Tuning Microelectrodes' Impedance to Improve Fast Ripples Recording

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Epilepsy is a neurological disorder marked by recurrent seizures due to abnormal neuronal activity.
• Identifying the Epileptogenic Zone (EZ) is crucial for pharmacoresistant epilepsy requiring surgery.
• Fast Ripples (FRs) are vital biomarkers for EZ delineation but are difficult to record with standard microelectrodes due to high impedance.

Purpose of the Study:

• To investigate the efficacy of a conductive polymer coating in enhancing Fast Ripple (FR) observability.
• To compare the performance of standard Gold (Au) microelectrodes with poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) coated Au microelectrodes.

Main Methods:

• Biophysical modeling was used to compare Au and Au/PEDOT:PSS microelectrodes.
• Microelectrodes were implanted into the CA1 hippocampal neural network of epileptic mice.
• Fast Ripples (FRs) were recorded during epileptogenesis to assess electrode performance.

Main Results:

• PEDOT:PSS coated electrodes exhibited two orders of magnitude lower impedance compared to uncoated electrodes.
• The coated electrodes showed higher transfer function amplitude and cut-off frequency.
• FRs recorded with PEDOT:PSS coated microelectrodes had significantly higher signal energy, improving observability and detection.

Conclusions:

• Conductive polymer coatings, specifically PEDOT:PSS, significantly enhance microelectrode performance for recording Fast Ripples (FRs).
• This improvement facilitates better detection of pathological biomarkers for epilepsy surgery.
• The study supports the development of specialized microelectrodes for improved targeting of the Epileptogenic Zone (EZ).