Enhance Your Learning Speed & Health Using Neuroscience Based Protocols | Dr. Poppy Crum

Andrew Huberman opens by posing a dichotomy: either the brain is far more plastic than most people believe and we simply have not accessed the ways to change it, or it is fairly fixed and progress as a species would require creating robots to do the work our brains cannot. His guest, Dr. Poppy Crum, is introduced as a neuroscientist, a professor at Stanford and the former chief scientist at Dolby Laboratories whose work focuses on how technology can accelerate neuroplasticity and learning.

I do think we're much more plastic than we talk about or we realize in our daily lives.

Crum's answer dissolves the robot alternative rather than choosing a side: the more we create robots, the more neuroplasticity comes with using them as humans in partnerships or as tools to accelerate our capabilities. She describes neuroplasticity less as a fixed quantity than as continuous shaping by everything we engage with, whether the statistics of our environments and context or the technologies we use daily, with attentive engagement mattering more than passive consumption, and with dependence on attention increasing as we age.

The claim that follows is deliberately normative: in the age of AI and immersive technologies, she says, everyone needs to think more about how the technologies they are using are shaping or architecting our brains as we move forward.

Crum takes the homunculus from any neuroscience 101 medical school textbook as her central exhibit. It is a data representation of how many cells in the brain are coding and representing information for the sense of touch, drawn as a distorted human with bigger lips and smaller parts of the back. The image comes from Wilder Penfield in the 1940s, who recorded the somatosensory cells of patients just before surgery for epilepsy; because we have no pain receptors in the cortex, an awake human could be touched on different parts of the brain and asked to report what sensation they felt on their bodies.

What's wrong with this image?

The puzzle she sets is that this is an image from 1940 that is still in every textbook. Any Stanford student, she says, will immediately answer that the thumb should be bigger because we use our fingers typing on a mobile device all day, or that the ankles are the same size even though we drive cars far more than people did in the 1940s, or that which side of the road you drive on depends on what part of the world you live in.

- The thumb should be bigger, because we spend the day typing on a mobile device and have more sensitivity in our fingers. - The ankles are the same size, even though we drive cars now a lot more than we did in the 1940s. - Depending on where you live you drive on one side versus the other, and in a few years we probably will not be driving at all.

And in a few years, we probably won't be driving, and those resources get optimized elsewhere.

The homunculus is therefore a representation of how the brain has allocated its limited cells to help us be successful in our world. Expertise adds resources but also specificity: Crum, a violinist, describes many more cells devoted to her left hand and right hemisphere somatosensory cortex for feeling with her fingertips, giving more sensitivity and more differentiated data, and says that practising as a musician versus playing video games both influence the brain and its plasticity.

when you develop expertise, you develop more support, more resources go to helping you do that thing, but they also get more specific.

Huberman later compresses the argument into the observation that our brains are customized to our experience, especially childhood experience but also adult experience.

Crum extends the same logic to hearing with a striking claim about being able to predict where someone lives from their hearing thresholds.

I think you can look at people's hearing thresholds and predict what city they live in.

Her explanation is that cities have sonic imprints: the types of vehicles, density, people and even construction change what noise exists and shape people's hearing thresholds, and at the lowest level shape their sensitivities, so that being used to hearing certain animals in an environment produces increased sensitivity to them. She mentions a neighbour who keeps chickens in the city, and Huberman recalls growing up near a rooster whose sounds are embedded deeply in his mind.

The mechanism she outlines has both a semantic context and a spectrum of different frequency amplitudes and their intensity, affecting the neural system from what the ear, brain and cochlea are exposed to up to amplification from higher-level areas that signal which frequencies are more important in a given context and environment.

The discussion of her absolute pitch is grounded in a film she consulted on, The Sound of Silence, with Peter Sarsgaard, whose makers talked to her because she has absolute pitch; the main character tunes people's lives by diagnosing a tritone from a water heater and a teapot.

Asked to define perfect pitch and whether it means always hitting a note with the voice, Crum rejects the term outright.

There is no such thing as perfect pitch. There's absolute pitch.

The reason is historical and physiological rather than truly absolute. A equal 440 hertz is a standard we use in modern time, whereas in the Baroque era A was 415 hertz, and what A is has changed throughout our lives with aesthetics and with the tools used to create music. Even the singer is not a stable reference: as the basilar membrane gets more rigid with age or temporal processing slows down, the brain still thinks it is singing 440 hertz.

my brain's going to still think I'm singing 440 hertz, but it might not be

A small disagreement about mechanism surfaces when Huberman defines the basilar membrane as the portion of the internal ear that converts sound waves into electrical signals and Crum answers with the qualifier mechanically, noting that it moves the hair cells; Huberman concedes he is talking to an auditory physiologist and says he teaches auditory physiology himself.

Huberman builds a detailed phenomenology of texting: writing with thumbs, hearing his own voice in his head, internalizing the voice of the person writing to him, the emotionally charged dot dot dot, and a conversation that happens almost entirely inside one's own head yet involves two or more players. He contrasts this with the slowed process of letters and email and asks whether, prior to about 2010, the brain was simply not involved in conversation in this way.

is it possible that we've now allocated an entire region of the homunculus, or of some other region of cortex brain to conversation that prior to 2010 or so, the brain just was not involved in conversations of any sort?

He pushes the dichotomy further: are we taking old brain areas and combining them in new ways, or fundamentally changing how the brain works to carry out something as now-trivial as texting? He recalls how quickly the technology moved from slow and clunky to autofill, to learning the user, to voice recognition that people picked up very fast.

Crum's answer is a clear negative on new neural hardware.

We aren't developing new resources.

She concedes neurogenesis but locates the change in how the same cells are getting allocated. The homunculus is one cortical map, and maps matter because cells that need to interact sit at shorter distance, giving specificity, speed and tight reaction times; maps retain a lot of motility and cross-input, and there are maps all over the brain. On her account, texting changes the specificity of cells that now interpret a text message, producing faster reaction times, faster interpretations, more repeatability, faster pattern matching and more integration, analogous to integrating sight, sound and smell into a holistic object experience.

A generational difference is offered as evidence rather than prescription. After a talk at Santa Clara University, a student in his early twenties told Huberman that he had adopted the technology after his brain had developed, and that when his phone runs out of charge he feels the life drain out of his body until it comes back on and he can communicate with his friends again.

When my phone runs out of charge, I feel the life drain out of my body

Huberman took this to mean the student's brain is fundamentally different from his own in social context, communication and feelings of safety. He adds that on trips up the coast to Big Sur, intentionally away from the phone, it takes about an hour or two or maybe even a half day to really drop into the local environment without looking for stimulation coming through the smartphone.

When Huberman asks whether technology is good, bad, neutral or something she is agnostic about in how it shapes the brain, Crum declines the taxonomy.

It goes in lots of different directions.

The substantive model comes from audio. Our ability to carry a lifetime of music and content with us rests on advances over the last 25 or 30 years in compression algorithms, perceptual compression, lossy perceptual algorithms, MP3 and her past work with companies like Dolby. The goal of content compression, she says, is to translate the entirety of the experience, the entirety of a signal with a lot of the information removed, but in intelligent ways.

She maps this onto the acronyms and shorthand used in texting, which she calls a rich communication and a lossy compression triggering a huge cognitive experience. Lossy means that in encoding and decoding there is information lost when you decode it, hopefully not affecting the perceptual experience: naively taking out every other 500 milliseconds of a song would sound horrible, whereas early models like MP3 are computational models of the brain that might stop at the auditory nerve and decide, through masking, that if two sounds are present at the same time one would not be heard and need not be coded. Perceptual here means what we get to take home.

there is actually information that's lost when you decode it

Crum says such acronyms have taken on a very rich life in internal life, that people can now have communication we cannot understand entirely, and that this lossy compression has a much richer perceptual experience but often needs context, using few bits of information to represent a much richer feeling and state, with a bigger physiological experience depending on how someone grew up with that context. She mentions a 10-year-old daughter whose acronym communication can be cryptic to her.

it often needs context

A genuine disagreement about evaluation runs through the exchange. Huberman reads her as seeing the great opportunity of data compression and characterizes the position as generally neutral to benevolent, even good; Crum's correction is flat.

It's just different.

Huberman states the takeaway that the richness of an experience can be maintained even when some elements of the exchange are completely removed, and Crum locates the mechanism in the neural connections built in those individuals and that generation. The cost side is a see-saw: quick communication raises expectations about frequency of contact but reduces expectations of depth, so that a message saying you were thinking of someone this morning can feel like a lot, whereas a letter saying the same would seem thin.

A limit of compression is drawn from Crum's own family history. Her daughter is at a camp where for two weeks only handwritten letters are allowed, and Crum describes saving 1865 Civil War courtship letters on parchment from a flood; the ink did not run, and she says that very different era of communication does not translate without that history.

Crum declares herself a huge advocate for the integration of technology and frames her stance in a single phrase.

for me, the world is data

She breaks the organism into a trifecta: sensory systems as they have evolved, including intrinsic noise degrading sensory receptors so that in a very noisy environment her brain has about the same access to information as someone with hearing loss; experientially established priors; and expectations, the context that has shaped where we are. The brain is framed as a Bayesian model in which things are not always deterministic, with Huberman glossing deterministic as input A leads to output B and Bayesian as depending on the statistics of what is happening externally and internally, a probabilistic model where A has a likelihood of driving B but also a probability of driving C, D or F.

things aren't always deterministic for us like they are for some creatures

Crum calls probabilistic inference a great indicator of success in an environment, whether a work environment or just walking down the street, and describes it as situational intelligence used to deal with data that does not simply tell us to go right or left.

The priors are illustrated by an anecdote: at two and a half, in the planetarium at the Smithsonian, her daughter saw the quintessential NASA image of the Earth, totally dark and silent, and yelled as loud as she possibly could, because her experientially established prior for that image came from the Universal logo.

Minions.

Crum treats the outburst as totally valid and as an honest part of being human: each of us has very different experiences of the same physical information, and this needs to be recognized.

driven by our exposures, and our priors, and our sensory systems

The limitation of her own advocacy is stated explicitly. She says we are sometimes penny-wise, pound-foolish with how we use technology, that the quick things that make us faster can also make us dumber and take away our cognitive capabilities, that people who use the technologies to write papers all the time may be compromised trying to do anything without that technology and in their learning of that information, and that this starts to produce bigger differentiations in cognitive capabilities by how a tool is used.

the quick things that make us faster can also make us dumber and take away our cognitive capabilities