Kilner J M, Fisher R J, Lemon R N
Functional Imaging Laboratory, Institute of Neurology, Queen Square, London, WC1N 3BG. UK.
J Neurophysiol. 2004 Aug;92(2):790-6. doi: 10.1152/jn.01247.2003. Epub 2004 Apr 7.
Oscillatory activity in the primate motor cortex has been shown to be phase locked to oscillations in contralateral hand and forearm muscle activity in the 15- to 30-Hz frequency range. Recent studies have shown that the degree of coupling between the cortex and the periphery is strongly influenced by the type and degree of movements of the digits. It has also been suggested that changes in corticomuscular and muscle-muscle coherence could be modulated by peripheral sensory inputs. In the current study, we investigated task-dependent changes in the coherent coupling of electromyographic (EMG) activity recorded from different intrinsic (abductor pollicis brevis and first dorsal interosseous) and two extrinsic (flexor digitorum superficialis and extensor digitorum communis) hand muscles during performance of a precision-grip task by normal subjects and by a single subject who has a total loss of touch, vibration, pressure, and kinesthetic sensation below the neck. The task required a hold-move-hold pattern of grip force to be exerted on a compliant object with the dominant right hand. We found significant task-related modulation of 15- to 30-Hz coherence between EMG activity in hand muscles in the control subjects. In contrast, the deafferented subject showed very low levels of significant coherence in the 15- to 30-Hz range and no peak at this frequency in the power spectra of her EMG activity. These results suggest that the presence of sensory afferent signals are necessary for the modulation of 15- to 30-Hz oscillations in the motor system.
灵长类动物运动皮层中的振荡活动已被证明与对侧手部和前臂肌肉活动在15至30赫兹频率范围内的振荡锁相。最近的研究表明，皮层与外周之间的耦合程度受手指运动类型和程度的强烈影响。也有人提出，皮质肌肉和肌肉间的相干性变化可由外周感觉输入调节。在本研究中，我们调查了正常受试者和一名颈部以下完全丧失触觉、振动觉、压力觉和本体感觉的受试者在执行精确抓握任务期间，从不同的手部固有肌（拇短展肌和第一背侧骨间肌）和两块手部外在肌（指浅屈肌和指总伸肌）记录的肌电图（EMG）活动的相干耦合的任务依赖性变化。该任务要求用优势右手在一个顺应性物体上施加握力的保持-移动-保持模式。我们发现，在对照受试者中，手部肌肉的EMG活动在15至30赫兹的相干性存在显著的任务相关调制。相比之下，去传入神经的受试者在15至30赫兹范围内的显著相干性水平非常低，并且其EMG活动的功率谱在该频率处没有峰值。这些结果表明，感觉传入信号的存在对于运动系统中15至30赫兹振荡的调制是必要的。
