Chronic subdural electrocorticography in nonhuman primates by an implantable wireless device for brain-machine interfaces

Abstract

BackgroundSubdural electrocorticography (ECoG) signals have been proposed as a stable, good-quality source for brain-machine interfaces (BMIs), with a higher spatial and temporal resolution than electroencephalography (EEG). However, long-term implantation may lead to chronic inflammatory reactions and connective tissue encapsulation, resulting in a decline in signal recording quality. However, no study has reported the effects of the surrounding tissue on signal recording and device functionality thus far.MethodsIn this study, we implanted a wireless recording device with a customized 32-electrode-ECoG array subdurally in two nonhuman primates for 15 months. We evaluated the neural activities recorded from and wirelessly transmitted to the devices and the chronic tissue reactions around the electrodes. In addition, we measured the gain factor of the newly formed ventral fibrous tissue in vivo.ResultsTime-frequency analyses of the acute and chronic phases showed similar signal features. The average root mean square voltage and power spectral density showed relatively stable signal quality after chronic implantation. Histological examination revealed thickening of the reactive tissue around the electrode array; however, no evident inflammation in the cortex. From gain factor analysis, we found that tissue proliferation under electrodes reduced the amplitude power of signals.ConclusionThis study suggests that subdural ECoG may provide chronic signal recordings for future clinical applications and neuroscience research. This study also highlights the need to reduce proliferation of reactive tissue ventral to the electrodes to enhance long-term stability.

Stable, chronic in-vivo recordings from a fully wireless subdural-contained 65,536-electrode brain-computer interface device

“…Taesung Jung 1 † , Nanyu Zeng 1 † , Jason D. Fabbri 1 , Guy Eichler 2 , Zhe Li 3,4.5 , Konstantin Willeke 3,4,5,6 , Katie E. Wingel 7,8 , Agrita Dubey 7,8 , Rizwan Huq 1 , Mohit Sharma 1 , Yaoxing Hu 1 , Girish Ramakrishnan 1 , Kevin Tien 1 , Paolo Mantovani 2 , Abhinav Parihar 1 , Heyu Yin 1 , Denise Oswalt 8,9,10 , Alexander Misdorp 2 , Ilke Uguz 1 , Tori Shinn 11 , Gabrielle J. Rodriguez 3,4,5 , Cate Nealley 3,4,5 , Ian Gonzales 12 , Michael Roukes 13 , Jeffrey Knecht 14 , Daniel Yoshor 8 , Peter Canoll 15 , Eleonora Spinazzi 12 , Luca P. Carloni 2 , Bijan Pesaran 7,8,9,10 , Saumil Patel 3,4,5 , Brett…”

“…By recording from the brain surface, ECoG minimizes brain tissue damage while being able to acquire higher signal-to-noise ratio (SNR), higher bandwidth, and more spatially localized signals compared to EEG ( 11 ). In vivo studies have shown that ECoG recordings taken from subdural arrays can remain stable for more than a year ( 12, 13 ), demonstrating the technology’s potential usage in chronic applications. Furthermore, advances in microfabrication techniques continue to improve the spatial resolution of the ECoG electrode array.…”