Paulk Angelique C, Dacks Andrew M, Phillips-Portillo James, Fellous Jean-Marc, Gronenberg Wulfila
Queensland Brain Institute, The University of Queensland, Brisbane, Australia.
J Neurosci. 2009 Aug 12;29(32):9987-99. doi: 10.1523/JNEUROSCI.1325-09.2009.
Visual scenes comprise enormous amounts of information from which nervous systems extract behaviorally relevant cues. In most model systems, little is known about the transformation of visual information as it occurs along visual pathways. We examined how visual information is transformed physiologically as it is communicated from the eye to higher-order brain centers using bumblebees, which are known for their visual capabilities. We recorded intracellularly in vivo from 30 neurons in the central bumblebee brain (the lateral protocerebrum) and compared these neurons to 132 neurons from more distal areas along the visual pathway, namely the medulla and the lobula. In these three brain regions (medulla, lobula, and central brain), we examined correlations between the neurons' branching patterns and their responses primarily to color, but also to motion stimuli. Visual neurons projecting to the anterior central brain were generally color sensitive, while neurons projecting to the posterior central brain were predominantly motion sensitive. The temporal response properties differed significantly between these areas, with an increase in spike time precision across trials and a decrease in average reliable spiking as visual information processing progressed from the periphery to the central brain. These data suggest that neurons along the visual pathway to the central brain not only are segregated with regard to the physical features of the stimuli (e.g., color and motion), but also differ in the way they encode stimuli, possibly to allow for efficient parallel processing to occur.
视觉场景包含大量信息，神经系统从中提取与行为相关的线索。在大多数模型系统中，对于视觉信息在视觉通路中传递时的转换情况知之甚少。我们利用以视觉能力著称的大黄蜂，研究了视觉信息从眼睛传递到大脑高阶中枢时在生理上是如何转换的。我们在大黄蜂大脑中部（外侧原脑）对30个神经元进行了细胞内活体记录，并将这些神经元与视觉通路中更远处区域（即髓质和小叶）的132个神经元进行了比较。在这三个脑区（髓质、小叶和中枢脑）中，我们研究了神经元的分支模式与其主要对颜色但也对运动刺激的反应之间的相关性。投射到前中枢脑的视觉神经元通常对颜色敏感，而投射到后中枢脑的神经元则主要对运动敏感。这些区域之间的时间响应特性存在显著差异，随着视觉信息处理从外周向中枢脑推进，跨试验的脉冲时间精度增加，平均可靠发放减少。这些数据表明，沿着通向中枢脑的视觉通路的神经元不仅在刺激的物理特征（如颜色和运动）方面存在分离，而且在编码刺激的方式上也有所不同，这可能是为了实现高效的并行处理。
