A Roadmap for Implanting Electrode Arrays to Evoke Tactile Sensations Through Intracortical Stimulation

Human Brain Mapping, 2024 · DOI: https://doi.org/10.1002/hbm.70118 · Published: December 11, 2024

Simple Explanation

This research focuses on restoring the sense of touch in paralyzed individuals using a brain-computer interface (BCI). The approach involves precisely placing electrodes in the somatosensory cortex, the brain region responsible for processing tactile sensations. The study outlines the pre-surgical imaging and planning needed to accurately implant these electrodes. Functional maps of the hand area in the somatosensory cortex are created using fMRI and MEG to guide the placement of microelectrode arrays. The goal is to evoke sensations in specific fingers by stimulating the cortex. The process was tested in five participants with spinal cord injuries, and the results provided a roadmap for future BCI studies aimed at restoring sensation.

Study Duration

2014 and 2022

Participants

Five participants with cervical spinal cord injury

Evidence Level

Not specified

Key Findings

1
The study successfully enabled ICMS-evoked sensations localized to at least the first four digits of the hand in five participants with cervical spinal cord injury.
2
Functional neuroimaging (fMRI and MEG) can be used to create individualized functional maps of somatosensation during attempted finger movements.
3
The position of sensory representations relative to the hand knob varied significantly across participants, highlighting the need for functional mapping to determine electrode placement.

Research Summary

This study presents a detailed methodology for targeting the hand representation in the somatosensory cortex using intracortical microstimulation (ICMS) to deliver tactile feedback for brain-computer interfaces (BCIs). The approach involves non-invasive neuroimaging (fMRI and MEG) to create individualized functional maps of somatosensation during attempted finger movements, followed by a structured pre-operative planning process. The results demonstrate that this method consistently leads to evoked sensations mapped to the desired digits, enabling the development of closed-loop BCI systems that provide tactile feedback during grasping.

Practical Implications

Improved BCI Design

Provides a roadmap for accurately placing electrodes to restore tactile sensation, improving the effectiveness of BCIs.

Personalized Treatment

Highlights the necessity for personalized functional maps due to variability in somatosensory cortex organization across individuals.

Advancements in Neuroimaging

Demonstrates the utility of fMRI and MEG in mapping somatosensory function, which can be applied to other neurological applications.

Study Limitations

1
Inability to identify the anteroposterior somatotopy, which dictates the distal aspect of the finger sensation.
2
Functional neuroimaging may not be broadly available at medical centers, which could create challenges for the translation of bidirectional BCI technology.
3
Most arrays also evoked sensations on digits that were not mapped under them.

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