Introduction
Losing a limb can be a life-altering experience that can have both physical and psychological impacts. For people who have undergone amputation, using a prosthesis can greatly improve their daily life.
In recent years, advancements in technology have allowed for the development of more advanced prostheses that can mimic the functionality and appearance of a human limb. But how does the use of a prosthesis affect the brain activity of amputees?
we’ll explore the research on how prosthetic rehabilitation can lead to changes in neural activity in upper limb amputees. The prevalence and causes of amputation: Losing a limb is a life-changing experience that affects millions of people around the world. According to various studies, almost two-thirds of the population falls into the category of upper limb amputees, which can be caused by various causes such as trauma, tumors, and vascular disease. Amputation not only affects a person’s appearance, but it also leads to changes in brain regions related to the control and sensation of the amputated limb.
Changes in the brain following amputation
These changes are evident in the contralateral motor and sensory cortices of the amputated limb and may extend to cortical areas responsible for hand movement and sensation as the amputee performs tasks with the foot. It’s interesting to note that the human body is incredibly adaptable and can rewire itself to compensate for lost limbs. This blog post aims to explore the changes that occur in the brain after amputation, how these changes affect amputees, and how technology can help overcome the challenges they face. Delve into the world of amputation and discover how the brain adapts to this life-changing event.
Types of prostheses
Upper limb amputees often face many challenges in their daily lives that can greatly affect their quality of life. To meet these challenges, many amputees choose prosthetic limbs. There are mainly two types of upper limb prostheses. passive and active. Passive prostheses are primarily cosmetic in nature and have no functional capacity. Active prostheses, on the other hand, are functional prostheses that can be controlled by the patient to perform daily tasks further They can be divided into two categories. Mechanical and surface electromyography (sEMG) prostheses. Mechanical prostheses are usually controlled by shoulder movements and have a clasp-like ( hook terminal device) structure that looks very different from a human hand. In contrast, sEMG prostheses closely resemble human limbs and are controlled by electromyographic signals produced by the appropriate muscles used to control the hand. These prostheses offer a greater range of hand motion with multiple degrees of freedom.
impact of prosthetic rehabilitation on brain activity
“For amputees who use a prosthesis, the prosthesis enables them to perform movements or activities that were impossible due to amputation. Their related cortices in the brain may also show changes with the introduction of the prosthesis. Indeed, numerous studies have shown changes in the brains of amputees following the use of prostheses [14,15,16]. In an fMRI study, researchers found that amputees who used prostheses daily showed more robust selective responses to images of prostheses in visual hand-selective areas of the brain [14]. Using cerebral blood perfusion as a functional indicator, Liu and her colleague (2016) found significant changes in multiple brain areas in amputees who underwent rehabilitation using prostheses [15].” The choice of prosthesis can greatly affect the level of function and satisfaction an individual experiences.
In particular, prostheses that closely mimic a human limb in terms of appearance and functionality can provide significant benefits. Not only do they help the individual feel more confident and comfortable in social situations, but they can also improve their ability to perform everyday tasks. With advanced technology, surface electromyography (sEMG) prostheses can even be controlled by the muscles used to control the hand, allowing for multiple degrees of freedom in hand movements. As such, choosing a prosthesis that closely mimics a human limb can greatly improve an individual`s quality of life and independence.
One such prosthesis “The Linksense hand collects EMG from the forearm through eight sEMG sensors placed on the targeted muscles. Then it uses algorithms to recognize the patterns of the EMG to control the prosthesis. Each finger of the hand can be controlled independently. The thumb has two degrees of freedom, whereas the rest of the fingers have one degree of freedom, adding up to six degrees of freedom. This allows for complex movements such as grabbing a complex-shaped object. Even though the functions of this prosthesis are still far from a human hand, it could still serve to improve an amputee’s quality of life significantly.”
This study used a novel approach
Monitor brain activity in amputees over a six-week rehabilitation period. This approach allowed us to gain a more detailed understanding of neural activity changes that occurred during rehabilitation, with a particular focus on the predicted timeframe during exercise where the neural activity changes were greatest.
The methodology involved in the research is that “ the participant received rehabilitation training for six weeks. He was trained six days a week and three hours per day. Each rehabilitation training session consisted of controlling the prosthesis (using EMG) to perform multiple movements, including the following: (1) thumb bending; (2) index finger bending; (3) middle finger bending; (4) fist; (5) pinching; (6) OK gesture; (7). a combination of either the fist, pinching, or OK gesture with the thumb and index finger spread out. The subject was instructed to practice the above movements at his own pace during the training session. After the first week of training, we added more complicated movements to our training session, including movements that frequently occur in daily life (e.g., grabbing a water mug and drinking water, transporting an object, opening and closing the door).”
The result shows
“We measured sEMG from the participant’s forearms before and at the end of each week’s training.” “We observed an increase in the MDF (refers to The median frequency) of the forearm of the left or amputated side over the training period, suggesting an increase in the proportion of fast muscle fibers. In comparison, the right or control side showed no noticeable change during the six weeks of training.” “We hypothesized that there would be changes in his muscle composition and brain activity during the rehabilitation training. We computed MDF based on EMG from both left and right forearms. MDF is an indicator of muscle composition, with a higher MDF indicating a higher proportion of fast muscle fibers. We observed an increase in MDF across time on the amputated side, suggesting a significant increase in fast muscle fibers with training. The fast muscle fibers are typically linked to strength and movement; it is possible that fast muscle fibers increased as a result of sustained hand movement training over the course of six weeks. In comparison, the MDF on the control side of the forearm showed little to no change over the six weeks This could be because the subject uses his right hand regularly and has maintained a sufficient amount of fast muscle fibers.” “Our study provides a first look at how muscle and brain activity changes over time in an amputee with sustained rehabilitation training using an sEMG prosthesis.
Many open questions remain
(1) How would different training protocols influence physiological and neural changes;
(2) Does the length of time a subject spends as an amputee affect the changes we observe?
Future studies could further investigate these questions to broaden our understanding of rehabilitation-promoted changes in amputees.”
References
Original research study :Physiological and Neural Changes with Rehabilitation Training in a 53-Year Amputee: A Case Study (https://www.mdpi.com/2076-3425/12/7/832
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