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

描述（由申请人提供）：神经科学的一个共同原则是，缺乏刺激的大脑具有重组的能力和倾向。也就是说，完整的感觉模态（如听觉、视觉）可以招募被剥夺模态的皮层，这被称为跨模态重组。耳聋是一种自然发生的感觉剥夺形式，其中交叉模态重组已被证明会发生。事实上，一些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的情况下招募听觉皮层。相比之下，相对较少的研究表明，在失聪动物和人类的体感觉系统中，听觉皮层的跨模态招募。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的装置。这些设备已被证明对许多失聪成人和儿童是有益的，其中许多人达到了高水平的行为熟练程度（例如，言语感知）。另一方面，有些孩子在ci方面没有取得很大的成功。此外，植入年龄、设备编程和使用一致性等因素只能解释CI儿童行为表现的一些差异。然而，最近的研究表明，成年CIs患者所表现出的视觉和听觉系统之间的跨模态重组程度与这些个体的行为表现相关。由于发育中的大脑具有高度的可塑性，而且跨模态重组似乎与行为结果有关，我们有理由相信跨模态重组可能会发生，并对CIs儿童的功能表现产生负面影响。据我们所知，还没有研究调查CIs儿童的体感-听觉（SS-A）跨模态重组。然而，由于体感系统和听觉系统在重叠的频率范围内对几乎相同的物理现象（即振荡形式的机械压力）做出反应，因此SS-A跨模态重组可能发生在听觉剥夺的系统中是非常合理的。也就是说，听觉系统已经准备好处理体感刺激，在大脑皮层的某些区域，甚至可能比视觉刺激更重要。如果CI儿童发生SS-A跨模态重组，可能会对其行为表现产生不利影响。因此，我们提出了以下研究目的：1)利用高密度脑电图检查植入人工耳蜗儿童的体感-听觉交叉模态重组；2)探讨植入人工耳蜗儿童体感-听觉跨模态重组与功能表现（言语感知）的关系。我们假设高密度脑电图和皮质活动的电流源重建将揭示CIs儿童的SS-A跨模态重组，并且这些发现将与这些儿童的行为结果负相关。理解并利用CIs儿童的皮质可塑性不仅是近期神经科学研究的焦点，也是一项有价值的努力，可以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.