Parsing pathways of visual perception

视觉引导的行为会引起感觉和运动回路中尖峰活动的广泛变化。确定这些复杂的神经元放电模式是如何读出(即解码)以产生感知和指导行为的，对于理解我们如何与世界互动至关重要，但很少有因果证据表明大脑是如何做到这一点的。来自视觉皮质(V1)的输出神经元表现出不同的动力学，这取决于它们是投射到皮质、皮质下还是后脑目标，最近的研究表明，简单的视觉行为可能比其他更强烈地依赖于某些V1的输出。这表明V1可能代表多个不同的信息流。然而，在不同的V1输出中产生的活动对视觉引导行为的不同影响程度值得进一步探讨。在这里，我们试图解决两个基本的问题，关于V1的尖峰如何引起感知和行动：1)在一些V1投射中产生的活动是否比其他投射与感知更紧密地联系在一起？2)相同的V1输出是否根据感觉输入和运动输出之间的偶然性而对行为产生不同的影响？我和我的受训者将专注于投射上丘(SC)或纹状体(Str)的V1神经元，因为这两个结构都接受V1直接输入并执行对知觉决策至关重要的感觉运动功能。将训练小鼠执行具有挑战性的感知任务，并在心理物理阈值下可靠地工作。我们将对投射到SC或Str的V1神经元的不同亚群中的活动进行光遗传学调节。在第一个实验中(目标1)，小鼠将报告V1投射神经元的直接光遗传激活。在这里，行为报告提供了明确的证据，表明实验者控制的活动模式可以被解码来指导行为，这与神经假体设备具有巨大的相关性。第二组小鼠(目标2)将被训练来报告在两个不同的视觉任务中视觉运动的变化(检测和辨别视觉运动)。我们将在不同的时间选择性地抑制对SC或STR的V1投射，以评估它们对行为的贡献的时机，以及这些贡献是否与任务有关。通过实验，行为过程中的活体电生理记录将帮助我们将感觉输入和任务表现与V1、SC和Str的群体尖峰联系起来(目标3)。这项研究计划将产生急需的洞察力，了解不同V1输出通道中的神经元信号如何产生感知和行为。此外，进行这项工作的HQP将发展强大的技能，为他们在学术界或私营行业(如新兴的神经技术部门)的职业生涯做好准备。

Visually-guided behaviours evoke widespread changes in spiking activity throughout sensory and motor circuits. Determining how these complex patterns of neuronal spiking are read out (i.e., decoded) to generate perception and guide behavior is of central importance for understanding how we interact with the world, yet there is very little causal evidence for how the brain accomplishes this. Output neurons from visual cortex (V1) exhibit distinct dynamics depending on whether they project to cortical, subcortical, or hindbrain targets and recent work shows that simple visual behaviours may depend more strongly on some V1 outputs than others. This suggests that V1 may represent multiple, distinct streams of information. However, the degree to which activity arising in distinct V1 outputs differentially impacts visually-guided behaviours warrants further exploration. Here, we seek to address two fundamental questions regarding how spiking in V1 gives rise to perception and action: 1) Is activity arising in some V1 projections more closely linked to perception than others? and 2) Does the same V1 output differentially affect behaviour depending on contingencies between sensory input and motor output? My trainees and I will focus on V1 neurons that project either the superior colliculus (SC) or the Striatum (Str) as both structures receive direct V1 input and perform sensorimotor functions that are critical for perceptual decision-making. Mice will be trained to perform challenging perceptual tasks and work reliably at psychophysical threshold. We will optogenetically modulate activity in distinct subpopulations of V1 neurons that project either to the SC or Str. In the first experiment (Objective 1), mice will report direct optogenetic activation of V1 projection neurons. Here, behavioral reports provide unequivocal evidence that the experimenter-controlled patterns of activity can be decoded to guide behavior, which has immense relevance for neuroprosthetic devices. A second set of mice (Objective 2) will be trained to report changes in visual motion in two different visual tasks (detect versus discriminate visual motion). We will selectively inhibit V1 projections to the SC or Str at different times to assess the timing of their contributions to behaviour and whether those contributions are task-dependent. Across experiments, in vivo electrophysiological recordings during behaviour will helps us link sensory input and task performance with population spiking in V1, SC, and the Str (Objective 3). This program of research will yield much needed insight into how neuronal signals in arising in different V1 output channels give rise to perception and behaviour. Furthermore, the HQP conducting this work will develop a strong skillset that will prepare them for careers in academia or private industries such as the emerging neurotechnology sector.