正常老年人情境脈絡引發錯誤再認之研究

Abstract

情境脈絡訊息（contextual information）在人類再認記憶中扮演重要的角色。錯誤再認除了由主題本身的訊息引發（text-induced）之外，也可能由主題所在的情境脈絡引發（context-induced），亦即情境脈絡引發之錯誤再認（context-induced false recognition），但很少有這方面的研究。很少文獻討論再認記憶之情境脈絡效果的神經心理機制，可能的解釋為主題與情境脈絡間的鍵結歷程會影響情境脈絡的效果。研究指出內側中央顳葉主要負責訊息的鍵結，而額葉主要負責鋪陳訊息間的關聯性，以便鍵結的進行。由於正常老年人鍵結能力有缺損，因此預期情境脈絡效果會有年齡差異性。有鑑於此，本研究嘗試探討正常老年人是否產生過多情境脈絡引發之錯誤再認，以及可能涉及的神經心理機制為何。二十位正常老年人與29位年輕成年人參與本研究，每位參與者接受神經心理檢查及操弄情境脈絡之再認記憶評估。結果發現老年人的認知功能比年輕人差，特別是執行功能與記憶功能；老年人較容易產生情境脈絡引發之錯誤再認，但年輕人不容易產生。因此，本研究結果顯示年輕成年人的再認記憶不易受情境脈絡影響，但正常老年人的再認記憶在特定條件下容易受情境脈絡影響；老年人相對年輕人於容易產生情境脈絡引發之錯誤再認，且可能反映出他們的執行功能與記憶功能有所改變，主要與額葉及內側中央顳葉功能改變有關。未來加入功能性神經影像技術之研究可以幫助釐清腦部特定部位之功能與情境脈絡引發之錯誤再認的關係。

Contextual information plays an important role in human recognition memory. A large body of studies shows a strong evidence of text-induced false recognition. However, little investigates the issue regarding whether there also exists the evidence of context-induced false recognition. Furthermore, few studies examine the possible neuropsychological mechanism underlying context effect of recognition memory though a binding processing between text and context has been proposed to account for it. Literature shows that medial temporal lobes get involved in binding processing per se while frontal lobes are responsible for generating binding process. Because of binding deficits evident in normal aging, it would be expected that normal elderly individuals’ recognition memory might be vulnerable to context effects. The present study was thus to explore issues of whether normal elderly people evidence context-induced false recognition, and of the possible neuropsychological mechanism underlying context-related false recognition. Twenty normal elderly and 29 young adults participated in the present study, and each subject received a battery of neuropsychological tests and a visual recognition memory task containing both text and context feature information. The results revealed remarkable evidence of context-induced false recognition memory in normal elderly subjects, but it is not the case for normal younger subjects. Normal elderly subjects’ performance on the neurocogntive tests, particularly the executive and memory function ones, was also significantly poor compared with their normal younger counterparts. Based on the results, it appears that normal elderly individuals’ recognition memory was vulnerable to context effects and the vulnerability might be associated with dorsal prefrontal- and mesial temporal-related neurocogntive changes mainly reflected by conventional neuropsychological tests. Further investigation with functional neuroimaging tools would be helpful for delineating specific neural substrates responsible for context-induced false recognition.