El Jammal, R. | bioRxiv Science

bioRxiv2026

Conserved fiber topography of the anterior limb of the internal capsule in treatment-resistant psychiatric patients

IntroductionThe anterior limb of the internal capsule (ALIC) is a major white matter highway connecting prefrontal cortical (PFC) regions to the thalamus, brainstem, and subthalamic nucleus. Structural and functional abnormalities within the ALIC circuit have been associated with many neuropsychiatric disorders, including obsessive-compulsive disorder (OCD) and depression, and deep brain stimulation (DBS) may provide effective treatment to some of these patients. However, it remains unclear whether the well-characterized topographic organization of the ALIC observed in healthy individuals and preclinical models is preserved in treatment-resistant psychiatric populations. MethodsWe first used diffusion tractography to evaluate the topography of PFC and subcortical fibers through the ALIC in patients with treatment-resistant OCD (n=18) and depression (n=5). In depression patients, we also evaluated ALIC topography using cerebro-cerebral evoked potentials (CCEPs) elicited by single-pulse electrical stimulation (SPES) of DBS leads in the ALIC and recordings in the ventral PFC (vPFC). ResultsThe topographic organization of PFC and subcortical projections is preserved in the ALIC among treatment-resistant psychiatric patients, consistent with patterns observed in healthy individuals and preclinical models. CCEP recordings in the ventral PFC showed a ventral ALIC to medial vPFC/dorsal ALIC to lateral vPFC response pattern in the left hemisphere, but not in the right. ConclusionOur findings confirm that topographic patterns within the ALIC previously identified using preclinical models and healthy controls are preserved in treatment-resistant psychiatric patients. Furthermore, by linking white matter topography to stimulation effects, this work supports more precise and individualized neuromodulatory strategies for neuropsychiatric disorders.

neuroscience↗

bioRxiv2025

Ultraflexible, Biodegradable ECoG Arrays via Rapid Fabrication Enables High-Resolution Cortical Mapping and Seizure Network Classification In Vivo

Neural interfaces are essential tools for diagnosing and managing neurological disorders, yet conventional electrocorticography (ECoG) devices are limited by mechanical mismatch with brain tissue, chronic inflammation, and poor scalability. Here, we introduce a fully inkjet-printed, flexible, and biodegradable ECoG array fabricated on ultrathin polycaprolactone films with gold nanoparticle electrodes. The arrays achieve among the highest electrode densities reported for additive manufacturing (7.44 electrodes/mm{superscript 2}) while maintaining low impedance (10.6 k{Omega} at 1 kHz) and high-fidelity recordings (SNR 28 dB). A rapid, maskless prototyping process relying on photonic sintering enables scalable, cost-effective fabrication. In vivo, the devices conformally mapped cortical seizure propagation and resolved distinct ictal dynamics in a rat model. Histology at 30 days confirmed preserved neuronal density and astrocytic response comparable to controls, indicating minimal chronic inflammation. A convolutional neural network trained on recorded signals classified seizure stages with >95% accuracy, underscoring the translational potential for real-time monitoring and closed-loop neuromodulation. This platform unites rapid prototyping, biodegradability, and high performance, providing a scalable route toward next-generation, patient-specific, and disposable neural interfaces for epilepsy and other neuroengineering applications.

bioengineering↗