Kazama Hokto, Wilson Rachel I
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA.
Nat Neurosci. 2009 Sep;12(9):1136-44. doi: 10.1038/nn.2376. Epub 2009 Aug 16.
Multineuronal recordings often reveal synchronized spikes in different neurons. The manner in which correlated spike timing affects neural codes depends on the statistics of correlations, which in turn reflects the connectivity that gives rise to correlations. However, determining the connectivity of neurons recorded in vivo can be difficult. We investigated the origins of correlated activity in genetically labeled neurons of the Drosophila antennal lobe. Dual recordings showed synchronized spontaneous spikes in projection neurons (PNs) postsynaptic to the same type of olfactory receptor neuron (ORN). Odors increased these correlations. The primary origin of correlations lies in the divergence of each ORN onto every PN in its glomerulus. Reciprocal PN-PN connections make a smaller contribution to correlations and PN spike trains in different glomeruli were only weakly correlated. PN axons from the same glomerulus reconverge in the lateral horn, where pooling redundant signals may allow lateral horn neurons to average out noise that arises independently in these PNs.
多神经元记录常常揭示出不同神经元中同步的尖峰信号。相关尖峰时间影响神经编码的方式取决于相关性的统计数据，而这又反过来反映了产生相关性的连接性。然而，确定在体内记录的神经元的连接性可能很困难。我们研究了果蝇触角叶中基因标记神经元相关活动的起源。双记录显示，在与同一类型嗅觉受体神经元（ORN）形成突触后的投射神经元（PN）中存在同步的自发尖峰信号。气味增强了这些相关性。相关性的主要起源在于每个ORN在其小球内投射到每个PN上。PN之间的相互连接对相关性的贡献较小，并且不同小球中的PN尖峰序列仅具有微弱的相关性。来自同一小球的PN轴突在侧角重新汇聚，在那里汇集冗余信号可能使侧角神经元能够平均掉这些PN中独立产生的噪声。
