Our ability to effectively retrieve complex semantic knowledge meaningfully impacts our daily lives, yet the neural processes that underly successful access and transient failures in access remain only partially understood. In this fMRI study, we contrast activation during successful semantic access, unsuccessful semantic access because of transient access failures (i.e., "tip-of-the-tongue," "feeling-of-knowing"), and trials where the semantic knowledge was not possessed. Twenty-four human participants (14 female) were presented 240 trivia-based questions relating to person, place, object, or scholastic knowledge domains. Analyses of the recall event indicated a relatively greater role of a dorsomedial section of the prefrontal cortex in unsuccessful semantic access and relatively greater recruitment of the pars orbitalis of the inferior frontal gyrus in successful access. Successful access was also associated with increased activation in knowledge domain-selective areas. Generally, knowledge domain-selective areas showed increased responses for both preferred and nonpreferred stimulus classes. The exception was place-selective regions (parahippocampal gyrus, transverse occipital sulcus, retrosplenial complex), which were recruited during unsuccessful access attempts for all stimulus domains. Collectively, these results suggest that prefrontal semantic control systems and classical spatial knowledge-selective regions work together to locate relevant information and that access to complex knowledge results in a broad activation of semantic representation extending to regions selective for other knowledge domains.

SIGNIFICANCE STATEMENT The ability to access the deep factual knowledge we possess has a meaningful influence on our scholastic, professional, and social lives. In this fMRI study, we investigate the neural processes associated with successful access to this knowledge as well as transient failures in semantic access (tip-of-the-tongue/feeling-of-knowing). Participants attempted to answer trivia-style general knowledge questions drawn from four different knowledge domains. Results suggest that prefrontal semantic control systems and classical spatial knowledge-selective regions work to locate relevant information and that access to complex knowledge results in a broad activation of semantic representation extending to regions selective for other knowledge domains.

我们有效地检索复杂语义知识的能力对我们的日常生活产生了有意义的影响，但对于成功访问和短暂访问失败的神经过程仍然只有部分理解。在这项 fMRI 研究中，我们对比了成功语义访问期间的激活、由于瞬时访问失败（即“舌尖”、“知道的感觉”）导致的不成功语义访问，以及语义知识不完整的试验没有拥有。向 24 名人类参与者（14 名女性）提出了 240 个与人、地点、物体或学术知识领域相关的基于琐事的问题。对回忆事件的分析表明，前额叶皮层的背内侧部分在不成功的语义访问中起着相对更大的作用，而在成功访问中，额下回的眶部的募集相对更大。成功访问也与知识领域选择领域的激活增加有关。通常，知识领域选择区域显示出对首选和非首选刺激类的响应增加。例外是位置选择性区域（海马旁回、横向枕骨沟、压后复合体），这些区域是在所有刺激域的访问尝试失败期间招募的。总的来说，

重要性声明获取我们所拥有的深刻事实知识的能力对我们的学业、职业和社交生活具有重大影响。在这项 fMRI 研究中，我们研究了与成功获取这些知识相关的神经过程，以及语义访问的短暂失败（舌尖/知晓感）。参与者试图回答来自四个不同知识领域的琐事式常识问题。结果表明，前额叶语义控制系统和经典空间知识选择区域致力于定位相关信息，并且访问复杂知识会导致语义表示的广泛激活，扩展到其他知识领域的选择性区域。