A research study on the electrode-tissue interface of epidural electrical stimulation of the visual cortex

Objective To evaluate the elementary characteristics of electrical stimulation on the cortex transferred from dura mater in order to verify the feasibility of a visual neuroprosthetic strategy based on epidural electrical stimulation.Methods This was an experimental study.A single square current was selected to stimulate the visual cortex of the cat through dura mater.The stimulus class and parameters of the single square current were varied and the voltage signal of the visual cortex was recorded.The visual cortex signal was recorded on paper and analyzed to study the attenuation of the transmission passing through dura mater, cerebrospinal fluid and pia mater. Results The cortical recordings agreed with some published experimental results when the stimulus type was altered.When the single-square current stimulus pulse width increased, the recorded voltage of the Vp-p phase changed noticeably but the Vp-p amplitude only changed within a narrow range.When the stimulus amplitude of the single-square current increased, the recorded voltage of the cortical Vp-p amplitude also increased.When the distance between the stimulating electrode and recording electrode decreased, the recorded voltage of the Vp-p amplitude increased.When the depth of the recording electrode gradually increased from 0 μm, 200 μm, 400 μm, 600 μm, 800 μm, the cortical recording of the vohage's amplitude decreased.Conclusion Cortical stimulation is still an effective signal,which originates from the epidural electrical stimulus by passing through dura mater,cerebrospinal fluid and pia mater.The strategy that epidural electrical stimulation can affect the visual cortex is verified to be feasible. Key words: Visual cortex ;  Mater,dura;  Electrical stimulation ;  Electrode-tissue interface