Neurology Clinic, Tor Vergata University, Rome, Italy.
Neuropsychologia. 2011 Jul;49(8):2199-208. doi: 10.1016/j.neuropsychologia.2010.11.013. Epub 2010 Nov 27.
The contribution of the thalamus to the functioning of prospective memory (PM) is currently unknown. Here we report an experimental investigation of the performance of two patients with bilateral infarcts in the anterior-mesial regions of the thalami on an event-based PM paradigm. One patient, G.P., had a pervasive declarative memory impairment but no significant executive deficit. The other patient, R.F., had a memory deficit limited to verbal material with associated behavioral abnormalities (inertia and apathy); she performed poorly on tests of executive functions. Although both patients performed poorly on the PM task, a qualitative analysis of performance revealed different mechanisms at the base of their impaired PM. G.P. had reduced declarative memory for target words compared with normal controls; but, unforgotten words were normally able to elicit his recall of the prospective intention. Conversely, R.F.'s declarative memory for target words was as accurate as that of normal controls, but she presented a dramatically reduced ratio between the number of target words she recalled and the number of times she activated the prospective intention on the PM task, suggesting that her deficit consisted of difficulty in activating the intention despite normal declarative memory for the target events. In conclusion, results of the present study demonstrate that thalamic structures have an important role in PM processes. They also document that damage to the anterior-mesial regions of the thalami affects PM abilities by two different mechanisms, respectively based on the relative disruption of declarative memory or executive processes functioning, which, in turn, is related to the specific intrathalamic structures involved by the lesions. Indeed, while G.P.'s pervasive declarative memory deficit was underlain by bilateral involvement of the mammillo-thalamic tract, R.F.'s executive and behavioral abnormalities were likely related to bilateral damage of the midline, intralaminar, and medio-dorsal nuclei.
丘脑对前瞻性记忆（PM）的作用目前尚不清楚。在这里，我们报告了对两名双侧丘脑前内侧区域梗死患者在基于事件的 PM 范式下的表现进行的实验研究。患者 G.P. 存在广泛的陈述性记忆障碍，但没有明显的执行功能缺陷。另一名患者 R.F. 的记忆缺陷仅限于言语材料，并伴有行为异常（惰性和冷漠）；她在执行功能测试中表现不佳。尽管两名患者在 PM 任务中表现不佳，但对表现的定性分析揭示了他们 PM 受损的基础上存在不同的机制。与正常对照组相比，G.P. 对目标词的陈述性记忆减少；但是，未被遗忘的词通常能够激发他对前瞻性意图的回忆。相反，R.F. 对目标词的陈述性记忆与正常对照组一样准确，但她在 PM 任务中回忆目标词的数量与激活前瞻性意图的次数之间的比例显著降低，这表明她的缺陷在于尽管对目标事件有正常的陈述性记忆，但很难激活意图。总之，本研究的结果表明，丘脑结构在 PM 过程中具有重要作用。它们还证明，前内侧丘脑区域的损伤通过两种不同的机制影响 PM 能力，分别基于陈述性记忆或执行过程功能的相对破坏，这又与损伤所涉及的特定丘脑内结构有关。事实上，虽然 G.P. 广泛的陈述性记忆缺陷是由双侧乳突丘脑束参与引起的，但 R.F. 的执行和行为异常可能与中线、内板层和中背核的双侧损伤有关。
