Department of Psychology, University of New Hampshire, Durham, New Hampshire 03824, USA.
Hippocampus. 2012 Apr;22(4):853-60. doi: 10.1002/hipo.20945. Epub 2011 May 3.
The reuniens (Re) and rhomboid (Rh) nuclei are organized to influence activity in distributed limbic networks involving hippocampus and medial prefrontal cortex (mPFC). To elucidate the role of these nuclei in spatial memory we inactivated Re and Rh in rats with the GABA(A) agonist muscimol and compared effects on two spatial delayed conditional discriminations: delayed nonmatching to position (DNMTP) and varying choice radial maze delayed nonmatching (VC-DNM). DNMTP is trained in operant chambers and requires rats to choose between the same two levers on all trials. VC-DNM is trained in automated radial mazes and requires rats to choose between two arms, randomly selected from eight alternatives on each trial. DNMTP is affected by hippocampal and mPFC lesions while VC-DNM is affected by hippocampal, but not mPFC lesions (Porter et al. (2000) Behav Brain Res 109:69-81). We found evidence of a localized (low dose) effect of ReRh inactivation on DNMTP but not VC-DNM. This was confirmed by comparison with muscimol injections in an anatomical control site. These results are consistent with evidence that Re and Rh affect measures of spatial working memory that depend on interactions between hippocampus and mPFC, but not measures that depend on hippocampus alone.
回视（Re）和菱形（Rh）核被组织起来以影响涉及海马体和内侧前额叶皮层（mPFC）的分布式边缘网络的活动。为了阐明这些核在空间记忆中的作用，我们用 GABA(A) 激动剂 muscimol 使大鼠的 Re 和 Rh 失活，并比较了对两种空间延迟条件辨别任务的影响：位置延迟非匹配（DNMTP）和变化选择放射状迷宫延迟非匹配（VC-DNM）。DNMTP 在操作性条件反射室中进行训练，要求大鼠在所有试验中在两个相同的杠杆之间进行选择。VC-DNM 在自动化放射状迷宫中进行训练，要求大鼠在每个试验中从八个替代臂中随机选择两个臂进行选择。DNMTP 受海马体和 mPFC 损伤的影响，而 VC-DNM 受海马体但不受 mPFC 损伤的影响（Porter 等人，2000 年，行为脑研究 109:69-81）。我们发现 ReRh 失活对 DNMTP 的局部（低剂量）影响的证据，但对 VC-DNM 没有影响。这通过与在解剖学对照部位的 muscimol 注射进行比较得到了证实。这些结果与证据一致，即 Re 和 Rh 影响依赖于海马体和 mPFC 之间相互作用的空间工作记忆测量，但不影响仅依赖于海马体的测量。
