Cimadevilla J M, Wesierska M, Fenton A A, Bures J
Department of Experimental Psychology and Psychobiology, University of Almeria, 04120, La Cañada de San Urbano, Spain.
Proc Natl Acad Sci U S A. 2001 Mar 13;98(6):3531-6. doi: 10.1073/pnas.051628398.
Unilateral intrahippocampal injections of tetrodotoxin were used to temporarily inactivate one hippocampus during specific phases of training in an active allothetic place avoidance task. The rat was required to use landmarks in the room to avoid a room-defined sector of a slowly rotating circular arena. The continuous rotation dissociated room cues from arena cues and moved the arena surface through a part of the room in which foot-shock was delivered. The rat had to move away from the shock zone to prevent being transported there by the rotation. Unilateral hippocampal inactivations profoundly impaired acquisition and retrieval of the allothetic place avoidance. Posttraining unilateral hippocampal inactivation also impaired performance in subsequent sessions. This allothetic place avoidance task seems more sensitive to hippocampal disruption than the standard water maze task because the same unilateral hippocampal inactivation does not impair performance of the variable-start, fixed hidden goal task after procedural training. The results suggest that the hippocampus not only encodes allothetic relationships amongst landmarks, it also organizes perceived allothetic stimuli into systems of mutually stable coordinates. The latter function apparently requires greater hippocampal integrity.
在主动异源性位置回避任务的特定训练阶段，通过单侧海马内注射河豚毒素来暂时使一侧海马失活。大鼠需要利用房间中的地标来避开缓慢旋转的圆形竞技场中由房间定义的一个区域。持续旋转使房间线索与竞技场线索分离，并使竞技场表面穿过施加足部电击的房间区域。大鼠必须远离电击区域以防止被旋转带到那里。单侧海马失活严重损害了异源性位置回避的习得和记忆提取。训练后单侧海马失活也损害了后续实验中的表现。与标准水迷宫任务相比，这种异源性位置回避任务似乎对海马破坏更敏感，因为相同的单侧海马失活在程序性训练后不会损害可变起始、固定隐藏目标任务的表现。结果表明，海马不仅编码地标之间的异源性关系，还将感知到的异源性刺激组织成相互稳定的坐标系统。后一种功能显然需要更高的海马完整性。
