Neuroscience Institute, Georgia State University, Atlanta, Georgia, USA.
Hippocampus. 2024 Oct;34(10):518-527. doi: 10.1002/hipo.23629. Epub 2024 Aug 3.
The dorsal region of the hippocampus (dHC) mediates many of the mnemonic functions traditionally associated with the hippocampus proper, such as spatial and episodic memory, whereas ventral hippocampus (vHC) has been extensively implicated in emotional memory and motivational processes. By contrast, the functions of the intermediate hippocampus (iHC) are far less understood. In this study, we aimed to investigate the mnemonic functions of iHC by reversibly inactivating iHC prior to testing memory in behavioral tasks dependent on the integrity of dHC, iHC, or vHC, namely, rapid place water maze, inhibitory avoidance, spontaneous alternation, and temporal ordering of odors. Given our previous findings showing that dHC and vHC are involved in mnemonic control of ingestive behavior, we also assessed the effects of iHC inactivation on sucrose intake. The results showed that pharmacological inhibition of iHC impairs rapid place water maze memory, which has been previously shown to be dependent on iHC but not dHC or vHC. iHC inactivation does not impact memory dependent on dHC (spontaneous alternation), vHC (temporal odor memory), or either dHC or vHC (inhibitory avoidance), and only modestly affects sucrose intake. These findings provide support for the involvement of iHC in mnemonic functions that are distinct from dHC and vHC and highlight the need to further advance our understanding of the functions of this hippocampal region that has been relatively understudied.
海马体背侧区域（dHC）介导了许多传统上与海马体本身相关的记忆功能，例如空间和情景记忆，而腹侧海马体（vHC）则广泛涉及情感记忆和动机过程。相比之下，中间海马体（iHC）的功能则知之甚少。在这项研究中，我们旨在通过在测试依赖于 dHC、iHC 或 vHC 完整性的行为任务之前可逆地抑制 iHC，来研究 iHC 的记忆功能，即快速位置水迷宫、抑制性回避、自发交替和气味的时间顺序。鉴于我们之前的研究结果表明 dHC 和 vHC 参与了摄食行为的记忆控制，我们还评估了 iHC 失活对蔗糖摄入的影响。结果表明，iHC 的药理学抑制会损害快速位置水迷宫记忆，而这一记忆之前被证明依赖于 iHC，但不依赖于 dHC 或 vHC。iHC 失活不会影响依赖于 dHC（自发交替）、vHC（时间气味记忆）或 dHC 和 vHC（抑制性回避）的记忆，并且仅适度影响蔗糖摄入。这些发现为 iHC 参与与 dHC 和 vHC 不同的记忆功能提供了支持，并强调需要进一步深入了解这个相对研究较少的海马体区域的功能。
