Neuronal mechanisms controlling the spatial attention and gaze movements

大量的胆碱能投射来自中脑臂旁区、桥脚被盖核（PPTN）和背侧被盖核（LDTN）。它们被定向到几个大脑区域，包括丘脑的外侧膝状核（LGN）、上丘（SC）、黑质中的多巴胺神经元和桥-延髓网状结构。最近的研究表明，PPTN胆碱能神经元有助于控制门控运动和注意行为。为了进一步阐明脑干胆碱能系统的功能，我们分析了3只清醒的日本猴子在执行视觉引导的GAP/NO-GAP扫视任务时PPTN神经元的单单位活性。大约64%（45/70）的被测神经元表现出活动的阶段性变化，这先于它们的眼跳到目标：26个细胞的活动增加（爆发型细胞），19个细胞的活动减少（暂停型细胞）。在间隙期(1)，除了它们的前额活动外，爆发神经元的活动倾向于增加，而暂停细胞的活动倾向于减少。E，注视点偏移和扫视目标开始之间的200毫秒空白期)。这些结果表明，PPTN神经元参与了眼跳到靶标的准备。此外，有7个神经元的活动在间隔时间（前一个实验的奖励和后一个实验的注视点开始之间的时间）到扫视结束时表现出强直性的增加。此外，当注视点首次出现时，29个神经元的活动增加，5个神经元的活动增加。后一种行为与成功完成即将到来的扫视到目标密切相关，从而表明这些神经元有助于控制动物的警觉性。

A substantial number of cholinergic projections originate from the parabrachial region in the midbrain the pedunculo-pontine tegmental nucleus(PPTN), and the latero-dorsal tegmental nucleus(LDTN). They are directed to several brain regions, icluding the lateral geniculate nusleus(LGN) of the thalamus, the superior colliculus(SC), dopamine neurons in substantia nigra, and the ponto-medullary reticular formation. Recent studies have suggested that the PPTN cholinergic neurons help control gating movements and attentive behaviors. To further clarify the function of the brainstem cholinergic system, we analyzed the single-unit activity of PPTN neurons in three awake Japanese monkeys while they were performing visually guided GAP/NO-GAP saccade tasks. About 64% (45/70) of the tested neurons exhibited a phasic change in their activity, which preceded their saccade-to-target : 26 cells had an increase in activity (burst-type cells), and 19 a decrease (pause-type cells). In addition to their presaccadic behavior, the burst neurons tended to show an increase in activity, and the pause cells a decrease, during the GAP period(i. e., the 200-ms blank period between the offset of the fixation point and onset of the saccade target). These results suggested that PPTN neurons are involved in the preparation for a saccade-to-target. Additionally, 7 neurons exhibited a tonic increase in their activity from the intertrial interval (the time between the reward in the preceding trial and onset of the fixation point in the succeeding trial) until the end of the saccade. Furthermore, 29 neurons had a tonic, and 5 a phasic, increase in activity when the fixation point first appeared. This latter behavior was closely correlated with the successful completion of the upcoming saccade-to-target, thereby suggesting that such neurons contribute to control of the animals' vigilance.