# Using deep brain stimulation of the parietal cortex to investigate the electrophysiology of human episodic memory

> **NIH NIH R01** · UT SOUTHWESTERN MEDICAL CENTER · 2024 · $395,962

## Abstract

Parietal regions, including the posterior cingulate cortex, participate in brain networks critical for recollection,
order memory, autobiographical retrieval, and episodic simulation. The importance of regions such as the
posterior cingulate to episodic processing has been highlighted by data from animal models, non—invasive
imaging studies, brain stimulation experiments, and rare reports that use directly recorded brain activity in
humans. However, significant knowledge gaps remain related to the specific neurophysiological processes
that occur within the posterior cingulate and how this region integrates with hippocampal memory networks.
We propose three highly innovative experiments to address these knowledge gaps. First, we will obtain
microelectrode recordings from the posterior cingulate cortex during episodic encoding and retrieval. We will
identify time cells, a population of neurons that provide direct representation of temporal contextual
information. We will also identify episodic boundary cells, which represent a complementary population of
neurons critical for episodic construction. We will identify neuronal assemblies in the MTL and concomitant
ripple activity in the PCC. Second, we will use the novel experimental manipulation of administering the
anticholinergic agent scopolamine to human intracranial EEG subjects performing an episodic memory task
and record simultaneous hippocampal and parietal activity (from the posterior cingulate cortex). Based on our
preliminary data using this manipulation in this patient population, we predict that we will observe a decrease in
activity in the 2-5 Hz `slow theta’ frequency range, as well as commensurate changes in hippocampal—parietal
connectivity in the 5-9 Hz `fast theta’ frequency band. The use of scopolamine has direct relevance for
understanding cholinergic modulation in hippocampal memory circuits and implications for understanding how
degenerative conditions such as Alzheimer’s Disease impact these circuits. Finally, we will use direct brain
stimulation applied to the posterior cingulate cortex and angular gyrus in the same experimental subjects to
understand how these regions may differentially modulate hippocampal theta oscillations, building on our
published work using this experimental approach. These experiments will take advantage of our unique
opportunity to obtain direct brain recordings from hippocampal networks in surgical epilepsy patients. Our
expertise in this area, demonstrated in our published findings from the previous funded period, supports our
ability to collect these proposed data and generative novel, high value datasets that will allow us to address the
knowledge gaps outlined above.

## Key facts

- **NIH application ID:** 10897245
- **Project number:** 5R01NS107357-07
- **Recipient organization:** UT SOUTHWESTERN MEDICAL CENTER
- **Principal Investigator:** Bradley C Lega
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $395,962
- **Award type:** 5
- **Project period:** 2018-09-01 → 2028-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10897245

## Citation

> US National Institutes of Health, RePORTER application 10897245, Using deep brain stimulation of the parietal cortex to investigate the electrophysiology of human episodic memory (5R01NS107357-07). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10897245. Licensed CC0.

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