Electrode stimulation parameter modifications elicit differential glial cell responses in vitro over a short 4-h timecourse.

A cell culture model to assess glial cell responses to electrically stimulating electrodes in real-time was developed. Our previous work measured glial cell responses to stimulation paradigms and highlighted the importance of electrical stimulation considerations when designing a biocompatible neural interfacing device. The formation of voids around stimulating platinum-iridium electrodes also prompted an investigation into the fate of cells that would have once populated that area.

Foundry-fabricated dual-color nanophotonic neural probes for photostimulation and electrophysiological recording.

Significance: Compact tools capable of delivering multicolor optogenetic stimulation to deep tissue targets with sufficient span, spatiotemporal resolution, and optical power remain challenging to realize. Here, we demonstrate foundry-fabricated nanophotonic neural probes for blue and red photostimulation and electrophysiological recording, which use a combination of spatial multiplexing and on-shank wavelength demultiplexing to increase the number of on-shank emitters.

Aim: We demonstrate silicon (Si) photonic neural probes with 26 photonic channels and 26 recording sites, which were fabricated on 200-mm diameter wafers at a commercial Si photonics foundry.

Safety of mapping the motor networks in the spinal cord using penetrating microelectrodes in Yucatan minipigs.

Objective: The goal of this study was to assess the safety of mapping spinal cord locomotor networks using penetrating stimulation microelectrodes in Yucatan minipigs (YMPs) as a clinically translational animal model.

Methods: Eleven YMPs were trained to walk up and down a straight line. Motion capture was performed, and electromyographic (EMG) activity of hindlimb muscles was recorded during overground walking.

Development of wafer-scale multifunctional nanophotonic neural probes for brain activity mapping.

Optical techniques, such as optogenetic stimulation and functional fluorescence imaging, have been revolutionary for neuroscience by enabling neural circuit analysis with cell-type specificity. To probe deep brain regions, implantable light sources are crucial. Silicon photonics, commonly used for data communications, shows great promise in creating implantable devices with complex optical systems in a compact form factor compatible with high volume manufacturing practices.

biocompatibility evaluation of functional electrically stimulating microelectrodes on primary glia.

Neural interfacing devices interact with the central nervous system to alleviate functional deficits arising from disease or injury. This often entails the use of invasive microelectrode implants that elicit inflammatory responses from glial cells and leads to loss of device function. Previous work focused on improving implant biocompatibility by modifying electrode composition; here, we investigated the direct effects of electrical stimulation on glial cells at the electrode interface.

GABA facilitates spike propagation through branch points of sensory axons in the spinal cord.

Movement and posture depend on sensory feedback that is regulated by specialized GABAergic neurons (GAD2) that form axo-axonic contacts onto myelinated proprioceptive sensory axons and are thought to be inhibitory. However, we report here that activating GAD2 neurons directly with optogenetics or indirectly by cutaneous stimulation actually facilitates sensory feedback to motor neurons in rodents and humans. GABA receptors located at or near nodes of Ranvier of sensory axons cause this facilitation by preventing spike propagation failure at the many axon branch points, which is otherwise common without GABA.

Laser-Microfabricated Polymer Multielectrodes for Intraspinal Microstimulation.

Objective: The overall goal of this study was to design, fabricate, and characterize a new polymer-based multielectrode for the spinal cord for the application of intraspinal microstimulation (ISMS).

Methods: Three-channel multielectrodes were fabricated from modified poly(dimethylsiloxane) (PDMS) and platinum-iridium (Pt-Ir) foil using nanosecond laser microfabrication techniques. These devices were compared against traditional 50 μm diameter Pt-Ir microwire electrodes mechanically and electrochemically in bench environments, and were assessed electrochemically and functionally in vivo in a domestic pig model.

Overground gait kinematics and muscle activation patterns in the Yucatan mini pig.

The objectives of this study were to assess gait biomechanics and the effect of overground walking speed on gait parameters, kinematics, and electromyographic (EMG) activity in the hindlimb muscles of Yucatan minipigs (YMPs).Nine neurologically-intact, adult YMPs were trained to walk overground in a straight line. Whole-body kinematics and EMG activity of hindlimb muscles were recorded and analyzed at six different speed ranges (0.

Pavlovian control of intraspinal microstimulation to produce over-ground walking.

Objective: Neuromodulation technologies are increasingly used for improving function after neural injury. To achieve a symbiotic relationship between device and user, the device must augment remaining function, and independently adapt to day-to-day changes in function. The goal of this study was to develop predictive control strategies to produce over-ground walking in a model of hemisection spinal cord injury (SCI) using intraspinal microstimulation (ISMS).