A primate genesis model of focal dystonia and repetitive strain injury .1. Learning-induced dedifferentiation of the representation of the hand in the primary somatosensory cortex in adult monkeys
A primate genesis model of focal dystonia and repetitive strain injury .1. Learning-induced dedifferentiation of the representation of the hand in the primary somatosensory cortex in adult monkeys
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DOI：
10.1212/wnl.47.2.508
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发表时间：
1996-08-01
期刊：
影响因子：
9.9
通讯作者：
Jenkins, WM
中科院分区：
文献类型：
--
作者：
Byl, NN;Merzenich, MM;Jenkins, WM
在这项研究中，我们测试了重复劳损(RSI)的神经可塑性/学习起源假说，包括职业性局灶性肌张力障碍。在特定形式和适当的行为背景下产生的重复运动会导致控制精细运动的感觉反馈信息的退化，从而导致RSI的“习得”起源。两只成年的新世界猫头鹰猴子接受了一项行为任务的训练，该任务要求它们在短距离内重复快速(20毫秒)打开和关闭的手柄上保持专注的抓握。这些猴子每天完成300次行为测试(1100到3000个运动事件)，准确率为80%到90%。在两只猴子身上都记录到了运动控制障碍。继续进行训练，直到表演准确率降至50%以下。随后，我们对手在初级躯体感觉(SI)皮质区的表征进行了电生理标测研究。在这些猴子中，发现在真正的初级躯体感觉皮质区，SI区3b中的手的表征显著退化，其特征是(1)手部皮肤的皮质表征的去分化，表现为感受野比正常大10到20倍，(2)出现许多覆盖单个手指的整个无毛表面或延伸到两个或更多指的表面的感受野，(3)手掌无毛和背部有毛皮肤的正常分隔区3b的分解，以及(4)区3b的局部移位-重叠的感受野地形图的破坏，由于许多数字感受场与皮质穿透中采样的神经元的场重叠，相隔距离比正常情况下高出四倍以上。因此，在学习环境中应用快速、重复、高度刻板印象的动作可以积极地降低大脑皮质对指导精细运动手运动的感觉信息的表征。这种来自手的感觉反馈信息的皮质可塑性/基于学习的去分化有助于职业性重复劳损的发生，包括手部的局灶性肌张力障碍。RSI患者的成功治疗似乎需要以学习为基础恢复手部感觉反馈信息的差异化表征。
In this study we tested a neuroplasticity/learning origins hypothesis for repetitive strain injuries (RSIs), including occupationally induced focal dystonia. Repetitive movements produced in a specific form and in an appropriate behavioral context cause a degradation of the sensory feedback information controlling fine (m)otor movements, resulting in the ''learned'' genesis of RSIs. Two adult New World owl monkeys were trained at a behavioral task that required them to maintain an attended grasp on a hand grip that repetitively and rapidly (20 msec) opened and closed over short distances. The monkeys completed 300 behavioral trials per day (1,100 to 3,000 movement events) with an accuracy of 80 to 90%. A movement control disorder was recorded in both monkeys. Training was continued until the performance accuracy dropped to below 50%. We subsequently conducted an electrophysiologic mapping study of the representations of the hand within the primary somatosensory (SI) cortical zone. The hand representation in the true primary somatosensory cortical field, SI area 3b, was found to be markedly degraded in these monkeys, as characterized by (1) a dedifferentiation of cortical representations of the skin of the hand manifested by receptive fields that were 10 to 20 times larger than normal, (2) the emergence of many receptive fields that covered the entire glabrous surface of individual digits or that extended across the surfaces of two or more digits, (3) a breakdown of the normally sharply segregated area 3b representations of volar glabrous and dorsal hairy skin of the hand, and (4) a breakdown of the local shifted-overlap receptive field topography of area 3b, with many digital receptive fields overlapping the fields of neurons sampled in cortical penetrations up to more than four times farther apart than normal. Thus, rapid, repetitive, highly stereotypic movements applied in a learning context can actively degrade cortical representations of sensory information guiding fine motor hand movements. This cortical plasticity/learning-based dedifferentiation of sensory feedback information from the hand contributes to the genesis of occupationally derived repetitive strain injuries, including focal dystonia of the hand. Successful treatment of patients with RSI will plausibly require learning-based restoration of differentiated representations of sensory feedback information from the hand.