Intracranial EEG to Test How Noninvasive Stimulation Affects Hippocampal-dependent Memory

NCT07397897 | Enrolling By Invitation

• 1 other identifier: IRB25-0756
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 1

Brief Summary

Human intracranial electroencephalography (EEG) can provide brain-activity correlates of memory with high spatial and temporal resolution. This project will test functional relevance of these neural signals for memory behavioral performance using a novel noninvasive stimulation method. Findings will advance understanding of brain mechanisms for memory, as is needed to accelerate progress in the treatment of memory disorders.

Conditions

Memory Performance; Hippocampal Network Activity

Outcome Measures

Primary Outcomes (2)

• Power of theta-band hippocampal electroencephalography (iEEG) activity

  Power of theta-band hippocampal iEEG activity will be recorded and used to measure local brain electrical activity evoked by task conditions

  Measured while research activities are being completed, including during stimulation and the performance of the task . Measurement will take 2 to 4 hours on a single day.

• Electroencephalography (iEEG) activity between hippocampus and the stimulated electrode

  iEEG is used to measure local brain electrical activity evoked by task conditions. iEEG will be recorded and analyzed to determine the synchrony of iEEG activity between hippocampus and the stimulated electrode.

  Measured while research activities are being completed, including during stimulation and the performance of the task . Measurement will take 2 to 4 hours on a single day.

Study Arms (2)

Single pulse TMS stimulation

EXPERIMENTAL

The investigators will measure neural activity evoked by single pulses of Hippocampal Indirectly Targeted Stimulation (HITS). Stimulation intensity will vary to yield dose-response information. The investigators will also stimulate a control location. The investigators hypothesize that hippocampus/hippocampal-network intracranial EEG (iEEG) activity will respond to HITS, but not to control-location stimulation. Moreover, the selectivity of EPs will vary with HITS intensity, with very high intensities yielding less-selective (off-target) EP responses outside the hippocampal network. Findings consistent with these hypotheses would indicate that HITS directly impacts hippocampal and/or hippocampal-network neural activity

Other: Transcranial magnetic stimulation (TMS)

Theta-burst TMS stimulation

EXPERIMENTAL

During task-free periods (fixation cross), HITS will be delivered in a theta-burst rhythm, versus two control non-theta rhythms and no-stimulation control. The investigators will test whether HITS entrains theta in the period immediately following 2-s trains of each condition. The investigators hypothesize that theta-burst HITS will entrain endogenous hippocampal and hippocampal-network theta more than control stimulation. Stimulation will also be delivered within a memory encoding task using naturalistic visual scenes. The investigators hypothesize that hippocampal theta entrainment by HITS will significantly increase during encoding relative to task-free periods, and that this effect will be selective versus the control stimulation conditions. Further, the investigators hypothesize that theta-burst HITS will improve memory relative to the control conditions. Such findings would indicate that HITS influences memory-related hippocampal theta activity.

Other: Transcranial magnetic stimulation (TMS)

Interventions

Transcranial magnetic stimulation (TMS) OTHER

Study conditions will involve different parameters for electrical stimulation delivered using non-invasive TMS.

Single pulse TMS stimulation; Theta-burst TMS stimulation

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 18+ years old
• Native English speakers
• Normal or corrected-to-normal near and far vision

You may not qualify if:

• iEEG electrode placement in area of parietal lobe that will interfere with placement of TMS coil for HITS stimulation

Sponsors & Collaborators

• University of Chicago: lead

Study Sites (1)

University of Chicago Medical Center

Chicago, Illinois, 60637, United States

Location

MeSH Terms

Interventions

Transcranial Magnetic Stimulation

Intervention Hierarchy (Ancestors)

Magnetic Field Therapy; Therapeutics

Study Officials

• Joel Voss, PhD

  University of Chicago

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: January 20, 2026
• First Posted: February 9, 2026
• Study Start: September 15, 2025
• Primary Completion (Estimated): April 30, 2028
• Study Completion (Estimated): June 30, 2028
• Last Updated: February 9, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)