Harris A E, Ermentrout G B, Small S L
Intelligent Systems Program, University of Pittsburgh, Pittsburgh, PA 15261, USA.
Proc Natl Acad Sci U S A. 1997 Sep 2;94(18):9944-9. doi: 10.1073/pnas.94.18.9944.
Recent experimental evidence has shown that application of certain neurotrophic factors (NTs) to the developing primary visual cortex prevents the development of ocular dominance (OD) columns. One interpretation of this result is that afferents from the lateral geniculate nucleus compete for postsynaptic trophic factor in an activity-dependent manner. Application of excess trophic factor eliminates this competition, thereby preventing OD column formation. We present a model of OD column development, incorporating Hebbian synaptic modification and activity-driven competition for NT, which accounts for both normal OD column development as well as the prevention of that development when competition is removed. In the "control" situation, when available NT is below a critical amount, OD columns form normally. These columns form without weight normalization procedures and in the presence of positive inter-eye correlations. In the "experimental" case, OD column development is prevented in a local neighborhood in which excess NT has been added. Our model proposes a biologically plausible mechanism for competition between neural populations that is motivated by several pieces of experimental data, thereby accounting for both normal and experimentally perturbed conditions.
最近的实验证据表明，将某些神经营养因子（NTs）应用于发育中的初级视觉皮层会阻止眼优势（OD）柱的形成。对这一结果的一种解释是，外侧膝状核的传入神经以活动依赖的方式竞争突触后营养因子。应用过量的营养因子消除了这种竞争，从而阻止了OD柱的形成。我们提出了一个OD柱发育模型，该模型结合了赫布突触修饰和对NT的活动驱动竞争，它既解释了正常的OD柱发育，也解释了竞争消除时该发育过程的阻止情况。在“对照”情况下，当可用的NT低于临界量时，OD柱正常形成。这些柱在没有权重归一化程序的情况下形成，并且存在眼间正相关。在“实验”情况下，在添加了过量NT的局部区域中，OD柱的发育被阻止。我们的模型提出了一种生物学上合理的神经群体之间竞争机制，该机制由几条实验数据推动，从而解释了正常和实验性扰动条件。
