Finnerty G T, Roberts L S, Connors B W
Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA.
Nature. 1999 Jul 22;400(6742):367-71. doi: 10.1038/22553.
Many representations of sensory stimuli in the neocortex are arranged as topographic maps. These cortical maps are not fixed, but show experience-dependent plasticity. For instance, sensory deprivation causes the cortical area representing the deprived sensory input to shrink, and neighbouring spared representations to enlarge, in somatosensory, auditory or visual cortex. In adolescent and adult animals, changes in cortical maps are most noticeable in the supragranular layers at the junction of deprived and spared cortex. However, the cellular mechanisms of this experience-dependent plasticity are unclear. Long-term potentiation and depression have been implicated, but have not been proven to be necessary or sufficient for cortical map reorganization. Short-term synaptic dynamics have not been considered. We developed a brain slice preparation involving rat whisker barrel cortex in vitro. Here we report that sensory deprivation alters short-term synaptic dynamics in both vertical and horizontal excitatory pathways within the supragranular cortex. Moreover, modifications of horizontal pathways amplify changes in the vertical inputs. Our findings help to explain the functional cortical reorganization that follows persistent changes of sensory experience.
新皮层中许多感觉刺激的表征都排列成地形图。这些皮层图谱并非固定不变，而是表现出依赖经验的可塑性。例如，感觉剥夺会导致体感、听觉或视觉皮层中代表被剥夺感觉输入的皮层区域缩小，而相邻的未受影响的表征区域扩大。在青少年和成年动物中，皮层图谱的变化在被剥夺和未受影响的皮层交界处的颗粒上层最为明显。然而，这种依赖经验的可塑性的细胞机制尚不清楚。长期增强和抑制作用曾被认为与之有关，但尚未被证明对皮层图谱重组是必要或充分的。短期突触动力学尚未得到考虑。我们开发了一种体外培养大鼠胡须桶状皮层的脑片制备方法。在此我们报告，感觉剥夺会改变颗粒上层内垂直和水平兴奋性通路中的短期突触动力学。此外，水平通路的改变会放大垂直输入的变化。我们的研究结果有助于解释感觉经验持续变化后发生的功能性皮层重组。
