ON-OFF型網膜神経節細胞の受容野構造と符号化様式 Receptive Fields and Coding Properties of ON-OFF Retinal Ganglion Cells

輝度の上昇と下降の双方に一過的に反応するON-OFF型網膜神経節細胞(RGC)のさまざまな光刺激に対する応答を電気生理学的に記録し,受容野の構造と輝度情報の符号化様式について定量的に検討した.反応を誘発する興奮部と反応を抑制する抑制部があり,方向選択性を示さないRGCではその中心は一致していたが,方向選択性RGCでは抑制部が最大応答方向にずれていた.白色Gauss雑音で輝度変調した刺激光によって誘発されたスパイク列は,Poisson過程とは異なる発火パターンを示した.明化,暗化の相互抑制と,暗化による明化反応の促通が見いだされた.

ON-OFF retinal ganglion cells (RGCs) were investigated electrophysiologically in the Japanese quail. Particularly, receptive field structures and coding properties of these cells were quantitatively analyzed. Centers of excitatory and inhibitory regions were aligned in the non-directionally-selective RGCs, but inhibitory regions were displaced toward the preferred the side where the null sweep starts. Spike trains did not show properties predicted from Poisson models. Mutual inhibition between ON and OFF stimuli and facilitation of ON responses by OFF stimuli were observed.