MultiSensDepthPercep: Midbrain Circuits Underlying Multisensory Depth Perception

为了对外部事件产生适当的反应，生物体通常需要联合收割机组合多种形式的感觉信息。特定的大脑区域权衡并联合收割机将这些信息组合起来，形成对外部世界的精确表示，并激发优化的行为输出。上级丘（SC）是一个进化上保守的结构，在这里，来自多种形式的感觉输入被整合在同一个坐标系中，以触发定向和逃避行为。SC中水平轴和垂直轴的空间表示已经得到了很好的表征，然而，判断第三维-源距离-的神经基础还不太清楚。光速和声速之间的差异为听觉信号相对于视觉信息引入了距离相关的滞后。SC中的视觉-听觉神经元对这种延迟很敏感。我们将通过进行大规模神经元记录来研究SC解剖学定义区域中空间的多感觉三维表示。我们将使用光遗传学和功能电路追踪方法研究时空多感觉整合的网络机制。然后，我们将确定动物如何结合联合收割机视听信息来估计威胁的位置，并指导防御反应的选择，如冻结和逃离。最后，我们将使用树突棘及其母树突的双光子钙和电压成像来确定SC神经元中的多感觉细胞计算。这种多尺度方法将揭示三维空间的多感官表征的机制，以及如何使用威胁位置的估计来指导行为反应。

In order to generate appropriate responses to external events, living organisms often need to combine sensory information of multiple modalities. Specific brain areas weigh and combine this information to form a precise representation of the outside world and instigate optimised behavioural outputs. The superior colliculus (SC) is an evolutionary conserved structure, where sensory inputs from multiple modalities are integrated in the same coordinate system to trigger orienting and escape behaviours. The representation of space in the horizontal and vertical axes in the SC has been well characterised, however, the neural bases for judging the third dimension - source distance - are less well understood. The difference between the velocities of light and sound introduces a distance dependent lag for auditory signals with respect to visual information. Visual-auditory neurons in the SC are sensitive to this delay. We will study the multisensory three dimensional representation of space in anatomically defined regions of the SC by performing large-scale neuronal recordings. We will investigate the network mechanisms underlying spatiotemporal multisensory integration using optogenetic and functional circuit tracing approaches. We will then determine how animals combine audio-visual information to estimate the location of a threat and to guide the selection of defensive responses, such as freezing and scape. Finally, we will determine multisensory cellular computations in SC neurons using two-photon calcium and voltage imaging of dendritic spines and their parent dendrites. This multiscale approach will reveal the mechanism underlying the multisensory representation of three dimensional space and how the estimation of threat location is used to guide behavioural responses.