abstract = "This work presents a novel, general-purpose algorithm
called Genetic Programming Artificial Features (GPAF),
which consists of a genetic programming (GP) algorithm
and a k-nearest neighbour classifier, and which
surpasses the performance of another recently published
method called Genetically Found, Neurally Computed
Artificial Features for addressing similar classes of
problems. Unlike conventional features, which are
designed based on human knowledge, experience, and/or
intuition, the artificial features ( i.e., features
that are computer-crafted and may not have a known
physical meaning) are systematically and automatically
designed by a computer from data provided. In this
dissertation, we apply the GPAF algorithm to one of the
most puzzling brain-disorder problems: the prediction
and detection of epileptic seizures. Epilepsy is a
neurological condition that makes people susceptible to
brief electrical disturbance in the brain thus
producing a change in sensation, awareness, and/or
behaviour; and is characterized by recurrent seizures.
It affects up to 1percent of the worldwide population,
or sixty million people, and 25percent cannot be fully
controlled by current pharmacological or surgical
treatment. The possibility that an implantable device
might eventually warn patients of an impending seizure
is of utmost importance, allowing on-the-spot
medication or safety measures. Epileptic
electroencephalographic (EEG) signals were treated from
a chaos theory perspective. First, we reconstructed the
EEG state-space trajectories via a delay-embedding
scheme. Then these pseudo-state-space vectors were
input to a genetic programming algorithm, which
designed one or more (non)linear features providing an
artificial space where the baseline (nonseizure data)
and preictal (preseizure data, or ictal data in case of
detection) classes are sufficiently separated for a
classifier to achieve better accuracy than using
principal components analysis, our benchmark feature
extractor. The GPAF algorithm was applied to data
segments extracted from 730 hours of EEG recording
obtained from seven patients. The machine automatically
discovered one or more patient-specific features that
predicted epileptic seizures with a time horizon from
one to five minutes before the unequivocal
electrographic onset of each seizure. Results showed
that 43 of 55 seizures were correctly predicted, for a
78.19percent correct classification rate, while 55
epochs out of 59 representative of baseline conditions
were classified correctly, for a low false positive
rate per hour of 0.0508. In the case of detection, a
low false-positive-per-hour-rate and a high detection
rate were also achieved. A generic (cross-patient)
model for prediction of epileptic seizures was also
found, at the expense of decreased performance with an
average of 69.09percent sensitivity. The GPAF algorithm
was additionally investigated to design seizure
detectors. Evaluating 730 hours of EEG recording showed
that with customized, artificially designed detectors,
83 of 86 seizures were detected. Seven previously
unreported seizures were also detected in this work.",
notes = "ProQuest Dissertations and Theses UMI Microform
3171456