Assessing Covert Consciousness During Dexmedetomidine and Ketamine Sedation: An fMRI Study

NCT07705022 | Not Yet Recruiting Phase 2 FDA Drug

• 2 other identifiers: HUM00285398R01GM103894
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

This research is studying whether mental functions take place during different levels of anesthesia, using a commonly used drug (either dexmedetomidine \[with propofol in some participants\] or ketamine), which shows areas in the brain involved in thinking at different depths of anesthesia. As a result of this study, the researchers expect to gain a deeper understanding of mental function during different levels of anesthesia.

Conditions

Healthy; Covert Consciousness

Keywords

Anesthesia; Functional magnetic resonance imaging (fMRI)

Outcome Measures

Primary Outcomes (1)

• Blood Oxygen Level Dependent (BOLD) response to mental imagery tasks

  Three mental imagery tasks will be used: tennis imagery, navigation imagery, and hand-squeeze imagery

  Up to approximately 130 minutes

Secondary Outcomes (1)

• Grip force (in mmHg) of participants' hand squeezing on a rubber ball in response to squeeze instructions

  Up to approximately 130 minutes

Study Arms (2)

Dexmedetomidine during fMRI

EXPERIMENTAL

About 30 healthy participants will be randomized to this arm.

Drug: Dexmedetomidine (+propofol as indicated)

Ketamine during fMRI

EXPERIMENTAL

About 30 healthy participants will be randomized to this arm.

Drug: Ketamine

Interventions

Dexmedetomidine (+propofol as indicated) DRUG

Dexmedetomidine dosing will follow FDA-labeled parameters for procedural sedation, with a loading dose of 1 mcg/kg administered intravenously over 10 minutes, followed by maintenance infusion within the range of 0.2 to 1.0 mcg/kg/hr, titrated to clinical effect under anesthesiologist supervision. Sedation depth will be assessed behaviorally using standardized squeeze-response testing to determine lost responsiveness (LOR). If LOR is not achieved within labeled dexmedetomidine dosing limits, low-dose propofol will be conditionally added using a target-controlled infusion at an effect-site concentration of 0.5-1.5 μg/ml, which is below typical induction levels and intended to provide supplemental sedation while preserving spontaneous ventilation. Once LOR is achieved, sedation will be maintained within the approved dexmedetomidine range, with adjunct propofol continued only as clinically indicated.

Dexmedetomidine during fMRI

Ketamine DRUG

participants will first receive a subanesthetic ketamine infusion of 0.5 mg/kg administered intravenously over 40 minutes. After that, 1.5 mg/kg ketamine will be administered slowly as a bolus over 60 seconds. Based on prior experience with this paradigm, most subjects who lose responsiveness do so for approximately 10 minutes following the bolus dose. For a 70 kg healthy subject, the total ketamine dose in this paradigm is approximately 140 mg. This dosing remains within the range of standard anesthetic induction dosing, which is typically 1.5 to 2 mg/kg in clinical practice.

Ketamine during fMRI

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy study subjects with American Society of Anesthesiologists (ASA)-1 status
• Right-handed
• Body mass index (BMI) less than 30
• Participants will have the experience of playing tennis (or other racquet sport) at least 30 times in their lifetime
• English speaking

You may not qualify if:

• Medical contraindication to MRI scanning; are unable to undergo MRI scanning because of possible pregnancy or currently breastfeeding
• BMI greater than or equal to 30
• Metallic substances in the body
• claustrophobia, anxiety, or cardiopulmonary disease; or have an intracranial structural abnormality on T1-weighted MRI scans
• history of allergy to dexmedetomidine, ketamine, propofol, or any components of these medications, eggs or egg products, soybean or soybean products
• neurological, cardiovascular, or pulmonary illness
• significant head injury with loss of consciousness; learning disability or other developmental disorder
• sleep apnea or any severe snoring history
• gastroesophageal reflux disease (GERD) or heartburn; pancreatitis or a history of pancreatitis,
• sensory/motor loss sufficient to interfere with performance of the study
• epilepsy/seizure disorder (including a history of seizures) or stroke (including a history of stroke).
• history of schizophrenia spectrum disorder, bipolar disorder, other psychotic disorder, or any prior adverse psychiatric reaction to ketamine or similar drugs
• Participants taking medications that, in the judgment of the investigators or attending anesthesiologist, may interact with the study drugs or increase the risk of participation will also be excluded
• participants with hypertension or diabetes mellitus
• tattoos in the head or neck region will be excluded from study; other tattoos are subject to determination by investigators based on their assessment regarding participant safety

Sponsors & Collaborators

• University of Michigan: lead
• National Institute of General Medical Sciences (NIGMS): collaborator

Study Sites (1)

University of Michigan

Ann Arbor, Michigan, 48109, United States

Location

MeSH Terms

Interventions

Dexmedetomidine; Propofol; Ketamine

Intervention Hierarchy (Ancestors)

Imidazoles; Azoles; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Phenols; Benzene Derivatives; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Hydrocarbons; Organic Chemicals; Cyclohexanes; Cycloparaffins; Hydrocarbons, Alicyclic

Study Officials

• Zirui Huang, PhD

  University of Michigan

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Aaron Ellis

CONTACT

734-647-8129; aaronel@umich.edu

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Research Assistant Professor of Anesthesiology and Director of Center for Consciousness Science

Study Record Dates

• First Submitted: July 10, 2026
• First Posted: July 15, 2026
• Study Start: July 1, 2026
• Primary Completion (Estimated): January 1, 2028
• Study Completion (Estimated): January 1, 2028
• Last Updated: July 15, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, ANALYTIC CODE
• Time Frame: The data will be deposited after the after the analysis have been completed and accepted for scientific publication. Access to the data deposited to OpenNeuro will not be controlled. Data will remain accessible as long as OpenNeuro hosts the data.
• Access Criteria: All research participants will be consented for sharing their de-identified data.

Locations

US (1)