Dr. Andrew Huberman hosts Dr. Casey Halpern, Chief of Stereotactic and Functional Neurosurgery at Penn Medicine and a specialist in deep brain stimulation surgery. Dr. Halpern focuses exclusively on implanting electrodes to deliver electrical stimulation for conditions like Parkinson's disease, OCD, and eating disorders.

The conversation explores how neurosurgeons can stimulate specific brain regions to immediately stop tremors, reduce compulsions, and interrupt pathological reward-seeking behaviors. Dr. Halpern discusses the challenges of treating severe psychiatric conditions that resist standard therapies, requiring surgical intervention with carefully placed electrodes in areas like the nucleus accumbens.

The discussion covers both invasive techniques like deep brain stimulation and emerging non-invasive approaches including transcranial focused ultrasound, which can ablate brain tissue without incisions. Dr. Halpern explains how his research aims to identify 'craving cells' and develop more precise targets for treating the 30% of patients who don't respond to conventional treatments.

Deep Brain Stimulation: Precision Surgery for Movement Disorders

Deep brain stimulation involves implanting a thin, insulated wire deep into specific brain regions, with the therapy being electrical stimulation delivered through multiple contacts at the wire's tip.

"I have to implant a tool to deliver you a medication, but that medication is going to be in the form of electricity" - Casey

Surgeons can hear tremor cells during electrode placement by converting electrical signals to audible frequencies that match the patient's hand tremor rhythm.

Stimulating the subthalamic nucleus provides immediate tremor relief for patients with 20-year tremor histories, demonstrating the precision of targeted brain intervention.

OCD Treatment: When Standard Therapies Fail

SSRIs and tricyclics targeting the serotonin system are first-line treatments for OCD, along with exposure response prevention therapy developed by researchers like Edna Foa at Penn.

Approximately 30% of OCD patients continue suffering despite medication and cognitive behavioral therapy, requiring surgical intervention with deep brain stimulation or capsulotomy ablations.

Current surgical approaches achieve only 50% responder rates, and even responders still have symptomatic OCD, highlighting the need for more precise targeting.

"You can actually destroy small parts of the brain... three or four millimeters in size. These little ablations can be really helpful for patients, but have no obvious side effects" - Casey

Nucleus Accumbens: The Brain's Compulsion Gateway

The nucleus accumbens, part of the ventral striatum, normally gates reward-seeking behavior but when perturbed causes compulsive behavior despite punishment or risk.

"When it's perturbed, it seems to gate compulsive behavior, meaning a rat will pursue a reward despite punishment, despite a foot shock" - Casey

This 'urge despite risk' pattern connects OCD, eating disorders, and addiction - patients will check locks until 3 AM, binge eat, or drug seek despite obvious dangers.

Researchers target this region because it represents a common circuit underlying compulsive behaviors across multiple psychiatric conditions affecting millions of Americans.

Identifying Craving Cells During Live Surgery

Surgeons can identify 'craving cells' in patients with eating disorders using the same techniques used to find tremor cells in Parkinson's patients.

Researchers use mood provocation techniques in laboratory settings, with psychiatrists inducing feelings that trigger binge episodes while recording brain activity.

"Even under video surveillance through a one-way mirror in a laboratory setting, when patients are very well aware that they're there to be studied if they're going to binge, still do" - Casey

Patients wear eye trackers to monitor exactly what they're eating and looking at, providing precise temporal resolution for understanding pre-binge brain signals.

Non-Invasive Brain Stimulation: The Future of Treatment

Transcranial magnetic stimulation (TMS) is FDA-approved for depression, OCD, and nicotine addiction, though spatial precision remains limited compared to invasive approaches.

Transcranial focused ultrasound is FDA-approved for tremor treatment and delivers brain ablations non-invasively without any incisions, achieving similar results to electrode placement.

"It's often kind of a miracle because there's no incision. I don't have to place an electrode into the brain to achieve a similar result" - Casey

Future ultrasound applications may include opening the blood-brain barrier for targeted medication delivery and modulatory stimulation rather than just ablation.

Machine Learning and Predictive Intervention

University of Washington researchers use voice pattern analysis and physiological monitoring to predict suicidal episodes before patients are consciously aware of them.

Machine learning algorithms may detect impulsive episodes by analyzing breathing patterns, sleep quality, and other physiological cues integrated over time.

"We have to get in the brain before we get out of it. And if we get in the brain and understand what these signals look like, we'll know what those non-invasive signals are" - Casey

Scalable solutions are essential since only 200,000 deep brain stimulation surgeries have ever been performed while 50 million Americans need treatment for related conditions.