Gustave Dit Duflo S, Borel L, Harlay F, Léonard J, Lacour M
UMR 6562 Neurobiologie Intégrative et Adaptative, Université de Provence/CNRS, Marseille, France.
Exp Brain Res. 1998 Jun;120(4):439-49. doi: 10.1007/s002210050417.
The purpose of this study was to investigate changes in neck muscle and eye movement responses during the early stages of vestibular compensation (first 3 weeks after unilateral vestibular neurectomy, UVN). Electromyographic (EMG) activity from antagonist neck extensor (splenius capitis) and flexor (longus capitis) muscles and eye movements were recorded during sinusoidal visual and/or otolith vertical linear stimulations in the 0.05-1 Hz frequency range (corresponding acceleration range 0.003-1.16 g) in the head-fixed alert cat. Preoperative EMG activity from the splenius and longus capitis muscles showed a pattern of alternate activation of the antagonist neck muscles in all the cats. After UVN, two motor strategies were observed. For three of the seven cats, the temporal activation of the individual neck muscles was the same as that recorded before UVN. For the other four cats, UVN resulted in a pattern of coactivation of the flexor and extensor neck muscles because of a phase change of the splenius capitis. In both subgroups, the response patterns of the antagonist neck muscles were consistent for each cat independently of the experimental conditions, throughout the 3 weeks of testing. Cats displaying alternate activation of antagonist neck muscles showed an enhanced gain of the visually induced neck responses, particularly in the high range of stimulus frequency, and a gain decrease in the otolith-induced neck responses at the lowest frequency (0.25 Hz) only. By contrast, for cats with neck muscle coactivation, the gain of the visually induced neck responses was basically unaffected relative to preoperative values, whereas otolith-induced neck responses were considerably decreased in the whole range of stimulation. As concerns oculomotor responses, results in the two subgroups of cats were similar. The optokinetic responses were not affected by the vestibular lesion. On the contrary, otolith-induced eye responses showed a gain reduction and a phase lead. Deficits and short-term changes after UVN of otolith- and semicircular canal-evoked collic and ocular responses are compared.
本研究的目的是调查前庭代偿早期阶段（单侧前庭神经切除术，UVN后前3周）颈部肌肉和眼球运动反应的变化。在头固定清醒猫中，于0.05 - 1 Hz频率范围（相应加速度范围0.003 - 1.16 g）进行正弦视觉和/或耳石垂直线性刺激期间，记录拮抗肌颈伸肌（头夹肌）和屈肌（头长肌）的肌电图（EMG）活动以及眼球运动。术前头夹肌和头长肌的EMG活动显示，所有猫的拮抗肌颈部肌肉均呈交替激活模式。UVN后，观察到两种运动策略。七只猫中的三只，单个颈部肌肉的时间激活与UVN前记录的相同。对于另外四只猫，由于头夹肌的相位变化，UVN导致屈肌和伸肌颈部肌肉共同激活模式。在两个亚组中，每只猫的拮抗肌颈部肌肉反应模式在整个3周测试期间均与实验条件无关，保持一致。表现出拮抗肌颈部肌肉交替激活的猫，视觉诱发颈部反应的增益增强，特别是在高刺激频率范围内，并且仅在最低频率（0.25 Hz）时耳石诱发颈部反应的增益降低。相比之下，对于颈部肌肉共同激活的猫，视觉诱发颈部反应的增益相对于术前值基本未受影响，而耳石诱发颈部反应在整个刺激范围内显著降低。关于动眼反应，两组猫的结果相似。视动反应不受前庭损伤影响。相反，耳石诱发的眼球反应显示增益降低和相位超前。比较了UVN后耳石和半规管诱发的丘系和眼反应的缺陷及短期变化。
