# Optimization of micro-coil arrays for precise stimulation of visual cortex

> **NIH NIH R01** · MASSACHUSETTS GENERAL HOSPITAL · 2021 · $407,124

## Abstract

Project Summary
Electrical stimulation of primary visual cortex (V1) via implanted microelectrode arrays has been proposed as a
means to restore vision to those suffering from a wide range of visual impairments. Despite some initial clinical
success, systematic advances have been limited by an inability of such devices to selectively target specific
neuronal sub-populations as well as by the foreign body responses and other reactions that can compromise
the long-term efficacy of implants. Our goal here is to enhance the efficacy and the reliability of cortical
implants by developing a micro-coil array for intracortical magnetic stimulation. Coil-based magnetic stimulation
has several important advantages when compared to electrode-based electric stimulation. First, the electric
fields induced by the coils are spatially asymmetric and can therefore be used to selectively activate vertical
pyramidal neurons in the cortex without also activating the horizontal passing axons of other cortical areas,
thereby enhancing the spatial resolution of cortical stimulation. Second, the magnetic fields arising from the
coils have high permeability to any biological tissue and so they can pass readily through the high impedance
glial scarring that encapsulates cortical implants and thus continue to reliably induce electric fields in the
targeted area. Third, the micro-coil array can be made more reliable by hermetically sealing the entire device
with dielectric coatings so that it will not be plagued by the device degradation caused by water infiltration
through the weak bonding between the exposed electrode and the dielectric coating and/or delamination of the
thin metal electrode from the substrate during chronic stimulation. Thus, the coil-based approach provides a
more effective and more reliable approach for neural stimulation with cortical prostheses. The aims of this
proposal are to further enhance the efficacy and reliability of visual prosthetics by optimizing the design of a
micro-coil array, developing more effective stimulation strategies, and establishing efficacy in mice that are
blind due to retinal degeneration (rd10).

## Key facts

- **NIH application ID:** 10086471
- **Project number:** 5R01EY029022-04
- **Recipient organization:** MASSACHUSETTS GENERAL HOSPITAL
- **Principal Investigator:** Seungwoo Lee
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $407,124
- **Award type:** 5
- **Project period:** 2018-04-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10086471

## Citation

> US National Institutes of Health, RePORTER application 10086471, Optimization of micro-coil arrays for precise stimulation of visual cortex (5R01EY029022-04). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10086471. Licensed CC0.

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