Clarke Blaise A, Lee Charles C
Department of Comparative Biomedical Sciences, LSU School of Veterinary Medicine, Baton Rouge, LA 70803, USA.
Brain Sci. 2018 Jun 9;8(6):103. doi: 10.3390/brainsci8060103.
The medial geniculate body (MGB) is the target of excitatory and inhibitory inputs from several neural sources. Among these, the inferior colliculus (IC) is an important nucleus in the midbrain that acts as a nexus for auditory projections, ascending and descending, throughout the rest of the central auditory system and provides both excitatory and inhibitory inputs to the MGB. In our study, we assessed the relative contribution from presumed excitatory and inhibitory IC neurons to the MGB in mice. Using retrograde tract tracing with cholera toxin beta subunit (CTβ)-Alexa Fluor 594 injected into the MGB of transgenic, vesicular GABA transporter (VGAT)-Venus mice, we quantitatively analyzed the projections from both the ipsilateral and contralateral IC to the MGB. Our results demonstrate inhibitory projections from both ICs to the MGB that likely play a significant role in shaping auditory processing. These results complement prior studies in other species, which suggest that the inhibitory tectothalamic pathway is important in the regulation of neuronal activity in the auditory forebrain.
内侧膝状体（MGB）是多个神经源兴奋性和抑制性输入的靶点。其中，下丘（IC）是中脑中的一个重要核团，它作为听觉投射的枢纽，在整个中枢听觉系统的其余部分进行上行和下行投射，并向MGB提供兴奋性和抑制性输入。在我们的研究中，我们评估了小鼠中假定的兴奋性和抑制性IC神经元对MGB的相对贡献。通过将携带霍乱毒素β亚基（CTβ）-Alexa Fluor 594的逆行束路示踪剂注射到转基因囊泡GABA转运体（VGAT）-金星小鼠的MGB中，我们定量分析了同侧和对侧IC向MGB的投射。我们的结果表明，两侧IC向MGB的抑制性投射可能在塑造听觉处理过程中发挥重要作用。这些结果补充了先前在其他物种中的研究，这些研究表明抑制性顶盖丘脑通路在调节听觉前脑的神经元活动中很重要。
