Title:
Designing implantable cortical prosthetics to restore visual perception in blind patients

 

Tetsuya Yagi
Division of Electrical, Electronic and Information Engineering, Graduate school of engineering, Osaka University

 

Abstract:
Electrical stimulus applied to the extracellular space of visual cortex induces a spot-like light percept called phosphen. This observation provoked the research of cortical prosthetics for blind patients. In visual cortical prosthetics, it is crucial to evoke image percepts that is useful to restore visually guided activities of blind patients with limited numbers of electrodes. In order to reconstruct phosphen images evoked by patterned cortical stimulations, spatiotemporal properties of electrically induced cortical activities were elucidated in terms of stimulus conditions using the voltage-sensitive dye imaging in rodents, under an assumption that neuronal activities directly reflect appearances of phosphens. We reconstructed phosphen patterns on a head-mount display taking account of the present and previous clinical experiments and examined the effects of stimulus conditions on image percepts evoked by the phosphen patterns in normally sighted subjects. Based on these physiological and psychophysical studies, we designed and implemented a prototype of implantable integrated circuit system that would effectively deliver electrical stimulations to evoke image percepts in blind patients.

 

References:
F.D. Tamas et.al : In vivo voltage-sensitive dye study of lateral spreading of cortical activity in mouse primary visual cortex inducedby a current impulse, PLOS ONE, 10.1371/journal.pone.0133853, 31July, 2015.

 

Y. Hayashida et.al. : Voltage-sensitive dye imaging of the visual cortices responding to electrical pulses at different intervals in mice in vivo, EMBC, 36th Annual International Conference of the IEEE, Chicago, USA, 26-30 Aug, pp.402-405, 2014.

 

亀田成司,林田祐樹,田中宏喜,八木哲也 : 高インピーダンス神経電極用多チャンネル電流刺激チップの開発, 計測自動制御学会論文集, vol.50, no.8, pp.594-601, 2014.