Philips Ryan T, Sur Mriganka, Chakravarthy V Srinivasa
Computational Neuroscience Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India.
Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
PLoS Comput Biol. 2017 Oct 27;13(10):e1005785. doi: 10.1371/journal.pcbi.1005785. eCollection 2017 Oct.
Orientation preference maps (OPMs) are present in carnivores (such as cats and ferrets) and primates but are absent in rodents. In this study we investigate the possible link between astrocyte arbors and presence of OPMs. We simulate the development of orientation maps with varying hypercolumn widths using a variant of the Laterally Interconnected Synergetically Self-Organizing Map (LISSOM) model, the Gain Control Adaptive Laterally connected (GCAL) model, with an additional layer simulating astrocytic activation. The synaptic activity of V1 neurons is given as input to the astrocyte layer. The activity of this astrocyte layer is now used to modulate bidirectional plasticity of lateral excitatory connections in the V1 layer. By simply varying the radius of the astrocytes, the extent of lateral excitatory neuronal connections can be manipulated. An increase in the radius of lateral excitatory connections subsequently increases the size of a single hypercolumn in the OPM. When these lateral excitatory connections become small enough the OPM disappears and a salt-and-pepper organization emerges.
方向偏好图（OPM）存在于食肉动物（如猫和雪貂）和灵长类动物中，但在啮齿动物中不存在。在本研究中，我们调查了星形胶质细胞树突与OPM存在之间的可能联系。我们使用横向互联协同自组织映射（LISSOM）模型的一个变体——增益控制自适应横向连接（GCAL）模型，通过改变超柱宽度来模拟方向图的发育，该模型有一个额外的层来模拟星形胶质细胞的激活。V1神经元的突触活动作为输入提供给星形胶质细胞层。现在，这个星形胶质细胞层的活动被用来调节V1层中横向兴奋性连接的双向可塑性。通过简单地改变星形胶质细胞的半径，可以操纵横向兴奋性神经元连接的范围。横向兴奋性连接半径的增加随后会增加OPM中单个超柱的大小。当这些横向兴奋性连接变得足够小时，OPM消失，出现椒盐组织。
