大鼠时间感知的行为学研究

A behavioral study of timing task in rats

目的 观察大鼠对时间的感知过程中各种行为之间的关系,探讨操作动机对大鼠时间感知的影响。方法 采用断水24h的雄性SD大鼠执行时间反应分辨任务。在听到声音信号并完成鼻触行为之后,大鼠要踩压杠杆并保持4～5s后松开杠杆,才能得到50μl水作为奖赏。若过早或过晚松开则没有奖赏。分析声音信号和鼻触行为之间的声音反应潜伏期及鼻触行为和踩杠杆之间的踩杠杆潜伏期与操作正确性之间的关系,以及这些潜伏期与保持踩压杠杆的时间（计时期,Timing）之间的关系。结果 在计时准确的操作中,声音反应潜伏期和踩杠杆潜伏期都比较短[计时正确的情况下分别是（4.20±0.20）s和（1.28±0.03）s,早反应情况下分别是（4.79±0.16）s和（1.70±0.08）s,晚反应情况下分别是（4.99±0.48）s和（1.65±0.10）s,P〈0.01];这两个潜伏期之间存在显著的正相关（P〈0.05）,但与计时期之间均无显著相关,相关系数范围分别是-0.14～0.1以及-0.21～0.23（P〉0.05）。结论 时间感知任务的操作可能与操作动机有密切的关系;操作动机较强时,动物倾向于更准确地估计时间,以便完成任务。

Objective To observe correlation of behaviors in an interval timing task of rats. Methods The timing task trial started with a cue light on. A sonalert sounded 2 sec after the cue light, after which the animal could extend a lever with a nose-poke. It was required to press the lever and hold it for 4 - 5 sec in order to obtain 50 μl of water. An incorrect timing would turn off the house light and no reward would be presented. Correlations between the tone-nose interval （interval between cue tone and nose-poke） and the nose-press interval （interval between nose-poke and lever-press） and the outcome of the timing task were analyzed. Results Tone-nose interval （4.20 ±0.20）：3 in correct timing trails, （4.79 ±0. 16） s in early timing trails and （4.99 ± 0.48） s in late timing trails and nose-press interval （ 1.28 ± 0.03 ） s in correct timing trails, （ 1.70± 0.08 ） s in early timing trails, 1.65 ± 0.10 in late timing trails） were usually shorter in the correct timing trials （ P 〈 0.01 ）. Meanwhile, tone-nose interval and nose-press interval were found positively correlated （ P〈 0.05 ）, while no correlation between timing interval （interval between lever press and release） and either tone-nose interval or nose- press interval could be observed （ P 〉 0.05 ）. Conclusion The performance of interval timing task may be partially determined by the motivation of the animals. Rats tended to do better when they were highly motivated.