scholarly journals Neural feedback strategies to improve grasping coordination in neuromusculoskeletal prostheses

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Enzo Mastinu ◽  
Leonard F. Engels ◽  
Francesco Clemente ◽  
Mariama Dione ◽  
Paolo Sassu ◽  
...  
Keyword(s):  
Motor Coordination ◽  
Sensory Information ◽  
Nerve Fibers ◽  
Tactile Feedback ◽  
Somatosensory Feedback ◽  
Afferent Nerve Fibers ◽  
Feedback Strategies ◽  
Neural Feedback ◽  
Novel Concept ◽  
Implant System

Abstract Conventional prosthetic arms suffer from poor controllability and lack of sensory feedback. Owing to the absence of tactile sensory information, prosthetic users must rely on incidental visual and auditory cues. In this study, we investigated the effect of providing tactile perception on motor coordination during routine grasping and grasping under uncertainty. Three transhumeral amputees were implanted with an osseointegrated percutaneous implant system for direct skeletal attachment and bidirectional communication with implanted neuromuscular electrodes. This neuromusculoskeletal prosthesis is a novel concept of artificial limb replacement that allows to extract control signals from electrodes implanted on viable muscle tissue, and to stimulate severed afferent nerve fibers to provide somatosensory feedback. Subjects received tactile feedback using three biologically inspired stimulation paradigms while performing a pick and lift test. The grasped object was instrumented to record grasping and lifting forces and its weight was either constant or unexpectedly changed in between trials. The results were also compared to the no-feedback control condition. Our findings confirm, in line with the neuroscientific literature, that somatosensory feedback is necessary for motor coordination during grasping. Our results also indicate that feedback is more relevant under uncertainty, and its effectiveness can be influenced by the selected neuromodulation paradigm and arguably also the prior experience of the prosthesis user.

scholarly journals Neural Readout of a Latency Code in the Active Electrosensory System

2021 ◽  
Author(s):  
Nathaniel B Sawtell ◽  
Krista Perks
Keyword(s):  
Sensory Information ◽  
Granular Cell ◽  
Nerve Fibers ◽  
Spike Count ◽  
Stimulus Amplitude ◽  
Electrosensory System ◽  
Afferent Nerve Fibers ◽  
Mormyrid Fish ◽  
Sensory Responses ◽  
Spike Latency

The latency of spikes relative to a stimulus conveys sensory information across modalities. However, in most cases it remains unclear whether and how such latency codes are utilized by postsynaptic neurons. In the active electrosensory system of mormyrid fish, a latency code for stimulus amplitude in electroreceptor afferent nerve fibers (EAs) is hypothesized to be read out by a central reference provided by motor corollary discharge (CD). Here we demonstrate that CD enhances sensory responses in postsynaptic granular cells of the electrosensory lobe, but is not required for reading out EA input. Instead, diverse latency and spike count tuning across the EA population gives rise to graded information about stimulus amplitude that can be read out by standard integration of converging excitatory synaptic inputs. Inhibitory control over the temporal window of integration renders two granular cell subclasses differentially sensitive to information derived from relative spike latency versus spike count.

Spontaneous action potential generation due to persistent sodium channel currents in simulated carotid body afferent fibers

2008 ◽  
Vol 104 (5) ◽  
pp. 1394-1401 ◽  
Author(s):  
David F. Donnelly
Keyword(s):  
Carotid Body ◽  
High Sensitivity ◽  
Nerve Fibers ◽  
Afferent Nerve ◽  
Random Pattern ◽  
Nerve Terminals ◽  
Discharge Rates ◽  
Afferent Nerve Fibers ◽  
Axonal Diameter ◽  
Spontaneous Action

The mechanism by which action potentials (APs) are generated in afferent nerve fibers in the carotid body is unknown, but it is generally speculated to be release of an excitatory transmitter and synaptic depolarizing events. However, previous results suggested that Na+ channels in the afferent nerve fibers play an important role in this process. To better understand the potential mechanism by which Na+ channels may generate APs, a mathematical model of chemoreceptor nerve fibers that incorporated Hodgkin-Huxley-type Na+ channels with kinetics of activation and inactivation, as determined previously from recordings of petrosal chemoreceptor neurons, was constructed. While the density of Na+ channels was kept constant, spontaneous APs arose in nerve terminals as the axonal diameter was reduced to that in rat carotid body. AP excitability and pattern were similar to those observed in chemoreceptor recordings: 1) a random pattern at low- and high-frequency discharge rates, 2) a high sensitivity to reductions in extracellular Na+ concentration, and 3) a variation in excitability that increased with AP generation rate. Taken together, the results suggest that an endogenous process in chemoreceptor nerve terminals may underlie AP generation, a process independent of synaptic depolarizing events.

Lung inflation: effects on heart rate, respiration, and vagal afferent activity in seals

1981 ◽  
Vol 240 (2) ◽  
pp. H190-H198 ◽  
Author(s):  
J. E. Angell-James ◽  
R. Elsner ◽  
M. De Burgh Daly
Keyword(s):  
Transpulmonary Pressure ◽  
Harbor Seal ◽  
Nerve Fibers ◽  
Cardiac Response ◽  
Impulse Frequency ◽  
Lung Inflation ◽  
Afferent Nerve Fibers ◽  
Close Relationship ◽  
Vagal Afferent ◽  
Carotid Body Chemoreceptors

In the anesthetized harbor seal, Phoca vitulina, the Hering-Breuer inflation reflex was weak and comparable to that in humans. Single inflations of the lungs from a syringe during the expiratory phase of normal breathing caused temporary inhibition of breathing and an immediate tachycardia dependent on the integrity of the cervical vagosympathetic nerves. A similar cardiac response occurred when the lungs were artificially inflated during an experimental dive and under conditions in which apnea and bradycardia were reflexly induced by a combination of stimulation of the carotid body chemoreceptors and of the trigeminal or laryngeal input. Recordings from single vagal afferent nerve fibers innervating presumptive pulmonary stretch receptors showed a close relationship between the increase in impulse frequency and increase in lung volume or transpulmonary pressure. It appears that in diving the decrease in pulmonary stretch receptor activity during apnea, combined with cessation of central inspiratory neuronal drive, is an important integrative mechanism that helps development of the reflex bradycardia of trigeminal, carotid, chemoreceptor, and baroreceptor origin.

Development of spontaneous activity and mechanosensitivity in axotomized afferent nerve fibers during the first hours after nerve transection in rats

1995 ◽  
Vol 74 (3) ◽  
pp. 1020-1027 ◽  
Author(s):  
M. Michaelis ◽  
K. H. Blenk ◽  
W. Janig ◽  
C. Vogel
Keyword(s):  
Spontaneous Activity ◽  
Discharge Rate ◽  
Nerve Fibers ◽  
Nerve Lesion ◽  
Nerve Transection ◽  
Unmyelinated Fibers ◽  
C Fibers ◽  
Afferent Nerve Fibers ◽  
Irregular Frequency ◽  
The Mean

1. Spontaneous activity and ectopic mechanical excitability of axotomized unmyelinated and myelinated fibers in the sural nerve were examined in anesthetized rats. The analysis was performed within 30 h after the nerve lesion using single-fiber recordings that were performed proximal to the severed nerve end. 2. Among all unmyelinated fibers tested (n = 865), 4-8% exhibited persistent spontaneous activity of low and irregular frequency. The percentage of spontaneously active C fibers did not change significantly during the first 30 h. Only 6 of 796 A fibers had spontaneous activity. 3. Mechanical stimulation of the cut nerve end excited 5-8% of all C fibers under investigation. No development with time could be detected in the frequency of mechanically excitable C fibers. In contrast, beginning 6 h after nerve transection, the number of mechanically excitable A fibers rose with time, reaching 27% after 22-30 h. 4. Among the A fibers (C fibers) that exhibited mechanical excitability or spontaneous activity, only 4% (25%) had both properties, whereas 96% (75%) were either mechanosensitive or spontaneously active. 5. With time after the nerve lesion, the mean discharge rate of all spontaneously discharging C fibers decreased significantly from 49 imp/min (0.5-9 h after nerve lesion) to 11 imp/min after 22-30 h. The mean discharge rate of C fibers exhibiting solely spontaneous activity and those C fibers that were additionally mechanosensitive did not differ significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The Urothelium: Life in a Liquid Environment

2020 ◽  
Vol 100 (4) ◽  
pp. 1621-1705 ◽  
Author(s):  
Marianela G. Dalghi ◽  
Nicolas Montalbetti ◽  
Marcelo D. Carattino ◽  
Gerard Apodaca
Keyword(s):  
Current Knowledge ◽  
Nerve Fibers ◽  
Liquid Environment ◽  
Afferent Nerve Fibers ◽  
Proximal Urethra ◽  
Key Aspects ◽  
And Function ◽  
Solute Composition ◽  
Extended Discussion

The urothelium, which lines the renal pelvis, ureters, urinary bladder, and proximal urethra, forms a high-resistance but adaptable barrier that surveils its mechanochemical environment and communicates changes to underlying tissues including afferent nerve fibers and the smooth muscle. The goal of this review is to summarize new insights into urothelial biology and function that have occurred in the past decade. After familiarizing the reader with key aspects of urothelial histology, we describe new insights into urothelial development and regeneration. This is followed by an extended discussion of urothelial barrier function, including information about the roles of the glycocalyx, ion and water transport, tight junctions, and the cellular and tissue shape changes and other adaptations that accompany expansion and contraction of the lower urinary tract. We also explore evidence that the urothelium can alter the water and solute composition of urine during normal physiology and in response to overdistension. We complete the review by providing an overview of our current knowledge about the urothelial environment, discussing the sensor and transducer functions of the urothelium, exploring the role of circadian rhythms in urothelial gene expression, and describing novel research tools that are likely to further advance our understanding of urothelial biology.

Sign in / Sign up

Export Citation Format

Share Document