In situ detection of neurotransmitters and epileptiform electrophysiology activity in awake mice brains using a nanocomposites modified microelectrode array

Abstract

A novel nanocomposites modified microelectrode array (MEA) was designed and fabricated for in situ detection of neurotransmitters (glutamate and dopamine) and electrophysiology activity. The MEAs were implanted into the hippocampus of four epileptic mice to detect the neuron activity along with their behaviours. Six spontaneous seizures were recorded, with each seizure having 5 periods. From the normal to the pre-seizure period, both the concentrations of neurotransmitters and the intensities of electrophysiology activities increased by 20%–70%. During the seizure period, the glutamate level dramatically increased to approximately 10 times its normal, while the dopamine level sharply decreased to approximately one third of the normal; the spike firing rate and the power of the local field potential significantly increased more than three-fold. During the inhibitory period, neurotransmitters and electrophysiology activities were significantly inhibited, and then they gradually returned to normal. These results revealed that seizures were highly correlated with glutamate, dopamine and electrophysiology activity and abnormalities in the neuron activity appeared earlier than any abnormal behaviour. Moreover, synchronized changes of these multiple signals in the pre-seizure period could be used to predict seizures. This novel MEA provides an effective technology and a new perspective for understanding the epileptic mechanism.