Neural mechanisms of color

描述（由申请人提供）：尽管大脑编码颜色信号的步骤相对来说已经被很好地理解了，但令人惊讶的是，人们对解码这些信号以产生颜色感知的神经计算知之甚少。一个线索来自恒河猴的下颞叶皮层（IT）损伤，它会导致颜色感知的严重丧失。通过在猴子中使用fmri引导的单单元记录，我们发现一个IT模块系统可能在表示颜色方面发挥重要作用，并且可能与人类的颜色区域具有同源性。颜色模块与其他IT部分之间的关系，以及它们内部的神经活动与感知之间的联系，目前还不太清楚。相比之下，人类的感知色彩机制已经得到了广泛的研究，产生了许多假设，可以在猴子身上用针对颜色模块的记录进行测试。但尚不清楚这两个物种是否具有相似的心理物理着色机制，这对该领域的进展构成了关键障碍。我们的首要目标是克服这一障碍，并利用fmri引导的微电极记录训练猴子从事颜色任务的IT，揭示颜色感知的神经计算。基于大量初步数据的中心假设是，猴子拥有与人类相似的基本色和高阶色机制；这些机制是通过基本的转换来实现的，这些转换最终在专门的IT颜色模块中表示感知颜色空间。这项建议包括三个目标。首先，我们将为猴子修改用于揭示人类心理物理着色机制的经典范式。其次，我们将使用功能磁共振成像来确定模块专门用于颜色和功能连接的程度。第三，我们将首次解决后验IT中颜色细胞活动与颜色辨别行为之间的联系，使用信号检测理论从动物执行颜色任务时获得的神经记录中计算选择概率估计。实现该提案的目标将有助于下一步的逻辑步骤，以实现我们的长期目标，即理解颜色感知的计算，包括构建一个生理学上合理的颜色模型。这项研究将为神经回路功能的一般原理提供信息，这对于理解精神疾病和神经疾病的病因、诊断和治疗至关重要；并将指导绕过眼睛的视觉障碍的治疗，并利用那些在失明的主要侮辱中幸存下来的皮质计算能力。

DESCRIPTION (provided by applicant): Although the steps by which the brain encodes color signals are relatively well understood, surprisingly little is known about the neural computations that decode these signals to yield color percepts. One hint comes from lesions of inferior temporal cortex (IT) in rhesus monkeys that cause a profound loss of color perception. Using fMRI-guided single-unit recording in monkeys, we found a system of IT modules that likely play an important role in representing color and are the probable homologue of color regions in humans. The relationship of the color modules to the rest of IT is poorly understood, as is the link between the neural activity within them and perception. By contrast, perceptual chromatic mechanisms in humans have been studied extensively, giving rise to many hypotheses that could be tested in monkeys with recordings targeted to the color modules. But it is unknown whether the two species possess similar psychophysical chromatic mechanisms, imposing a critical barrier to progress in the field. Our overarching aim is to overcome this obstacle and to uncover the neural computations for color perception using fMRI-guided microelectrode recording of IT in trained monkeys engaged in color tasks. The central hypothesis, based on substantial preliminary data, is that monkeys possess both cardinal and higher-order chromatic mechanisms similar to humans; and that these mechanisms are implemented by essential transformations that culminate in the representation of perceptual color space within specialized IT color modules. The proposal consists of three aims. First, we will modify for monkeys the classic paradigm used to reveal psychophysical chromatic mechanisms in humans. Second, we will use fMRI to determine the extent to which the modules are specialized for color and functionally connected. Third, we will address for the first time the link from color-cell activityin posterior IT to color-discrimination behavior, using signal-detection theory to compute choice-probability estimates from neural recordings obtained while animals perform a color task. Achieving the proposal's aims will facilitate the next logical steps toward our long-term goal of understanding the computations underlying color perception, including the construction of a physiologically plausible model of color. The research will inform general principles of neural circuit function, which is critical for understanding the etiology, diagnosis and treatment of mental illness and neurological disease; and will guide treatments for visual impairment that bypass the eye and exploit those cortical computations that survive the primary insult in blindness.