Towards Causal Mapping of Episodic Memory iEEG Networks Via Multi-method Brain Stimulation

Conditions

• Hippocampal Activity
• Memory Performance

Eligibility Criteria

Sex

ALL

Age

18 Years - N/A

Healthy Volunteers

Not accepted

Interventions

• TMS electrical stimulation parameters during cognitive and memory demands — OTHER
  Study conditions will involve electrical stimulation delivered through non-invasive TMS. These different stimulation parameters will include the presence of stimulation (no stimulation versus stimulation) and the location of stimulation.
• DES electrical stimulation parameters during cognitive and memory demands — OTHER
  Study conditions will involve direct electrical stimulation delivered through implanted iEEG electrodes. These different stimulation parameters will include the presence of stimulation (no stimulation versus stimulation) and the location of stimulation across the same electrode or a different electrode.

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 novel noninvasive and invasive stimulation methods. 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

44 participants (estimated)

Allocation

NON_RANDOMIZED

Intervention model

PARALLEL

Primary purpose

BASIC_SCIENCE

Arms

• Experimental: TMS stimulation using HITS
  Hippocampal indirectly targeted stimulation (HITS) will be applied in patients with epilepsy undergoing intracranial electroencephalography (iEEG) monitoring. iEEG signals of episodic memory behavioral performance will be obtained from clinical macroelectrodes and research microelectrodes in a specialized memory task involving encoding and retrieval of naturalistic scenes along with eye-movement tracking. Memory behaviors of interest will include recollection during old/new decisions and spatiotemporal replay of eye-movement patterns. HITS will be applied for \~2 s immediately before each scene onset during encoding, using parameters that have yielded enhanced versus impaired performance in this experiment design
• Experimental: DES stimulation using HITS parameters
  We will test the behavioral significance of iEEG correlates of memory enhancement and impairment using a rigorous approach involving DES. Direct electrical stimulation (DES) parameters will be identified that reproduce as closely as possible the iEEG signatures of memory enhancement or impairment caused by HITS. This will be accomplished using a closed-loop machine learning approach to maximize the similarity of the iEEG signals evoked by DES and the iEEG signals evoked by HITS, during memory encoding.
• Experimental: Normative model of DES
  We will develop, test, and refine for future experiments a normative model of DES parameters to achieve experimental bi-directional manipulation of iEEG correlates of episodic memory. We will identify common features of the DES parameters that were algorithmically determined to mimic the iEEG signals of memory enhancement or impairment by HITS in the Experiment 2 dataset. Analyses will account for individual differences in stimulated electrode locations, in iEEG functional connectivity of stimulated electrodes, in the success of behavioral modification, and in the accuracy of mimicking the iEEG effects of HITS, to enable predictions about how to apply DES parameters in stimulation-naïve subjects given their idiosyncratic electrode placements and brain activity patterns.

Primary Outcome Measure

Power of theta-band hippocampal iEEG activity [ Time Frame: Measured during the performance of the task while research activities are completed. Measurement will take 2 to 4 hours on a single day ]

Locations (3)

Find similar trials in Chicago, IL

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