Automated sleep classification with chronic neural implants in freely behaving canines

Large Animal Epilepsy Model Platform: Kainic Acid Porcine Model of Mesial Temporal Lobe Epilepsy

Objective

Translational animal models are essential for advancing neuromodulation therapies for drug-resistant epilepsy. Large animal epilepsy models that accommodate implantable neuromodulation devices designed for humans are needed to advance electrical brain stimulation and sensing applicaitons. We establish a kainic acid (KA) porcine model of mesial temporal lobe epilepsy (mTLE) for pre-clinical research and development of novel stimulating therapies.

Methods

We developed a platform integrating MRI-guided stereotactic electrode and chemotoxin delivery with intraoperative and long-term electrophysiology monitoring. Six domestic pigs underwent MRI-guided stereotactic implantation of bilateral hippocampal (HPC) and anterior nucleus of the thalamus (ANT) electrodes, followed by KA infusion into the right HPC. Local field potential (LFP) monitoring was conducted intraoperatively with a bedside workstation and chronically with an implantable neural sensing and recording (INSR) device designed for human use. Cresyl violet staining, commonly used to visualize neurons, was used to assess the neuropathophysiological effect of the KA infusion.

Results

KA infusion led to the emergence of interictal epileptiform discharges (IEDs), acute status epilepticus (SE), and spontaneous seizure activity. Acute IEDs and electrographic SE was observed in all cases, with two pigs euthanized due to uncontrolled seizures. Of the surviving four pigs, spontaneous IEDs were detected in all, and spontaneous seizures within 2 weeks were observed in three. Seizures in freely behaving animals varied from subclinical events to focal and generalized tonic-clonic seizures. Single pulse evoked response potentials (SPEP) measured in two pigs demonstrated functional connectivity between ANT and HPC circuits. Neuronal disorganization and loss, both major components of mTLE neuropathology were observed.

Significance

The KA-induced porcine mTLE model supports the feasibility of testing human neuromodulation devices and provides a translational platform for studying therapeutic electrical sensing and stimulation. In particular, the model should be useful for advancing automated seizure diaries, closed-loop and adaptive therapies targeting Papez circuit nodes.

A platform for brain network sensing and stimulation with quantitative behavioral tracking: Application to limbic circuit epilepsy

Temporal lobe epilepsy is a common neurological disease characterized by recurrent seizures. These seizures often originate from limbic networks and people also experience chronic comorbidities related to memory, mood, and sleep (MMS). Deep brain stimulation targeting the anterior nucleus of the thalamus (ANT-DBS) is a proven therapy, but the optimal stimulation parameters remain unclear. We developed a neurotechnology platform for tracking seizures and MMS to enable data streaming between an investigational brain sensing-stimulation implant, mobile devices, and a cloud environment. Artificial Intelligence algorithms provided accurate catalogs of seizures, interictal epileptiform spikes, and wake-sleep brain states. Remotely administered memory and mood assessments were used to densely sample cognitive and behavioral response during ANT-DBS. We evaluated the efficacy of low-frequency versus high-frequency ANT-DBS. They both reduced seizures, but low-frequency ANT-DBS showed greater reductions and better sleep and memory. These results highlight the potential of synchronized brain sensing and behavioral tracking for optimizing neuromodulation therapy.