Simons Daniel J, Carvell George E, Kyriazi Harold T, Bruno Randy M
Department of Neurobiology, University of Pittsburgh School of Medicine, E1452 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261, USA.
J Neurophysiol. 2007 Nov;98(5):2842-7. doi: 10.1152/jn.00800.2007. Epub 2007 Sep 5.
Studies of the rodent whisker system indicate that somatosensory cortical circuitry operates at a millisecond timescale to transform sensory afferent signals from the thalamus. We measured axon conduction times and whisker-evoked responses of 48 thalamocortical (TC) neurons in the rat whisker-to-barrel pathway. Conduction times were derived from spike-triggered averages of local field potentials evoked in layer 4 cortical whisker-related barrels by the spontaneous firing of individual topographically aligned neurons in the ventral posterior medial thalamus. Conduction times varied fourfold, from 0.31 to 1.34 ms, and faster conducting TC neurons responded earlier and more robustly to controlled whisker deflections. Early arrival of highly responsive TC inputs, thought to contact inhibitory barrel neurons preferentially, could prime the cortical network, rendering it more selective for later-arriving signals.
对啮齿动物胡须系统的研究表明，体感皮层回路以毫秒级的时间尺度运作，以转换来自丘脑的感觉传入信号。我们测量了大鼠胡须到桶状皮层通路中48个丘脑皮层（TC）神经元的轴突传导时间和胡须诱发反应。传导时间来自于腹后内侧丘脑单个地形对齐神经元的自发放电在第4层皮层胡须相关桶状区诱发的局部场电位的触发尖峰平均值。传导时间变化了四倍，从0.31毫秒到1.34毫秒，传导速度更快的TC神经元对受控的胡须偏转反应更早且更强烈。高反应性TC输入的早期到达，被认为优先接触抑制性桶状神经元，可能会启动皮层网络，使其对后来到达的信号更具选择性。
