Synchronous beta oscillation of epileptiform activities detected by microelectrode arrays in the awake and anesthetized mice

Abstract

Isoflurane is a reversible anesthetic which is widely used in the surgery and animal experiments. It was still not clear whether isoflurane would affect the pattern of epileptiform signals even without seizure. In this work, an implantable and nanocomposites coated microelectrode array (MEA) was fabricated to study the neural spike firing and local field potential (LFP) in the hippocampus of awake and isoflurane anesthetized epileptic mice. The MEA recorded the neural activities during anesthesia, wakefulness and seizures at same location in the hippocampus. The results demonstrated that LFP power and neural spike firing rate were higher under anesthesia than under wakefulness. A peak appeared in the beta frequency band of epileptic LFP power distribution. There were remarkable differences in neural activities during seizures, with peak spike firing rate, amplitude and LFP power values being the largest. The epileptic animal without seizure exhibit normal behavior, but shows higher power than normal ones. The neural spike and LFP exhibited synchronous change with a similar power spectral distribution showing an epileptic peak at 11.6 Hz and higher power in the beta frequency band of 10–25 Hz. The MEA technology used in the mice brain provides an effective platform to reveal the real mechanism underlying epilepsy.