Neurons in human epileptic cortex. Response to direct cortical stimulation

Area of Science:

• Neuroscience
• Epileptology
• Neuron physiology

Background:

• Medically intractable epilepsy often requires surgical intervention, such as craniotomy.
• Identifying the epileptogenic zone is crucial for successful epilepsy surgery.
• Understanding neuronal responses to stimulation can help delineate affected brain regions.

Purpose of the Study:

• To investigate the response of single neurons in the lateral temporal cortex to repetitive cortical stimulation.
• To determine if neurons in suspected epileptogenic cortex exhibit different firing patterns compared to normal cortex.

Main Methods:

• Single neuron recordings were performed in 11 awake patients undergoing craniotomy for epilepsy surgery.
• 83 neurons were recorded from the lateral temporal cortex.
• Neurons were stimulated with repetitive direct cortical stimulation using frequency ramps (1-10 Hz), and their responses were evaluated.

Main Results:

• Neurons in suspected epileptogenic cortex showed augmented action potential bursts in response to stimulation frequencies between 5-20 Hz more often than neurons in non-epileptogenic cortex.
• This burst response could persist for up to 30 seconds after stimulation.
• The burst response was generally not associated with electroencephalography (EEG) afterdischarge.

Conclusions:

• Neurons in suspected epileptogenic cortex demonstrate a heightened propensity for burst firing in response to repetitive stimuli.
• This neuronal hyperexcitability may serve as an indicator of epileptogenic tissue.
• These findings could inform surgical strategies for epilepsy by helping to identify critical brain regions.