based on the knowledge and experience of the host and guest and do not necessarily reflect those of any affiliated organizations or individuals.
