Dr. Charan Ranganath: How to Improve Memory & Focus Using Science Protocols

High-Level Overview

Andrew Huberman reconnects with an old colleague, Dr. Charan Ranganath, professor of psychology and neuroscience at UC Davis, one of the world's leading memory researchers and author of Why We Remember. Ranganath's starting point reframes the whole topic: memory isn't really about the past, it's about using the past to make sense of the present and predict the future. From there, the two explore how curiosity primes the brain to learn, what the hippocampus and prefrontal cortex actually do, why memory falters with age, the lifestyle factors that protect the brain, and how emotion, perspective and storytelling reshape memories over time.

The tone is lively, nerdy and personal. Ranganath talks openly about discovering as an adult that he has ADHD and the tools that help him, and the two bond over punk rock, dogs and a shared past in academia. The conversation flows from basic science to highly practical advice on phones, multitasking, photos and brain health, then into deja vu, trauma, psychedelics, rumination and nostalgia, ending with Ranganath's neuroscientist cover band, Pavlov's Dogz.

The Discussion Explores:

• Why memory serves the present and future, and how it shapes perception, orientation and our sense of self
• Curiosity as a driver of dopamine-related brain activity that boosts memory, even for unrelated information
• What the hippocampus and prefrontal cortex do, and why older adults struggle to remember what matters
• Lifestyle factors that dramatically reduce dementia risk, including sleep, exercise, diet, hearing, vision and oral health
• Ranganath's ADHD, the role of purpose and values, and the difference between attention and intention
• How phones, task switching and mindless photo-taking fragment memory, and how to use them better
• Deja vu, and how emotion, perspective, group sharing and psychedelic-induced plasticity can change memories
• Rumination, nostalgia and why memory is constantly being rewritten

Deep Dive into Main Ideas

Memory Is About the Present and the Future

Asked how much of our thinking is driven by the past, Ranganath flips the question: "I actually don't think memory is about the past. I think memory is about the present and the future". Memory lets us selectively pull what we need from the past to interpret what's happening now and predict what comes next. Walking back into a room you've seen before, your eyes go straight to the landmarks you expect, almost pre-consciously. The famous gorilla video, in which roughly 40% of viewers miss a person in a gorilla suit walking through a basketball game, shows that we perceive an internal model built from expectations rather than raw reality. Memory also lets us detect surprises and grab the most informative information.

Episodic memory, our memory for specific events, is also how we know where we are. Waking in a hotel room, you do a quick memory search to orient yourself, which is why people with memory disorders need familiar surroundings and why Huberman briefly didn't know where he was after waking from a nap in a dark room. People with amnesia still know who they are, but their sense of self gets stuck at the point of injury. Personality stabilizes in adolescence but keeps changing; on average people grow more optimistic with age, as Laura Carstensen's work shows.

Plasticity, Aging and Getting Stuck

Huberman suggests people get set in their ways because neuroplasticity declines with age. Ranganath says that's overstated: healthy older adults have "gobs" of plasticity, though dopamine activity does decline. People get stuck because of changes in the prefrontal cortex that reduce flexibility and because accumulated knowledge makes it harder to be surprised. The scientists who stay vital, he says, constantly challenge their beliefs, surround themselves with diverse people and stay open to prediction error, to being wrong.

Curiosity, Dopamine and Memory

Ranganath credits his former postdoc Matthias Gruber with a study he initially dismissed as a dumb topic. Participants in an fMRI scanner saw trivia questions, rated how curious they were, then waited several seconds for the answer. The more curious they were, the more activity appeared in dopamine-related areas of the midbrain and the nucleus accumbens, driven by the question itself rather than the answer. The clever part: during the wait, participants saw an unrelated face. When they were curious, they remembered those unrelated faces better. Ranganath is careful to note fMRI doesn't measure dopamine directly, and that assigning one function to one chemical is risky, but he believes dopamine promotes plasticity, and a theory called synaptic tagging explains how a dopamine burst can strengthen nearby memories.

So one answer to how to boost the dopamine system is to engage curiosity. Huberman quotes a line he attributes to Dorothy Parker: "The cure for boredom is curiosity. There is no cure for curiosity". Ranganath notes the curiosity effect on memory holds just as well in older adults and in kids. Novelty and surprise drive the same system, so exposing yourself to new people, places and situations, and to the possibility of being proven wrong, keeps plasticity engaged. Huberman adds that Esther Perel identified curiosity as a key to sustaining long relationships.

On dopamine more broadly, Ranganath sees it as energizing movement toward rewards and information. Kent Berridge's work on wanting versus liking shows dopamine-depleted animals will eat rewards placed in front of them but won't work for them. His Davis colleague Brian Wiltgen found dopamine activity from the locus coeruleus helps animals link a tone to a shock that came many seconds later. Huberman mentions a University of Copenhagen PET study showing increased striatal dopamine during yoga nidra, or non-sleep deep rest. For people whose curiosity gets channeled only into video games or scrolling, Ranganath says curiosity is "a process of cultivation, and it's a process of appraisal". A loud noise at night can be appraised as a gunshot or a great band nearby. Mindfulness helps by making the mundane interesting again, like noticing that each breath or each backyard sound is different.

The Hippocampus, the Prefrontal Cortex and Why Memory Fades With Age

Ranganath explains that the hippocampus links experiences to a specific context, a particular place and time, which supports episodic memory: remembering your trip to the Smithsonian rather than just knowing it's in Washington, D.C. The prefrontal cortex, about a third of the primate brain, provides cognitive control, directing perception, thought and action toward higher goals. Patients with prefrontal damage can hold numbers in mind until something distracts them, and on the Wisconsin Card Sorting Test one patient kept using an old rule even though he knew it wasn't working, because knowledge alone can't turn beliefs into action without the prefrontal cortex.

This matters for aging. Ranganath describes a study by Karen Campbell and Lynn Hasher in which older adults were worse than young adults at remembering what they were supposed to remember, but just as good at remembering what they were supposed to ignore. Their problem is controlling attention, not storing information. Ranganath describes neurons as competing coalitions, like a democracy, where shiny, salient things shout down what's important unless the prefrontal cortex biases the competition. When white matter connections degrade, often from tiny vascular events linked to hypertension and diabetes and visible on MRI as white matter hyperintensities, "the inane gets remembered at the expense of the important". People with these changes can perform as poorly as people with early Alzheimer's-related hippocampal atrophy. Depression is also "dangerous for memory it's terrible for memory", he says; he has seen depressed older adults more impaired than people with mild cognitive impairment, and depression appears to be a risk factor for Alzheimer's. Media multitasking, he adds, is bad for memory, especially for older adults, who are more distractible in what Herbert Simon called the attention economy.

Lifestyle Factors That Protect Memory

As a memory researcher, Ranganath admits the most important factors are simply good health habits. He describes a study of 29,000 people in China followed for 10 years: those with four to six healthy lifestyle factors (such as cognitive activity, social engagement, exercise, healthy diet, not smoking and limited alcohol) performed almost twice as well on memory tests as those with zero or one. He points to the Mediterranean-style diet and a Rush University study of a diet emphasizing leafy greens. On nicotine, he notes it may improve cognition in people with schizophrenia but stresses huge individual differences and inverted-U dose responses, citing his postdoc mentor Mark D'Esposito's work on dopaminergic drugs; he cautions against simple claims that any drug is good or bad, noting high-THC cannabis can raise psychosis risk in genetically vulnerable people.

Other protective factors: treating hearing loss (a Lancet report recommends screening and hearing aids for Alzheimer's prevention, and Ranganath got custom earplugs for his loud band), treating cataracts, and oral hygiene, since gum disease is linked to Alzheimer's risk. Neuroinflammation appears to deplete cognitive reserve; he cites long COVID's measurable cognitive effects, a rat study in which sugary water equal to about a can of soda a day caused hippocampal damage that transferred with gut bacteria, air pollution research by his Davis colleague Pam Lein, and diabetes. Current Alzheimer's drugs targeting amyloid have only modest effects, but lifestyle changes involving sleep, diet, exercise and social stimulation can reduce risk "by at least 40% if not more", reinforce each other and improve mood soon. Avoiding head injuries matters too.

ADHD, Purpose and Intention

Ranganath shares that after finishing his book, exhausted after a hard stretch that included his mother's hospitalization and his cat dying on his birthday, his daughter told him he clearly has ADHD. He recalled that as a child in the 1970s his school had said the same, though nothing was done. Now he manages it deliberately. He walks his energetic shelter dog every morning, which provides exercise, sunlight and a sense of purpose. He cites research linking purpose to cognitive reserve, and notes that retirees who lose their sense of purpose often drift into doomscrolling. Because he hates exercise he doesn't enjoy, he spent his book advance on a personal trainer.

An ADHD coach had him write and rank his values. He thought it was a waste of time until he realized he wasn't giving himself credit for why he did things. Now, when he doesn't feel like doing a task, he reminds himself which value it serves. As he puts it, "relating what I do to values is a game changer for me". This leads to a key distinction: attention can be grabbed by anything loud or shiny, while intention means directing attention based on an internal goal, which is exactly what the prefrontal cortex supports. Motivation, he stresses, isn't simply wanting to do the right thing; it's keeping those values in mind and retrieving them when needed.

Phones, Task Switching and Fragmented Memories

Ranganath explains that everyone forgets most of the details of life. Hermann Ebbinghaus found he had lost about half of what he memorized within 20 minutes and about two-thirds within 24 hours; he praises Huberman's advice to "assume that you will forget". The real question, and the title of his book, is why we remember, and the answer is intention.

Every time you check your phone mid-conversation, you pay switching costs: you're slower, several seconds behind, and straining cognitive control. Worse, memories get fragmented. The hippocampus shows activity peaks at event boundaries, when a scene or topic shifts, which is why walking through doorways can make you forget why you entered the kitchen. Switching between texts, email and conversation chops experience into fragments that compete with each other, a big part of forgetting. In his words, "it's the shifting that really kills you", so do one thing, then another. Simply thinking about checking your phone costs some control too. Huberman describes putting social media only on an old phone kept in a box, with a daily timer, which has greatly improved his focus. Ranganath calls this engineering your environment to regain control.

Mindless photo-taking also tends to impoverish memory, because you grab everything instead of noticing what's distinctive. But mindful photos help: capture meaningful moments, like friends laughing, and later use them as cues to actively recall the experience. He describes seeing the Descendents, whose drummer Bill Stevenson walked to the front of the stage to talk about finally appreciating his connection with the audience; Ranganath took one deliberate photo, which made him focus on the moment. Recalling a memory makes it more accessible but also more story-like and less immersive. Huberman wonders whether Polaroids, which require waiting, get kept and viewed more. Ranganath adds that the prefrontal cortex can regulate dopamine and noradrenaline systems from the top down, which may explain how strong goal focus sustains motivation.

Deja Vu

Ranganath's best explanation for deja vu starts with neurologist Hughlings Jackson's observation that some temporal lobe epilepsy patients feel intense deja vu before seizures, and Wilder Penfield's finding that stimulating the anterior temporal lobe could trigger it. The perirhinal cortex, near the hippocampus, generates a fast sense of familiarity, which is why you know instantly you've never eaten a rambutan, or why a face in the grocery store feels familiar before you can place it. Rebecca Burwell's rat experiments showed stimulating the perirhinal cortex at different frequencies could make familiar objects seem novel or novel ones seem familiar. Anne Cleary's virtual reality studies found people often experience deja vu in environments that share the exact spatial layout of places they've seen but look completely different. Deja vu likely arises when strong familiarity is triggered but a mismatch blocks the actual memory from coming up.

Emotion, Perspective and Changing Memories

Huberman describes how vagus nerve stimulation, SSRIs, psilocybin and MDMA-assisted therapy can transform how people feel about the same memories. Ranganath explains that neuromodulators like serotonin stabilize plasticity, and every time we retrieve a memory it can change. Emotional memories feel stored in the body because physiological responses are part of the memory and act as retrieval cues, and the narrative we build around an event shapes it too. Traumatic memories resist change because intense neuromodulator release during the event drives so much plasticity, and repeated retrieval can retraumatize. Sometimes a big prediction error or a window of plasticity is needed.

His UC Davis neighbor David Olson studies how psychedelics trigger neurotrophic factors like BDNF. Huberman stresses that "plasticity is an opportunity for learning it's not the actual learning", which is why integration and trained therapists matter. Ranganath adds that psychedelics also shift perspective, and research shows viewing the same memory from a different perspective changes what you remember and the story you tell. In animals, reconsolidation means retrieving a memory reopens it to change. He saw the power of shared memory as a young clinician running group therapy with Vietnam veterans: hearing others' reflections turned private trauma into a collective memory in a new context. On a lighter note, a near-death paddleboarding mishap with computational neuroscientist Randy O'Reilly became a funny story through retelling; "there's no point in having a bad experience in life if you don't get a great story out of that". Huberman cautions that retelling can also make memories worse, so trauma work should be done with trained professionals.

Rumination and Nostalgia

Rumination is so harmful in depression because recalling a negative memory brings a negative mood, which makes more negative memories easier to recall and strengthens them each time. Ranganath credits philosopher-neuroscientist Felipe De Brigard with the history of nostalgia, originally coined by a Swiss physician as a disease describing soldiers made miserable by longing for home. Research shows nostalgia can benefit mental health when it fuels gratitude, but becomes toxic if it turns into a sense that life used to be so great and now it is terrible. The past, like the present, holds good and bad; what matters is the narrative we build.

Punk Rock and Pavlov's Dogz

Ranganath plays guitar and sings in Pavlov's Dogz, a cover band of neuroscientists and psychologists who met at a memory meeting and play songs by the Ramones, the Clash, Gang of Four and Blondie at conferences. They cram rehearsals, the opposite of spaced learning, and he gets nervous when he sees friends in the crowd. At his last show he wore sunglasses, which let him get into the flow instead of overthinking. He connects this to research on choking under pressure: when you know something well, too much cognitive control can hurt, and it's better to let it run automatically.

Conclusion

Ranganath's big idea is that memory exists to guide the present and future, and that what we remember depends far more on intention, curiosity and context than on raw storage. Curiosity and novelty prime the brain to learn; the prefrontal cortex decides what matters; and aging, depression, inflammation and constant task switching erode that control. The practical takeaways are clear: stay curious and open to being wrong, connect daily tasks to your values, do one thing at a time, take fewer but more meaningful photos, and protect your brain with sleep, exercise, a whole-food diet, social connection and care for your hearing, vision and teeth, habits that together may cut dementia risk by 40% or more. And because memories are rewritten every time we recall them, the stories we tell about our past, and who we tell them with, can help us heal rather than ruminate.

This is a summary of "Dr. Charan Ranganath: How to Improve Memory & Focus Using Science Protocols" from Huberman Lab, giving you the GIST so you can decide if you want the REST. Listen to the full episode.