Pang K C, Yoder R M, Olton D S
Department of Psychology and J. P. Scott Center for Neuroscience, Mind and Behavior, Bowling Green State University, Bowling Green, OH 43403, USA.
Neuroscience. 2001;103(3):615-28. doi: 10.1016/s0306-4522(01)00018-5.
The frontal cortex is an important brain area for divided attention. Lesions of the lateral agranular frontal cortex in rats disrupt divided attention in a simultaneous temporal processing task. In the present study, the activity of lateral agranular neurons was examined while rats performed a simultaneous temporal processing procedure. Rats were trained to time two stimuli (a light and a tone), each associated with a different fixed interval. Simple trials, in which a single stimulus was presented, and compound trials, in which both stimuli were presented simultaneously, occurred randomly in a session. Rats were able to divide attention between the two stimuli, as assessed by the pattern of lever presses. Approximately 50% of lateral agranular neurons responded to at least one phase of the task with four response patterns observed. The activity of type 1 cells (60%) was altered to compound, but not simple, stimuli. Type 2 cells (10%) responded to both types of simple stimuli and to compound stimuli. Type 3 cells (27%) had changes in firing rate to one type of simple stimulus and to compound stimuli. Type 4 cells (3%) responded to one type of simple stimulus, but were unresponsive to all other stimuli. The large proportion of type 1 cells supports the hypothesis that the lateral agranular cortex is important in divided attention. Previous studies have suggested that the lateral agranular cortex in rats is equivalent to the primary motor cortex. If so, the results from the present study provide evidence that the lateral agranular cortex may have some cognitive functions, in addition to being part of the motor system.
额叶皮质是进行分散注意力的重要脑区。大鼠外侧无颗粒额叶皮质受损会破坏其在同时性时间处理任务中的分散注意力能力。在本研究中，在大鼠执行同时性时间处理程序时，检测了外侧无颗粒神经元的活动。训练大鼠对两种刺激（光和声音）计时，每种刺激都与不同的固定间隔相关联。在一个实验环节中，简单试验（呈现单个刺激）和复合试验（同时呈现两种刺激）随机出现。通过杠杆按压模式评估，大鼠能够在两种刺激之间分散注意力。大约50%的外侧无颗粒神经元以四种反应模式对任务的至少一个阶段做出反应。1型细胞（60%）的活动因复合刺激而改变，但对简单刺激无反应。2型细胞（10%）对两种简单刺激和复合刺激均有反应。3型细胞（27%）对一种简单刺激和复合刺激的放电频率有变化。4型细胞（3%）对一种简单刺激有反应，但对所有其他刺激无反应。1型细胞的高比例支持了外侧无颗粒皮质在分散注意力中很重要这一假说。先前的研究表明，大鼠的外侧无颗粒皮质等同于初级运动皮质。如果是这样，本研究结果提供了证据，表明外侧无颗粒皮质除了作为运动系统的一部分外，可能还具有一些认知功能。
