Arizona State University, Department of Psychology, P.O. Box 871104, Tempe, AZ, 85287-1104, USA.
Arizona State University, Department of Psychology, P.O. Box 871104, Tempe, AZ, 85287-1104, USA; Columbia University, Department of Psychiatry, 1051 Riverside Drive, New York, NY, 10032, USA.
Behav Brain Res. 2019 Dec 30;376:112184. doi: 10.1016/j.bbr.2019.112184. Epub 2019 Aug 29.
This study investigated the role of the dorsal hippocampus (dHPC) in the temporal entrainment of behavior, while addressing limitations of previous evidence from peak procedure experiments. Rats were first trained on a switch-timing task in which food was obtained from one of two concurrently available levers; one lever was effective after 8 s and the other after 16 s. After performance stabilized, rats underwent either bilateral NMDA lesions of the dHPC or sham lesions. After recovery, switch-timing training resumed. In a subsequent condition, the switch-timing task was modified such that food was available after either 8 or 32 s. Although dHPC lesions had subtle and complex effects on when rats stopped seeking for food at the 8-s lever (departures), it more systematically reduced the time when rats started seeking for food at the 16-s and 32-s lever (switches). No systematic effect of dHPC lesions were observed on the coefficient of quartile variation (normalized dispersion) of latencies to switch. Within the context of the pacemaker-accumulator framework of interval timing, these findings suggest that partially or wholly independent mechanisms control the initiation and termination of timed responses, and that the dHPC is primarily involved in encoding the time to start responding.
本研究旨在探讨背侧海马（dHPC）在行为的时间同步中的作用，同时解决了先前基于峰程序实验的证据的局限性。研究中，大鼠首先接受了一个开关定时任务的训练，在该任务中，食物可以从两个同时可用的杠杆中获得；一个杠杆在 8 秒后有效，另一个在 16 秒后有效。在表现稳定后，大鼠接受了双侧 NMDA 背侧海马区损伤或假手术损伤。恢复后，重新开始进行开关定时训练。在随后的条件下，修改了开关定时任务，使得食物可以在 8 秒或 32 秒后获得。尽管 dHPC 损伤对大鼠在 8 秒杠杆上停止寻找食物的时间（偏离）有微妙而复杂的影响，但它更系统地减少了大鼠在 16 秒和 32 秒杠杆上开始寻找食物的时间（转换）。dHPC 损伤对潜伏期的四分位变异系数（标准化离散度）没有系统的影响。在间隔计时的起搏器-累加器框架内，这些发现表明，部分或完全独立的机制控制着定时反应的开始和结束，而 dHPC 主要参与编码开始反应的时间。
