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

Conditions

• Hippocampal Network Activity
• Memory Performance

Eligibility Criteria

Sex

ALL

Age

18 Years - N/A

Healthy Volunteers

Not accepted

Interventions

• Transcranial magnetic stimulation (TMS) — OTHER
  Study conditions will involve different parameters for electrical stimulation delivered using non-invasive TMS.

Study Details

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.

Key Dates

Start date

Sep 15, 2025

Status verified

Jan 2026

Primary completion

Apr 30, 2028

Completion

Jun 30, 2028

Study Design

Enrollment

12 participants (estimated)

Allocation

NON_RANDOMIZED

Intervention model

SINGLE_GROUP

Primary purpose

BASIC_SCIENCE

Arms

• Experimental: Single pulse TMS stimulation
  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
• Experimental: Theta-burst TMS stimulation
  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.

Primary Outcome Measure

Power of theta-band hippocampal electroencephalography (iEEG) activity [ Time Frame: 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. ]

Locations (1)

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