Liu Ping, Jarrard Leonard E, Bilkey David K
Department of Psychology, Neuroscience Research Centre, University of Otago, Dunedin, New Zealand.
Hippocampus. 2004;14(1):107-16. doi: 10.1002/hipo.10161.
To determine what influence the pre- and parasubiculum regions of the hippocampal formation have on neural representations within the dorsal hippocampus, single-unit recordings were made as rats with bilateral ibotenic acid lesions centered on the former regions (n = 4) or control surgeries (n = 3) foraged freely. Spatial firing specificity was measured using an information content procedure. Cells from lesioned animals (n = 57) provided significantly less spatial information than cells from control animals (n = 44). Whereas some degree of location-related activity (place fields) was observed in 98% of neurons recorded from control animals, it was observed in only 65% of the neurons from lesioned animals. The spatial resolution of the intact place fields appeared to be compromised in lesioned animals as a result of their having a higher firing rate outside the place field. These findings indicate that the pre- and parasubiculum regions have a major role in maintaining the specificity of the place field firing of hippocampal pyramidal cells. Since previous data indicate that these lesioned animals displayed delay-dependent deficits in spatial tasks, these findings also suggest that a disruption in place field activity may be a causal factor in this spatial memory deficit.
为了确定海马结构的前下托和旁下托区域对背侧海马内神经表征有何影响，在以这些区域为中心进行双侧鹅膏蕈氨酸损伤的大鼠（n = 4）或接受对照手术的大鼠（n = 3）自由觅食时进行了单单元记录。使用信息含量程序测量空间放电特异性。损伤动物的细胞（n = 57）提供的空间信息明显少于对照动物的细胞（n = 44）。在对照动物记录的98%的神经元中观察到一定程度的位置相关活动（位置野），而在损伤动物的神经元中只有65%观察到这种活动。由于损伤动物在位置野之外具有较高的放电率，完整位置野的空间分辨率似乎受到了损害。这些发现表明，前下托和旁下托区域在维持海马锥体细胞位置野放电的特异性方面起着主要作用。由于先前的数据表明这些损伤动物在空间任务中表现出延迟依赖性缺陷，这些发现还表明位置野活动的破坏可能是这种空间记忆缺陷的一个因果因素。
