Dr. Andrew Huberman, Professor, Department of Neurobiology, Stanford University School of Medicine; Host, The Huberman Lab Podcast


Brainstorm Health 2022 - Imbedded Intelligence 

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Brainstorm Health 2022 - Imbedded Intelligence 


So in the next eight minutes or so, I'm going to talk about neural plasticity. Some of you may be familiar with this term neural plasticity in short is your nervous system's ability to change in response to experience. And when I say nervous system, I do mean nervous system, not just brain, you have a brain obviously that's locked inside your cranial vault. Um there are two little pieces of brain that are outside your cranial vault. Those are your neural retinas. So now you'll never look at somebody's eyes the same way those are literally two pieces of the brain that been extruded out of the cranial vault during development to give information about what's going on in the outside world. Now, you also have a spinal cord and then the brain, the spinal cord connects with all the organs of the body and all the organs of the body communicate back to the brain and spinal cord and that's what we call the nervous system. The nervous system is unique among other organs of the body in that it can modify itself. I think the best way to think about the nervous system is that despite all the many things that it can do, it is a prediction making machine and it makes predictions about all sorts of things where things are going to be, where they're not going to be etcetera, we could do a deep dive down that, but let's talk about neural plasticity because it is what distinguishes the nervous system from the other organs. First of all, neural plasticity occurs mainly by one mechanism. So while it is true, although still hotly debated that you can get new neurons in the adult brain frankly, the data point to the fact that that doesn't happen all that much. Most of the neural plasticity that you will experience. Whether or not you're learning something, forgetting something, whether or not it's pleasant or unpleasant. Reshaping your emotional experience to something occurs by the strengthening of connections between existing cells, not the addition of new cells. Again somewhat controversial but easily 90 plus percentage of neural plasticity is the consequence of that strengthening. You may have heard the term fire together, Wire together. I'm here to correct the record. Those are not the words of Donald Hebb, those are the words of dr carla Shatz, my colleague at stanford but she said them long ago when she was at this other university, I think it's called Berkeley across the bay. I went to Berkeley so I can make that joke in any event fire together, Wire together beautifully encapsulates this idea that the more active neurons are, the more likely they are to be active together in the future. Not unlike human connections that work. So how do you get your a plasticity? Well, neural plasticity is a process. It's not an event like all things in biology and really today, if you take away nothing else from what I say, Please take away this. Which is that neural neural plasticity excuse me, is triggered in a two step process. First it requires alertness, focus and often a state of agitation that accompanies that that state of agitation is something that many people trying to avoid. And that's a shame because that state of agitation occurs by the deployment of a molecule called epinephrine or adrenaline, which is released both in the brain and body and beautiful studies from James, McGaugh, Larry, cahill and others for those either familiar with the name is great if you're not, no problem, illustrate over and over and over again in animal models and humans that when adrenaline spikes after the acquisition of information, there's a much greater probability that that information will be retained and learned for a long period of time stored in areas like the hippocampus et cetera after learning. So if you're like myself, you need a lot of coffee and water and exercise to get alert and focused to work. Well, think about this seems that all the data points to the fact that spikes of adrenaline after learning are probably the most beneficial in terms of consolidating the information that went right before it, which makes a lot of sense when you think about the kind of neural plasticity that nobody wants something like trauma, right? Nobody's getting a spike of adrenaline and then experiencing trauma happens in the other direction. And unfortunately there is one form of one trial learning that we are aware of and those are called negative experiences. Now the contour of neural plasticity is you need alertness, focus and ideally a little bit of agitation and frustration because that accused the brain that something different is happening. Why would the brain ever change if it didn't have this deployment of molecules that say the state of things is different? Right? So the idea that you change in response to every experience or everything that happens to you, that is absolutely false. Not everything I say will be retained, not everything you experience will be retained. And thankfully so it's only when the brain chemically cues that something important happened like a highlighter pen, something that just happened is vital and it's making your state of mind and body change. It's important in studies where they've actually blocked just peripheral just bodily epinephrine. Also called adrenaline shows that the bodily state is what becomes associated with the mental or physical experience that preceded it. Very important point we can return to this later. Perhaps in another talk for sake of time. The second part of neural plasticity is that the actual rewiring the reconfiguration, the strengthening of those connections does not occur during the learning episode. It occurs during periods of deep sleep in particular in the first half of the night's sleep. For motor learning and in the second half of the night's sleep during so called rem sleep or when rem sleep predominant predominant. Excuse me for emotional learning and for cognitive or content type learning language mathematics concepts, new emotional relations contingencies and so forth. So to access neural plasticity you need alertness, focus and agitation and then you need deep sleep. Now there's a beautiful set of studies in the last few years. Unfortunately not from my laboratory, but from other laboratories showing that brief naps of about 20 to 90 minutes can also accelerate the learning and retention of new information. It doesn't matter when those occur relative to that focus, agitation and alertness, but they do accelerate that process. Many people say, well then I don't like to nap, that's okay. There's a new set of data emerging from our lab and others focus on what I call an str because we like acronyms, military and academics love acronyms and SDR simply stands for non sleep depressed, very distinct from meditation. Meditation involves generally speaking, going into a state of heightened focus but calm. Non sleep depressed is a kind of liminal state between waking and alertness. You can find an SDR scripts as they're called various places on the internet in the sort of um traditions of yoga, there's actually something called yoga mudra which involves no movement, which is why I like it and you just lie down and it's a deep relaxation script. Those states of deep relaxation are actually when neural plasticity is consolidated. Now there is one exception to this which is called childhood during childhood a lot of passive learning occurs. Children obviously still need to sleep but The mirror experience of something really does rewire and shape the brain. But as adults after about age 25 or so you need more focus, more alertness and even more agitation and then you need more rest in order to access neural plasticity. I think this has been unfortunately overlooked in a lot of the modern literature. Um, a couple of points about other things that can cure or accelerate plasticity. One of the more impressive literature is at least to me. So these are pure reviewed studies and quality journals is something called gap effects. So if you're trying to learn something and this has been explored with music, motor learning, cognitive learning of various kinds, 12th pauses introduced at random, create a rapid replay of the sequence or thing that you're trying to learn during those pauses what to do during those pauses as little as possible. Clearing the mind is very hard for people in waking states. So pausing at random at a ratio of about 10 minutes of work to every one minute of these pauses, but the pauses are only 10 seconds. You can do the math there and just kind of spread them out. Maybe put a random buzzer on or something of that sort. I wouldn't obsess too much about the how many of those to insert just that you insert those that rapid replay of the sequence that you're trying to learn. It turns out this rapid replay, let's say I'm trying to learn scales on the piano and I'm struggling I'm struggling I'm struggling keep in mind that struggle is skewing your brain that there is something new to learn. If I could perform it perfectly there was no sense of agitation, there's no reason for the nervous system to learn in a pause. That repeat of the scales has done 20x. So you're getting more repetitions per unit time overall when you introduce these pauses and then people always say can't I just do the pauses and of course the answer is no what's going on there. These rapid replays within the hippocampus and the neocortex the exact same thing occurs during deep sleep rapid replay and for reasons we still don't understand during deep sleep the replay is in reverse order. The brain is a mysterious place. So in just these final couple of seconds I just want to remind you neural plasticity is a process. It's what makes your nervous system special. You can learn new things and unlearn new things across the lifespan. After about age 25 you need a state of alertness, focus and ideally some agitation. Maybe even spike adrenaline after a learning episode if that's your goal and then try and access deep sleep on a regular basis. Obviously sleep is the foundation of mental physical health and performance of all kinds. I think we're now all on board that finally after such a long time and in addition to that brief naps or these shallow naps even if you don't sleep or N. S. D. R. As it's called can be very beneficial if you are a napper who also has trouble with sleeping. There's a very simple rule that's been verified by the sleep expert Matt walker, my friend and colleague at the university of California Berkeley, which is if naps prevent you from sleeping well and deeply at night, then don't nap otherwise you're good to nap, neural plasticity is accessible to us all. I hope some of this information has been useful despite the short period of time. Thanks so much. Who cares?