Stimulating Brains

Doris D. Wang is an associate professor of neurological surgery at the University of California, San Francisco, a functional neurosurgeon specializing in movement disorders, and a systems neuroscientist studying how human brain circuits generate and restore movement.
In this episode of Stimulating Brains, we focus on her new study in Nature Medicine. In five people with Parkinson’s disease, her team identified personalized brain signals associated with individual phases of walking and used them to adjust deep brain stimulation within fractions of a second. Three participants subsequently tested the fully implantable system at home in a blinded crossover study.
We discuss why gait and balance remain difficult to treat even when DBS successfully controls tremor, rigidity, and bradykinesia; how falls and freezing may reflect different circuit problems; why useful neural signals differ between people and hemispheres; and what it means to synchronize stimulation with the moment-by-moment rhythm of walking.
Doris also describes her path from developmental neuroscience to neurosurgery, the move from brief laboratory recordings to chronic brain sensing during everyday life, and the challenge of combining surgery, patient care, engineering, and human neurophysiology. We explore motor learning, focused ultrasound, patient agency, scientific collaboration, and whether future neuromodulation systems might do more than suppress pathological activity – perhaps restoring physiological dynamics at precisely the right moment.

Theodore H. Schwartz is a neurosurgeon, author, and the David and Ursel Barnes Endowed Professor of Minimally Invasive Neurosurgery at Weill Cornell Medical Center and New York-Presbyterian Hospital.
In this episode of Stimulating Brains, we talk about his book Gray Matters: A Biography of Brain Surgery, a vivid account of what brain surgery really is – personally, technically, historically, psychologically, and morally.
We discuss what it actually feels like to be a neurosurgeon: the preparation before a difficult case, the pressure of thousands of micro-decisions, the responsibility for movement, language, memory, and personhood, and the question of when to enter the brain further and when to stop.
We also talk about Ted's path from music and astrophysics toward neurosurgery, the culture of surgical training, trauma and gunshot wounds, the history of pioneers such as Cushing, Penfield, Dandy and others, as well as modern brain surgery, pituitary and skull-base surgery, awake mapping, aneurysms, epilepsy, psychosurgery and deep brain stimulation. We even wander toward consciousness, free will, brain-computer interfaces, and the future of less invasive and more computational neurosurgery.
At the center of these more philosophical questions lies a deceptively simple question: what can brain surgery teach us about the brain, the self, and the stories we use to understand who we are?

In this episode of Stimulating Brains, I am delighted to welcome back Michael Okun, neurologist, movement-disorders specialist, Adelaide Lackner Distinguished Professor of Neurology at the University of Florida, Director of the Norman Fixel Institute for Neurological Diseases, and National Medical Advisor of the Parkinson's Foundation.

Mike was previously on the podcast in episode 25 together with Kelly Foote. This time, we focus on his new book with Ray Dorsey, The Parkinson's Plan: A New Path to Prevention and Treatment.

The book argues that Parkinson's disease should not only be treated after diagnosis, but also understood as a public-health challenge that demands prevention, better care models, patient advocacy, and policy. We talk about the PLAN framework: Prevent the disease, Learn why it begins, Amplify the voices of people affected, and Navigate the frontiers of treatment.

We discuss environmental risk factors such as pesticides, solvents, dry-cleaning chemicals, air pollution, and paraquat; the idea that "prevention is not a pill, it is policy"; the Parkinson's 25 and the 0-10-100 by 2035 goal.

We also talk about what a real care plan should look like for people living with Parkinson's today, including movement-disorder care, rehabilitation, mental health, caregiver support, exercise, speech and swallow therapy, sensors, and access to multidisciplinary teams.

Since this is Stimulating Brains, we also return to deep brain stimulation and neuromodulation: where DBS fits into the broader Parkinson's Plan, what circuit-based therapies may still teach us, and how future treatments might connect prevention, biology, devices, genetics, and care.

Karl Friston is one of the most influential neuroscientists of our time and a central figure in the history of human brain mapping. Many listeners will know him for the free energy principle, active inference, dynamic causal modeling, voxel-based morphometry, and many other theoretical contributions.
In this episode, we take a different route and go back to the early history of Statistical Parametric Mapping, or SPM: the software and statistical framework that helped turn functional neuroimaging from a local craft into a shared scientific language.
We discuss how Karl moved from psychiatry into brain imaging, what the first PET activation experiments felt like, how SPM emerged at the MRC Cyclotron Unit and later the Functional Imaging Laboratory, how the software spread through the neuroimaging community, and how key collaborators helped shape modern PET, fMRI, VBM, DCM, EEG, and MEG analysis.
We also talk about mentorship, the culture of the FIL, open software, MNI space, spatial normalization, and what it means for a scientific tool to become infrastructure for an entire field.

In this episode of Stimulating Brains, I speak with Keith R. Mullett, who can uniquely tell a part of the DBS history that is often skipped.

We often begin the story of modern DBS in Grenoble around 1987, when Alim-Louis Benabid and colleagues showed that high-frequency VIM stimulation could suppress tremor. Keith reminds us that Medtronic's first DBS system had already been implanted in 1969, not for tremor or Parkinson's disease, but for severe chronic pain. Keith joined Medtronic in May 1972 and spent 37 years there, first in Minneapolis and later at the Bakken Research Center in Maastricht, where he arrived shortly after Frans Gielen.

The conversation goes back before the Benabid era, into the period when Medtronic and its physician collaborators built the devices, surgical know-how, clinical relationships, and regulatory experience that later made DBS for movement disorders possible. We discuss Yoshio Hosobuchi and the first pain implants, RF systems with belt-worn transmitters, the transition from cardiac pacing to neurostimulation, the FDA call for data, ITREL, the Bakken Research Center, and the 1992 tremor study: the moment Keith describes as "the rest is history."

This episode also connects to our recent conversations with Todd Langevin (episode 46) and Frans Gielen (episode 75). Todd described the internal venturing and business side of DBS after Benabid, while Frans described the engineering, clinical studies, training, imaging, and new indications that followed. Keith, who was Frans' boss, helps us ask what had to exist inside Medtronic before those later teams could build the modern field.