Somatosensory-to-auditory cross-modal plasticity in cochlear implanted children

描述(申请人提供)：神经科学的一个共同原则是，失去刺激的大脑具有重组的能力和倾向。也就是说，完整的感觉通道(例如，听力、视觉)可以招募剥夺通道的皮层--称为跨通道重组。一种自然发生的感觉剥夺形式是耳聋，在这种形式下，已经被证明发生了跨模式的重组。事实上，几项研究已经在动物和人类身上证明了令人信服的证据，即视觉系统可以在耳聋时招募听觉皮质。相比之下，相对较少的研究表明，在聋人动物和人类中，体感系统对听觉皮质的跨模式招募。人工耳蜗(CI)是一种通过电刺激VIII神经为听觉系统提供声音通道的装置。事实证明，这些设备对许多聋人成人和儿童都有好处，许多人达到了很高的行为熟练程度(例如，言语感知)。另一方面，一些孩子在使用CI方面并不是很成功。此外，植入年龄、设备编程和使用一致性等因素只能解释CI儿童行为表现的部分差异。然而，最近的研究表明，患有顺应性障碍的成年人在视觉和听觉系统之间表现出的跨模式重组程度与这些个体的行为表现有关。由于发育中大脑的高度可塑性，以及跨模式重组似乎与行为结果有关，有理由相信跨模式重组可能发生，并对顺铂儿童的功能表现产生负面影响。据我们所知，目前还没有关于顺应性脑损伤儿童躯体感觉-听觉(SS-A)跨模式重组的研究。然而，由于躯体感觉和听觉系统在重叠的频率范围内对几乎相同的物理现象(即以振荡形式的机械压力)做出反应，因此SS-A跨模式重组很可能发生在听觉缺失的系统中。也就是说，听觉系统已经做好了处理体感刺激的准备，在大脑皮层的某些区域，可能比视觉刺激更能处理体感刺激。如果在CI儿童中发生SS-A跨模式重组，可能会对他们的行为表现产生不利影响。因此，我们提出了一项具有以下目的的研究：1)使用高密度脑电检测人工耳蜗术后儿童的体感-听觉跨模式重组；2)研究人工耳蜗术后儿童体感-听觉跨模式重组与功能表现(言语知觉)的关系。我们假设，高密度脑电和皮层活动的电流源重建将揭示顺式脑缺血儿童的SS-A跨模式重组，并且这些发现将与这些儿童的行为结局负相关。了解和利用顺铂儿童的皮质可塑性不仅是神经科学研究的最近焦点，而且是一项有价值的努力，可能会改善这些患者的临床治疗和管理。

DESCRIPTION (provided by applicant): A common tenet of neuroscience is that a brain deprived of stimulation has the ability and tendency to re-organize. That is, intact sensory modalities (e.g., hearing, vision) can recruit the cortices of deprived modalities-known as cross-modal re-organization. A naturally occurring form of sensory deprivation in which cross-modal re-organization has been shown to occur is deafness. In fact, several studies have demonstrated convincing evidence in both animals and humans that the visual system can recruit the auditory cortex in deafness. In contrast, relatively few investigations have shown cross-modal recruitment of the auditory cortex by the somatosensory system in deaf animals and humans. Cochlear implants (CI) are devices that provide access to sound for the auditory system by electrically stimulating the VIII nerve. These devices have proven to be beneficial to many deaf adults and children, with many achieving high levels of behavioral proficiency (e.g., speech perception). On the other hand, some children do not have a great deal of success with CIs. Furthermore, factors such as age of implantation, device programming, and consistency of use have only been able to explain some of the variation in behavioral performance in CI children. However, recent studies have revealed that the degree of cross-modal re-organization between the visual and auditory systems exhibited by adults with CIs is correlated with behavioral performance in these individuals. Due to the high degree of plasticity in the developing brain and because cross-modal re-organization appears to have bearing on behavioral outcomes, it is reasonable to believe that cross-modal re-organization could occur and negatively affect functional performance in children with CIs. No study, to our knowledge, has been done to investigate somatosensory-to-auditory (SS-A) cross-modal re-organization in children with CIs. However, because the somatosensory and auditory systems are responsive to virtually the same physical phenomena (i.e., mechanical pressure in the form of oscillations) in overlapping frequency ranges, it is highly plausible that SS-A cross-modal re-organization could occur in an auditorily deprived system. That is, the auditory system is primed to process somatosensory stimuli, maybe even more so than visual stimuli in some areas of the cortex. If SS-A cross-modal re-organization is occurring in CI children, it may be adversely affecting their behavioral performance. Thus, we propose a study with the following aims: 1) To examine somatosensory-to-auditory cross-modal reorganization using high-density EEG in children with cochlear implants; 2) To examine the relationship between somatosensory-to-auditory cross-modal re-organization and functional performance (speech perception) in children with cochlear implants. We hypothesize that high-density EEG and current source reconstruction of cortical activity will reveal SS-A cross-modal re- organization in children with CIs, and that these findings will be negatively correlated with behavioral outcome in these children. Understanding and being able to harness cortical plasticity in children with CIs is not only a recent focus of neuroscientific research, but also represents a worthy endeavor that could lead to improved clinical treatment and management for these patients.