Skilled independent control of individual motor units via a non-invasive neuromuscular-machine interface

Objective.Brain-machine interfaces (BMIs) have the potential to augment human functions and restore independence in people with disabilities, yet a compromise between non-invasiveness and performance limits their relevance.Approach.Here, we hypothesized that a non-invasive neuromuscular-machine interface providing real-time neurofeedback of individual motor units within a muscle could enable independent motor unit control to an extent suitable for high-performance BMI applications.Main results.Over 6 days of training, eight participants progressively learned to skillfully and independently control three biceps brachii motor units to complete a 2D center-out task. We show that neurofeedback enabled motor unit activity that largely violated recruitment constraints observed during ramp-and-hold isometric contractions thought to limit individual motor unit controllability. Finally, participants demonstrated the suitability of individual motor units for powering general applications through a spelling task.Significance.These results illustrate the flexibility of the sensorimotor system and highlight individual motor units as a promising source of control for BMI applications.

Experimental and Computational Study on Motor Control and Recovery After Stroke: Toward a Constructive Loop Between Experimental and Virtual Embodied Neuroscience

Being able to replicate real experiments with computational simulations is a unique opportunity to refine and validate models with experimental data and redesign the experiments based on simulations. However, since it is technically demanding to model all components of an experiment, traditional approaches to modeling reduce the experimental setups as much as possible. In this study, our goal is to replicate all the relevant features of an experiment on motor control and motor rehabilitation after stroke. To this aim, we propose an approach that allows continuous integration of new experimental data into a computational modeling framework. First, results show that we could reproduce experimental object displacement with high accuracy via the simulated embodiment in the virtual world by feeding a spinal cord model with experimental registration of the cortical activity. Second, by using computational models of multiple granularities, our preliminary results show the possibility of simulating several features of the brain after stroke, from the local alteration in neuronal activity to long-range connectivity remodeling. Finally, strategies are proposed to merge the two pipelines. We further suggest that additional models could be integrated into the framework thanks to the versatility of the proposed approach, thus allowing many researchers to achieve continuously improved experimental design.

Electrical spinal cord stimulation must preserve proprioception to enable locomotion in humans with spinal cord injury

Epidural electrical stimulation (EES) of the spinal cord restores locomotion in animal models of spinal cord injury but is less effective in humans. Here we hypothesized that this interspecies discrepancy is due to interference between EES and proprioceptive information in humans. Computational simulations and preclinical and clinical experiments reveal that EES blocks a significant amount of proprioceptive input in humans, but not in rats. This transient deafferentation prevents modulation of reciprocal inhibitory networks involved in locomotion and reduces or abolishes the conscious perception of leg position. Consequently, continuous EES can only facilitate locomotion within a narrow range of stimulation parameters and is unable to provide meaningful locomotor improvements in humans without rehabilitation. Simulations showed that burst stimulation and spatiotemporal stimulation profiles mitigate the cancellation of proprioceptive information, enabling robust control over motor neuron activity. This demonstrates the importance of stimulation protocols that preserve proprioceptive information to facilitate walking with EES.

Closed-loop control of trunk posture improves locomotion through the regulation of leg proprioceptive feedback after spinal cord injury

After spinal cord injury (SCI), sensory feedback circuits critically contribute to leg motor execution. Compelled by the importance to engage these circuits during gait rehabilitation, assistive robotics and training protocols have primarily focused on guiding leg movements to reinforce sensory feedback. Despite the importance of trunk postural dynamics on gait and balance, trunk assistance has comparatively received little attention. Typically, trunk movements are either constrained within bodyweight support systems, or manually adjusted by therapists. Here, we show that real-time control of trunk posture re-established dynamic balance amongst bilateral proprioceptive feedback circuits, and thereby restored left-right symmetry, loading and stepping consistency in rats with severe SCI. We developed a robotic system that adjusts mediolateral trunk posture during locomotion. This system uncovered robust relationships between trunk orientation and the modulation of bilateral leg kinematics and muscle activity. Computer simulations suggested that these modulations emerged from corrections in the balance between flexor- and extensor-related proprioceptive feedback. We leveraged this knowledge to engineer control policies that regulate trunk orientation and postural sway in real-time. This dynamical postural interface immediately improved stepping quality in all rats regardless of broad differences in deficits. These results emphasize the importance of trunk regulation to optimize performance during rehabilitation.

Mechanisms Underlying the Neuromodulation of Spinal Circuits for Correcting Gait and Balance Deficits after Spinal Cord Injury

Epidural electrical stimulation of lumbar segments facilitates standing and walking in animal models and humans with spinal cord injury. However, the mechanisms through which this neuromodulation therapy engages spinal circuits remain enigmatic. Using computer simulations and behavioral experiments, we provide evidence that epidural electrical stimulation interacts with muscle spindle feedback circuits to modulate muscle activity during locomotion. Hypothesis-driven strategies emerging from simulations steered the design of stimulation protocols that adjust bilateral hindlimb kinematics throughout gait execution. These stimulation strategies corrected subject-specific gait and balance deficits in rats with incomplete and complete spinal cord injury. The conservation of muscle spindle feedback circuits across mammals suggests that the same mechanisms may facilitate motor control in humans. These results provide a conceptual framework to improve stimulation protocols for clinical applications.

Anorectal and perineal pain: new pathophysiological hypothesis

Anorectal and perineal pain has been described in association with a variety of organic conditions but can also occur under circumstances in which organic disorders are absent and pathophysiology is uncertain. The three most common functional disorders causing anorectal and perineal pain are levator ani syndrome, coccygodynia and proctalgia fugax; Alcock's canal syndrome is also responsible for pain in these areas. We review current concepts about these disorders and the approach to diagnosis and management, and offer a provocative interpretation of the role of psychological factors.

[Diverticular disease and its treatment]

Diverticular disease of the colon is being seen with increasing frequency. Not infrequently, the first attack of diverticulitis may result in serious and potentially fatal complications. A period of observation and conservative management is necessary to determine the outcome of a particular attack. Approximately 30% of symptomatic patients require surgical intervention. Controversy still surrounds the appropriate operative approach to be employed in the management of diverticular disease, moreover when it presents with a complication. In general, resection is the procedure of choice for perforating diverticulitis. There is an emerging role for down-staging interventions in the recent literature; with few exception, there is no role for three-stages procedure for diverticular disease. In the setting of stage I or stage II disease (Hinchey classification) primary resection with anastomosis is safe and should be performed. Proximal colostomy formation may be carried out at the discretion of the surgeon if warranted by such local circumstances as contiguous inflammation or macroscopic contamination. For patients with stage III and stage IV disease endcolostomy with Hartmann closure of the rectum is the procedure of choice, although anastomosis with proximal stoma may prove to be an acceptable alternative. We reviewed the changing patterns in the operative treatment in 46 patients admitted to our Division for perforated diverticulitis. We performed the resection with anastomosis in 39 patients with perforation at the II stage; in 7 patients with generalized peritonitis (stage III-IV by Hinchey) we preferred Hartmann intervention in 4 cases and the three-stages procedure in 3 cases. We had no death at all. From 1979 to 1994 we noticed an increasing use of down-staging procedures.

[Treatment of Crohn's disease in the acute phase]

The authors sent a questionnaire containing a series of questions dealing with acute manifestations of Crohn's disease, to eminent surgeons of different surgical schools. Results are interesting because differences are quite evident. In terminal ileitis mimicking acute appendicitis, 75% of surgeons perform an appendectomy. In the case of on acute intestinal obstruction, resection of the diseased bowel with primary anastomosis is preferred. In case of free perforation of the lesion, abdominal and massive hemorrhage, answers need to be analyzed in details.

[Tumors of the large intestine in acute phase]

A retrospective study was carried out on 406 patients operated on for tumours of the large bowel in the acute stage between 1975 and 1985. 285 cases were operated immediately, 53 for acute perforations and 232 for complete occlusions, whereas 121 were operated on with deferred urgency. The surgical approach was generally conservative in 230 cases while in 159 immediate tumour resection was carried out. In the event of conservative operation, a second resection was possible in 94 cases (51.36% of survivors). Immediate resections had a five year survival better than those carried out in several stages (27.50% against 18.28%). However, the immediate postoperative course reported lower mortality. The present study and reported data show that surgical treatment of obstructions and neoplastic perforations of the large bowel is not completely standardised.

[Transduodenal papillosphincteroplasty]

On the basis of a thourough anatomosurgical study of Vater's ampulla and after a critical survey of all surgical techniques for the sphincter of Oddi, the indications for and technique of total papillosphincteroplasty are presented. The results obtained in 544 total papillosphincteroplasties, their possible complications and failure supported by long-term (from 6 months to 7 years) follow-up are discussed. The conclusion is drawn that papillosphincteroplasty is to be considered the surgical technique of choice in the treatment of benign pathology of the main bile way.

[Intrapericardial diaphragmatic hernia]

A case of intrapericardial diaphragmatic hernia with stomach and colon migration is reported. Stress is laid on the problem of early diagnosis, as the condition is usually asymptomatic: the scpra-umbilical median laparotomy approach route is proposed.

[Multiple diverticulosis of the small intestine]

A case of jejunum-ileum multiple diverticulosis observed during a cholecystectomy due to cholelithiasis, is reported. Stress is laid on this unusual localization of diverticulosis in the small intestine. The clinical picture can be silent or present an acute or chronic symptomatology and radical surgical treatment can performed or not. When the disease involves all the intestine, without presenting serious inflammatory phenomena and without clinical symptoms (as in the case observed), medical and not surgical treatment can be envisaged.

[Hepatic echinococcosis. Surgical treatment]

After some general observations on liver echinococcosis (epidemiology, liver topographic anatomy, diagnostics), various surgical techniques proposed for the treatment of this disease are described. Case series observed from 1967 to 1978 and the technique of choice, cystotomy with partial cysto-resection, are presented. The favourable results obtained are underlined.

[Surgery of malignant neoplasms of the esophagus]

A series of malignant cancers of the oesophagus operated in the period 1968-1978 is reported. The importance of preoperative denutrition is considered and the various nutritional techniques are outlined, with a note on their advantages and defects. Right intrathoracic oesophagogastroplasty carried out in malignant cancers of the middle third of the oesophagus is particularly discussed. This surgical technique is held to be preferable to intestinal transpositions in substitution of the oesophagus, and the results obtained in this series support the opinion.

[Ectopic pancreas in the duodenum]

Aberrant pancreas to the duodenal site is a by no means simple problem of diagnosis as it is only rarely that X-ray, gastroscopy or biopsy suggest it. The case of aberrant pancreas in the duodenum, simulating a peptic lesion, is reported. Following an anatomo-pathological study, the typical aspects of the case are stressed.

[Carcinomas of the small intestine]

Two cases of carcinoma of the small intestine are described. In spite of its large epithelial surface, this organ is rarely a cancer site. For these reason, an account is given of cases observed over the previous year. In addition, mention is made of the pathological anatomy, symptomatology, preoperative investigation, and treatment of this form.

[Cholecystosis]

Cholecystosis conditions include those diseases of the gallbladder whose aetiopathogenesis is to be sought in a hyperplasia of the tissues making up the cholecystic wall (hyperplastic forms) and in an overload of this wall on the part of organic substances or minerals such as lipides or calcium salts (thesaurismosic forms). After discussing the classification, pathological anatomy, aetiopathogenesis, frequency, symptomatology, laboratory and radiological examinations, prognosis complications and treatment of these conditions, a personal series of 36 surgically treated cholecystoses is reported.

[Aberrant pancreas in gastric site]

The conclusions contained in recent and past literature regarding the heterotopic pancreas are reviewed. A case of accessory pancreas located in the stomach, whose clinical, radiological and endoscopic aspects simulated a carcinomatous process, is reported. The case is studied anatomo-pathologically and important aspects, including surgical, noted.

[Hepatic artery aneurysm as a cause of hemobilia]

1) Haemobilia must be kept in mind as a cause of gastrointestinal haemorrage. 2) The presence of an hepatic artery aneurysm gives a peculiar triad of symptoms: abdominal pain, gastrointestinal haemorrage and jaundice. 3) Selective angiography is the elective diagnostic aid. 4) The diagnosis may be difficult also at operation, because the aneurysms can be very small. 5) The most used surgical treatment are ligation of the hepatic artery, the excision of aneurism, the endoaneurysmorrhaphy or the end-to-end anastomosis.

[Clinical considerations on retroperitoneal liposarcoma. Report of 2 cases]

Liposarcoma is one of the more common tumours of the soft retroperitoneal tissues. It usually occurs in aged subjects and displays a marked contrast between its malignant histological picture and its protracted, poorly symptomatic clinical picture. Eventually, compression or invasion of nearby organs appears, whereas the patient's general condition is not affected. Two personal cases are described.