Cox Charles L, Reichova Iva, Sherman S Murray
Department of Neurobiology, State University of New York, Stony Brook, New York 11794-5230, USA.
J Neurosci. 2003 Aug 20;23(20):7642-6. doi: 10.1523/JNEUROSCI.23-20-07642.2003.
Relay neurons of the lateral geniculate nucleus innervate visual cortex, but they also provide axonal collaterals to neurons in the thalamic reticular nucleus, and these thalamic reticular neurons provide feedback inhibition to relay cells. An alternative source of inhibitory inputs onto geniculate relay neurons arises from intralaminar interneurons that provide feedforward inhibition via retinogeniculate innervation, and perhaps feedback inhibition via the corticothalamic pathway, analogous to that involving thalamic reticular neurons. Several reports indicate that relay neurons may also give rise to axonal collaterals within the lateral geniculate nucleus, constituting another route for feedback or local integration. We now provide new data indicating that collaterals from geniculate relay neurons provide excitatory input to local intralaminar interneurons and that this pathway may serve as a previously unknown means of local feedback inhibition. This circuitry could prove important in such activities as surround inhibition of receptive fields or increasing signal gain over noise.
外侧膝状核的中继神经元支配视觉皮层，但它们也向丘脑网状核的神经元提供轴突侧支，并且这些丘脑网状神经元向中继细胞提供反馈抑制。对膝状中继神经元的抑制性输入的另一个来源是层内中间神经元，它们通过视网膜膝状体神经支配提供前馈抑制，并且可能通过皮质丘脑通路提供反馈抑制，类似于涉及丘脑网状神经元的情况。几份报告表明，中继神经元也可能在外侧膝状核内产生轴突侧支，构成反馈或局部整合的另一条途径。我们现在提供新的数据表明，膝状中继神经元的侧支向局部层内中间神经元提供兴奋性输入，并且这条通路可能作为一种以前未知的局部反馈抑制方式。这种神经回路在诸如感受野的周围抑制或增加信号相对于噪声的增益等活动中可能被证明是重要的。
