Bowles Ben, Duke Devin, Rosenbaum R Shayna, McRae Ken, Köhler Stefan
Brain and Mind Institute and Department of Psychology, Western University, London, Ontario, Canada; Department of Psychology, UC Berkeley, Berkeley, California, United States.
Brain and Mind Institute and Department of Psychology, Western University, London, Ontario, Canada.
Neuropsychologia. 2016 Sep;90:170-9. doi: 10.1016/j.neuropsychologia.2016.06.035. Epub 2016 Jul 1.
The ability to recognize the prior occurrence of objects can operate effectively even in the absence of successful recollection of episodic contextual detail about a relevant past object encounter. The pertinent process, familiarity assessment, is typically probed in humans with recognition-memory tasks that include an experimentally controlled study phase for a list of items. When meaningful stimuli such as words or pictures of common objects are employed, participants must judge familiarity with reference to the recent experimental encounter rather than their lifetime of autobiographical experience, which may have involved hundreds or thousands of exposures across numerous episodic contexts. Humans can, however, also judge the cumulative familiarity of objects concepts they have encountered over their lifetime. At present, little is known about the cognitive and neural mechanisms that support this ability. Here, we tested an individual (NB) with a rare left anterior temporal-lobe lesion that included perirhinal cortex but spared the hippocampus, who had previously been found to exhibit selective impairments in familiarity assessment on verbal recognition-memory tasks. As NB exhibits normal recollection abilities, her case presents a unique opportunity to examine potential links between both types of familiarity. In Experiment 1, we demonstrated that NB's impairment in making recognition judgments affects cumulative frequency judgments for exposure to concept names in a recent study episode. Experiments 2 and 3 revealed, with a task borrowed from the semantic-memory literature, that NB's impairments do indeed extend to abnormalities in judging cumulative lifetime familiarity for object concepts. These abnormalities were not limited to verbal processing, and were present even when pictures were offered as additional cues. Moreover, they showed sensitivity to concept structure as reflected in semantic feature norms; we only observed them for judgments on object concepts with high feature overlap. In Experiment 4, we found that an amnesic patient (HC) with previously established deficits in autobiographical recollection, due to a selective lesion of the extended hippocampal system, does not exhibit any abnormalities in assessing lifetime familiarity. Together, these findings provide support for a functional link between the assessment of recent changes in familiarity, as probed with experimental study-test paradigms, and cumulative lifetime familiarity based on autobiographical experience accrued outside the laboratory. They argue in favor of the notion that familiarity is closely related to the representation of concept knowledge, likely through computations in perirhinal cortex.
即使在未能成功回忆起与过去相关物体相遇的情景背景细节的情况下，识别物体先前出现的能力仍能有效发挥作用。相关过程，即熟悉度评估，通常在人类中通过识别记忆任务进行探究，这些任务包括对一系列项目进行实验控制的研究阶段。当使用诸如单词或常见物体图片等有意义的刺激时，参与者必须根据最近的实验接触来判断熟悉度，而不是参照他们一生的自传体经历，因为这一生可能涉及在众多情景背景下数百次或数千次的接触。然而，人类也能够判断他们一生中遇到的物体概念的累积熟悉度。目前，对于支持这种能力的认知和神经机制知之甚少。在此，我们测试了一名个体（NB），她患有罕见的左前颞叶病变，病变包括鼻周皮质但海马体未受影响，此前发现她在言语识别记忆任务的熟悉度评估中表现出选择性损伤。由于NB表现出正常的回忆能力，她的病例为研究这两种熟悉度之间的潜在联系提供了独特的机会。在实验1中，我们证明了NB在进行识别判断时的损伤会影响对最近一次研究阶段中概念名称曝光的累积频率判断。实验2和实验3借助语义记忆文献中的一项任务揭示，NB的损伤确实扩展到了在判断物体概念的累积终生熟悉度时出现异常。这些异常并不局限于言语处理，即使提供图片作为额外线索时也依然存在。此外，它们表现出对概念结构的敏感性，这在语义特征规范中有所体现；我们仅在对具有高特征重叠的物体概念进行判断时才观察到这些异常。在实验4中，我们发现一名失忆患者（HC），由于扩展海马体系统的选择性损伤，先前在自传体回忆方面存在缺陷，但在评估终生熟悉度时未表现出任何异常。总之，这些发现为基于实验研究 - 测试范式探究的近期熟悉度变化评估与基于实验室外积累的自传体经历的累积终生熟悉度之间的功能联系提供了支持。它们支持了这样一种观点，即熟悉度很可能通过鼻周皮质中的计算与概念知识的表征密切相关。
