Beraneck Mathieu, Idoux Erwin
Centre d'Etude de la SensoriMotricité, CNRS UMR 8194, Université Paris Descartes, Sorbonne Paris Cité Paris, France.
Front Neurol. 2012 Feb 28;3:25. doi: 10.3389/fneur.2012.00025. eCollection 2012.
The sensorimotor transformations performed by central vestibular neurons constantly adapt as the animal faces conflicting sensory information or sustains injuries. To ensure the homeostasis of vestibular-related functions, neural changes could in part rely on the regulation of 2° VN intrinsic properties. Here we review evidence that demonstrates modulation and plasticity of central vestibular neurons' intrinsic properties. We first present the partition of Rodents' vestibular neurons into distinct subtypes, namely type A and type B. Then, we focus on the respective properties of each type, their putative roles in vestibular functions, fast control by neuromodulators and persistent modifications following a lesion. The intrinsic properties of central vestibular neurons can be swiftly modulated by a wealth of neuromodulators to adapt rapidly to temporary changes of ecophysiological surroundings. To illustrate how intrinsic excitability can be rapidly modified in physiological conditions and therefore be therapeutic targets, we present the modulation of vestibular reflexes in relation to the variations of the neuromodulatory inputs during the sleep/wake cycle. On the other hand, intrinsic properties can also be slowly, yet permanently, modified in response to major perturbations, e.g., after unilateral labyrinthectomy (UL). We revisit the experimental evidence, which demonstrates that drastic alterations of the central vestibular neurons' intrinsic properties occur following UL, with a slow time course, more on par with the compensation of dynamic deficits than static ones. Data are interpreted in the framework of distributed processes that progress from global, large-scale coping mechanisms (e.g., changes in behavioral strategies) to local, small-scale ones (e.g., changes in intrinsic properties). Within this framework, the compensation of dynamic deficits improves over time as deeper modifications are engraved within the finer parts of the vestibular-related networks. Finally, we offer perspectives and working hypotheses to pave the way for future research aimed at understanding the modulation and plasticity of central vestibular neurons' intrinsic properties.
当动物面对相互冲突的感觉信息或遭受损伤时，中枢前庭神经元所执行的感觉运动转换会不断适应。为确保前庭相关功能的稳态，神经变化可能部分依赖于对二级前庭神经元（2° VN）内在特性的调节。在此，我们回顾了证明中枢前庭神经元内在特性具有调制和可塑性的证据。我们首先介绍将啮齿动物的前庭神经元划分为不同亚型，即 A 型和 B 型。然后，我们聚焦于每种类型的各自特性、它们在前庭功能中的假定作用、神经调质的快速控制以及损伤后的持续改变。中枢前庭神经元的内在特性可被大量神经调质迅速调制，以快速适应生态生理环境的临时变化。为说明内在兴奋性在生理条件下如何能够快速改变并因此成为治疗靶点，我们介绍了与睡眠/觉醒周期中神经调质输入变化相关的前庭反射调制。另一方面，内在特性也可因重大扰动（例如单侧迷路切除术后）而缓慢但永久性地改变。我们重新审视实验证据，其表明单侧迷路切除术后中枢前庭神经元的内在特性会发生剧烈改变，且时间进程缓慢，更多地与动态缺陷而非静态缺陷的补偿相符。数据在从全局、大规模应对机制（例如行为策略的变化）到局部、小规模机制（例如内在特性的变化）的分布式过程框架内进行解释。在此框架内，随着更深层次的改变在前庭相关网络的更精细部分中得以铭刻，动态缺陷的补偿会随时间改善。最后，我们提供观点和工作假设，为未来旨在理解中枢前庭神经元内在特性的调制和可塑性的研究铺平道路。
