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

Welcome to Huberman Lab Essentials, where we pull the most actionable science for mental and physical performance. I’m Andrew Huberman, and today we revisit my conversation with neurosurgeon Dr. Casey Halpern, the space explorer of the brain, to clarify what neurosurgeons do and how they think about the circuits that drive mood, movement, and behavior.

To set the table, what does a neurosurgeon actually do, and how do you conceptualize the brain when you operate?

Neurosurgery covers the whole nervous system, from brain tumors and aneurysms to spine and peripheral nerves, but many of us subspecialize. I lead stereotactic and functional neurosurgery, where we use deep brain stimulation to deliver tiny pulses of electricity to precise targets and, when appropriate, MRI‑guided focused ultrasound to make a small, incision‑free lesion; both can quickly relieve symptoms like tremor, and their moment‑to‑moment effects reveal which circuits govern movement, mood, and motivation.

Let’s focus on obsessive‑compulsive disorder. What defines it, which circuits are involved, and how do you treat it—and how is that different from someone who’s just very meticulous?

Traits like carefulness can help in surgery or business, but OCD becomes a disorder when intrusive thoughts and rituals feel uncontrollable and harmful. I study the circuits behind those urges with invasive recordings, imaging, and genetics, because the most severe patients I treat have already tried medications—typically serotonin‑targeting agents like SSRIs or tricyclics—and exposure‑based therapy; surgery is reserved for those who remain highly impaired. We can modulate circuits with deep brain stimulation or, in select cases, create a tiny lesion with a capsulotomy, and while about half of patients improve, many still have symptoms, so we’re pushing toward more symptom‑specific targeting.

Which brain areas stand out in OCD and related compulsive states?

We often see overactive prefrontal and orbitofrontal regions talking to the basal ganglia, especially the ventral striatum and the nucleus accumbens, a hub for evaluating rewards and gating actions. When that system is hijacked, people pursue the urge despite the risk—checking all night, repeated washing, binge‑purge cycles, or drug seeking—so we aim to normalize that loop.

And what role does the nucleus accumbens play in healthy motivation versus pathology?

Desire for reward is normal; the problem is when the drive persists even as consequences mount. Repeated exposure to powerful rewards can rewire the accumbens, so in the operating room we adapted techniques from Parkinson’s surgery—where we listen for tremor‑linked cells—to probe for neural patterns tied to obsession or craving; we use “craving” because patients relate to it, and we can sometimes map and modulate those signals during awake procedures.

How far can we go without surgery—using tools like transcranial magnetic stimulation or focused ultrasound?

We should embrace noninvasive tools, even as we refine their precision. TMS is cleared for depression, OCD, and nicotine addiction and can help define circuits that might later justify an implant; eating disorders are underexplored here. MRI‑guided focused ultrasound already treats tremor on one side with no incision, and researchers are testing it for modulation and for opening the blood‑brain barrier, but psychiatry needs clearer targets first. Stereoencephalography—thin electrodes placed safely across the brain—has transformed epilepsy care and now guides circuit‑based trials in depression; with enough cases, converging data could point to new ultrasound targets. For obesity and binge eating, preclinical work in mice gave us a human target to test, but many mood disorders still require mapping directly in people.

It seems like catching yourself just before a binge or drug use could change the outcome. Can building that awareness help?

Awareness helps many people, but the most refractory patients still lose control even under lab observation. We recreate the emotional context that precedes a binge, record brain activity with implanted devices, synchronize it with video and eye‑tracking, and often see reliable signals before the bite; therapy like exposure‑response prevention can be powerful, but benefits may fade without continued practice, so our goal is to restore control in those who remain stuck.

Could machine learning flag risk states before someone feels them, the way some systems predict depressive spirals from voice or sleep patterns?

Yes, but we need to learn the brain’s ground‑truth signals first, then link them to noninvasive markers. We focus on impulsivity and compulsion because they drive crises from overdose to suicide, and while surgery can only reach a tiny fraction of those in need, rigorous, data‑driven tools—rather than flashy but empty wearables—could scale real help; we use machine learning in the lab now and are just beginning to see what’s possible.

Thank you for sharing your tools and vision; I suspect you just inspired future neurosurgeons. I’m grateful for your time and for pushing the front edge of how the brain works and how we can repair it.