Electroencephalography-Based Recording Technique to Record the Epileptiform Activity

Chemical neurotransmitters released from a neuron affect neighboring cells, allowing electrical impulses to pass between neurons. Excess of excitatory neurotransmitters cause disturbances to the brain's electrical activity, leading to recurrent seizures — abnormal repetitive neuron excitation and gradual neuronal death, leading to epilepsy. 

To record epileptiform activity ex vivo, begin by taking a membrane insert containing rat pup brain-derived, rhinal cortex-hippocampus organotypic slices, which depict evolving epileptic events. Each slice has a defined dentate gyrus — DG region and cornu ammonis — CA region, consisting of tightly-packed multipolar pyramidal neurons.

Culture the slices for a prolonged duration, simulating gradual serum deprivation-induced stress conditions which lead to neuronal death, resembling in vivo epileptic conditions. Place one organotypic slice in the recording chamber of an electrophysiology — EEG — set up, with the hippocampus touching the bottom of the chamber.

The recording chamber is prefilled with a medium containing L-glutamine — a neurotransmitter precursor — that initiates neuronal excitation. Place the receiving electrode attached to a glass capillary containing artificial cerebrospinal fluid into a pyramidal neuron-rich CA3 region.

Record the electrical activity. Generate an electrograph, which briefly shows ictal events — areas with sudden peaks — corresponding to the beginning of epileptiform activity.

An increased number of ictal events, lasting for prolonged periods, indicates recurrent seizures.