Anwar A R, Muthalib M, Perrey S, Galka A, Granert O, Wolff S, Deuschl G, Raethjen J, Heute U, Muthuraman M
Department of Digital Signal Processing and System Theory, University of Kiel, Kiel, Germany.
Annu Int Conf IEEE Eng Med Biol Soc. 2012;2012:2287-90. doi: 10.1109/EMBC.2012.6346419.
Directionality analysis of signals originating from different parts of brain during motor tasks has gained a lot of interest. Since brain activity can be recorded over time, methods of time series analysis can be applied to medical time series as well. Granger Causality is a method to find a causal relationship between time series. Such causality can be referred to as a directional connection and is not necessarily bidirectional. The aim of this study is to differentiate between different motor tasks on the basis of activation maps and also to understand the nature of connections present between different parts of the brain. In this paper, three different motor tasks (finger tapping, simple finger sequencing, and complex finger sequencing) are analyzed. Time series for each task were extracted from functional magnetic resonance imaging (fMRI) data, which have a very good spatial resolution and can look into the sub-cortical regions of the brain. Activation maps based on fMRI images show that, in case of complex finger sequencing, most parts of the brain are active, unlike finger tapping during which only limited regions show activity. Directionality analysis on time series extracted from contralateral motor cortex (CMC), supplementary motor area (SMA), and cerebellum (CER) show bidirectional connections between these parts of the brain. In case of simple finger sequencing and complex finger sequencing, the strongest connections originate from SMA and CMC, while connections originating from CER in either direction are the weakest ones in magnitude during all paradigms.
在运动任务期间，对源自大脑不同部位的信号进行方向性分析已引起了广泛关注。由于大脑活动可以随时间进行记录，时间序列分析方法也可应用于医学时间序列。格兰杰因果关系是一种用于发现时间序列之间因果关系的方法。这种因果关系可被称为方向性连接，并不一定是双向的。本研究的目的是基于激活图区分不同的运动任务，并了解大脑不同部位之间存在的连接性质。本文分析了三种不同的运动任务（手指敲击、简单手指序列和复杂手指序列）。从功能磁共振成像（fMRI）数据中提取每个任务的时间序列，该数据具有非常好的空间分辨率，能够观察大脑的皮质下区域。基于fMRI图像的激活图显示，在复杂手指序列的情况下，大脑的大部分区域是活跃的，这与手指敲击不同，手指敲击时只有有限的区域显示活动。对从对侧运动皮层（CMC）、辅助运动区（SMA）和小脑（CER）提取的时间序列进行方向性分析，结果显示大脑这些部位之间存在双向连接。在简单手指序列和复杂手指序列的情况下，最强的连接源自SMA和CMC，而在所有范式中，源自CER的双向连接在强度上都是最弱的。
