DMN and the Amygdala in Neuropsychiatric Issues

Hey there, everybody, and welcome to this presentation on the Default Mode network in neuropsychiatric issues. I'm your host, Dr. Donnelly Snipes. In this presentation, we're going to describe the function and interactions of the Default mode network, the Salience and Emotion Network, and the Executive Control Network. All three of these networks are referred to as intentional control networks. We'll explore network dysfunction as a result of physical or emotional trauma, explain how these networks have been implicated in neuropsychiatric issues, and explain how activities that promote neuroplasticity can be used to improve the regulation of these networks. As I mentioned, there are three networks, and the roles of these networks include consolidation of memory, facilitation of working memory, continuous situational awareness, processing of emotionally salient stimuli, and the interplay between emotional processing and cognitive functioning. Let's start out with the Salience and Emotion network. And I know I said we were going to talk about the DMN and it is a big player in neuropsychiatric issues, but first we need to understand the other players. So the Salience and Emotion network I refer to as the scout, and it includes the amygdala. The scout detects and filters salient emotional and sensory stimuli from most important to least important and then recruits either the DMN or the ecn, the Default Mode network, or the Executive Control Network as appropriate. Connectivity between the SEN A, especially the amygdala portion of the sen, and the Executive Control Network may facilitate superior adaptive behavior in the context of emotionally salient information. So basically what that means is you have this scout who's going around and just taking in all of the data, all of the information that it can gather, and it says, okay, I got this stuff. What do I do with it? And it filters it out. And if it has a good connection with the Executive Control Network, what we'll learn is kind of like the logical mind. Then people are better able to process information in context and make purposeful choices about how to deal with the information. The Executive Control Network is that logical mind, and sometimes it's referred to as the cognitive control network. It takes control and actively processes information to allow for voluntary control of behavior in accordance with people's goals. For example, if you are trying to meditate, when you are focusing on your breath, you are actively processing the information about what it feels like when you inhale. You're actively processing the information about, you know, what your stomach is doing. We use the Executive Control Network when we are using biofeedback because we are actively trying to control generally reduce heart rate, respiration, blood pressure. We are actively using this executive control network when we engage in purposeful action. We're not just willy nilly reacting on autopilot. We, we are being mindful in the present moment, we are noting what is and we are making a conscious active choice about how to act and react to that situation. Context, informed decision making is another function of the ecn. And we're going to talk about the DMN in just a second. But with the ECN it is taking this current information. It's not relying just on schema that we have in the past and doing what we've always done, but it's saying, okay, I know what we've always done and what we've been through before, but let's also consider what's going on in the present moment. Now, the default mode network operates in antithesis opposite of the executive control network. So when the ECN is engaged, the DMN is disengaged and vice versa. The default mode is what I call your autopilot mode. And it is the mode that we are often in when we are alert but not actively involved in attention demanding or goal directed tasks. And it interprets salient stimuli, the stuff that the SEN brings to it based on prior experiences or schema. It says, okay, been here before, recognize this? So we're going to react this way. You smell smoke, for example. Well, your SEN will take that to the dmn, it'll say, okay, we've been here before, what do we do with it? And the DMN says we smell smoke, then we need to react in a certain way. Or we hear a fire alarm, we need to do a particular thing, we don't stop and think about it. It's sort of an automatic response about what we need to do. The default mode is also implicated in projection. And projection is when we take information from experiences that we've had in the past and place them on current experiences without considering the current context. So if you're in a relationship with somebody now and they start doing things like withdrawing and being sort of apathetic, maybe not wanting to go out as much, sleeping more, whatever, you may take that information and say, well, I was in a relationship with somebody in the past who did that, and that meant that they were addicted to drugs, therefore you must be addicted to drugs and I need to, you know, get panicked about it. And in reality, in the current context, yes, those things are going on. But it could be that this person has a virus or is just Overwhelmed with things at work. So projection is when we use information from our past without considering the present in order to inform our decision making. And that is part and parcel of the default mode network. Now, the anterior default mode network participates in emotion regulation. So it says, okay, been here before, I know how we should react to this. I know whether we should get angry, whether we should be afraid. So it pulls from prior learning and basically decides how to regulate the emotions. The posterior DMN directs attention to the internal world and expectations therein. Awareness of the self. Now that sounds very metacognitive and it kind of is. But it's important to recognize that the dmn, the default mode network, is very self referential. So if the person says, I hurt yesterday, therefore I expect to hurt today and I expect to be helpless to change it. So the DMN is operating on autopilot. People who've experienced an injury, who've experienced pain, may be stuck in that default mode network because they're self reference, their reference to themselves as someone who experiences chronic excruciating pain pretty much constantly. Until that changes, Then they are going to anticipate and view the world through the lens of somebody who experiences chronic excruciating pain. They are not expecting anything different because they're in their default mode. What we need to do is help people start activating or recruiting the executive control network to take into consideration those schemas and say, okay, that's right, you have been hurting for a long time. Let's look at what's going on in the present context and instead of assuming you know how you feel, hey, let's actually check in and see. Do you hurt today? Do you hurt right now? Now the amygdala, we talk a lot about the amygdala. That part of the brain gets thrown around a lot. It's not actually part of the default mode network. It's part of the salience and emotion network. But remember, the amygdala is involved in fear processing. The amygdala, you know, part of the salience and emotion network. When it notices threatening stimuli, it is really connected to the default mode network. It has lots of little projections that literally connect the SEN to the dmn. So when people are experiencing pain, when their amygdala is regularly activated, when they are regularly perceiving threats or fear, those connections with the DMN often get strengthened and reactions become more intense. Now, it's not overly important to know all the different parts of the default mode network, but I thought it was kind of interesting. So I figured I'd just put it in here. One part of the DMN is called the posterior cingulate cortex. It's a key node in the DMN and shows increased activity when people retrieve autobiographical memories. So when they think back to what happened to them in the past, when they're retrieving those schema, the PCC is activated. It's also activated when the brain starts to wander. Because a lot of times when the brain wanders, it wanders back to memories. It wanders back to regrets, threats, anxieties, sometimes happy things. But a lot of times we notice our brain will wander towards stressful thoughts. The medial temporal lobe provides information from prior experiences in the form of memories and associations that form the building blocks for mental schema. So we have these memories and associations that are kind of put together to create pictures and expectations for stimuli. You know, when you encounter a yellow light, you have a schema that tells you to expect that it will turn red. And if it turns green, that schema is just kind of out of whack and you get caught by surprise. Now, the orbital frontal cortex identifies the reward value or the importance of sensory stimuli, especially taste and smell. Think about it. When you're eating, you don't have to think about whether chocolate tastes good. You eat it, it tastes good, you take a, take a Hershey's kiss or something, you expect it to taste good. And you also don't have to constantly evaluate if something's rotten. We are sort of pre programmed in our default mode to identify things that are rotten. They taste nasty, you don't have to. Every bite you take, you don't have to think, is this good or is it rotten? Your default mode network is just kind of in operation, theoretically, basing decisions and basing thoughts and reactions on prior experiences and saying, yep, everything's fine here, nothing to see. And finally, the medial prefrontal cortex is also part of the DMN and it's involved in empathy and being able to interpret the other people's emotions. And we're going to talk in a few minutes about how a hyperactive DMN is very common in people with anxiety and major depressive disorder. And people with these anxiety and major depressive disorder often tend to have more rumination. So we see the default mode network kicking in and people basically getting into a stuck in a loop of anxiety triggers a reaction. That reaction tells people that they are unsafe, that increases their anxiety, and it's just this negative self referential loop. The salience and Emotion network is constantly noting stimuli and based on their salience either allows the default mode network to stay activated or so it says, nothing to see here. We got this handled. We don't need to call the boss. So the salience and emotion network and the DMN just keep their little conversation going on or if it's something that requires input and reasoning, then it recruits the ecn. And the best analogy I could make was lane assist. And I think a lot of us have driven a car with lane assist. Think of your default mode network as lane assist. And it says no matter what, you're supposed to stay between these two lanes when you're driving on the road. And if you swerve out, if you cross the yellow line, I'm going to pull you back into the lane. And it's automatic. It doesn't take into consideration any other information. Now the executive control network is like turning that off. So I regularly, no matter what you think about it, will see I don't want to hurt turtles. And where we are, there are a lot of turtles that walk into the middle of the road and hang out there to sunbathe. Not really in their best interest. So there have been occasions when I've had my lane assist on and I have cross the yellow line, just no to avoid the turtle. Now, I knew no other cars were coming toward me and I knew I was crossing that yellow line, but I was intentionally, intentionally doing it based on information I had in the current moment that was different than the standard schema when trying to alter our behaviors, like reduce our impulsivity. A combination of learning new skills, okay, what do I do instead? And active reflection generally through backward chaining helps us use the executive control network and with practice can inform and modify our situational and self referential schema. So what does that mean? Well, that means when we are trying to learn new behaviors, it's not easy and it generally takes a little while to break a habit or learn a new behavior, whatever you want to call it. But by learning these new skills, we're activating that ecn. We say okay, in the future in situations like this, I want to react this way instead of the old way. All right, so we learn those new skills. We tell ourselves, this is what I want to do. Hopefully we mentally rehearse that, that strengthens that connection between the SEN and the ecn. And it says okay when you encounter these stimuli. We want to engage these processes. When we use backward chaining after a situation, sometimes we don't use our new behaviors and we're like, crap, you know, I didn't intend to do that. All right, that's fine. All is not lost. Because what you can do is, is examine the behavior and say, okay, this stimulus triggered this behavior. Now why was that? What led up to it? So you are broadening, you're informing that schema about the behavior. So in the future you can notice vulnerabilities. You can notice things that might lead up to, for example, an anger outburst. That can help you make better choices in the future. Because ultimately you want this new reaction to become a default reaction. But in order to do that, we have to modify that schema. We have to modify the way we default to reacting when we are angry. Trauma is when a person is exposed to a threat to their person or safety or the safety of a significant other. That's really over generalized. But basically that's what we're talking about here. When people experience chronic trauma, and it can be chronic to the extent that they are regularly being exposed to a traumatic situation in real life, they are in a domestically violent relationship, they are living in an unsafe environment, whatever the case may may be, they can be regularly exposed to that in real life, or they can be regularly exposed to it through flashbacks and other issues that come up when somebody has ptsd. Regardless of whether the threat is right there in front of you or whether it's due to flashbacks. The stress is chronic. The amygdala activation is chronic. The HPA axis activation is chronic. This leads to the hippocampus actually shrinking. And the hippocampus is one of those areas involved in emotion regulation. So our ability to regulate our emotions becomes impaired and the connectivity of the salience and emotion network to the amygdala salience and emotion network, specifically the amygdala to the default mode network increases. So as people experience stress, the more they experience trauma and stressful situations, the more think about the more projections the amygdala or the stronger the projections the amygdala has with the default mode network. So every time the amygdala is activated, it activates the dmn and each time it's a stronger activation because of its strong connection to the default mode network. When the amygdala is hyperactive, it prompts autopilot or fear based reactive responses. Your brain is basically saying no time to think, just fight or flee. You are in that default mode. When this happens, when people are regularly dropped back into this default mode, their self reference may become one of being helpless and in danger. So they see themselves as being in danger. With ptsd, with flashbacks, with night terrors, people often feel very helpless because they can't. They don't feel like they can control them and they don't know when they're going to have a flashback. So they can feel like they could be assaulted at any moment. So their self reference becomes one of being in constant danger. They react in the only ways they know how, which doesn't alter the schema or fix the problem. So they react in a default way when this happens to fight or flee, but it doesn't end up fixing the problem. So they continue to encounter the issue. And we'll talk about this more in specifics when we get down to depression in a minute. This reinforces their self reference of being powerless and unsafe and further strengthens those amygdala connections. Increases in connectivity between the Default Mode Network and the Salience and Emotion Network lead to reduced task induced deactivation. Which basically means, remember I said the dmn, The Default Mode Network and the Executive Control Network operate opposite one another. When one is turned on, the other is turned off, and vice versa. Unfortunately, when the DMN and the SEN are strongly connected, the Executive Control Network is kind of left out of the loop and it is not strong enough to be kicked in. So it's kind of like the Salience and EMotion Network become BFFs with the default Mode Network and they ostracize the Executive Control Network. They're just, they sit there and they communicate because they're thick as thieves. When the DMN cannot be turned off in order to activate the Executive Control Network, this is called a reduction in task induced deactivation. This is associated with reduced cognitive performance, higher levels of anxiety and rumination, and an inability to appreciate the current context. So prior learning is applied and reinforced and fear extinction becomes impaired. You're not taking into consideration new information, you're just basing it off old information which is steeped in fear. So you're not changing the schema at all. So the person continues to stay fearful and feeling unsafe and seeing themselves as being one that is unsafe and powerless. Default Mode Network dysfunction is implicated in Alzheimer's disease, Parkinson's disease, epilepsy, attention deficit Disorder, prenatal cocaine exposure, anxiety, depression, PTSD personality disorders, especially your cluster B antisocial, narcissistic, borderline personality disorder, and even in chronic pain issues. Now think about it. With chronic pain, what's going on? Pain tells your body something ain't right. Pain tells your body there's a threat. You're vulnerable. So that pain itself can cause the amygdala to become more active and more strongly connected with that default mode network. Because basically the person's default perception is I'm always in danger, I'm always afraid. Increased amygdala connectivity to the default mode network and people with anxiety contributes to hypervigilance and stimulus overgeneralization. When you are more aware of what's going on, when you have. Well, let's back up. When you have anxiety and you're fearful, you tend to pay more attention. You tend to be more aware of what's going on. So you don't get caught unawares because you don't want to be vulnerable. So that's your hypervigilance. Now when you're hyper vigilance, you're going to notice more things. So you're in this anxiety state, you start noticing more things, those things start to become associated with anxiety. So you start having a lot more stimulus over generalization. Amygdala hyperactivity has also been reported during facial emotion processing in major depressive disorder. So people with major depressive disorder when they interact with others remember we talked about part of the DMN is involved in empathy and understanding other people's feelings. That can be overwhelming to a person with major depressive disorder and can contribute. When people feel overwhelmed, guess what? Their amygdala kicks in. Major depressive disorder is characterized also by a reduced executive control network salience and emotion network connection. So that executive control network is weaker. So people are. When they feel stressed, they go to their default responses. Instead of saying, all right, let me notice mindfully and non judgmentally what's going on in the present moment and make an active conscious choice about what to do. When the default mode network is active, it often drifts to the thoughts that are most salient for the person. Hence the reason for the salience and emotion network salience. It brings the DMN the most important information, the most salient information. Oftentimes from a survival standpoint. That means our brain often defaults or drifts to fear or stress based thoughts. Like the mistakes I've made, the thing I did to embarrass myself, regrets I have or things I need to do. You know, anxiety about can I get everything done, I'm overwhelmed, I really should be doing this. That's where our mind often defaults to instead of going to happy places. They have found doing research that greater levels of mind wandering occur within the depressed group and are associated with stronger salience and emotion network and default mode network connectivity. So when people are more in the default mode, their mind tends to just kind of wander about. Other research in persistent pain states, depression, anxiety and ptsd, the rate of communication, and I thought this was fascinating, the rate of communication between the sen, the salience and emotion network, and the DMN is doubled. So instead of communicating, you know, once every 10 seconds, for example, it starts communicating once every five seconds. So not only are the connections stronger, but there's more information flowing because the SEN is just constantly going, hey, hey, you need to be aware. Hey, wow. Just even thinking about that can be exhausting. The result is the person becomes increasingly aware of their internal state of distress. Remember, the DMN is very self referential, so it increases people's awareness of their own internal state of distress, Whether it be depression, anxiety, trauma, pain, whatever, or addictions. In people with addictions, connectivity of the SEN to the anterior dmn, which is where we have emotion regulation, tends to be decreased. So people with addictions tend to have more difficulty with default emotion regulation. Connectivity of the SEN to the posterior DMN directs attention to the internal world and is increased. So they become increasingly aware of their cravings, of their neurochemical imbalances, of their pain, of their distress. Wow, that's, you know, think about that. They become increasingly aware of the discomfort, physical and emotional, and less able to modulate those emotions. There's also, as you would expect, when the SEN and DMN become BFFs, the ECN or the executive control network drifts off. It becomes weaker. So there's reduced connectivity between the DMN and the ECN and can lead to autopilot. And the person has problems with task induced deactivation. The DMN stays prominently engaged, so the ECN is just not able to fight the dmn. And the person is ever aware of their withdrawal symptoms and their preoccupation, their cravings during addiction. So what can we do about it? Well, remember, what we're talking about is an intentional network. We're not talking about the whole bottle of wax. There is so much that goes into emotions and, and physical and mental health. We have the HPA axis, the HPG axis, the HPT axis, the gut brain axis, the gut microbiome. You know, I could go on our gonadal hormones. There are a lot of things that all have to be synthesized in order to understand how we get from one place to another. And a dysfunction in one or more of those areas can cause mental or physical distress. Now with this Intentional network. What we are noticing is that what people pay attention to impacts their HPA axis, their HPG axis, and their HPT axis, as well as the gut brain axis and the gut microbiome. So what we pay attention to and how we interpret the world informs a lot of those other pieces which have the result of affecting the levels of different neurotransmitters and hormones. The more you consciously force the activation of the executive control network through mindfulness and active situational processing, the stronger its connections will become. This neuroplasticity is associated with new learning and involves constant changing of the ways that nerve cells connect to each other and organize in networks. As people start changing these interactions and start informing and altering their schema in the default mode network, they begin to see themselves as hopefully safe and empowered. It's thought that the DMN will reflect that and handle the input from the SEN accordingly. So as we start to change those schema that our brain uses when it's in default mode, we can change our actions. When we see ourselves as safe, empowered, loved, loved, lovable, we tend to react, we tend to regulate our emotions differently than if we see ourselves as damaged, victimized, disempowered, unsafe. Like weightlifting, when a person starts exercising, the muscles tend to be very weak and can be easily overpowered. With training, muscles become stronger and more effective at moving the body. With training our neural networks through neuroplasticity, our neural networks can become stronger. But it takes time, and it's important to encourage people to be kind to themselves and recognize this isn't something that's going to happen overnight. For 15, 20, 30 years, you've been strengthening the connection between the SEN and the DMN. Now we need to turn our attention and bring that executive control network into the fray as well to help balance things out. When the brain is directed toward a task or goal or being in the present moment, including things like guided imagery or mindfulness, the default mode network deactivates and there's an increase in functional connectivity with the executive control network. The logical mind Meditation can help curtail mind wandering, can help down regulate that DMN because it is encouraging, not necessarily forcing, encouraging the person to be present in the current moment and focus on something. Right now, that's that ECN getting engaged. You're not in default mode anymore. You're doing something new and different. You're focusing on the present moment, which is ever changing and new and different. Now I do want to point out, remember I said that we can't understand psychopathology or physical ill health just by looking at one aspect. Like these attentional control networks. Attention is regulated by dopamine, norepinephrine and serotonin, among other things. So if people have biological dysfunction in one of those networks or more, no matter how much meditation you do, it may be difficult for them to curtail that mind wandering or the monkey mind. It is important to recognize that not everybody is going to be able to reprogram these networks at the same rate. Research has shown that it's possible to do it, you know, for pretty much everybody. But some people will have better success than others, and some people, it will take longer than others. Body scan awareness exercises and progressive muscular relaxation can also be super helpful. Because people are becoming aware in the current moment of their physical sensations. They're not just assuming, well, I hurt yesterday, I hurt last week, so of course I hurt today. Well, with body scan awareness, they're actually going through and identifying where do I hurt, how much do I hurt? What is the quality of the pain? Is it sharp, is it dull, is it moving? That can be really important because when we're dealing with chronic pain, a lot of times we want to see a reduction in the frequency, intensity and or duration of the pain. The pain's not just going to magically go away overnight. But if people can start noticing incremental improvements, it can help them inform themselves, inform that schema, inform the default mode network that hey, things are getting better, which is contrary to the default schema of this is hopeless. Guided imagery can be used either for relaxation or rehearsal. If you use guided imagery like walking through a ph forest or on the beach, that helps the mind paint. You know, it's kind of like an active painting of mental picture of where the person wants to be. And it engages their senses, it engage. Engages memories of things, but is an active process. And that can help people relax because it directs their attention to, to the present moment, to this simulation. Rehearsal is another great aspect or another great technique for guided imagery because people can envision themselves doing something, successfully implementing these new skills, reacting to something instead of getting angry, doing something different, instead of succumbing to their craving and relapsing, doing something different. If they rehearse this in their mind, they rehearse this process, they are actually strengthening those connections. You can look in sports psychology research and there is a lot of information dating way back to like the 1980s where athletes will envision themselves even when they're not practicing. You know, they will spend time each day envisioning Themselves doing the perfect whatever. And I believe Greg Louganis was the first one that really started talking a lot about it. That's the first one I remember at least. But he would envision himself doing the perfect dive. He would see it even though he was not physically doing it. He was creating that neural connection. Mindful eating and movement like yoga and Tai Chi help us become just more aware of the present moment. If you're mindful, that means you're focused non judgmentally on the present moment, which means your mind is not wandering, it's not in default mode. Just assuming it's not. You know, sometimes when we eat, we're in default mode. We're just shoveling it in. We're not even noticing what the taste is. We're just filling our beaks. When we eat mindfully, we are actively engaging our ECN in the present moment. Same thing with yoga and Tai Chi. One of the nice things with yoga is there's lots of benefits because you become aware of your body in space, but you also learn how to regulate your breathing and develop better vagal tone. Backward chaining we already talked about. Now that's a post hoc analysis of something that you did. And you can do backward chaining when things go right, as well as when it goes wrong. Looking at what did I do here? If it went right, what did I do here? So I can do it again if it went wrong, what did I do here? What did I want to do? And let me envision myself doing it correctly this time or doing it the way I want to this time. And finally, one of my favorites is awe provoking experiences. When we have those experiences of awe, like when we watch a meteor shower or we see a baby born, or we see a double rainbow. For me, you know, just sometimes even seeing the little hummingbirds that come to my hummingbird feeder doesn't take much to inspire awe in me. But when we have those experiences, it suddenly draws our attention to the present moment, where we are almost stuck in the present moment in this sense of awe and wonder that triggers the ecn because our brain becomes curious. Kind of like, you know, a two or a three year old that asks why about everything. Our brain is just stuck trying to understand this in the present moment. And that forces the ecn, activates the ECN and forces the DMN to down regulate these networks help guide our understanding of attention and cognitive processes. But this knowledge needs to be integrated into our understanding of mental and physical health by gaining an understanding of how these attentional networks interact. With the hpa, hpg, HPT axes, the gut brain axes, the gut microbiome, we will start to better understand how they all influence each other to impact mood, inflammation, immunity, etc. Knowledge of these networks also helps us understand the long tail benefits of things like meditation, which over time improve the connectivity of the sen, the salience and emotion network, to the ecn, the executive control network, and enhance task induced deactivation of the dmn. So it basically improves the switch between the ECN and the DMN and may even reduce hyperconact connectivity of the amygdala to the dmn. As people start using the ecn, the executive control network, to alter their schema about the universe, about themselves, about their safety and empowerment, as they start to feel safer and more empowered in their environment, then the amygdala doesn't need to be as activated. Remember, amygdala is fear processing. If they are perceiving the world from a more powerful, safer place, then that amygdala is less active. So those connections will actually become less active and potentially reduce. I hope this has given you a little bit of insight into the dmn, ECN and sen. It is a relatively new area of research and I know it's one that we certainly didn't cover in graduate school. So this was a really high level overview and I will be talking about that. I will be integrating these networks into my presentations on personality disorders and mood disorders and other psychiatric issues as we start talking about understanding them from an integrative behavioral health perspective.