Anticipatory Hemodynamic Signals in Primary Visual Cortex

项目负责人/主要研究者（最后一名、第一名、中间名）： 项目摘要 我们的长期目标是了解视觉处理的早期皮层通路的神经机制。 为此，我们记录恒河猴视觉皮层使用的组合的内在信号光学 成像和电生理学，而动物从事视觉形式处理任务。 本项目的目标是双重的。我们建议研究一种新的刺激无关的预期 血液动力学信号，我们观察到较早的警觉猕猴V1（初级视觉皮层）。通过这个 我们还建议更好地理解包括fMRI在内的神经成像信号的生理基础。 这个项目源于我们最近的发现，警觉猴V1的血液动力学信号有两个不同的 件.一个组成部分是可预测的视觉输入和相关的V1神经元活动。另 分量-强度相当-是迄今未知的血液动力学信号标记任务预期。它 反映了一种动脉泵送机制，在预期的视觉事件中将新鲜血液带到皮层。 与光学成像同时进行的电极记录表明，这种新的血流动力学 信号不是由局部V1神经元活动驱动的，与获得的视觉诱发响应形成鲜明对比 来自同一个录音地点 我们假设，预期的刺激非依赖性血流动力学信号是一种预测机制， 兴奋我们建议通过表征预期和视觉诱发信号来测试这一假设， 他们的互动，并询问是否预期信号可以调节视觉诱发的反应和行为。 我们对新的血液动力学信号的发现也挑战了目前对神经影像信号的理解， 特别是功能性磁共振成像（fMRI），这是人类神经成像最常用的工具。 通过这个项目的过程中，我们将研究神经影像信号之间的联系， 电生理学在警觉猕猴在各种视觉感知任务。这将是一个无与伦比的 有机会在最接近人类的动物模型中获得对fMRI的新见解。 我们的新发现是由于我们实验室开发的一种新的成像技术， 连续双波长固有信号光学成像，结合电极记录，处于警戒状态 举止优雅的猕猴对于成像，一个波长优先被氧合血红蛋白吸收， 从而监测血液氧合;另一个波长，在氧合和脱氧中同样吸收 血红蛋白，测量血容量。同时进行的电极记录给出了电生理学结果。 测量潜在的神经元活动。连续的录音让我们能够区分 持续的信号和刺激诱发的反应。这项技术将构成目前项目的基础， 提供了一个独特的工具组合来回答手头的问题。 PHS 398/2590（Rev. 11/07）

Program Director/Principal Investigator (Last, First, Middle): PROJECT SUMMARY Our long-term goal is to understand the neural mechanisms of visual processing early in the cortical pathway. To this end we record from rhesus macaque visual cortex using a combination of intrinsic-signal optical imaging and electrophysiology while the animals are engaged in visual form processing tasks. The goal of the current project is two-fold. We propose to study a novel stimulus-independent anticipatory haemodynamic signal that we observed earlier in alert macaque V1 (primary visual cortex). Through this process we also propose to better understand the physiological basis of neuroimaging signals including fMRI. This project derives from our recent discovery that haemodynamic signals in alert monkey V1 have two distinct components. One component is predictable by visual input and associated V1 neuronal activity. The other component - of comparable strength - is a hitherto unknown haemodynamic signal marking task anticipation. It reflects an arterial pumping mechanism bringing fresh blood to cortex in anticipation of predicted visual events. Electrode recordings conducted simultaneously with the optical imaging showed that this novel haemodynamic signal is not driven by local V1 neuronal activity, in dramatic contrast to visually evoked responses obtained from the same recording sites. We hypothesize that the anticipatory stimulus-independent haemodynamic signal is a mechanism of predictive arousal. We propose to test this hypothesis by characterizing the anticipatory and visually evoked signals, and their interaction, and asking if the anticipatory signal can modulate visually evoked responses and behavior. Our finding of the novel haemodynamic signal also challenges current understandings of neuroimaging signals, notably functional magnetic resonance imaging (fMRI), the most commonly used tool for human neuroimaging. Through the course of this project we will investigate the links between neuroimaging signals and electrophysiology in the alert macaque in a variety of visual perceptual tasks. This will be an unparalleled opportunity to gain new insights into fMRI in an animal model that is the closest possible to the human. Our novel findings were obtained as a result of a new imaging technique developed in our laboratory, continuous dual-wavelength intrinsic-signal optical imaging, combined with electrode recordings, in alert behaving macaques. For the imaging, one wavelength is absorbed preferentially in oxygenated haemoglobin, thus monitoring blood oxygenation; the other wavelength, absorbed equally in oxygenated and deoxygenated haemoglobin, measures blood volume. The simultaneous electrode recordings give an electrophysiological measure of the underlying neuronal activity. The continuous recording allows us to distinguish between ongoing signals and stimulus-evoked responses. This technique will form the basis of the current project, giving a unique combination of tools to answer the questions at hand. PHS 398/2590 (Rev. 11/07) Page Continuation Format Page