Roles of the mushroom body in locomotory control in an insect

蘑菇体（MB）是昆虫脑中最显著的神经元结构，对各种形式的联想记忆至关重要。为了阐明MB在高级运动控制中的作用，本研究对美洲大蠊（Periplaneta americana）的输出神经元活动和MB的细胞结构进行了研究.观察了自由活动蟑螂的MB输出神经元的活动。直径为17 μ m的漆包铜线长期植入MB输出神经元，并记录单位活动，而蟑螂自由行走在竞技场。在记录之后，通过使正电流通过来浸渍铜离子，以显示电极尖端附近的神经元的轮廓。记录的神经元分为：（1）对各种感觉刺激有反应的感觉单位，（2）在运动过程中活跃的运动相关神经元，（3）在感觉刺激和运动过程中活跃的感觉-运动神经元，（4）在特定运动动作开始之前活动的神经元.用还原银染色和高尔基体染色法研究了蟑螂MB的细胞结构。我发现MB输出神经元中存在两种不同大小的重复模块亚单位。第一个，我称之为薄片，是由200-1000个凯尼恩细胞轴突形成的薄（1 μ m或更小）网状结构。这些板进一步组织成更大的结构分组，这里称为板，其宽度为3 μ m或更大。总共约30个或多或少均匀间隔的深色和浅色板片在输出神经元的整个长度上交替。我的结论是，MB，昆虫的记忆中心，由两种类型的重复模块亚基，哺乳动物的大脑皮层。

The mushroom body (MB) is the most conspicuous neuropil structure in the insect brain, critical to various forms of associative memory. In order to elucidate the role of the MB in the higher locomotory control, activities of output neurons and the cellular organization of the MB in the cockroach, Periplaneta americana, were studied.1. Activities of MB output neurons of freely behaving cockroaches were examined. Enamel-coated copper wires of 17 mum in diameter were implanted chronically into the MB output neuropil, and unit activity was recorded while the cockroach walked freely in an arena. After the recording, copper ions were impregnated by passing a positive current to reveal profiles of neurons in the vicinity of the electrode tip. The recorded neurons were classified into (1) sensory units which respond to various sensory stimuli, (2) motor-related neurons which are active during locomotory, (3) sensory-motor neurons which are active during sensory stimulation and also during motor action, and (4) neurons whose activity preceded the initiation of specific locomotory action.2. Cellular organization of the cockroach MB was studied by means of reduced-silver and Golgi stainings. I found that two types of repetitive modular subunits with different sizes exist in the MB output neuropil. The first, which I refer to as a sheet, is a thin (1 mum or less) meshwork formed by 200-1000 axons of Kenyon cells. The sheets are further organized into a larger structural grouping, referred to here as a slab, with a width of 3 mum or more. A total of about 30 dark and pale slabs of more or less evenly spaced alternate throughout the length of the output neuropil. I conclude that the MB,insect memory center, consists of two types of repetitive modular subunits, as does the mammalian cerebral cortex.