Brain surgery meets brain science: probing how a memory-related chemical system influences cognition

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Study Population Inclusion Criteria for Essential Tremor Patients: * Diagnosis of Essential Tremor * Recommended to undergo deep brain stimulation implantation surgery for surgical management of medication-resistant tremor based on clinical indications Exclusion Criteria for Essential Tremor Patients: * Patients with recent use (within one week) of anticoagulant or antiplatelet agent * Contraindication to use of cholinergic modulation Inclusion Criteria for Epilepsy Patients * Diagnosis of intractable epilepsy * Undergoing neuromodulation procedure that utilizes insertion of electrodes into subcortical structures, including the thalamus or hippocampus * Undergoing neuromodulation procedure that utilizes frame-based insertion of electrodes into the thalamus (ANT or CM) Exclusion Criteria for Epilepsy Patients: * Patients with recent use (within one week) of anticoagulant or antiplatelet agent * Contraindication to use of cholinergic modulation Contraindication for cholinergic modulation in both patient sets will be assessed by members of the treatment team (e.g. epileptologist), as well as a neuroanesthesiologist. Multiple medications and conditions are singular disqualifiers; however some medications are eliminated only in combination following neuroanesthesiologist evaluation. Patients at risk of reaction to the treatment arm based on concurrent or recent medications or other health conditions will be excluded from participation. Inclusion Criteria for Study Participation * Is patient between 18-70? * In general good health, aside from history of epilepsy or essential tremor, as ascertained by medical history, physical exam, clinical labs, and ECG? * Candidate for surgery as determined independently by the patient's treating physician/clinical team as part of the patient's routine medical care? * Able to read, understand, and provide written, dated informed consent, and participate in cognitive tasks? Exclusion Criteria for Study Participation * Female that is pregnant, breastfeeding, or has a positive pregnancy test? * Under 18, over 70, or currently a prisoner on medical release? * Hepatic impairment (moderate or severe)? * Renal impairment (moderate or severe)? * Untreated narrow angle glaucoma? * Bladder obstruction, prostatic hyperplasia (BPH), diabetic cystopathy, pre-existing urinary retention? * History of hypersensitivity to COBENFY or trospium chloride? * Biliary disease, including symptomatic gallstones, gallbladder disorders, pancreatitis? * Fluoxetine, paroxetine, bupropion, terbinafine? * Buspirone or eletriptan? * Digoxin, colchicine, apixaban? * Diphenhydramine, beztropine, oxybutynin? * Benztropine, trihexyphenidyl, tolterodine, solifenacin, darifenacin, fesoterodine, hyoscyamine, dicyclomine, scopolamine?