| 1. |
|
|
| 2. |
- Bergmeister, Konstantin D., et al.
(författare)
-
Broadband prosthetic interfaces: Combining nerve transfers and implantable multichannel EMG technology to decode spinal motor neuron activity
- 2017
-
Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 11, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- Modern robotic hands/upper limbs may replace multiple degrees of freedom of extremity function. However, their intuitive use requires a high number of control signals, which current man-machine interfaces do not provide. Here, we discuss a broadband control interface that combines targeted muscle reinnervation, implantable multichannel electromyographic sensors, and advanced decoding to address the increasing capabilities of modern robotic limbs. With targeted muscle reinnervation, nerves that have lost their targets due to an amputation are surgically transferred to residual stump muscles to increase the number of intuitive prosthetic control signals. This surgery re-establishes a nerve-muscle connection that is used for sensing nerve activity with myoelectric interfaces. Moreover, the nerve transfer determines neurophysiological effects, such as muscular hyper-reinnervation and cortical reafferentation that can be exploited by the myoelectric interface. Modern implantable multichannel EMG sensors provide signals from which it is possible to disentangle the behavior of single motor neurons. Recent studies have shown that the neural drive to muscles can be decoded from these signals and thereby the user's intention can be reliably estimated. By combining these concepts in chronic implants and embedded electronics, we believe that it is in principle possible to establish a broadband man-machine interface, with specific applications in prosthesis control. This perspective illustrates this concept, based on combining advanced surgical techniques with recording hardware and processing algorithms. Here we describe the scientific evidence for this concept, current state of investigations, challenges, and alternative approaches to improve current prosthetic interfaces.
|
|
| 3. |
- Bergmeister, Konstantin Davide, et al.
(författare)
-
Motor unit characteristics after selective nerve transfers
- 2021
-
Ingår i: Bionic Limb Reconstruction. - Cham : Springer International Publishing. ; , s. 83-91
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Selective nerve transfers are used in biological and bionic extremity reconstruction to restore and improve extremity function. Here, peripheral nerves are rerouted to various target muscles, and thereby the structural composition of motor units is surgically altered. Previous studies have shown a high success rate of successful reinnervation of above 90% after these nerve transfers. In targeted muscle reinnervation, nerve transfers are applied to reroute amputated nerves to more proximal muscles in the stump and thereby increase the number of prosthetic control signals. Because donor nerves physiologically supply multiple muscles but are transferred to a single target muscle, the innervation ratio between donor and recipient is substantially altered. This changes the characteristics of the motor unit of the target muscles that we extensively investigated in a novel nerve transfer animal model. In this chapter, we illustrate this model, the effect of nerve transfers on motor unit physiology, as well as the implications on improving the interface between man and machine in prosthetic extremity reconstruction. In addition, first results on the effect of targeted muscle reinnervation on human motor unit physiology are described.
|
|
| 4. |
- Bergmeister, Konstantin D, et al.
(författare)
-
Peripheral nerve transfers change target muscle structure and function
- 2019
-
Ingår i: Science advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5:1
-
Tidskriftsartikel (refereegranskat)abstract
- Selective nerve transfers surgically rewire motor neurons and are used in extremity reconstruction to restore muscle function or to facilitate intuitive prosthetic control. We investigated the neurophysiological effects of rewiring motor axons originating from spinal motor neuron pools into target muscles with lower innervation ratio in a rat model. Following reinnervation, the target muscle's force regenerated almost completely, with the motor unit population increasing to 116% in functional and 172% in histological assessments with subsequently smaller muscle units. Muscle fiber type populations transformed into the donor nerve's original muscles. We thus demonstrate that axons of alternative spinal origin can hyper-reinnervate target muscles without loss of muscle force regeneration, but with a donor-specific shift in muscle fiber type. These results explain the excellent clinical outcomes following nerve transfers in neuromuscular reconstruction. They indicate that reinnervated muscles can provide an accurate bioscreen to display neural information of lost body parts for high-fidelity prosthetic control.
|
|
| 5. |
- Campanini, Isabella, et al.
(författare)
-
Fundamental Concepts of Bipolar and High-Density Surface EMG Understanding and Teaching for Clinical, Occupational, and Sport Applications: Origin, Detection, and Main Errors
- 2022
-
Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 22:11
-
Forskningsöversikt (refereegranskat)abstract
- Surface electromyography (sEMG) has been the subject of thousands of scientific articles, but many barriers limit its clinical applications. Previous work has indicated that the lack of time, competence, training, and teaching is the main barrier to the clinical application of sEMG. This work follows up and presents a number of analogies, metaphors, and simulations using physical and mathematical models that provide tools for teaching sEMG detection by means of electrode pairs (1D signals) and electrode grids (2D and 3D signals). The basic mechanisms of sEMG generation are summarized and the features of the sensing system (electrode location, size, interelectrode distance, crosstalk, etc.) are illustrated (mostly by animations) with examples that teachers can use. The most common, as well as some potential, applications are illustrated in the areas of signal presentation, gait analysis, the optimal injection of botulinum toxin, neurorehabilitation, ergonomics, obstetrics, occupational medicine, and sport sciences. The work is primarily focused on correct sEMG detection and on crosstalk. Issues related to the clinical transfer of innovations are also discussed, as well as the need for training new clinical and/or technical operators in the field of sEMG.
|
|
| 6. |
- Clarke, Alexander Kenneth, et al.
(författare)
-
Deep learning for robust decomposition of high-density surface EMG signals
- 2021
-
Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531. ; 68:2, s. 526-534
-
Tidskriftsartikel (refereegranskat)abstract
- Blind source separation (BSS) algorithms, such as gradient convolution kernel compensation (gCKC), can efficiently and accurately decompose high-density surface electromyography (HD-sEMG) signals into constituent motor unit (MU) action potential trains. Once the separation matrix is blindly estimated on a signal interval, it is also possible to apply the same matrix to subsequent signal segments. Nonetheless, the trained separation matrices are sub-optimal in noisy conditions and require that incoming data undergo computationally expensive whitening. One unexplored alternative is to instead use the paired HD-sEMG signal and BSS output to train a model to predict MU activations within a supervised learning framework. A gated recurrent unit (GRU) network was trained to decompose both simulated and experimental unwhitened HD-sEMG signal using the output of the gCKC algorithm. The results on the experimental data were validated by comparison with the decomposition of concurrently recorded intramuscular EMG signals. The GRU network outperformed gCKC at low signal-to-noise ratios, proving superior performance in generalising to new data. Using 12 seconds of experimental data per recording, the GRU performed similarly to gCKC, at rates of agreement of 92.5% (84.5%-97.5%) and 94.9% (88.8%-100.0%) respectively for GRU and gCKC against matched intramuscular sources.
|
|
| 7. |
|
|
| 8. |
- Dall'orso, Sofia, 1992, et al.
(författare)
-
Development of functional organization within the sensorimotor network across the perinatal period
- 2022
-
Ingår i: Human Brain Mapping. - : Wiley. - 1097-0193 .- 1065-9471. ; 43:7, s. 2249-2261
-
Tidskriftsartikel (refereegranskat)abstract
- In the mature human brain, the neural processing related to different body parts is reflected in patterns of functional connectivity, which is strongest between functional homologs in opposite cortical hemispheres. To understand how this organization is first established, we investigated functional connectivity between limb regions in the sensorimotor cortex in 400 preterm and term infants aged across the equivalent period to the third trimester of gestation (32–45 weeks postmenstrual age). Masks were obtained from empirically derived functional responses in neonates from an independent data set. We demonstrate the early presence of a crude but spatially organized functional connectivity, that rapidly matures across the preterm period to achieve an adult-like configuration by the normal time of birth. Specifically, connectivity was strongest between homolog regions, followed by connectivity between adjacent regions (different limbs but same hemisphere) already in the preterm brain, and increased with age. These changes were specific to the sensorimotor network. Crucially, these trajectories were strongly dependent on age more than age of birth. This demonstrates that during the perinatal period the sensorimotor cortex undergoes preprogrammed changes determining the functional movement organization that are not altered by preterm birth in absence of brain injury.
|
|
| 9. |
- Dall'orso, Sofia, 1992, et al.
(författare)
-
The “Little Person” in the Brain Who Helps to Direct Our Movements
- 2023
-
Ingår i: Frontiers for Young Minds. - : Frontiers Media SA. - 2296-6846. ; 11
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Brain Is Organized for Maximum Efficiency Our brains interpret the world around us, think, imagine, control our movements, and much more. This seems like a lot of work for one small organ! How can the brain control so many different tasks? The best way to deal with many duties is to distribute the work, and this is how the brain does it. Specific parts of the brain are responsible for processing what we see, controlling how we speak, regulating how we move, and so on. In a busy office building, people who need to speak to each other regularly will often have their desks near each other, but people who have very different jobs and tasks can work on separate floors. It would not make sense for members of the same team to go up and down the stairs all day when they could just sit together! Putting people with similar tasks near each other allows them to work faster. The brain uses a similar strategy. Similar brain functions are controlled by brain regions that are close to each other. This means that the brain regions that often work together can communicate quickly and efficiently.
|
|
| 10. |
- Dideriksen, Jakob L., et al.
(författare)
-
Electrical stimulation of afferent pathways for the suppression of pathological tremor
- 2017
-
Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 11, s. 1-11
-
Tidskriftsartikel (refereegranskat)abstract
- Pathological tremors are involuntary oscillatory movements which cannot be fully attenuated using conventional treatments. For this reason, several studies have investigated the use of neuromuscular electrical stimulation for tremor suppression. In a recent study, however, we found that electrical stimulation below the motor threshold also suppressed tremor, indicating involvement of afferent pathways. In this study, we further explored this possibility by systematically investigating how tremor suppression by afferent stimulation depends on the stimulation settings. In this way, we aimed at identifying the optimal stimulation strategy, as well as to elucidate the underlying physiological mechanisms of tremor suppression. Stimulation strategies varying the stimulation intensity and pulse timing were tested in nine tremor patients using either intramuscular or surface stimulation. Significant tremor suppression was observed in six patients (tremor suppression > 75% was observed in three patients) and the average optimal suppression level observed across all subjects was 52%. The efficiency for each stimulation setting, however, varied substantially across patients and it was not possible to identify a single set of stimulation parameters that yielded positive results in all patients. For example, tremor suppression was achieved both with stimulation delivered in an out-of-phase pattern with respect to the tremor, and with random timing of the stimulation. Overall, these results indicate that low-current stimulation of afferent fibers is a promising approach for tremor suppression, but that further research is required to identify how the effect can be maximized in the individual patient.
|
|
