Essentials: Compulsive Behaviors & Deep Brain Stimulation | Dr. Casey Halpern

**Andrew Huberman** (0:00)
Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health and performance.
I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. And now for my discussion with Dr. Casey Halpern. Casey, I should say Dr. Halpern, welcome.

**Casey Halpern** (0:23)
Thank you, great to be here.

**Andrew Huberman** (0:24)
You're a neurosurgeon, which I consider the astronauts of neuroscience. For those that aren't familiar with the differences between neurosurgery, neurology, psychiatry, you just educate us a bit. What does a neurosurgeon do and what do you think about and conceptualize the brain?

**Casey Halpern** (0:40)
The scope of neurosurgery is quite broad. We take out brain tumors, we clip aneurysms in the brain, we take care of patients that have had traumatic brain injury, concussion, spine surgeries. Ninety percent of what neurosurgeons do around the country, taking care of herniated disks and lumbar fusions. So the scope is the entire central nervous system, including the peripheral nervous system. We take care of patients with carpal tunnel syndrome and nerve disorders. Historically, neurosurgeons did everything in that domain, but now we subspecialize and I'm lucky to be at Penn Medicine where we can focus on one of these areas. So I'm chief of stereotactic functional neurosurgery.
All I do is deep brain stimulation surgery, and a complement to that is focus ultrasound or transcranial focus ultrasound, which is a non-invasive way to do an ablation in the brain, recently FDA approved, and it's FDA approved for tremor at the moment. Deep brain stimulation is a procedure where we have to place a very thin wire that's insulated deep into a part of the brain that's involved in Parkinson's disease, for example.
But that's actually not the therapy. The therapy is delivering electrical stimulation through the tip of that wire, or one of the tips, as there actually are multiple contacts at the bottom of the wire. They're very small. It's a bit more like I have to implant a tool to deliver you a medication. But that medication is going to be in the form of electricity, and it's going to be delivered into a very small region of the brain. I'm very privileged to be able to interact with the human brain in this way. It's always in the, with the goal of trying to provide somebody with a meaningful therapy. But when we deliver electrical stimulation, these electrodes, while they might be sitting in a very small region of the brain, there are regions within a few millimeters of where these electrodes are that if stimulated could cause a temporary, very brief side effect, a moment of laughter, like you said, or a moment of panic. And of course we can just shut that electrode off. But often these side effects could be therapeutic. And actually that's how we have discovered ways to use deep brain stimulation, not just for movement disorders like Parkinson's disease, but for example, patients with Parkinson's disease that have a psychiatric comorbidity like depression or obsessive compulsive disorder. A lot of these patients are highly compulsive and impulsive.
Sometimes these problems actually melt away. And we're trying to help their tremor, but the patients also tell us that their gambling issue has gotten better or their mood has improved. And why is that? Well, you know, there's probably more than one reason. You know, you can help somebody's mood by making their tremor go away, of course. But we see laughter in the clinic sometimes. And why is that? And that's because we're stimulating parts of the brain that are not just involved in these motor circuits, but they're also involved in what we call a limbic circuit or part of the brain involved in emotion. And if we learn how to modulate those areas therapeutically, step by step, we can actually develop these therapies for other indications like depression. I would say the most impressive and consistent effect we have, and we have a patient with tremor who has been tremoring for the past 20 years, if we can deliver stimulation through that electrode in the clinic, we have immediate relief of tremor. And that is the effect that inspired me to be a neurosurgeon when I was in college. I've never really wanted to do anything else, except help develop that type of therapeutic for another kind of symptom.

**Andrew Huberman** (4:19)
I'd love to learn more from you about OCD. Could you perhaps just tell us what is OCD? Sure.
What are some brain areas involved? What are the current range of treatments? And what's the difference between someone who is obsessive and somebody who has true OCD?