Li Y, Strausfeld N J
Arizona Research Laboratories, Division of Neurobiology, The University of Arizona, Tucson 85721, USA.
J Comp Neurol. 1999 Jul 12;409(4):647-63. doi: 10.1002/(sici)1096-9861(19990712)409:4<647::aid-cne9>3.0.co;2-3.
Previous electrophysiological studies of cockroach mushroom bodies demonstrated the sensitivity of efferent neurons to multimodal stimuli. The present account describes the morphology and physiology of several types of efferent neurons with dendrites in the medial lobes. In general, efferent neurons respond to a variety of modalities in a context-specific manner, responding to specific combinations or specific sequences of multimodal stimuli. Efferent neurons that show endogenous activity have dendritic specializations that extend to laminae of Kenyon cell axons equipped with many synaptic vesicles, termed "dark" laminae. Efferent neurons that are active only during stimulation have dendritic specializations that branch mainly among Kenyon cell axons having few vesicles and forming the "pale" laminae. A new category of "recurrent" efferent neuron has been identified that provides feedback or feedforward connections between different parts of the mushroom body. Some of these neurons are immunopositive to antibodies raised against the inhibitory transmitter gamma-aminobutyric acid. Feedback pathways to the calyces arise from satellite neuropils adjacent to the medial lobes, which receive axon collaterals of efferent neurons. Efferent neurons are uniquely identifiable. Each morphological type occurs at the same location in the mushroom bodies of different individuals. Medial lobe efferent neurons terminate in the lateral protocerebrum among the endings of antennal lobe projection neurons. It is suggested that information about the sensory context of olfactory (or other) stimuli is relayed by efferent neurons to the lateral protocerebrum where it is integrated with information about odors relayed by antennal lobe projection neurons.
先前对蟑螂蘑菇体的电生理研究表明，传出神经元对多模态刺激敏感。本报告描述了几种在内侧叶具有树突的传出神经元的形态和生理特征。一般来说，传出神经元以特定情境的方式对多种模态做出反应，对多模态刺激的特定组合或特定序列做出反应。表现出内源性活动的传出神经元具有树突特化结构，延伸至配备有许多突触小泡的肯扬细胞轴突层，即所谓的“暗”层。仅在刺激期间活跃的传出神经元具有树突特化结构，主要在具有少量小泡并形成“淡”层的肯扬细胞轴突之间分支。已鉴定出一类新的“循环”传出神经元，它们在蘑菇体的不同部分之间提供反馈或前馈连接。其中一些神经元对针对抑制性递质γ-氨基丁酸产生的抗体呈免疫阳性。向花萼的反馈通路来自与内侧叶相邻的卫星神经纤维网，其接收传出神经元的轴突侧支。传出神经元具有独特的可识别性。每种形态类型在不同个体的蘑菇体中出现在相同位置。内侧叶传出神经元在触角叶投射神经元的末梢之间终止于外侧原脑。有人提出，关于嗅觉（或其他）刺激的感觉情境的信息由传出神经元传递到外侧原脑，在那里它与触角叶投射神经元传递的气味信息整合。
