リカレントネットワークで異方的興奮伝導を安定に起こす興奮性と抑制性細胞の軸索投射領域

摘要

興奮性細胞と抑制性細胞からなるローカル結合のリカレントネットワークにおいて，興奮性細胞の軸索投射を可塑的に変化させることで興奮伝導を生成できる．その際，抑制性細胞の軸索投射領域によって，生成される興奮伝導が等方的な放射状の伝導から異方的な一方向への伝導に変化することが分かっている．本報告では，興奮性細胞と抑制性細胞の軸索投射領域を変化させて，興奮伝導に対する水平と垂直方向の抑制の強さを調べ，其方的興奮伝導の生じやすさを評価した．結論として，興奮性細胞の軸索投射領域を興奮伝導と直角方向に細長くし，抑制性細胞の軸索投射領域を興奮伝導方向に細長くしたとき，異方的興奮伝導が生じやすい．最後に，異方的興奮伝導の生じやすさを表す指標には現れない，安定的な其方的興奮伝導を起こす要因についても議論する．%It has been demonstrated that spike propagation emerges in a locally connected recurrent network, which consists of excitatory and inhibitory neurons, when synaptic weights between excitatory neurons are changed through spike-timing dependent synaptic plasticity. Moreover, it has been reported that radial spike propagation becomes directional one depending on the shape of axonal projection areas of inhibitory interneurons. In this report, we changed the aspect ratio of the axonal projection areas of excitatory neurons and/or inhibitory interneurons, and obtained the ratio of the inhibitory strengths to spike propagation in vertical and horizontal directions in order to evaluate how easy to produce directional spike propagation. We suggest that thin axonal projection areas of excitatory and inhibitory neurons, which are long in the vertical and horizontal directions respectively, facilitate an emergence of directional spike propagation in the horizontal direction. Finally, we discuss another factor to facilitate the emergence.