Your Brain on Autopilot: How UCLA Is Using Electric Zaps to Reset OCD's Broken Habit Machine

By The Biomedical Observer

Ever walked into a room and completely forgotten why you went there? Now imagine that feeling, but instead of forgetting, your brain gets stuck in an endless loop of checking whether you locked the door. Welcome to the neurological traffic jam that is obsessive-compulsive disorder. A UCLA study (NCT04075890) is trying to untangle the brain circuitry behind this phenomenon - and they're using electricity to do it.

The Two Ways Your Brain Makes Decisions (And Why OCD Breaks One of Them)

Here's a fun neuroscience fact that explains a lot about human behavior: your brain has two competing systems for deciding what to do. There's the goal-directed system, which carefully evaluates options and chooses actions based on expected outcomes. Then there's the habitual system, which just does stuff because you've done it before.

When you first learned to drive, every action required conscious thought. Check mirror. Signal. Check blindspot. Turn wheel. That was goal-directed behavior - deliberate, effortful, flexible. Now? You probably arrive at work with zero memory of the actual driving because your habitual system took over. Same actions, no conscious thought required.

Both systems are useful. Goal-directed behavior helps you adapt to new situations. Habitual behavior frees up mental bandwidth for other things. In a healthy brain, there's an "arbitration mechanism" that balances these two systems, deploying each one when appropriate.

In OCD, this arbitration mechanism appears to be broken. The result? The habitual system runs wild while the goal-directed system can't get a word in edgewise.

The OCD Paradox: When Habits Attack

Here's the weird thing about compulsions in OCD: people KNOW their behaviors don't make sense. The person washing their hands for the 47th time today KNOWS their hands aren't contaminated. The person checking the stove KNOWS it's off. The goal-directed part of their brain has evaluated the situation and reached a clear conclusion: this behavior is unnecessary.

But the habitual system doesn't care about conclusions. It just keeps firing the same motor patterns, over and over, because that's what it does. Research has shown that people with OCD have an over-reliance on habitual behavior at the expense of goal-directed control. Their brains default to doing rather than evaluating.

Dr. Reza Tadayon-Nejad and his team at UCLA are investigating exactly how this imbalance works at the neural circuit level - and whether they can fix it by zapping the brain with electricity. And yes, that's exactly as sci-fi as it sounds.

The Study: fMRI, Decision Tasks, and Brain Stimulation

NCT04075890 is recruiting 30 adults with OCD and 30 matched healthy controls for a sophisticated study that combines computational cognitive neuroscience, brain imaging, and non-invasive neurostimulation. Here's how it works:

Session 1: Baseline clinical assessment and structural MRI scan. This gives researchers a map of each participant's brain anatomy.

Sessions 2 and 3: This is where things get interesting. Participants complete two different tasks:

1. A decision-making task designed to separate goal-directed from habitual behavior
2. A symptom provocation-avoidance task that triggers OCD symptoms in a controlled way

Here's the twist: these tasks are done under two different conditions. Sometimes participants do them inside an MRI scanner (so researchers can watch their brain activity in real time). Other times, they do them while receiving transcranial direct current stimulation (tDCS) - a mild electrical current applied to the scalp that can increase or decrease activity in specific brain regions.

By comparing brain activity during tasks, and comparing performance with and without brain stimulation, researchers can start to understand which circuits are malfunctioning in OCD and whether tweaking those circuits changes behavior.

Transcranial Direct Current Stimulation: What It Is and Why It Matters

tDCS sounds intimidating, but it's actually remarkably simple. You attach two electrodes to someone's scalp and run a weak electrical current (1-2 milliamps - less than a AA battery) between them. The current passes through the skull and slightly changes how excitable the neurons underneath become.

Under the positive electrode (anode), neurons become more easily activated. Under the negative electrode (cathode), they become less easily activated. It's like adjusting the sensitivity on a thermostat - you're not directly controlling the temperature, but you're changing how readily the system responds.

The UCLA study is using "neuronavigated" tDCS, meaning they use each participant's MRI scan to precisely target the stimulation. They're focusing on frontal brain regions involved in the arbitration between goal-directed and habitual behavior - specifically areas that might be able to put the brakes on runaway habitual responding.

What We Already Know About tDCS and OCD

Meta-analyses of tDCS for OCD have shown mixed but promising results. One analysis found that active tDCS significantly reduced OCD symptoms compared to sham (fake) stimulation, with effects persisting for at least a month. Another study found that patients who received tDCS before exposure and response prevention (ERP) therapy showed faster "safety learning" - their brains more quickly learned that feared outcomes weren't actually occurring.

The mechanism might involve modulating activity in the default mode network and the medial prefrontal cortex - brain systems involved in self-referential thinking and emotional regulation. If tDCS can temporarily restore better communication in these networks, it might give the goal-directed system more influence over behavior.

But here's the honest truth: not all studies have shown benefits, and some meta-analyses have found null or even negative results. That's why studies like NCT04075890 are so valuable - they're trying to understand not just whether tDCS works, but why and how, which could lead to better-targeted treatments.

The Computational Modeling Angle

What sets this study apart is the integration of computational cognitive neuroscience. Researchers aren't just measuring symptoms or looking at brain blobs lighting up on scans. They're using mathematical models of decision-making to quantify exactly how much each participant relies on goal-directed versus habitual strategies.

These models come from reinforcement learning theory and can calculate things like "model-based" behavior (where you simulate possible outcomes before acting) versus "model-free" behavior (where you just repeat whatever worked before). By fitting these models to participants' choices during the decision task, researchers can get precise measures of how OCD affects the balance between these two systems.

Then they can ask: does tDCS shift this balance? Does it make people with OCD more goal-directed and less habitually driven? Does this shift correlate with symptom improvement?

Why This Matters Beyond Academic Curiosity

Over 40% of people with OCD don't respond adequately to existing treatments - neither SSRIs nor cognitive-behavioral therapy fully resolves their symptoms. That's a lot of people suffering without good options.

If we can understand exactly which brain circuits malfunction in OCD and how to modulate them, we open up entirely new treatment approaches. tDCS is non-invasive, portable, and relatively inexpensive. It could potentially be used to:

• Enhance the effectiveness of existing therapies
• Provide relief for treatment-resistant patients
• Offer a maintenance treatment that patients could eventually use at home

The arbitration mechanism framework also provides a new way to think about compulsive behavior that applies beyond OCD. Addiction, eating disorders, and certain aspects of autism all involve imbalances between goal-directed and habitual control. Understanding how to restore this balance could have broad implications.

The Bottom Line

NCT04075890 is a well-designed study asking fundamental questions about why OCD brains get stuck in compulsive loops. By combining brain imaging, computational modeling, and targeted neurostimulation, the UCLA team is building toward a mechanistic understanding that could transform treatment.

The brain's habit system is supposed to make life easier - letting you tie your shoes without thinking about every step. In OCD, that same system becomes a tyrant, forcing repetitive behaviors even when the conscious mind objects. Learning to reset this balance, to restore the arbitration mechanism that keeps habits in check, might be the key to helping millions of people reclaim control over their own actions.

And if the solution involves a little electricity? Well, our brains are electrical organs anyway. Sometimes they just need a nudge in the right direction.

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References:

1. ClinicalTrials.gov Identifier: NCT04075890 - Arbitration Between Habitual and Goal-directed Behavior in Obsessive-compulsive Disorder: Circuit Dynamics and Effects of Noninvasive Neurostimulation

2. Gillan CM, et al. Disruption in the Balance Between Goal-Directed Behavior and Habit Learning in Obsessive-Compulsive Disorder. Am J Psychiatry. 2011;168(7):718-726. DOI: 10.1176/appi.ajp.2011.10071062

   

3. Transcranial direct current stimulation targeting the medial prefrontal cortex modulates functional connectivity and enhances safety learning in OCD. Mol Psychiatry. 2022. DOI: 10.1038/s41380-021-01371-2

4. Berlim MT, et al. Transcranial Direct Current Stimulation for Obsessive-Compulsive Disorder: A Systematic Review. J ECT. 2018;34(3):157-165. DOI: 10.1097/YCT.0000000000000465

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Disclaimer: This blog post is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider regarding any medical conditions or treatments. Clinical trial results may not reflect individual outcomes. Images and graphics are for illustrative purposes only and do not depict actual medical devices, procedures, mechanisms, or research findings from the referenced studies.