Neural mechanisms of top-down control in primate prefrontal cortex : from single neuron to functional brain imaging

了解从细胞事件到个体行为的记忆和认知的大脑机制是很重要的。为了实现这一目标，本项目旨在研究自上而下的记忆控制机制（Hasegawa et al Science 281, 814-818, 1998），结合(1)神经元活动的单细胞记录和(2)功能磁共振成像（fMRl），使用猕猴动物模型。(1)对部分裂脑猴的下颞叶皮层进行单单元记录。我们已经证明，在没有自下而上信号的情况下，前额叶皮层自上而下的信号可以诱导记忆回忆过程中颞下神经元的活动（Nature 401, 699-703）。1999)。我们还记录了动眼肌任务中前额叶神经元的活动，发现即使在非空间线索指示目标位置切换（Soc）的情况下，前额叶神经元也可以编码空间记忆信息来指导行为。>。摘要26,404。2, 2000)。(2)建立了1.5T和4.7T磁铁扫描猕猴的功能磁共振成像系统。使用1.5T磁铁，我们已经证明了fMRl在初级和第二体感觉皮层（Eur）显示躯体解剖的可行性。神经科学学报，11,451-56,1999)。利用4.7T磁体，我们制作了皮层眼肌区（Soc）的高对比度激活图。>。摘要27,345。12, 2001)。未来，我们计划制作认知记忆任务的功能激活图，并在此基础上进行功能失活和单单元实验

It is important to understand the brain mechanisms underlying memory and cognition from cellular events to individual behaviors. Toward this objective, the present project aims to investigate the mechanisms of top-down memory control (Hasegawa et al Science 281, 814-818, 1998) combining (1)single cell recordings of neuronal activity and (2) functional magnetic resonance imaging (fMRl), using animal models with macaque monkeys.(1) We conducted single unit recording from inferior temporal cortex in partial split-brain monkeys. We have shown that activity of inferior temporal neurons during memory recall can be induced by top-down signals from prefrontal cortex in the absence of bottom-up signals (Nature 401, 699-703. 1999). We also have recorded activity of prefrontal neurons during oculomotor tasks, and found that prefrontal neurons can code spatial memory information to guide behavior, even when non-spatial cues instruct switch of the target location (Soc. Neurosci. Abstr. 26, 404. 2, 2000).(2) We have built fMRl systems for scanning macaque monkeys using 1.5T and 4.7T magnets. With 1.5T magnet, we have shown the feasibility of fMRl to reveal somatotopy in primary and second somatosensory cortex (Eur. J. Neurosci. 11, 4451-56, 1999). With 4.7T magnet we have been making high-contrast activation maps of cortical oculomor areas (Soc. Neurosci. Abstr. 27, 345. 12, 2001). In future, we plan to make functional activation maps with cognitive memory tasks, with the aid of which we will perform functional inactivation and single unit experiments