In vivo Multichannel Visual Cortex Recording During Electrical Stimulation of the Retina

Abstract

Purpose: : To assess the function of implanted retinal prosthesis, electrically evoked cortical potentials (EECP) in the visual cortex is useful. In this experiment, simultaneous multichannel recording of visual cortex was adopted to analyze the regional responses in the visual cortex under various stimulation parameters by implanted microelectrode array (MEA) in the retina.

Methods: : MEA was implanted into the suprachoroidal space of the New Zealand white rabbit. Silicone-framed, 16-channel tungsten needle electrode array was made for the simultaneous multichannel EECP recording, and was implanted onto the visual cortex through 4 x 4 mm of craniotomy over the visual cortex. During the electrical stimulation of the retina with the suprachoroidally located MEA, EECP was recorded simultaneously in 16 channels and recorded by the multichannel recorder. The threshold of the cortical responses to the electrical stimulation of the retina was determined by the discernable N1 and P1 peak on the waveform.

Results: : The amplitude of EECP was increased according to the increment of the stimulation amplitude in all 16 channels. Retinotopic activation of the visual cortex according to the stimulated sites of MEA could be identified, and these findings were reproducible during consecutive stimulations.

Conclusions: : Multichannel EECP recording device and technique were established. The retinotopic responses of the visual cortex were identified according to the locations of stimulation by MEA. These results will enhance the objective evaluation of the visual prosthesis in preclinical study.

Keywords: retina • electrophysiology: non-clinical • visual cortex