Quantitative Evaluation Of Inhibitory Effects Of Epileptic Spikes On Theta Rhythms In Patients With Temporal Lobe Epilepsy

Epilepsy is a dynamical disease in the brain systems.The effect of epilepsy on cognition is one of important work in neuron-science whose goal is to improve the life quality of epileptic patients.But the underlying mechanisms of epileptic effects on cognition remain unknown.So here,by using the intracranial electroencephalogram(iEEG)on 4 patients,we analyze the transient effects of the interictal spikes and waves(SW)on Theta oscillations.To address the issue,intracerebral EEG recordings with both sporadic spikes(SSs)(experiment group)and no-spike recovery period between adjacent spikes(control group)were selected in 4 patients in quiet sleep state with temporal lobe epilepsy(TLE)under the pre-surgical monitoring.The electrodes of CA3 and EC were employed,since CA3 and EC built up one of key loops to investigate cognition and epilepsy.These SSs occurred only in CA3,only in EC,and in both CA3 and EC synchronously.Firstly,in order to investigate the effects of the SSs on theta oscillation of CA3 and EC,theta power was respectively estimated by Gabor wavelet transform and Hilbert transform.It is found that the spikes could transiently reduce theta power,and the inhibitory effect was more severer around SSs in both CA3 and EC synchronously than around either SSs only in EC or SSs only in CA3.Secondly,in order to investigate the effects of no-spike recovery period between adjacent spikes,theta power was also respectively estimated by Gabor wavelet transform and Hilbert transform.It is found that during the recovery period,theta rhythms were interrupted with the intermittent theta rhythms left,and the intermittent extend of theta rhythms was converged to the inhibitory extend around SSs;And the average theta power level during the recovery period mightn't be in line with the inhibitory extend of theta rhythms around SSs.Finally,transfer entropy was calculated between CA3 and EC,and the results showed that the transfer entropy was higher in either SSs only in EC or SSs only in CA3 than SSs in both CA3 and EC synchronously.