GABAergic feedforward projections from the inferior colliculus to the medial geniculate body.

A novel and robust projection from gamma-aminobutyric acid-containing (GABAergic) inferior colliculus neurons to the media] geniculate body (MGB) was discovered in the cat using axoplasmic transport methods combined with immunocytochemistry. This input travels with the classical inferior colliculus projection to the MGB, and it is a direct ascending GABAergic pathway to the sensory thalamus that may be inhibitory. This bilateral projection constitutes 10-30% of the neurons in the auditory tectothalamic system. Studies by others have shown that comparable input to the corresponding thalamic visual or somesthetic nuclei is absent. This suggests that monosynaptic inhibition or disinhibition is a prominent feature in the MGB and that differences in neural circuitry distinguish it from its thalamic visual and somesthetic counterparts. IMAGES:

本研究借助轴浆运输技术联合免疫细胞化学方法，在猫脑组织中发现了一条全新且稳定的γ-氨基丁酸能（GABAergic）下丘神经元投射至内侧膝状体（MGB）的通路。该输入通路与经典的下丘至内侧膝状体投射伴行，属于一条直接上行至感觉丘脑的GABA能通路，其介导的信号功能可能为抑制性。此类双侧投射的神经元占听觉中脑丘脑系统总神经元数的10%~30%。已有其他学者的研究表明，在对应的丘脑视觉或躯体感觉核团中，并不存在此类等效的输入通路。这提示单突触抑制或去抑制是内侧膝状体的显著神经特征，且其神经环路机制与丘脑视觉、躯体感觉对应核团存在明显差异。IMAGES: 图像：