semantics

语义
  • 文章类型: Journal Article
    结直肠癌(CRC)是世界范围内常见的消化系统肿瘤,发病率和死亡率均较高。目前,使用计算机辅助结肠镜技术检测息肉相对成熟,但是它仍然面临一些挑战,如漏检或误检息肉。因此,如何更准确地提高息肉的检出率是结肠镜检查的关键。为了解决这个问题,本文提出了一种改进的基于YOLOv5的结直肠癌息肉检测方法。该方法设计了一种称为P-C3的新结构,该结构被合并到模型的主干和颈部网络中,以增强特征的表达。此外,在骨干网络的底部引入了上下文特征增强模块,以增加多尺度特征信息的感受域,并通过协调注意力机制关注息肉特征。实验结果表明,与一些传统的目标检测算法相比,本文提出的模型对息肉的检测精度有显著的优势,特别是在召回率方面,这在很大程度上解决了息肉漏检的问题。本研究将有助于提高内镜医师在结肠镜检查过程中息肉/腺瘤的检出率,对临床工作的发展也具有重要意义。
    Colorectal cancer (CRC) is a common digestive system tumor with high morbidity and mortality worldwide. At present, the use of computer-assisted colonoscopy technology to detect polyps is relatively mature, but it still faces some challenges, such as missed or false detection of polyps. Therefore, how to improve the detection rate of polyps more accurately is the key to colonoscopy. To solve this problem, this paper proposes an improved YOLOv5-based cancer polyp detection method for colorectal cancer. The method is designed with a new structure called P-C3 incorporated into the backbone and neck network of the model to enhance the expression of features. In addition, a contextual feature augmentation module was introduced to the bottom of the backbone network to increase the receptive field for multi-scale feature information and to focus on polyp features by coordinate attention mechanism. The experimental results show that compared with some traditional target detection algorithms, the model proposed in this paper has significant advantages for the detection accuracy of polyp, especially in the recall rate, which largely solves the problem of missed detection of polyps. This study will contribute to improve the polyp/adenoma detection rate of endoscopists in the process of colonoscopy, and also has important significance for the development of clinical work.
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  • 文章类型: Journal Article
    与环境中的物体交互需要确定它们的位置,通常相对于周围的物体(即,分配)。根据场景语法框架,这些通常很小,局部对象在场景中是可移动的,并且代表场景层次结构的最低级别。场景语法的更高层次如何影响内存引导动作的分配中心编码?我们专注于大的影响,不可移动的对象(锚)对本地对象位置的编码。在虚拟现实研究中,参与者(n=30)观看了四个可能的场景之一(两个厨房或两个浴室),有两个用架子连接的锚,在其上呈现三个局部对象(与一个锚一致)(编码)。场景被重新呈现(测试),其中1)局部对象缺失和2)锚之一移位(移位)或不移位(无移位)。参与者,然后,看到一个浮动的局部对象(目标),他们抓住它,并把它放在架子上记住的位置(回应)。眼球追踪数据显示,局部物体和锚点都被固定住了,首选本地对象。此外,锚引导的局部对象的分配中心编码,尽管与任务无关。总的来说,锚点隐式影响自然(虚拟)环境中内存引导动作的本地对象位置的空间编码。
    Interacting with objects in our environment requires determining their locations, often with respect to surrounding objects (i.e., allocentrically). According to the scene grammar framework, these usually small, local objects are movable within a scene and represent the lowest level of a scene\'s hierarchy. How do higher hierarchical levels of scene grammar influence allocentric coding for memory-guided actions? Here, we focused on the effect of large, immovable objects (anchors) on the encoding of local object positions. In a virtual reality study, participants (n = 30) viewed one of four possible scenes (two kitchens or two bathrooms), with two anchors connected by a shelf, onto which were presented three local objects (congruent with one anchor) (Encoding). The scene was re-presented (Test) with 1) local objects missing and 2) one of the anchors shifted (Shift) or not (No shift). Participants, then, saw a floating local object (target), which they grabbed and placed back on the shelf in its remembered position (Response). Eye-tracking data revealed that both local objects and anchors were fixated, with preference for local objects. Additionally, anchors guided allocentric coding of local objects, despite being task-irrelevant. Overall, anchors implicitly influence spatial coding of local object locations for memory-guided actions within naturalistic (virtual) environments.
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  • 文章类型: Journal Article
    人类可以快速阅读和理解文本,暗示读者可能会处理每个固定的多个单词。然而,在何种程度上,半心词被预览和整合到不断发展的句子上下文仍然存在争议。我们通过使用MEG和眼动仪记录大脑活动和眼球运动,研究了自然阅读过程中的旁凹处理,而参与者则默默地阅读一行句子。句子包含一个不可预测的目标单词,该单词与句子上下文一致或不一致。为了测量半凹加工,我们以60Hz闪烁目标单词,并测量由此产生的大脑反应(即快速隐形频率标记,RIFT)在对预目标单词的注视期间。我们的结果表明,与相同的目标单词相比,与先前上下文不一致的目标单词的标记响应显着较弱,甚至在100ms内固定的单词紧前面的目标。还发现RIFT反应的这种降低可以预测个体的阅读速度。我们得出的结论是,语义信息不仅可以从parafovea中提取,而且可以在固定单词之前与先前的上下文集成。这种早期和广泛的半凹处理支持自然阅读所需的快速文字处理。我们的研究表明,自然阅读的理论框架应纳入深的副凹加工的概念。
    Humans can read and comprehend text rapidly, implying that readers might process multiple words per fixation. However, the extent to which parafoveal words are previewed and integrated into the evolving sentence context remains disputed. We investigated parafoveal processing during natural reading by recording brain activity and eye movements using MEG and an eye tracker while participants silently read one-line sentences. The sentences contained an unpredictable target word that was either congruent or incongruent with the sentence context. To measure parafoveal processing, we flickered the target words at 60 Hz and measured the resulting brain responses (i.e. Rapid Invisible Frequency Tagging, RIFT) during fixations on the pre-target words. Our results revealed a significantly weaker tagging response for target words that were incongruent with the previous context compared to congruent ones, even within 100ms of fixating the word immediately preceding the target. This reduction in the RIFT response was also found to be predictive of individual reading speed. We conclude that semantic information is not only extracted from the parafovea but can also be integrated with the previous context before the word is fixated. This early and extensive parafoveal processing supports the rapid word processing required for natural reading. Our study suggests that theoretical frameworks of natural reading should incorporate the concept of deep parafoveal processing.
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  • 文章类型: Journal Article
    创造力的联想理论提出,创意思想是通过将记忆中远程相关的概念联系起来而产生的。先前的研究发现,创造性较高的个体表现出更灵活的语义记忆组织,产生更多不常见的单词联想,并判断远程概念更相关。在这项研究中(N=93),我们使用功能磁共振成像来研究涉及判断语义距离不同的概念的相关性的大脑区域,以及这种神经参与如何与创造力的个体差异有关。活动随着语义相关性增加的大脑区域主要与默认重叠,control,显著性,语义控制,和多个需求网络。在评估更多远程关联时,默认和语义控制网络的参与度增加。最后,更有创造力的人,平均而言,谁提供了更高的相关性判断,在这些地区表现出较低的活动,可能反映了更高的神经效率。我们在创造力的神经认知过程的背景下讨论这些发现。总的来说,我们的发现表明,判断远程概念相关反映了创造力背后的认知机制,并揭示了这种机制的神经相关性。
    The associative theory of creativity proposes that creative ideas result from connecting remotely related concepts in memory. Previous research found that higher creative individuals exhibit a more flexible organization of semantic memory, generate more uncommon word associations, and judge remote concepts as more related. In this study (N = 93), we used fMRI to investigate brain regions involved in judging the relatedness of concepts that vary in their semantic distance, and how such neural involvement relates to individual differences in creativity. Brain regions where activity increased with semantic relatedness mainly overlapped with default, control, salience, semantic control, and multiple demand networks. The default and semantic control networks exhibited increased involvement when evaluating more remote associations. Finally, higher creative people, who provided higher relatedness judgements on average, exhibited lower activity in those regions, possibly reflecting higher neural efficiency. We discuss these findings in the context of the neurocognitive processing underlying creativity. Overall, our findings indicate that judging remote concepts as related reflects a cognitive mechanism underlying creativity and shed light on the neural correlates of this mechanism.
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  • 文章类型: Journal Article
    本研究通过定时单词关联任务中的语言和位置模拟(LASS)和词频效应(WFE)的镜头调查了语义漂移现象。我们的主要目标是确定是否可以在自由词关联任务(LASS的预测推论)的短时间(25秒)内识别语义漂移,以及是否在过程中更早生成更频繁的术语(如预期的那样,由于WFE)。向受访者提供了五个提示词(树,狗,质量,塑料和爱),并要求写尽可能多的协会。我们假设在任务后期生成的术语(第四次四分位数,最后19-25秒)在语义上比以前生成的词更远(余弦相似性)(第一个四分位数,前1-7秒),表示语义漂移。此外,我们通过假设较早生成的单词会更频繁和更少的多样性来探索WFE。利用与GloVe300B单词嵌入匹配的数据集,BERT和WordNet语法集,我们分析了1569个独特术语对中所有提示词的语义距离。我们的结果支持语义漂移的存在,有大量证据表明参与者内部,语义漂移从第一到第四时间(LASS)和频率(WFE)四分位数。就WFE而言,我们观察到任务早期产生的术语多样性显著下降,虽然在第4次四分位数中产生了更多的独特项(更大的多样性和相对独特性),与我们的假设一致,即更频繁使用的单词在单词关联任务的早期阶段占主导地位。我们还发现,效果的大小在不同的线索之间变化很大,这表明一些线索可能会引发更强、更独特的模拟。理论上,我们的研究有助于理解LASS和WFE。这表明语义漂移可以作为LASS中语言与模拟系统调用的可扩展指标,也可以更广泛地用于探索单词关联任务中的认知。这些发现还为WFE增加了时间和关系维度。实际上,我们的研究强调了单词关联任务在理解语义漂移和子分钟任务中单词用法扩散方面的效用,可以说是最短的实际可行的时间框架,提供了一种可扩展的方法来探索语义关系中的群体和个体变化,无论是通过营销活动中有针对性的影响力扩散,或寻求更广泛地理解认知差异。讨论了可能的实际用途和未来研究的机会。
    This study investigates the phenomena of semantic drift through the lenses of language and situated simulation (LASS) and the word frequency effect (WFE) within a timed word association task. Our primary objectives were to determine whether semantic drift can be identified over the short time (25 seconds) of a free word association task (a predicted corollary of LASS), and whether more frequent terms are generated earlier in the process (as expected due to the WFE). Respondents were provided with five cue words (tree, dog, quality, plastic and love), and asked to write as many associations as they could. We hypothesized that terms generated later in the task (fourth time quartile, the last 19-25 seconds) would be semantically more distant (cosine similarity) from the cue word than those generated earlier (first quartile, the first 1-7 seconds), indicating semantic drift. Additionally, we explored the WFE by hypothesizing that earlier generated words would be more frequent and less diverse. Utilizing a dataset matched with GloVe 300B word embeddings, BERT and WordNet synsets, we analysed semantic distances among 1569 unique term pairs for all cue words across time. Our results supported the presence of semantic drift, with significant evidence of within-participant, semantic drift from the first to fourth time (LASS) and frequency (WFE) quartiles. In terms of the WFE, we observed a notable decrease in the diversity of terms generated earlier in the task, while more unique terms (greater diversity and relative uniqueness) were generated in the 4th time quartile, aligning with our hypothesis that more frequently used words dominate early stages of a word association task. We also found that the size of effects varied substantially across cues, suggesting that some cues might invoke stronger and more idiosyncratic situated simulations. Theoretically, our study contributes to the understanding of LASS and the WFE. It suggests that semantic drift might serve as a scalable indicator of the invocation of language versus simulation systems in LASS and might also be used to explore cognition within word association tasks more generally. The findings also add a temporal and relational dimension to the WFE. Practically, our research highlights the utility of word association tasks in understanding semantic drift and the diffusion of word usage over a sub-minute task, arguably the shortest practically feasible timeframe, offering a scalable method to explore group and individual changes in semantic relationships, whether via the targeted diffusion of influence in a marketing campaign, or seeking to understand differences in cognition more generally. Possible practical uses and opportunities for future research are discussed.
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  • 文章类型: Journal Article
    背景:语义流畅性是在有限的时间内从给定类别中命名项目的能力,它依赖于语义知识,工作记忆,和执行功能。与帕金森病(PD)患者相似,进行性核上性麻痹(PSP)患者在完善的语义流利度测试中得分低于健康成人.然而,目前还不清楚产生的单词有多独特。这项研究检查了PSP患者的语义流畅性与单词\'独特性之间的关系。
    方法:27例PSP理查森综合征(PSP-RS)患者,37例PD患者,41名健康对照(HC)进行了标准的语义流畅性测试(动物),他们的口头反应是录音的。我们用独特性来反映产生原创和有效作品的能力,也就是说,创造力。
    结果:与PD和HC组相比,PSP-RS组产生的正确单词和唯一单词更少。此外,HC和PD组的流畅性和独特性之间的相关性为正相关,而PSP-RS组则为负。重要的是,实际的左旋多巴剂量与流畅度呈正相关,但与PSP-RS的独特性呈负相关。服用较大剂量左旋多巴的PSP-RS患者倾向于产生更多正确的单词,但独特的单词较少。
    结论:这些结果表明,左旋多巴可能在PSP-RS的早期阶段调节语义流畅性和独特性。
    BACKGROUND: Semantic fluency is the ability to name items from a given category within a limited time, which relies on semantic knowledge, working memory, and executive function. Similar to patients with Parkinson\'s disease (PD), patients with progressive supranuclear palsy (PSP) scored lower than healthy adults in the well-established semantic fluency test. However, it is unclear how unique are the produced words. This study examined the relationship between semantic fluency and words\' uniqueness in patients with PSP.
    METHODS: Twenty-seven patients with PSP Richardson\'s syndrome (PSP-RS), 37 patients with PD, and 41 healthy controls (HC) performed a standard semantic fluency test (animals), and their verbal responses were audio-recorded. We used the uniqueness to reflect the ability to produce both original and effective work, that is, creativity.
    RESULTS: The PSP-RS group produced fewer correct words and fewer unique words than the PD and HC groups. Moreover, the correlation between fluency and uniqueness was positive in the HC and PD groups but negative in the PSP-RS group. Importantly, the actual levodopa dose was positively correlated with the fluency but negatively correlated with the uniqueness in PSP-RS. The PSP-RS patients who took a greater dose of levodopa tended to produce more correct words but fewer unique words.
    CONCLUSIONS: These results suggested that levodopa may modulate semantic fluency and uniqueness in the early stages of PSP-RS.
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  • 文章类型: Journal Article
    背景:生物背景知识在生物数据库记录的手动质量保证(QA)中起着重要作用。一个这样的QA任务是检测基于文献的基因本体注释(GOA)中的不一致性。此手动验证基于对用作证据的文献的全面审查,确保了GO注释的准确性。基因本体论(GO)术语,以及GOA记录中的注释基因。虽然已经开发了用于检测GOA中语义不一致的自动方法,它们在预定的环境中运作,缺乏利用更广泛证据的能力,特别是相关领域的背景知识。本文研究了各种类型的背景知识,这些知识可以改善对GOA中普遍存在的不一致性的检测。此外,本文提出了几种将背景知识集成到自动GOA不一致检测过程中的方法。
    结果:我们使用几种与GOA相关的背景知识扩展了以前开发的GOA不一致数据集,包括GeneRIF声明,证据文本中提到的生物学概念,GO的分级和现有的GO注解特定基因。作为自动GOA不一致检测过程的一部分,我们提出了几种有效的方法来集成背景知识。所提出的方法可以改善对自我一致性和几种最普遍的不一致类型的自动检测。
    这是第一个探索利用背景知识的优势并提出一种实用的方法来将知识纳入自动GOA不一致性检测的研究。我们为这项任务的绩效建立了新的基准。我们的方法可能适用于涉及结合生物学背景知识的各种任务。
    方法:https://github.com/jiyuc/de-inconsistency。
    BACKGROUND: Biological background knowledge plays an important role in the manual quality assurance (QA) of biological database records. One such QA task is the detection of inconsistencies in literature-based Gene Ontology Annotation (GOA). This manual verification ensures the accuracy of the GO annotations based on a comprehensive review of the literature used as evidence, Gene Ontology (GO) terms, and annotated genes in GOA records. While automatic approaches for the detection of semantic inconsistencies in GOA have been developed, they operate within predetermined contexts, lacking the ability to leverage broader evidence, especially relevant domain-specific background knowledge. This paper investigates various types of background knowledge that could improve the detection of prevalent inconsistencies in GOA. In addition, the paper proposes several approaches to integrate background knowledge into the automatic GOA inconsistency detection process.
    RESULTS: We have extended a previously developed GOA inconsistency dataset with several kinds of GOA-related background knowledge, including GeneRIF statements, biological concepts mentioned within evidence texts, GO hierarchy and existing GO annotations of the specific gene. We have proposed several effective approaches to integrate background knowledge as part of the automatic GOA inconsistency detection process. The proposed approaches can improve automatic detection of self-consistency and several of the most prevalent types of inconsistencies.
    This is the first study to explore the advantages of utilizing background knowledge and to propose a practical approach to incorporate knowledge in automatic GOA inconsistency detection. We establish a new benchmark for performance on this task. Our methods may be applicable to various tasks that involve incorporating biological background knowledge.
    METHODS: https://github.com/jiyuc/de-inconsistency.
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  • 文章类型: Journal Article
    方面级情感分析(ABSA)是神经机器人领域的一项关键任务,有助于理解细粒度的文本情感。尽管对ABSA进行了广泛的研究,训练数据的有限可用性仍然是阻碍先前研究表现的重要障碍。此外,以前的作品主要集中在连接语义和句法特征来预测情绪极性,无意中切断了内在联系。一些研究试图利用多层图卷积来提取句法特征。然而,这种方法遇到了梯度爆炸的问题。本文研究了利用ChatGPT进行方面级文本增强的可能性。此外,我们引入了一种专门为图卷积网络设计的改进的门控注意力机制,以减轻梯度爆炸的问题。通过使用情感知识库丰富依赖图的功能,我们加强了方面词与语境情感极性之间的关系。值得一提的是,我们采用交叉融合来有效地整合文本语义和句法特征。实验结果证实了我们的模型在性能方面优于基线模型。
    Aspect-level sentiment analysis (ABSA) is a pivotal task within the domain of neurorobotics, contributing to the comprehension of fine-grained textual emotions. Despite the extensive research undertaken on ABSA, the limited availability of training data remains a significant obstacle that hinders the performance of previous studies. Moreover, previous works have predominantly focused on concatenating semantic and syntactic features to predict sentiment polarity, which inadvertently severed the intrinsic connection. Several studies have attempted to utilize multi-layer graph convolution for the purpose of extracting syntactic characteristics. However, this approach has encountered the issue of gradient explosion. This paper investigates the possibilities of leveraging ChatGPT for aspect-level text augmentation. Furthermore, we introduce an improved gated attention mechanism specifically designed for graph convolutional networks to mitigates the problem of gradient explosion. By enriching the features of the dependency graph with a sentiment knowledge base, we strengthen the relationship between aspect words and the polarity of the contextual sentiment. It is worth mentioning that we employ cross-fusion to effectively integrate textual semantic and syntactic features. The experimental results substantiate the superiority of our model over the baseline models in terms of performance.
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  • 文章类型: Journal Article
    来自环境的信息通过感官输入到达大脑和身体系统,这些感官输入可以在有意识的意识之外运行,并以不同的方式影响决策过程。具体来说,决策过程可能会受到源自个体相关因素的各种形式的隐含偏差的影响(例如,决策风格的个体差异)和/或刺激相关信息,如视觉输入。然而,以前没有在资历不同的专业人员中研究过这些决策的主客观因素之间的关系。这项研究探讨了与组织中的一群新来者相比,专业人士的决策风格与认知偏见抵抗之间的关系。向参与者提出了视觉“图片-图片”语义启动任务。该任务基于素数和探针类别成员资格(动物与对象),在动物原始刺激呈现之后,探测器可以是五个物体(不一致的条件)或五个物体和一个动物(一致的条件)。行为(即,精度-ACC,和反应时间-RT)和自我报告数据(通过一般决策量表管理)被收集。RTs代表任务所需的工作量和认知努力的间接测量,因为它们代表神经系统接收和整合传入的感觉信息所需的时间,诱导身体做出反应。对于这两个群体来说,两种情况下的ACC水平相同,而不一致情况下的RTs较高。有趣的是,对于一群专业人士来说,在全等条件下,GDMS依赖的决策风格与ACC负相关,与RT正相关。这些发现表明,在不一致的决策条件下,抵抗认知偏见需要同样水平的认知努力,不管资历。然而,随着资历的提高,在专业人士群体中,已经证明,依赖的决策风格与对认知偏见的较低抵抗力有关,尤其是在需要更简单决策的情况下。这个结果是否取决于年龄或工作经验需要从未来的研究中解脱出来。
    Information that comes from the environment reaches the brain-and-body system via sensory inputs that can operate outside of conscious awareness and influence decision processes in different ways. Specifically, decision-making processes can be influenced by various forms of implicit bias derived from individual-related factors (e.g., individual differences in decision-making style) and/or stimulus-related information, such as visual input. However, the relationship between these subjective and objective factors of decision making has not been investigated previously in professionals with varying seniority. This study explored the relationship between decision-making style and cognitive bias resistance in professionals compared with a group of newcomers in organisations. A visual \"picture-picture\" semantic priming task was proposed to the participants. The task was based on primes and probes\' category membership (animals vs. objects), and after an animal prime stimulus presentation, the probe can be either five objects (incongruent condition) or five objects and an animal (congruent condition). Behavioural (i.e., accuracy-ACC, and reaction times-RTs) and self-report data (through the General Decision-Making Scale administration) were collected. RTs represent an indirect measure of the workload and cognitive effort required by the task, as they represent the time it takes the nervous system to receive and integrate incoming sensory information, inducing the body to react. For both groups, the same level of ACC in both conditions and higher RTs in the incongruent condition were found. Interestingly, for the group of professionals, the GDMS-dependent decision-making style negatively correlates with ACC and positively correlates with RTs in the congruent condition. These findings suggest that, under the incongruent decision condition, the resistance to cognitive bias requires the same level of cognitive effort, regardless of seniority. However, with advancing seniority, in the group of professionals, it has been demonstrated that a dependent decision-making style is associated with lower resistance to cognitive bias, especially in conditions that require simpler decisions. Whether this result depends on age or work experience needs to be disentangled from future studies.
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  • 文章类型: Journal Article
    语义记忆表示通常在老化时保持得很好,而语义控制被认为受到的影响更大。为了解释这种现象,这项研究测试了与补偿相关的神经电路利用假说(CRUNCH)的预测,关注老龄化中的任务需求,作为一个可能的框架。CRUNCH效应将通过语义控制网络区域中神经激活的补偿性增加而在语义任务中表现出来,但仅达到任务需求的特定阈值。这项研究比较了在fMRI扫描仪中执行的基于三元组的语义判断任务中39名年轻(20-35岁)和39名年龄较大的参与者(60-75岁),同时通过语义距离操纵任务需求水平(低与高)。根据CRUNCH的预测,在神经功能激活和行为表现(准确性和反应时间)的差异预计在年轻和老年参与者在低和高需求条件下,这应该表现在语义控制感兴趣区域(ROI)中。我们年长的参与者有完整的行为表现,如文献中提出的语义记忆任务(保持准确性和较慢的响应时间(RT))。与年轻组相比,年龄不变的行为表现对于测试CRUNCH预测是必要的。老年人的特征还在于高认知储备,正如我们的神经心理学测试所显示的。我们的行为结果证实,我们的任务成功地操纵了任务需求:错误率,RTs和感知难度随着两个年龄组任务需求的增加而增加。我们没有发现年龄组和任务需求之间的相互作用,或在RTs或准确性的低需求和高需求条件之间的激活有统计学意义的差异。至于大脑激活,我们没有通过任务需求交互找到预期的年龄组,或任务需求的显著主效应。总的来说,我们的结果与语义网络和语义控制网络中的一些神经激活相一致,主要在额孢子顶区域。ROI分析表明,任务需求在左右额下回有显著影响(但没有相互作用),左侧颞中后回,颞下后回和前额回。总的来说,我们的测试没有证实CRUNCH的预测。
    Semantic memory representations are generally well maintained in aging, whereas semantic control is thought to be more affected. To explain this phenomenon, this study tested the predictions of the Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH), focusing on task demands in aging as a possible framework. The CRUNCH effect would manifest itself in semantic tasks through a compensatory increase in neural activation in semantic control network regions but only up to a certain threshold of task demands. This study compares 39 younger (20-35 years old) with 39 older participants (60-75 years old) in a triad-based semantic judgment task performed in an fMRI scanner while manipulating task demand levels (low versus high) through semantic distance. In line with the CRUNCH predictions, differences in neurofunctional activation and behavioral performance (accuracy and response times) were expected in younger versus older participants in the low- versus high-demand conditions, which should be manifested in semantic control Regions of Interest (ROIs). Our older participants had intact behavioral performance, as proposed in the literature for semantic memory tasks (maintained accuracy and slower response times (RTs)). Age-invariant behavioral performance in the older group compared to the younger one is necessary to test the CRUNCH predictions. The older adults were also characterized by high cognitive reserve, as our neuropsychological tests showed. Our behavioral results confirmed that our task successfully manipulated task demands: error rates, RTs and perceived difficulty increased with increasing task demands in both age groups. We did not find an interaction between age group and task demand, or a statistically significant difference in activation between the low- and high-demand conditions for either RTs or accuracy. As for brain activation, we did not find the expected age group by task demand interaction, or a significant main effect of task demand. Overall, our results are compatible with some neural activation in the semantic network and the semantic control network, largely in frontotemporoparietal regions. ROI analyses demonstrated significant effects (but no interactions) of task demand in the left and right inferior frontal gyrus, the left posterior middle temporal gyrus, the posterior inferior temporal gyrus and the prefrontal gyrus. Overall, our test did not confirm the CRUNCH predictions.
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