McEown Kristopher, Treit Dallas
Department of Psychology and Division of Neuroscience, P-449 Biological Sciences Building, University of Alberta, Edmonton AB, Canada T6G 2E9.
Brain Res. 2009 Jan 28;1251:185-94. doi: 10.1016/j.brainres.2008.11.041. Epub 2008 Nov 24.
The roles of the dorsal and ventral hippocampus in fear and memory are unclear. This study examined the effects of temporary inactivation of the dorsal or ventral hippocampus on unconditioned and conditioned fear, using the shock-probe test. In Experiment 1, rats received either dorsal or ventral hippocampal infusions of lidocaine or saline, before exposure to an electrified shock-probe (acquisition I). In Experiment 2, rats received lidocaine or saline infusions after exposure to the shock-probe (acquisition II). In both experiments, a retention test in the same apparatus was given 24 h later, at which time the hippocampus was no longer inactivated, and the probe was disconnected from the shock-source. Because ventral hippocampal inactivation impaired fear behaviour during acquisition, and dorsal hippocampal inactivation impaired fear behaviour (probe avoidance) during retention, we concluded that 1) the ventral hippocampus plays a role in the expression of untrained fear reactions whereas 2) the dorsal hippocampus plays a role in encoding memory of the fearful experience.
背侧海马体和腹侧海马体在恐惧和记忆中的作用尚不清楚。本研究使用电击探针试验，检测了背侧或腹侧海马体暂时失活对无条件恐惧和条件性恐惧的影响。在实验1中，大鼠在接触带电电击探针之前（初次习得），接受背侧或腹侧海马体注射利多卡因或生理盐水。在实验2中，大鼠在接触电击探针之后（再次习得）接受利多卡因或生理盐水注射。在两个实验中，24小时后在同一装置中进行记忆保持测试，此时海马体不再失活，且探针与电击源断开连接。由于腹侧海马体失活会损害习得过程中的恐惧行为，而背侧海马体失活会损害记忆保持过程中的恐惧行为（探针回避），我们得出结论：1）腹侧海马体在未训练的恐惧反应表达中起作用，而2）背侧海马体在恐惧经历的记忆编码中起作用。
