Natarajan Kannathal, Acharya U Rajendra, Alias Fadhilah, Tiboleng Thelma, Puthusserypady Sadasivan K
ECE Division, Ngee Ann Polytechnic, 535 Clementi Road, Singapore 599489.
Biomed Eng Online. 2004 Mar 16;3(1):7. doi: 10.1186/1475-925X-3-7.
The EEG (Electroencephalogram) is a representative signal containing information about the condition of the brain. The shape of the wave may contain useful information about the state of the brain. However, the human observer can not directly monitor these subtle details. Besides, since bio-signals are highly subjective, the symptoms may appear at random in the time scale. Therefore, the EEG signal parameters, extracted and analyzed using computers, are highly useful in diagnostics. This work discusses the effect on the EEG signal due to music and reflexological stimulation.
In this work, nonlinear parameters like Correlation Dimension (CD), Largest Lyapunov Exponent (LLE), Hurst Exponent (H) and Approximate Entropy (ApEn) are evaluated from the EEG signals under different mental states.
The results obtained show that EEG to become less complex relative to the normal state with a confidence level of more than 85% due to stimulation.
It is found that the measures are significantly lower when the subjects are under sound or reflexologic stimulation as compared to the normal state. The dimension increases with the degree of the cognitive activity. This suggests that when the subjects are under sound or reflexologic stimuli, the number of parallel functional processes active in the brain is less and the brain goes to a more relaxed state
脑电图（EEG）是一种代表性信号，包含有关大脑状况的信息。波形形状可能包含有关大脑状态的有用信息。然而，人类观察者无法直接监测这些细微细节。此外，由于生物信号具有高度主观性，症状可能在时间尺度上随机出现。因此，使用计算机提取和分析的脑电图信号参数在诊断中非常有用。这项工作讨论了音乐和反射疗法刺激对脑电图信号的影响。
在这项工作中，从不同心理状态下的脑电图信号中评估了诸如关联维数（CD）、最大李雅普诺夫指数（LLE）、赫斯特指数（H）和近似熵（ApEn）等非线性参数。
所得结果表明，由于刺激，脑电图相对于正常状态变得不那么复杂，置信水平超过85%。
发现与正常状态相比，受试者在声音或反射疗法刺激下这些测量值明显更低。维度随着认知活动程度的增加而增加。这表明当受试者受到声音或反射疗法刺激时，大脑中活跃的并行功能过程数量减少，大脑进入更放松的状态。
