ANNALS OF BIOMEDICAL ENGINEERING, cilt.37, ss.2626-2630, 2009 (SCI-Expanded)
https://link.springer.com/article/10.1007%2Fs10439-009-9795-x
https://pubmed.ncbi.nlm.nih.gov/19757057/
ABSTRTACT
In this study, normal
EEG series recorded from healthy volunteers and epileptic EEG series recorded
from patients within and without seizure are classified by using Multilayer
Neural Network (MLNN) architectures with respect to several time domain entropy
measures such as Shannon Entropy (ShanEn), Log Energy Entropy (LogEn), and
Sample Entropy (Sampen). In tests, the MLNN is performed with several numbers
of neurons for both one hidden layer and two hidden layers. The results show
that segments in seizure have significantly lower entropy values than normal
EEG series. This result indicates an important increase of EEG regularity in
epilepsy patients. The LogEn approach, which has not been experienced in EEG
classification yet, provides the most reliable features into the EEG
classification with very low absolute error as 0.01. In particular, the MLNN
can be proposed to distinguish the seizure activity from the seizure-free
epileptic series where the LogEn values are considered as signal features that
characterize the degree of EEG complexity. The highest classification accuracy
is obtained for one hidden layer architecture.
DISCUSSION AND
CONCLUSION
n
this study, three datasets consisting of normal and epileptic records in
addition to ictal series are classified by using several MLNN architectures.
The inputs of the NNs, i.e., the signal features, are computed by addressing
the ShanEn, LogEn, and SamEn.
The
results show that epileptic records (Set-D and Set-E) show lower entropies in
comparison to healthy records (Set-A). In particular, seizure activity produces
significantly lower entropies. It means that electrophysiological behavior of
epileptogenic regions is less complex than behavior of healthy brain. It can be
said that lower entropy indicates the severity of epilepsy. Since the LogEn
values meet the most reliable features to analyze the nonlinear dynamics of
both cortical and intracortical neuronal interactions, we propose the LogEn
values as inputs of the MLNN in discriminating the seizure.
Entropy
is a useful quantity to recognize the certain features of EEG series such that
small number of dominating process provides the low entropy. Results show that
the LogEn is highly sensitive to the degree of EEG complexity. Since, seizure
is a synchronous neuronal activity producing spike discharges, the LogEn can be
used for seizure detection. The LogEn can also be proposed to critical analysis
of EEG in many diagnostic applications such as discriminating of sleep
disorders and monitoring of anesthetic depth.