Characterization of Active Electrode Yield for Intracortical Arrays: Awake versus Anesthesia

Abstract

Intracortical microelectrode arrays are used for recording neural signals at single-unit resolution and are promising tools for studying brain function and developing neuroprosthetics. Research is being done to increase the chronic performance and reliability of these probes, which tend to decrease or fail within several months of implantation. Although recording paradigms vary, studies focused on assessing the reliability and performance of these devices often perform recordings under anesthesia. However, anesthetics—such as isoflurane—are known to alter neural activity and electrophysiologic function. Therefore, we compared the neural recording performance under anesthesia (2% isoflurane) followed by awake conditions for probes implanted in the motor cortex of both male and female Sprague-Dawley rats. While the single-unit spike rate was significantly higher by almost 600% under awake compared to anesthetized conditions, we found no difference in the active electrode yield between the two conditions two weeks after surgery. Additionally, the signal-to-noise ratio was greater under anesthesia due to the noise levels being nearly 50% greater in awake recordings, even though there was a 14% increase in the peak-to-peak voltage of distinguished single units when awake. We observe that these findings are similar for chronic time points as well. Our observations indicate that either anesthetized or awake recordings are acceptable for studies assessing the chronic reliability and performance of intracortical microelectrode arrays.

Reactive Amine Functionalized Microelectrode Arrays Provide Short-Term Benefit but Long-Term Detriment to In Vivo Recording Performance

“…For implantation of the first device cohort (functional devices), the surgical procedure was performed following established protocols. , Briefly, adult male rats (275–530 g) were anesthetized using vaporized isoflurane (1.8–2.2%) mixed with medical grade oxygen (500 mL/min; SomnoSuite for Mice & Rats, Kent Scientific Corporation, Torrington, CT, US). Following removal of scalp fur, animals were transferred onto a stereotaxic frame (David Kopf Instruments, Tujunga, CA, US).…”

“…The incision was then closed using surgical staples and the animals were given 5 mg/kg intramuscular cefazolin (Med-Vet International, Mettawa, IL, US) as infection prophylaxis, and depending on availability either 1.2 mg/kg of subcutaneous slow-release buprenorphine (ZooPharm, LLC., Laramie, WY, US) or 1.3 mg/kg subcutaneous extended-release buprenorphine (Ethiqa XR, Fidelis Animal Health, North Brunswick, NJ, USA) for pain management every 72 h for 5 days. Animals were provided sulfamethoxazole and trimethoprim oral suspension (200 mg and 40 mg per 5 mL, Aurobindo Pharma, Dayton, NJ, US) in their drinking water (1 mL suspension/100 mL drinking water) for 1 week postimplantation. ,, For the second cohort, animals were prepared for surgery and device implantation, as detailed above. Craniotomies of approximately 1 mm × 1 mm were made ±3 mm lateral from midline and 2 mm anterior/posterior from bregma.…”

“…Animals were provided sulfamethoxazole and trimethoprim oral suspension (200 mg and 40 mg per 5 mL, Aurobindo Pharma, Dayton, NJ, US) in their drinking water (1 mL suspension/100 mL drinking water) for 1 week postimplantation. 6 , 24 , 47 For the second cohort, animals were prepared for surgery and device implantation, as detailed above. Craniotomies of approximately 1 mm × 1 mm were made ±3 mm lateral from midline and 2 mm anterior/posterior from bregma.…”

Behavioral paradigm for the evaluation of stimulation-evoked somatosensory perception thresholds in rats

“…Rats underwent a surgical procedure for sham and MEA implantation as previously described ( Sturgill et al, 2022 ). Briefly, animals were anesthetized using vaporized isoflurane (1.8–2.5%) mixture with medical grade oxygen (500 ml/min, SomnoSuite® for Mice & Rats, Kent Scientific Corporation, Torrington, CT, US).…”

Bacteria Invade the Brain Following Sterile Intracortical Microelectrode Implantation

“…6A with end points of 4-weeks and 12-weeks post-implantation. All surgical procedures followed established protocols in our combined labs 110,111 . Brie y, mice were anesthetized in an iso urane chamber (3.5% at 0.8 L/min O 2 ).…”