Default network contributions to episodic and semantic processing during divergent creative thinking: A representational similarity analysis.
- 作者列表："Beaty RE","Chen Q","Christensen AP","Kenett YN","Silvia PJ","Benedek M","Schacter DL
:Cognitive and neuroimaging evidence suggests that episodic and semantic memory-memory for autobiographical events and conceptual knowledge, respectively-support different aspects of creative thinking, with a growing number of studies reporting activation of brain regions within the default network during performance on creative thinking tasks. The present research sought to dissociate neural contributions of these memory processes by inducing episodic or semantic retrieval orientations prior to performance on a divergent thinking task during fMRI. We conducted a representational similarity analysis (RSA) to identify multivoxel patterns of neural activity that were similar across induction (episodic and semantic) and idea generation. At the behavioral level, we found that semantic induction was associated with increased idea originality, assessed via computational estimates of semantic distance between concepts. RSA revealed that multivoxel patterns during semantic induction and subsequent idea generation were more similar (compared to episodic induction) within the left angular gyrus (AG), posterior cingulate cortex (PCC), and left anterior inferior parietal lobe (IPL). Conversely, activity patterns during episodic induction and subsequent generation were more similar within left parahippocampal gyrus and right anterior IPL. Together, the findings point to dissociable contributions of episodic and semantic memory processes to creative cognition and suggest that distinct regions within the default network support specific memory-related processes during divergent thinking.
: 认知和神经影像学证据表明，情节和语义记忆 -- 分别对自传体事件和概念知识的记忆 -- 支持创造性思维的不同方面,随着越来越多的研究报告在创造性思维任务执行期间默认网络内脑区的激活。本研究试图通过在 fMRI 过程中执行发散思维任务之前诱导情节或语义检索取向，分离这些记忆过程的神经贡献。我们进行了代表性相似性分析 (RSA)，以确定跨诱导 (情节和语义) 和想法生成相似的神经活动的多体素模式。在行为层面，我们发现语义归纳与增加的想法原创性相关，通过计算概念之间的语义距离估计来评估。RSA 揭示了在语义诱导和随后的想法生成过程中的多体素模式在左角回 (AG) 、后扣带回皮质 (PCC) 内更相似 (与情节诱导相比),和左前下顶叶 (IPL)。相反，发作性诱导和随后生成期间的活动模式在左侧海马旁回和右侧前侧 IPL 内更相似。总之，研究结果指出情节和语义记忆过程对创造性认知的可分离贡献，并提示默认网络内的不同区域支持发散思维期间特定的记忆相关过程。
METHODS::In recent years, transcranial electrical stimulation (tES) has been used to improve cognitive and perceptual abilities and to boost learning. In the visual domain, transcranial random noise stimulation (tRNS), a type of tES in which electric current is randomly alternating in between two electrodes at high frequency, has shown potential in inducing long lasting perceptual improvements when coupled with tasks such as contrast detection. However, its cortical mechanisms and online effects have not been fully understood yet, and it is still unclear whether these long-term improvements are due to early-stage perceptual enhancements of contrast sensitivity or later stage mechanisms such as learning consolidation. Here we tested tRNS effects on multiple spatial frequencies and orientation, showing that tRNS enhances detection of a low contrast Gabor, but only for oblique orientation and high spatial frequency (12 cycles per degree of visual angle). No improvement was observed for low contrast and vertical stimuli. These results indicate that tRNS can enhance contrast sensitivity already after one training session, however this early onset is dependent on characteristics of the stimulus such as spatial frequency and orientation. In particular, the shallow depth of tRNS is likely to affect superficial layers of the visual cortex where neurons have higher preferred spatial frequencies than cells in further layers, while the lack of effect on vertical stimuli might reflect the optimization of the visual system to see cardinally oriented low contrast stimuli, leaving little room for short-term improvement. Taken together, these results suggest that online tRNS effects on visual perception are the result of a complex interaction between stimulus intensity and cortical anatomy, consistent with previous literature on brain stimulation.
METHODS:OBJECTIVE:There is growing interest in treating diseases by electrical stimulation and block of peripheral autonomic nerves, but a paucity of studies on excitation and block of small diameter autonomic axons. We conducted in vivo quantification of the strength-duration properties, activity-dependent slowing (ADS), and responses to kilohertz frequency (KHF) signals for the rat vagus nerve (VN). APPROACH:We conducted acute in vivo experiments in urethane-anesthetised rats. We placed two cuff electrodes on the left cervical VN and one cuff electrode on the anterior subdiaphragmatic VN. The rostral cervical cuff was used to deliver pulses to quantify recruitment and ADS. The caudal cervical cuff was used to deliver KHF signals. The subdiaphragmatic cuff was used to record compound action potentials (CAPs). MAIN RESULTS:We quantified the input-output recruitment and strength-duration curves. Fits to the data using standard strength-duration equations were qualitatively similar, but the resulting chronaxie and rheobase estimates varied substantially. We measured larger thresholds for the slowest fibres (0.5 to 1 m/s), especially at shorter pulse widths. Using a novel cross-correlation CAP-based analysis, we measured ADS of ~2.3% after 3 min of 2 Hz stimulation, which is comparable to ADS reported for sympathetic efferents in somatic nerves, but much smaller than ADS in cutaneous nociceptors. We found greater ADS with higher stimulation frequency and non-monotonic changes in CV in select cases. We found monotonically increasing block thresholds across frequencies from 10 to 80 kHz for both fast and slow fibres. Further, following 25 s of KHF signal, neural conduction could require tens of seconds to recover. SIGNIFICANCE:The quantification of mammalian autonomic nerve responses to conventional and KHF signals provides essential information for development of peripheral nerve stimulation therapies and for understanding their mechanisms of action.
METHODS:BACKGROUND:Early accounts of forced thought were reported at the onset of a focal seizure, and characterized as vague, repetitive, and involuntary intellectual auras distinct from perceptual or psychic hallucinations or illusions. Here, we examine the neural underpinnings involved in conceptual thought by presenting a series of 3 patients with epilepsy reporting intrusive thoughts during electrical stimulation of the left lateral prefrontal cortex (PFC) during invasive surgical evaluation. We illustrate the widespread networks involved through two independent brain imaging modalities: resting state functional magnetic resonance imaging (fMRI) (rs-fMRI) and task-based meta-analytic connectivity modeling (MACM). METHODS:We report the clinical and stimulation characteristics of three patients with left hemispheric language dominance who demonstrate forced thought with functional mapping. To examine the brain networks underlying this phenomenon, we used the regions of interest (ROI) centered at the active electrode pairs. We modeled functional networks using two approaches: (1) rs-fMRI functional connectivity analysis, representing 81 healthy controls and (2) meta-analytic connectivity modeling (MACM), representing 8260 healthy subjects. We also determined the overlapping regions between these three subjects' rs-fMRI and MACM networks through a conjunction analysis. RESULTS:We identified that left PFC was associated with a large-scale functional network including frontal, temporal, and parietal regions, a network that has been associated with multiple cognitive functions including semantics, speech, attention, working memory, and explicit memory. CONCLUSIONS:We illustrate the neural networks involved in conceptual thought through a unique patient population and argue that PFC supports this function through activation of a widespread network.