Of breeds and brains
Many Minds
It's hard to say exactly when, but some tens of thousands of years ago, our best friends were born. I'm referring, of course, to dogs. This didn't happen overnight—it was a long process. And it not only changed how those canids behaved and what they looked like, it also changed their brains. As wolves gave way to proto-dogs, and proto-dogs gave way to dingoes and dalmatians and Dobermanns and all the rest, their brains have continued to change. What can we learn from this singular saga? What does it tell us about dogs, about domestication, and about brains? My guest today is . Erin is...
info_outline
Monsters and their makers
Many Minds
It seems we've always had monsters among us. We've long been enthralled by dragons and giants, by the likes of Frankenstein and Godzilla and Dracula, by witches and werewolves and countless others. They roam our maps and creation myths; they crop up in our dreams, in our children's books, in our political rhetoric. Where do these beings spring from? What do they do for us? How have they changed over time? And, ultimately, what do our monsters say about their makers? My guests today are and . Both are historians of science and authors of recent books on monsters: Natalie's book is . Surekha's...
info_outline
The age of social AI
Many Minds
AI therapists and caregivers. Digital tutors and advisors and friends. Artificial lovers. Griefbots trained to imitate dead loved ones. Welcome, to the bustling world of AI-powered chatbots. This was once the stuff of science fiction, but it's becoming just the stuff of everyday life. What will these systems do to our society, to our relationships, to our social skills and motivations? Are these bots destined to leave us hollowed out, socially stunted, screen-addicted, and wary of good-old-fashioned, in-the-flesh human interaction? Or could they actually be harnessed for good? My guest today...
info_outline
Brains of a feather
Many Minds
Birds do the darnedest things. They fly, of course. They sing. They hunt in pitch darkness. They hide their food and remember where they put it. They use tools and migrate over astonishingly vast distances—sometimes even sleeping while in flight. How do they do all this? What's going on in their brains that makes these and other remarkable behaviors possible? How did their evolutionary path mold them into the incredible creatures they are today? My guests today are and . Andrew is a comparative neuroscientist and Associate Professor at the University of Lethbridge in Canada. Georg is a...
info_outline
How nature restores the mind
Many Minds
One afternoon you decide to snub your responsibilities and go for a hike. You spend a few hours in the woods or the mountains. You study the bark of trees, you bathe in birdsong, you let your eyes roam along a distant ridgeline. And you come back feeling better, restored somehow—like you have more energy, more patience, more bandwidth. We've all, I'm guessing, had experiences like this. But what's behind these effects? Why would nature restore us? What's the evidence that it really does? And what is even being restored, actually? My guest today is . Marc is an Associate Professor in the...
info_outline
From the archive: Revisiting the dawn of human cognition
Many Minds
Hi friends! We're taking a much-needed summer pause—we'll have new episodes for you later in September. In the meanwhile, enjoy this pick from our archives! ------- [originally aired June 1, 2023] There's a common story about the human past that goes something like this. For a few hundred thousand years during the Stone Age we were kind of limping along as a species, in a bit of a cognitive rut, let’s say. But then, quite suddenly, around 30 or 40 thousand years ago in Europe, we really started to come into our own. All of a sudden we became masters of art and ornament, of symbolism and...
info_outline
From the archive: Of molecules and memories
Many Minds
Hi friends! We're taking a much-needed August pause—we'll have new episodes for you in September. In the meanwhile, enjoy this pick from our archives! _____ [originally aired February 8, 2024] Where do memories live in the brain? If you've ever taken a neuroscience class, you probably learned that they're stored in our synapses, in the connections between our neurons. The basic idea is that, whenever we have an experience, the neurons involved fire together in time, and the synaptic connections between them get stronger. In this way, our memories for those experiences become minutely etched...
info_outline
From the archive: Consider the spider
Many Minds
Hi friends! We're taking a much-needed August pause—we'll have new episodes for you in September. In the meanwhile, enjoy this pick from our archives! _____ [originally aired May 30, 2024] Maybe your idea of spiders is a bit like mine was. You probably know that they have eight legs, that some are hairy. Perhaps you imagine them spending most of their time sitting in their webs—those classic-looking ones, of course—waiting for snacks to arrive. Maybe you consider them vaguely menacing, or even dangerous. Now this is not all completely inaccurate—spiders do have eight legs, after...
info_outline
The shaman with a thousand faces
Many Minds
When you hear the word "shaman," I'm guessing a web of associations starts to form in your mind. Perhaps you imagine strange ceremonies and strong substances; maybe you think of an earlier time when magic and superstition reigned. But shamanism is not just some relic of the past, or a curio from exotic lands. It's part of our present, and it will almost certainly be part of our future. This is because the roots of shamanism lie within us all. My guest today is . Manvir is an Assistant Professor of Anthropology at the University of California, Davis and to The New Yorker. He's also the author...
info_outline
Varieties of childhood
Many Minds
Childhood is a special time, a strange time. Children are adored and catered to—they're given their own menus and bedrooms. They're considered delicate and precious, and so we cushion them from every imaginable risk. Kids are encouraged to play, of course—but very often it's under the watchful eye of anxious adults. This, anyway, is how childhood looks in much of the United States today. But is this the way childhood looks everywhere? Is this the way human childhoods have always been? My guests today are and . Dorsa is an Assistant Professor of Psychology & Neuroscience at Duke...
info_outlineHi friends!
We're taking a much-needed August pause—we'll have new episodes for you in September. In the meanwhile, enjoy this pick from our archives!
_____
[originally aired February 8, 2024]
Where do memories live in the brain? If you've ever taken a neuroscience class, you probably learned that they're stored in our synapses, in the connections between our neurons. The basic idea is that, whenever we have an experience, the neurons involved fire together in time, and the synaptic connections between them get stronger. In this way, our memories for those experiences become minutely etched into our brains. This is what might be called the synaptic view of memory—it's the story you'll find in textbooks, and it's often treated as settled fact. But some reject this account entirely. The real storehouses of memory, they argue, lie elsewhere.
My guest today is Dr. Sam Gershman. Sam is Professor of Psychology at Harvard University, and the director of the Computational Cognitive Neuroscience Lab there. In a recent paper, he marshals a wide-ranging critique of the synaptic view. He makes a compelling case that synapses can't be the whole story—that we also have to look inside the neurons themselves.
Here, Sam and I first discuss the synaptic view and the evidence that seems to support it. We then talk about some of the problems with this classic picture. We consider, for example, cases where memories survive the radical destruction of synapses; and, more provocatively, cases where memories are formed in single-celled organisms that lack synapses altogether. We talk about the dissenting view, long lurking in the margins, that intracellular molecules like RNA could be the real storage sites of memory. Finally, we talk about Sam's new account—a synthesis that posits a role for both synapses and molecules. Along the way we touch on planaria and paramecia; spike-timing dependent plasticity; the patient H.M.; metamorphosis, hibernation, and memory transfer; the pioneering work of Beatrice Gelber; unfairly maligned ideas; and much, much more.
Before we get to it, one important announcement: Applications are now open for the 2024 Diverse Intelligences Summer Institute (or DISI)! The event will be held in beautiful, seaside St Andrews, Scotland, from June 30 to July 20. If you like this show—if you like the conversations we have and the questions we ask—it's a safe bet that you'd like DISI. You can find more info at disi.org—that's disi.org. Review of applications will begin on Mar 1, so don't delay.
Alright friends, on to my conversation about the biological basis of memory with Dr. Sam Gershman. Enjoy!
Notes and links
4:00 - A general audience article on planarian memory transfer experiments and the scientist who conducted them, James V. McConnell.
8:00 - For more on Dr. Gershman’s research and general approach, see his recent book and the publications on his lab website.
9:30 - A brief video explaining long-term potentiation. An overview of “Hebbian Learning.” The phrase “neurons that fire together wire together” was, contrary to widespread misattribution, coined by Dr. Carla Shatz here.
12:30 - The webpage of Dr. Jeremy Gunawardena, Associate Professor of Systems Biology at Harvard University. A recent paper from Dr. Gunawardena’s lab on the avoidance behaviors exhibited by the single-celled organism Stentor (which vindicates some disputed, century-old findings).
14:00 - A recent paper by C. R. Gallistel describing some of his views on the biological basis of memory.
19:00 - The term “engram” refers to the physical trace of a memory. See recent reviews about the so-called search for the engram here, here, and here.
20:00 - An article on the importance of H.M. in neuroscience.
28:00 - A review about the phenomenon of spike-timing dependent plasticity.
33:00 - An article, co-authored by former guest Dr. Michael Levin, on the evidence for memory persistence despite radical remodeling of brain structures. See our episode with Dr. Levin here.
35:00 - A study reporting the persistence of memories in decapitated planarians. A popular article about these findings.
36:30 - An article reviewing one chapter in the memory transfer history. Another article reviewing evidence for “vertical” memory transfer (between generations).
39:00 - For more recent demonstrations of memory transfer, see here and here.
40:00 - A paper by Dr. Gershman, Dr. Gunawardena, and colleagues reconsidering the evidence for learning in single cells and describing the contributions of Dr. Beatrice Gelber. A general audience article about Gelber following the publication of the paper by Dr. Gershman and colleagues.
45:00 – A recent article arguing for the need to understand computation in single-celled organisms to understand how computation evolved more generally.
46:30 – Another study of classical conditioning in paramecia, led by Dr. Todd Hennessey.
49:00 – For more on plant signaling, see our recent episode with Dr. Paco Calvo and Dr. Natalie Lawrence.
56:00 – A recent article on “serial reversal learning” and its neuroscientific basis.
1:07:00 – A 2010 paper demonstrating a role for methylation in memory.
Recommendations
The Behavior of the Lower Organisms, by Herbert Spencer Jennings
Memory and the Computational Brain, by C. R. Gallistel and Adam Philip King
Wetware, by Dennis Bray
Many Minds is a project of the Diverse Intelligences Summer Institute, which is made possible by a generous grant from the John Templeton Foundation to Indiana University. The show is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte and with creative support from DISI Directors Erica Cartmill and Jacob Foster. Our artwork is by Ben Oldroyd. Our transcripts are created by Sarah Dopierala.
Subscribe to Many Minds on Apple, Stitcher, Spotify, Pocket Casts, Google Play, or wherever you listen to podcasts. You can also now subscribe to the Many Minds newsletter here!
We welcome your comments, questions, and suggestions. Feel free to email us at: manymindspodcast@gmail.com.
For updates about the show, visit our website or follow us on Twitter (@ManyMindsPod) or Bluesky (@manymindspod.bsky.social).