移植：新手上感觉的恢复

在移植手术后四个月一位35年前经历过手切除手术的54岁的男性，在移植手术后大脑中原先“手掌区域”又显示出触摸的感觉
这个发现主要集中在这个男人右侧移植的附带主要神经，骨骼、筋腱、和肌肉的手掌上。“这还需要确认”这个研究的负责人Scott H. Frey谈到：“大脑中关于每根手指的感觉将会慢慢增加。在手术后四个月，基本的触摸感觉就被报告出现在手掌底部的拇指下方的肌肉和拇指侧面靠近桡神经的区域。”
磁共振技术被用于记录当感官刺激被传达到手和面对移植接受体时大脑的活动。结果显示感觉信号的传导从移植的手上传递到截肢手术之前大脑接受手部感觉信号的区域。
从大脑的角度来说这个个体是非常独特的。Frey谈到“我们知道当一个人失去了他的手，大脑接收手部感觉信号的区域会重新组织已取代原来的感觉传导方式。现在，甚至在截肢35年之后，这个感觉传入的恢复看起来可以找回原来手部感觉，这种大脑接受这些改变的能力完全是因为在接受截肢手术时他的大脑已经完全发育成熟”
重新组织感觉区域开始在失去肢体一小时后开始。研究显示神经元开始从新的肢体上接受感觉信号。“在那里发生了什么还不完全清楚，也不清楚这个改变会持续多长时间”，Frey说：“但是一种思路是。于这个情况没有大脑的会让这种空白的状态停留很长。”之后这个受伤的男人报告称幻觉逐渐的减少并且疼痛的报告经常出现在接受移植的患者中。
Frey还谈到“什么是手的移植在历史上第一次允许我们在去问的问题是：在从新组织建立之后是否可能去保留这个感觉的恢复到大脑？这个回答看起来会是“是”答案将随着在移植手术之案例增多而更加确定。”

Transplantation: Signs of Sensory Recovery in New Hand
Four months after a hand transplant - 35 years after amputation - a 54-year-old man’s emerging sense of touch is registered in the former "hand area" of his brain, says a neuroscientist. 10/10/2008
The finding centres only on the man's right palm of a donated hand, which was attached along with major nerves, bones, tendons, and muscle. Still to be determined, lead author Scott H. Frey said, is how the brain’s map of the individual fingers will evolve with increasing sensation. Just four months post-surgery, initial touch sensations were reported on the thenar eminence - muscle on the palm just below the thumb - and on the lateral base of the thumb near the radial nerve.
Functional magnetic resonance imaging was used to record brain activity while sensory stimuli were delivered to the hands and faces of the transplant recipient and four control participants. Results showed that sensory signals from the transplanted hand are being processed in the same brain regions that would have formerly handled sensations from the hand prior to amputation.
"This individual is very unique from a brain standpoint," Frey said. "We know that when someone loses a hand, there are reorganisational changes that take place in areas of the brain that have received sensory input from that hand. Yet, even after 35 years, the restoration of sensory input seems capable of recapturing the former territory of the hand. The capacity of the brain to reverse these changes is all the more striking in light of the fact that his brain was fully mature when the amputation occurred.”
Reorganisation in sensory regions begins within hours of a limb loss. Research has shown that neurons that had been devoted to receiving sensory inputs from the limb take on new duties. Exactly what happens is not entirely clear, nor is it certain how long such changes continue, Frey said, "but one way to think about it is that none of the brain's real estate is left vacant for very long". Over time, the injured man reported gradual reductions of phantom sensations and pain often reported by amputees.
"What this hand transplant allows us to ask for the very first time in history is: Following reorganisational changes, is it possible to reverse the restoration of sensory input into the brain? The answer, which appears to be yes, extends well beyond the case of hand transplants," Frey said.