Cross-sectional Imaging Anatomy and Pathologic Conditions Affecting Thoracic Nerves.

While in many cases they are not directly visualized, awareness of the thoracic nerves and their courses at cross-sectional imaging is important for radiologists. An understanding of the normal function of each nerve is important, as many patients present with neurologic signs and symptoms that can be used to reinforce search patterns for disease and detection of supportive radiologic abnormalities. In the case of primary neoplasms, understanding the expected presence of a nerve in the location of a mass can enhance and improve the accuracy of differential diagnoses. Even in the absence of neurologic symptoms, secondary involvement of these structures by malignancy or close proximity to other intrathoracic disease can prompt significant alterations in oncologic or surgical management. The major components of the thoracic nervous system with which the thoracic radiologist must be familiar are the phrenic, vagus, recurrent laryngeal, intercostal, and long thoracic nerves in addition to the sympathetic chain and brachial plexus. The anatomic structure and course of each component are described including its major functions. Major clinical signs and symptoms attributable to nerve dysfunction or disease are reviewed as well as any associated radiologic signs. Emphasis is placed on primary and secondary malignant involvement of the nerves and iatrogenic and traumatic injuries. Online supplemental material is available for this article. ©RSNA, 2016.

Thoracodorsal nerve transfer for triceps reinnervation in partial brachial plexus injuries.

PURPOSE: To report the clinical outcomes of thoracodorsal nerve (TDN) transfers to the triceps motor branches for elbow extension restoration in patients with partial brachial plexus injuries (BPI). METHODS: Eight male patients of mean age 23 years and suffering from a partial BPI underwent direct coaptation of the TDN to the nerve of the upper medial and long heads of the triceps, an average 6 months after their accident. RESULTS: Seven patients achieved M4 elbow extension strength and one patient M3, according to the BMRC scale, after a mean follow-up of 21 months. DISCUSSION: Direct TDN transfer might be a valid surgical procedure for the restoration of elbow extension in patients with partial BPI.

The effect of sensory feedback on crayfish posture and locomotion: II. Neuromechanical simulation of closing the loop.

Neuromechanical simulation was used to determine whether proposed thoracic circuit mechanisms for the control of leg elevation and depression in crayfish could account for the responses of an experimental hybrid neuromechanical preparation when the proprioceptive feedback loop was open and closed. The hybrid neuromechanical preparation consisted of a computational model of the fifth crayfish leg driven in real time by the experimentally recorded activity of the levator and depressor (Lev/Dep) nerves of an in vitro preparation of the crayfish thoracic nerve cord. Up and down movements of the model leg evoked by motor nerve activity released and stretched the model coxobasal chordotonal organ (CBCO); variations in the CBCO length were used to drive identical variations in the length of the live CBCO in the in vitro preparation. CBCO afferent responses provided proprioceptive feedback to affect the thoracic motor output. Experiments performed with this hybrid neuromechanical preparation were simulated with a neuromechanical model in which a computational circuit model represented the relevant thoracic circuitry. Model simulations were able to reproduce the hybrid neuromechanical experimental results to show that proposed circuit mechanisms with sensory feedback could account for resistance reflexes displayed in the quiescent state and for reflex reversal and spontaneous Lev/Dep bursting seen in the active state.

The effect of sensory feedback on crayfish posture and locomotion: I. Experimental analysis of closing the loop.

The effect of proprioceptive feedback on the control of posture and locomotion was studied in the crayfish Procambarus clarkii (Girard). Sensory and motor nerves of an isolated crayfish thoracic nerve cord were connected to a computational neuromechanical model of the crayfish thorax and leg. Recorded levator (Lev) and depressor (Dep) nerve activity drove the model Lev and Dep muscles to move the leg up and down. These movements released and stretched a model stretch receptor, the coxobasal chordotonal organ (CBCO). Model CBCO length changes drove identical changes in the real CBCO; CBCO afferent responses completed the feedback loop. In a quiescent preparation, imposed model leg lifts evoked resistance reflexes in the Dep motor neurons that drove the leg back down. A muscarinic agonist, oxotremorine, induced an active state in which spontaneous Lev/Dep burst pairs occurred and an imposed leg lift excited a Lev assistance reflex followed by a Lev/Dep burst pair. When the feedback loop was intact, Lev/Dep burst pairs moved the leg up and down rhythmically at nearly three times the frequency of burst pairs when the feedback loop was open. The increased rate of rhythmic bursting appeared to result from the positive feedback produced by the assistance reflex.

Age and gender related neuromuscular changes in trunk flexion-extension.

BACKGROUND: The root mean square surface electromyographic activity of lumbar extensor muscles during dynamic trunk flexion and extension from a standing position and task specific spine ranges of motion objectively assess muscle function in healthy young and middle age individuals. However, literature on neuromuscular activation and associated spine and hip kinematics in older individuals is sparse. This cross sectional study sought to examine the sex and age (<40 versus >60 years) related differences in the neuromuscular activation profiles of the lumbar extensors and the related spine and hip kinematics from healthy individuals during a standardized trunk flexion-extension task. METHODS: Twenty five older (13 females, 60-90 years) and 24 younger (12 females, 18-40 years) healthy individuals performed trunk flexion-extension testing by holding static positions at half-flexion way and full range of motion between standing and maximum trunk flexion. The associated lumbar extensor muscle activity was derived from measurements at standing, half, and maximum flexion positions. The range of motion at the hip and lumbar spine was recorded using 3d accelerometers attached to the skin overlying the multifidus and semispinalis thoracis muscles lateral to the L5 and T4 spinous processes, respectively. Statistical calculations were performed using a permutation ANOVA with bootstrap confidence intervals. RESULTS: The muscle activity in the half related to the maximum flexion position (half flexion relaxation ratio) was significantly smaller in older males when compared with younger males. Moreover, measurements revealed smaller activity changes from standing to the half and from half to the maximum flexion position in older compared to younger individuals. Older males displayed smaller gross trunk range of motion from standing to maximum flexion than any other group. CONCLUSIONS: Gender and normal aging significantly affect both the activation patterns of the lumbar extensor muscles and the kinematics of the trunk during a standardized trunk flexion-extension task. Measurement results from healthy young and middle age individuals should not be used for the assessment of individuals older than 60 years of age.

Do cutaneous nerves cross the midline?

Standard cutaneous innervation maps show strict midline demarcation. Although authors of these maps accept variability of peripheral nerve distribution or occasionally even the midline overlap of cutaneous nerves, this concept seems to be neglected by many other anatomists. To support the statement that such transmedian overlap exists, we performed an extensive literature search and found ample evidence for all regions (head/neck, thorax/abdomen, back, perineum, and genitalia) that peripheral nerves cross the midline or communicate across the midline. This concept has substantial clinical implications, most notably in anesthesia and perineural tumor spread. This article serves as a springboard for future anatomical, clinical, and experimental research.

[Vascular relationships of the right great splanchnic nerve in the thorax]. / Rapports vasculaires thoraciques du nerf grand splanchnique droit.

AIM: The surgical assumption of responsibility of the pancreatic pain requires either a truncular coelioscopic or radicular neurectomy of greater splanchnic nerves (gsn). The goal of our work is to describe the way and relations of the right gsn which are variable and rarely described. This constitutes an undeniable peroperational hemorrhagic risk during splanchnicectomy. MATERIAL AND METHODS: After a double side thoracotomy and a bilateral sterno-clavicular desarticulation on 15 adult cadaveric subjects preserved by method of Winckler we removed the sterno-costal drill plate as well as the ventral rib arch and proceeded to a mediastinal evisceration of the thorax. Then we respected only the thoracic aorta and the oesophagus, the azygos venous system, the thoracic duct and the thoracic sympathetic chain. In some of the subjects, the azygos vein was injected (after catheterization of its stick) using gelatine coloured with blue paint. We studied the way and vascular relations of the right gsn. We measured the transverse distances between the origin of the gsn on one hand and the longitudinal axes of the azygos vein and the thoracic duct on the other hand. RESULTS: The relations of the right gsn trunk during its way related to the azygos vein in particular its constitutive origin and its affluents: ascending lumbar vein and twelfth intercostal vein. Sometimes the thoracic duct even a lymphatic node was near the gsn in the posterior infra-mediastinal space. A classification of the way and vascular relations of the right gsn in the thorax identified 3 anatomical types. The average distances separating the right gsn on one hand from the azygos vein and the thoracic duct on the other hand were respectively 5.7 mm and 11.2 mm. CONCLUSION: The vascular relations of the right gsn are very variable from one subject to another but primarily venous, sometimes lymphatic. They concerned the great thoracic vessels whose respect is essential in particular at the time of mini-invasive access procedure for a cœlioscopic splanchnicectomy.

[Clinical diagnostic features of surgical treatment for thoracic outlet syndrome].

The thoracic outlet syndrome is characterized by a variety of clinical signs due to multiple causes resulting in compression of a neurovascular bundle in a relatively narrow anatomical space. Despite the frequently encountered clinical symptoms, inadequate attention is paid to their analysis, and their diagnostic and surgical aspects require a modern approach. The study included 46 patients. The main clinical sign is a persistent pain syndrome of the cervico-occipital localization that affects the shoulder girdle, suprascapular and infrascapular regions and spreads to the arm in combination with trophic, sensory and vascular disorders. SCT angiography of the superior thoracic outlet structures has been used as a priority instrumental method of research. The macro- and micro factors of compression are the main cause for the development of neurological symptoms, and their removal is the main task of surgical treatment. Surgical approaches were planned depending on the nature and extent of injury. 36 patients underwent 42 surgical interventions. The proper assessment of the neurological status in combination with modern paraclinical diagnostic methods and selection of an adequate surgical approach provided satisfactory outcomes in 33 cases.

Differences in the microstructure and biomechanical properties of the recurrent laryngeal nerve as a function of age and location.

Idiopathic onset of unilateral vocal fold paralysis (UVP) is caused by damage to the recurrent laryngeal nerve (RLN) and results in difficulty speaking, breathing, and swallowing. This damage may occur in this nerve as it loops around the aortic arch, which is in a dynamic biomechanical environment. The goal of this study is to determine if the location-dependent biomechanical and microstructural properties of the RLN are different in piglets versus adolescent pigs. The neck/distal and thoracic/proximal (near the aortic arch) regions of the RLN from eight adolescent pigs and six piglets were isolated and mechanically assessed in uni-axial tension. Two-photon imaging (second harmonic) data were collected at 5%, 10%, and 15% strain during the mechanical test. The tangential modulus (TM) and the strain energy density (W) were determined at each level of strain. The mean mode of the preferred fiber angle and the full width at half maximum (FWHM, a measure of fiber splay) were calculated from the imaging data. We found significantly larger values of TM, W, and FWHM in the proximal segments of the left RLN when compared to the distal segments (18.51 MPa ± 1.22 versus 10.78 MPa ± 1.22, p < 0.001 for TM, 0.046 MPa ± 0.01 versus 0.026 MPa ± 0.01, p < 0.003 for W, 15.52 deg ± 1.00 versus 12.98 deg ± 1.00, p < 0.001 for FWHM). TM and W were larger in the left segments than the right (15.32 MPa ± 1.20 versus 11.80 MPa ± 1.20, p < 0.002 for TM, 0.038 MPa ± 0.01 versus 0.028 MPa ± 0.01, p < 0.0001 for W). W was larger in piglets when compared to adolescent pigs (0.042 MPa ± 0.01 versus 0.025 MPa ± 0.01, p < 0.04). The proximal region of the left porcine RLN is more stiff than the distal region and has a higher degree of fiber splay. The left RLN of the adolescent pigs also displayed a higher degree of strain stiffening than the right. These differences may develop as a result of the more dynamic environment the left RLN is in as it loops around the aortic arch.

[Subpopulation of calbindin-immunoreactive interneurons in the dorsal horn of the mice spinal cord].

In the dorsal horn of the spinal cord in the plates I-IV on the thoracic and lumbar levels different subpopulations of interneurons immunoreactive for calbindin 28 kDa (CAB IR), which are specific to each plate. In the area of the medial edge of the dorsal horn, we have found a special subpopulation of CAB IR interneurons whose morphometric characteristics differ from CAB IR interneurons subpopulations of said plates. The number of CAB IR interneurons was maximal in the plate II at all levels of the spinal cord. Leveled differences are more CAB IR interneurons and larger area of the cross sections at the lumbar level.

TRPV1 properties in thoracic dorsal root ganglia neurons are modulated by intraperitoneal capsaicin administration in the late phase of type-1 autoimmune diabetes.

Pharmacological therapies in type 1 diabetes for efficient control of glycemia and changes in pain alterations due to diabetic neuropathy are a continuous challenge. Transient receptor potential vanilloid type 1 (TRPV1) from dorsal root ganglia (DRG) neurons is one of the main pharmacological targets in diabetes, and its ligand capsaicin can be a promising compound for blood-glucose control. Our goal is to elucidate the effect of intraperitoneal (i.p.) capsaicin administration in type 1 diabetic mice against TRPV1 receptors from pancreatic DRG primary afferent neurons. A TCR(+/-)/Ins-HA(+/-) diabetic mice (dTg) was used, and patch-clamp and immunofluorescence microscopy measurements have been performed on thoracic T(9)-T(12) DRG neurons. Capsaicin (800 µg/kg, i.p. three successive days) administration in the late-phase diabetes reduces blood-glucose levels, partly reverses the TRPV1 current density and recovery time constant, without any effect on TRPV1 expression general pattern, in dTg mice. A TRPV1 hypoalgesia profile was observed in late-phase diabetes, which was partly reversed to normoalgesic profile upon capsaicin i.p. administration. According to the soma dimensions of the thoracic DRG neurons, a detailed analysis of the TRPV1 expression upon capsaicin i.p. treatment was done, and the proportion of large A-fiber neurons expressing TRPV1 increased in dTg capsaicin-treated mice. In conclusion, the benefits of low-dose capsaicin intraperitoneal treatment in late-phase type-1 diabetes should be further exploited.

The effects of clipping on thoracic sympathetic nerve in rabbits: early and late histopathological findings.

BACKGROUND: The clipping of the thoracic sympathetic nerve, which has been a technique used for approximately the past 10 years, has rapidly become popular because of its "bring-back" claim. However, the information regarding the mechanism behind this claim is based on investigator's comments and has not been proven by objective research, such as the histopathological examination of the clipped nerve and/or ganglion. We aimed to evaluate sympathetic regeneration and degeneration after clip removal. METHODS: The rabbits were divided into two groups with six rabbits per group. For the first group (group A), the sympathetic chain was clipped using two titanium clips, and a right thoracotomy was made at the T4 and T5 levels. For the second group (group B), the animals were also operated on, which was similar to the rabbits in group A. At the end of a 48-hour follow-up period, the clips were removed after a second operation. The rabbits in group B were followed for 45 days and sympathetic nerves were also examined histopathologically. RESULTS: In group A, hemorrhage, fibrinous material, polymorphonuclear leukocyte infiltration, and acute inflammation with fat necrosis were observed in and around the sympathetic ganglia and trunk. Loss of nuclei and vacuolization in some sympathetic ganglia cells were also observed. These findings demonstrated severe degeneration of the sympathetic ganglia and trunk. For group B, microscopic examination revealed a loss of sympathetic ganglion cells as well as fibrosis within and around the ganglia. No signs of regeneration were detected and the progression of nerve degeneration was observed. CONCLUSIONS: The clips used in our study were shown to cause the degeneration of neural structures within 2 days. At the end of the 45 days following the removal of the clips, progressive, degenerative changes radiating along the axons of the sympathetic cells were seen.

Nerves of the Thorax: Anatomy, Clinical Signs, and Imaging Findings of Pathological Conditions.

BACKGROUND: Radiological diagnosis of thoracic nerve diseases is difficult because they are rare, and nerves cannot be seen directly on radiological images. The major nerves of the thorax can be listed as the phrenic, vagus, recurrent laryngeal, long thoracic nerve pairs, sympathetic chains, costal nerves, and brachial plexus. Diseases of thoracic nerves have various causes, including traumatic injury, neuromuscular diseases, infection, compression, radiation, drugs, and tumors. OBJECTIVE: This pictorial review aims to describe the anatomic locations of the major thoracic nerves on radiological images, comprehensively describe the causes of thoracic nerve diseases and define the clinical signs and primary and secondary imaging findings of dysfunction of the thoracic nerves. METHODS: This paper was designed to illustrate primary and secondary imaging findings of nerve diseases. Firstly, the normal anatomy of nerves is shown with diagrams. Secondly, we explained primary and secondary imaging features with variable radiological methods, including chest X-Ray, magnetic resonance imaging, and computed tomography. CONCLUSION: Primary findings of nerve diseases can be detected if radiologists are familiar with the courses of the nerves on radiological images. Knowledge of the normal functions of the nerves can aid in diagnosing thoracic nerve diseases identified from secondary imaging findings such as diaphragmatic elevation, muscular atrophy, and winged scapula. It is essential to know the normal anatomy, function, and possible causes of thoracic nerve diseases to make a correct diagnosis and apply the prompt treatment.

Intercostal vessels and nerves are at risk for injury during supracostal percutaneous nephrostolithotomy.

PURPOSE: We characterized key intercostal anatomical relationships relevant to supracostal percutaneous nephrostolithotomy using anatomical dissection. MATERIALS AND METHODS: We performed 20 cadaveric dissections of the 11th intercostal space to characterize key anatomical relationships relevant to percutaneous upper pole renal access. Specific data recorded included intercostal rib distance at the lateral border of the paraspinous muscles, and the mid scapular and posterior axillary lines. We also recorded the distance between the 12th and 11th ribs to the intercostal nerve, artery and vein at the same 3 sites. RESULTS: The average intercostal distance was 21, 23 and 26 mm at the lateral border of the paraspinous muscles, and the mid scapular and posterior axillary lines, respectively. The intercostal nerve was exposed to injury in 85%, 100% and 100% of patients at the 3 sites, respectively. The intercostal artery was exposed below the 11th rib in 30%, 60% and 70% of cadavers, respectively, and it was 6 mm from the rib in 25% of interspaces. The intercostal vein, which was exposed below the 11th rib in 0%, 5% and 10% of cadavers, respectively, was least likely to be injured. CONCLUSIONS: Intercostal vessels are at risk for damage during percutaneous nephrostolithotomy in a significant number of patients. Access placement lateral to the paraspinous muscles and in the lower half of the 11th intercostal space may decrease damage to the intercostal artery and nerve. Injury to the intercostal vessels and nerve may explain the increased risk of bleeding and pain during supracostal percutaneous nephrostolithotomy. Minimizing injury may decrease blood loss and pain.

Surface anatomy and surface landmarks for thoracic surgery: Part II.

Surface anatomy is an integral part of a thoracic surgeon's armamentarium to assist with the diagnosis, staging, and treatment of thoracic pathology. As reviewed in this article, the surface landmarks of the lungs, heart, great vessels, and mediastinum are critical for appropriate patient care and should be learned in conjunction with classic anatomy.

Thoracolumbar interfascial plane block for postoperative analgesia in spine surgery: A systematic review and meta-analysis.

INTRODUCTION: Thoracolumbar interfascial plane (TLIP) block has been discussed widely in spine surgery. The aim of our study is to evaluate analgesic efficacy and safety of TLIP block in spine surgery. METHOD: We performed a quantitative systematic review. Randomized controlled trials that compared TLIP block to non-block care or wound infiltration for patients undergoing spine surgery and took the pain or morphine consumption as a primary or secondary outcome were included. The primary outcome was cumulative opioid consumption during 0-24-hour. Secondary outcomes included postoperative pain intensity, rescue analgesia requirement, and adverse events. RESULT: 9 randomized controlled trials with 539 patients were included for analysis. Compared with non-block care, TLIP block was effective to decrease the opioid consumption (WMD -16.00; 95%CI -19.19, -12.81; p<0.001; I2 = 71.6%) for the first 24 hours after the surgery. TLIP block significantly reduced postoperative pain intensity at rest or movement at various time points compared with non-block care, and reduced rescue analgesia requirement ((RR 0.47; 95%CI 0.30, 0.74; p = 0.001; I2 = 0.0%) and postoperative nausea and vomiting (RR 0.58; 95%CI 0.39, 0.86; p = 0.006; I2 = 25.1%). Besides, TLIP block is superior to wound infiltration in terms of opioid consumption (WMD -17.23, 95%CI -21.62, -12.86; p<0.001; I2 = 63.8%), and the postoperative pain intensity at rest was comparable between TLIP block and wound infiltration. CONCLUSION: TLIP block improved analgesic efficacy in spine surgery compared with non-block care. Furthermore, current literature supported the TLIP block was superior to wound infiltration in terms of opioid consumption.

Neurogenetics: singing in the brain.

The fruitless gene is well-known to play a key role in determining the sexual identity of the fruitfly's nervous system, but new results show that doublesex is also required in thoracic neurons to generate normal male lovesongs.

Mortality after traumatic spinal cord injury: 50 years of follow-up.

OBJECTIVE: To study mortality and causes of death in an unselected geographically defined cohort of patients with traumatic spinal cord injury (TSCI), 1952-2001. METHODS: Patients were identified from hospital records. The date of death was obtained from the National Population Register, and causes of death recorded by linkage to the Norwegian Cause of Death Registry. Patient mortality was compared with mortality in the Norwegian population using standardised mortality ratios (SMR) adjusted for age and gender. RESULTS: 401 patients (70 women and 331 men) were identified. By 31 August 2008, 173 were dead. Median survival time in deceased patients was 7.4 years; 6.9 years for patients with cervical injuries and 8.2 years for patients with thoracolumbosacral injuries (TLS). TSCI patients had an increased mortality (SMR 1.85) compared with the Norwegian population. SMR did not change during the observation period. SMR was significantly higher for women than for men (2.88 vs 1.72), and higher in patients with complete TSCI compared with patients with incomplete TSCI (4.23 vs 1.25). SMR was 6.70 for patients with complete cervical injuries and 3.07 for patients with complete TLS injuries. Cause specific SMR were 1.96 for respiratory disease, and for suicide including accidental poisoning 3.70 for men and 37.59 for women. CONCLUSIONS: Patients with a TSCI, and especially women, have an increased mortality despite modern treatment and care. Special attention should be paid to respiratory dysfunction and pulmonary infections, and to prevent suicide and accidental poisoning.

Sensory capacity of reinnervated skin after redirection of amputated upper limb nerves to the chest.

Targeted reinnervation is a new neural-machine interface that has been developed to help improve the function of new-generation prosthetic limbs. Targeted reinnervation is a surgical procedure that takes the nerves that once innervated a severed limb and redirects them to proximal muscle and skin sites. The sensory afferents of the redirected nerves reinnervate the skin overlying the transfer site. This creates a sensory expression of the missing limb in the amputee's reinnervated skin. When these individuals are touched on this reinnervated skin they feel as though they are being touched on their missing limb. Targeted reinnervation takes nerves that once served the hand, a skin region of high functional importance, and redirects them to less functionally relevant skin areas adjacent to the amputation site. In an effort to better understand the sensory capacity of the reinnervated target skin following this procedure, we examined grating orientation thresholds and point localization thresholds on two amputees who had undergone the targeted reinnervation surgery. Grating orientation thresholds and point localization thresholds were also measured on the contralateral normal skin of the targeted reinnervation amputees and on analogous sites in able-bodied controls. Grating orientation thresholds for the reinnervated skin of the targeted reinnervation amputees were found to be similar to normal ranges for both the amputees' contralateral skin and also for the control population. Point localization thresholds for these amputees were found to be lower for their reinnervated skin than for their contralateral skin. Reinnervated point localization thresholds values were also lower in comparison to homologous chest sites on the control population. Mechanisms appear to be in place to maximize re-established touch input in targeted reinnervation amputees. It seems that sound sensory function is provided to the denervated skin of the residual limb when connected to afferent pathways once serving highly functionally relevant regions of the brain. This suggests that tactile interface devices could be used to give a physiologically appropriate sense of touch to a prosthetic limb, which would likely help with better functional utilization of the prosthetic device and possibly help to more effectively integrate the device with the user's self-image.

Redirection of cutaneous sensation from the hand to the chest skin of human amputees with targeted reinnervation.

Amputees cannot feel what they touch with their artificial hands, which severely limits usefulness of those hands. We have developed a technique that transfers remaining arm nerves to residual chest muscles after an amputation. This technique allows some sensory nerves from the amputated limb to reinnervate overlying chest skin. When this reinnervated skin is touched, the amputees perceive that they are being touched on their missing limb. We found that touch thresholds of the reinnervated chest skin fall within near-normal ranges, indicating the regeneration of large-fiber afferents. The perceptual identity of the limb and chest was maintained separately even though they shared a common skin surface. A cutaneous expression of proprioception also occurred in one reinnervated individual. Experiments with peltier temperature probes and surface electrical stimulation of the reinnervated skin indicate the regeneration of small diameter temperature and pain afferents. The perception of an amputated limb arising from stimulation of reinnervated chest skin may allow useful sensory feedback from prosthetic devices and provides insight into the mechanisms of neural plasticity and peripheral regeneration in humans.