Bilateral Subdiaphragmatic Vagal Nerve Stimulation Using a Novel Waveform Decreases Body Weight, Food Consumption, Adiposity, and Activity in Obesity-Prone Rats.

Introduction: Obesity affects millions of Americans. The vagal nerves convey the degree of stomach fullness to the brain via afferent visceral fibers. Studies have found that vagal nerve stimulation (VNS) promotes reduced food intake, causes weight loss, and reduces cravings and appetite.

Both high fat and high carbohydrate diets impair vagus nerve signaling of satiety.

Obesity remains prevalent in the US. One potential treatment is vagus nerve stimulation (VNS), which activates the sensory afferents innervating the stomach that convey stomach volume and establish satiety. However, current VNS approaches and stimulus optimization could benefit from additional understanding of the underlying neural response to stomach distension.

Quantification of clinically applicable stimulation parameters for precision near-organ neuromodulation of human splenic nerves.

Neuromodulation is a new therapeutic pathway to treat inflammatory conditions by modulating the electrical signalling pattern of the autonomic connections to the spleen. However, targeting this sub-division of the nervous system presents specific challenges in translating nerve stimulation parameters. Firstly, autonomic nerves are typically embedded non-uniformly among visceral and connective tissues with complex interfacing requirements.

Toward Standardization of Electrophysiology and Computational Tissue Strain in Rodent Intracortical Microelectrode Models.

Progress has been made in the field of neural interfacing using both mouse and rat models, yet standardization of these models' interchangeability has yet to be established. The mouse model allows for transgenic, optogenetic, and advanced imaging modalities which can be used to examine the biological impact and failure mechanisms associated with the neural implant itself. The ability to directly compare electrophysiological data between mouse and rat models is crucial for the development and assessment of neural interfaces.

Temporal Modulation of the Response of Sensory Fibers to Paired-Pulse Stimulation.

Multi-channel nerve cuff electrode arrays can provide sensory feedback to prosthesis users. To develop efficacious stimulation protocols, an understanding of the impact that spatio-temporal patterned stimulation can have on the response of sensory fibers is crucial. We used experimental and modelling methods to investigate the response of nerve fibers to paired-pulse stimulation.

Artificial tactile and proprioceptive feedback improves performance and confidence on object identification tasks.

Somatosensory feedback of the hand is essential for object identification. Without somatosensory feedback, individuals cannot reliably determine the size or compliance of an object. Electrical nerve stimulation can restore localized tactile and proprioceptive feedback with intensity discrimination capability similar to natural sensation.

Home Use of a Neural-connected Sensory Prosthesis Provides the Functional and Psychosocial Experience of Having a Hand Again.

The loss of a hand has many psychosocial repercussions. While advanced multi-articulated prostheses can improve function, without sensation, they cannot restore the full experience and connection of a hand. Direct nerve interfaces can restore naturalistic sensation to amputees.

Sensory adaptation to electrical stimulation of the somatosensory nerves.

Objective: Sensory systems adapt their sensitivity to ambient stimulation levels to improve their responsiveness to changes in stimulation. The sense of touch is also subject to adaptation, as evidenced by the desensitization produced by prolonged vibratory stimulation of the skin. Electrical stimulation of nerves elicits tactile sensations that can convey feedback for bionic limbs.

Hypoglossal nerve stimulation in a pre-clinical anesthetized rabbit model relevant to OSA.

We tested the functional effects of hypoglossal (CNXII) stimulation in the anesthetized rabbit before and after injections of saline into the tongue base to obstruct the airway. Data (n = 6) show little or no effect of CN XII trunk stimulation; however, medial branch stimulation (20-100 Hz; 50-500 μs pulse width, and incremental increases from 10 μA) reduced upper airway resistance. Medial branch stimulation was less effective in reducing resistance than anterior advancement of the hyoid.

The neural basis of perceived intensity in natural and artificial touch.

Electrical stimulation of sensory nerves is a powerful tool for studying neural coding because it can activate neural populations in ways that natural stimulation cannot. Electrical stimulation of the nerve has also been used to restore sensation to patients who have suffered the loss of a limb. We have used long-term implanted electrical interfaces to elucidate the neural basis of perceived intensity in the sense of touch.

Stability and selectivity of a chronic, multi-contact cuff electrode for sensory stimulation in human amputees.

Objective: Stability and selectivity are important when restoring long-term, functional sensory feedback in individuals with limb-loss. Our objective is to demonstrate a chronic, clinical neural stimulation system for providing selective sensory response in two upper-limb amputees.

Approach: Multi-contact cuff electrodes were implanted in the median, ulnar, and radial nerves of the upper-limb.

A neural interface provides long-term stable natural touch perception.

Touch perception on the fingers and hand is essential for fine motor control, contributes to our sense of self, allows for effective communication, and aids in our fundamental perception of the world. Despite increasingly sophisticated mechatronics, prosthetic devices still do not directly convey sensation back to their wearers. We show that implanted peripheral nerve interfaces in two human subjects with upper limb amputation provided stable, natural touch sensation in their hands for more than 1 year.

Efficient search and fit methods to find nerve stimulation parameters for multi-contact electrodes.

This paper describes a method to efficiently sample EMG recruitment space over a wide range of pulse amplitude (PA) and pulse width (PW). A gradient based search method is developed to find high information areas of a recruitment surface. This search method is first examined in the context of simulated EMG recruitment data and its ability to sample and subsequently fit Gompertz-Function-inspired surfaces to it.

Probabilistic modeling of selective stimulation of the human sciatic nerve with a flat Interface Nerve Electrode.

Proper ankle control is critical to both standing balance and efficient walking. This study hypothesized that a Flat Interface Nerve Electrode (FINE) placed around the sciatic nerve with a fixed number of contacts at predetermined locations and without a priori knowledge of the nerve's underlying neuroanatomy can selectively control each ankle motion. Models of the human sciatic nerve surrounded by a FINE of varying size were created and used to calculate the probability of selective activation of axons within any arbitrarily designated group of fascicles.

Probabilistic modeling of selective stimulation of the human sciatic nerve with a flat interface nerve electrode.

Ankle control is critical to both standing balance and efficient walking. The hypothesis presented in this paper is that a Flat Interface Nerve Electrode (FINE) placed around the sciatic nerve with a fixed number of contacts at predetermined locations and without a priori knowledge of the nerve's underlying neuroanatomy can selectively control each ankle motion. Models of the human sciatic nerve surrounded by a FINE of varying size were created and used to calculate the probability of selective activation of axons within any arbitrarily designated, contiguous group of fascicles.

Intraoperative demonstration of selective stimulation of the common human femoral nerve with a FINE.

We have tested the hypothesis that the Flat Interface Nerve Electrode (FINE) can selectively stimulate each muscle innervated by the common femoral nerve of the human, near the inguinal ligament in a series of intraoperative trials. During routine vascular surgeries, an 8-contact FINE was placed around the common femoral nerve between the inguinal ligament and the first branching point. The efficacy of the FINE to selectively recruit muscles innervated by the femoral nerve was determined from electromyograms (EMGs) recorded in response to electrical stimulation.

Fascicular perineurium thickness, size, and position affect model predictions of neural excitation.

The number of applications using neural prosthetic interfaces is expanding. Computer models are a valuable tool to evaluate stimulation techniques and electrode designs. Although our understanding of neural anatomy has improved, its impact on the effects of neural stimulation is not well understood.

A model of selective activation of the femoral nerve with a flat interface nerve electrode for a lower extremity neuroprosthesis.

Functional electrical stimulation (FES) can restore limb movements through electrically initiated, coordinated contractions of paralyzed muscles. The peripheral nerve is an attractive site for stimulation using cuff electrodes. Many applications will require the electrode to selectively activate many smaller populations of axons within a common nerve trunk.

Models of selective stimulation with a flat interface nerve electrode for standing neuroprosthetic systems.

The long-term goal of our research is to restore standing function via selective activation of target fascicles in the femoral nerve by a flat interface nerve electrode (FINE). The optimal number and location of contacts within a FINE had not been determined previously. A realistic three-dimensional finite element model based on a cross section of human femoral nerve and FINE is presented.

Sites of neuronal excitation by epiretinal electrical stimulation.

Action potentials arising from retinal ganglion cells ultimately create visual percepts. In persons blind from retinitis pigmentosa and age-related macular degeneration, viable retinal ganglion cells remain, and the retina can be stimulated electrically to restore partial sight. However, it is unclear what neuronal elements in the retina are activated by epiretinal electrical stimulation.

Structural mechanisms to produce differential dendritic gains.

The axons of sacral parasympathetic preganglionic neurons (PGNs) originate on a primary dendrite between 10 and 110 mum from the soma. Therefore, it was hypothesized that the location of the axon origin would impact the relative efficacy of ipsilateral and contralateral synaptic inputs. The morphology of two PGNs was reconstructed, and the transfer impedance was used to quantify the influence of synaptic inputs on the transmembrane potential at the axon initial segment.