Patient Independent System to Detect the Electrical Onset of Temporal Lobe Epileptic Seizure

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Epilepsy is the most common neurological disease comprises a heterogeneous group of disorders, characterized by recurrent and unprovoked seizures due to the huge electrical discharges of large synchronized neurons. This hypersynchronous neuronal activity produces sustained action potential and repolarisation followed by hyperpolarisation, designated as Paroxysmal Depolarization Shift (PDS), as illustrated in Fig. 1.1. This abnormal activity changes the frequency and amplitude characteristics of the normal EEG and produces sustained oscillations with high amplitude and low-frequency spikes and slow-wave complexes. This huge potential affects the normal function of the neuronal network which leads to the loss of consciousness and involuntary body movements. The cerebral cortex of the brain consists of many layers of neurons that are responsible for action potential propagation. There are two types of neurons named the Principal or Projection neurons and the Inter neurons or local neurons. The principal neurons are producing excitatory synaptic potential and the inter neurons produces inhibitory synaptic potential. In the neuronal network connection, both neurons are interconnected and the response of these neurons are summed up to activate the neighbour neurons. The inter neuron is connected with the projection neuron and provides feed-forward inhibition, The projection neuron is connected with inter neuron and then the inter neuron induces feed-back inhibition on projection neuron. Thus the combined activity of these two neurons control the synchronous activity of large neurons population. Moreover the inhibition and excitation of neurons are the electro-chemical processes. Seizure may develop as a result of inheriting a mutation in a molecular mechanism that regulates neuron behavior, or organization of neuronal network. Alternatively, it may develop as a result of brain trauma such as a severe blow to the head, a stroke, a cerebral infection, or a brain malignancy. The symptomless gradual transformation from normal neuronal network to abnormal neural network is the period called as silent period. During the silent period, the changes occur in the organization of axons, loss of specific neuron (in particular inter-neurons and projection neurons driving inter-neurons), sprouting of axons to elicit large population of neurons and voltage-gated and ligand-gated channels property changes. This extensive change in synchronisation results permanent changes in the physical and biochemical structure of brain cells.