Obsessive-Compulsive Disorder Response Tract (ORT) [Neurosurgery Wiki]

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====== Obsessive-Compulsive Disorder Response Tract (ORT) ======

The Obsessive-Compulsive Disorder Response Tract (ORT) refers to a specific subset of white matter fibers identified through [[connectomic_analysis]] as being strongly associated with clinical improvement in patients undergoing [[deep_brain_stimulation]] (DBS) for [[treatment-resistant_obsessive-compulsive_disorder|treatment-resistant OCD]].

===== Origin and Concept =====
The ORT was defined retrospectively from aggregated stimulation data in multiple DBS cohorts, correlating fiber engagement with positive treatment outcomes. It represents a reproducible bundle of fibers modulated in successful responders, particularly across different DBS targets.

The tract connects subcortical regions to cortical areas such as the [[dorsomedial_prefrontal_cortex]] (dmPFC).

It traverses key limbic structures involved in affective regulation and cognitive control.

It overlaps anatomically with parts of the [[superolateral_medial_forebrain_bundle]] (slMFB), particularly its medial and ventral components.

===== Clinical Significance =====

The ORT serves as a predictive biomarker for therapeutic response to DBS in OCD.

It offers a network-based framework for targeting, moving beyond traditional nucleus-based stimulation.

Precise engagement of the ORT during DBS programming may enhance efficacy and reduce side effects.

===== Research Context =====
In the 2025 study by Coenen et al. (Mol Psychiatry), the ORT is:

Shown to be entirely embedded within the slMFB.

Identified as a "fiber selection" within a broader and more distributed connectomic target.

De-emphasized as a singular pathway, supporting the idea that different OCD sub-networks converge via slMFB and structures like the [[anteromedial_subthalamic_nucleus]].

===== Limitations =====

Definition is based on retrospective data; prospective validation and standardization across centers are needed.

May vary in structure and cortical projections depending on individual anatomy.