Cortical current imaging in human infants with babySQUID

描述(申请人提供)：这个探索性项目将评估一种新开发的名为婴儿鱿鱼的仪器在评估人类婴儿大脑功能方面的有用性。小鱿鱼是一种高分辨率脑磁图(MEG)系统，旨在以前所未有的灵敏度和空间分辨率检测婴儿的皮质活动。在距头皮6毫米的地方可以放置一个76兆克传感器阵列，而不是像传统的兆克传感器那样放置在-20毫米处。由于新生儿头皮和头盖骨的总厚度为-4 mm，因此脑磁图信号可以在距脑表面10 mm而不是25 mm处测量。由于脑磁图信号衰减为距离的平方，因此小鱿鱼的脑磁图信号应该是传统脑磁图系统的5倍。在下一阶段的开发中，间隔将从6毫米减少到3毫米，这样信号将增强约10倍。由于具有更小的间隙和更高的传感器密度(成人Megs的通道间距为12-14 mm，而不是30-40 mm)，空间分辨率约为传统系统的3-4倍。初步结果表明，在高信噪比的情况下，可以清楚地测量自发活动，在健康婴儿的信号平均很少的情况下，可以测量到诱发活动。与脑电不同的是，脑磁图信号不会被颅骨的颧骨和缝合线扭曲。脑磁图的这一特性极大地简化了信号的解释。由于脑磁图和小鱿鱼的这些特点，进行皮层电流成像(CCI)是可能的。我们的模拟研究表明，小鱿鱼提供了皮层神经元电流分布的图像，而不是偶极子方法。我们建议使用CCI来测定健康婴儿和患有脑性瘫痪(CP)和新皮质癫痫的婴儿的皮质活动。目标1将描述大脑不同区域的自发活动，重点是阐明健康婴儿的局部性纺锤波的基础。我们预测，由于高灵敏度和空间分辨率，发电机可以被识别。目的2测定脑性瘫痪患儿的自发和躯体诱发活动。诱发的反应将定位身体不同部位的投影区。初步研究表明，无论是受影响的大脑皮层还是未受影响的大脑皮层，都具有深刻的可塑性。我们预测，由CCI确定的这些特定投射区域的自发活动在健侧和患侧都是异常的。目的3测定新皮质癫痫患儿的癫痫样活动。我们预测，CCI将能够区分产生尖峰的区域中的功能离散区域。人脑开发是生物医学研究的一个领域，由于很难找到安全而又强大的工具，该领域仍处于初级阶段。我们相信，如果该项目成功，将为了解健康婴儿和患有各种神经疾病的婴儿的大脑发育打开新的窗口。

DESCRIPTION (provided by applicant): This exploratory project will evaluate the usefulness of a newly developed instrument called baby SQUID for assessing brain functions in human infants. The baby SQUID is a high-resolution magnetoencephalography (MEG) system designed to detect cortical activity in infants with an unprecedented level of sensitivity and spatial resolution. An array of 76 MEG sensors can be placed 6 mm from the scalp, rather than -20 mm as in conventional MEGs. Since the combined thickness of scalp and skull is -4 mm in neonates, MEG signals can be measured at 10 mm, rather than 25 mm, from brain surface. Since MEG signals fall off as a square of distance, they should be as much as 5 times stronger for the baby SQUID compared to conventional MEG systems. In the next phase of development, the gap will be reduced from 6 mm to 3 mm so that the signals would be about 10 times stronger. The spatial resolution is about 3-4 times higher than the conventional systems because of the smaller gap and higher sensor density (12-14 mm channel spacing instead of 30-40 mm for adult MEGs). Preliminary results show that spontaneous activity can be measured clearly with high SNR and evoked activity can be measured with very little signal averaging from healthy infants. Unlike EEG, MEG signals are not distorted by the fontanels and sutures in the skull. This property of MEG greatly simplifies the interpretation of the signals. Due to these characteristics of MEG and baby SQUID, it is possible to perform a cortical current imaging (CCI). Instead of the dipole approach, our simulation study shows that the baby SQUID provides images of the cortical neuronal current distribution. We propose to use the CCI to determine cortical activity in healthy infants and infants with cerebral palsy (CP) and with neocortical epilepsy. Aim 1 will characterize the spontaneous activity from different regions of the brain with a focus on elucidating the basis of localized spindles seen in healthy babies. We predict that the generators can be identified due to the high sensitivity and spatial resolution. Aim 2 will measure spontaneous and somatically evoked activity in CP infants with hemiparesis. The evoked response will localize the projection areas of different parts of the body. Preliminary studies have shown a profound level of plasticity in both the affected and unaffected cortices. We predict that the spontaneous activity from these specific projection areas, identified by the CCI, is abnormal in the unaffected as well as affected side. Aim 3 will measure the epileptiform activity in infants with neocortical epilepsy. We predict that the CCI will be able to distinguish functionally discrete areas in the zone producing the spikes. Human brain development is an area of biomedical research that is still in its infancy because of difficulties in finding tools that are safe and yet powerful. We believe that this project, if successful, will open new windows into brain development in healthy infants as well as infants with various neurological disorders.