Neural correlates of Eureka moment Sprugnoli, Giulia; Rossi, Simone; Emmendorfer, Alexandra ...
Intelligence,
20/May , Letnik:
62
Journal Article
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Insight processes that peak in “unpredictable moments of exceptional thinking” are often referred to as Aha! or Eureka moments. During insight, connections between previously unrelated concepts are ...made and new patterns arise at the perceptual level while new solutions to apparently insolvable problems suddenly emerge to consciousness. Given its unpredictable nature, the definition, and behavioral and neurophysiological measurement of insight problem solving represent a major challenge in contemporary cognitive neuroscience. Numerous attempts have been made, yet results show limited consistency across experimental approaches. Here we provide a comprehensive overview of available neuroscience of insight, including: i) a discussion about the theoretical definition of insight and an overview of the most widely accepted theoretical models, including those debating its relationship with creativity and intelligence; ii) an overview of available tasks used to investigate insight; iii) an ad-hoc quantitative meta-analysis of functional magnetic resonance imaging studies investigating the Eureka moment, using activation likelihood estimation maps; iv) a review of electroencephalographic evidence in the time and frequency domains, as well as v) an overview of the application of non-invasive brain stimulation techniques to causally assess the neurobiological basis of insight as well as enhance insight-related cognition.
•EEG data suggest a primary role for alpha oscillations in prefrontal and parietal lobes.•fMRI data do not support overall right hemispheric dominance during Eureka moments.•Right temporal lobe shows concordant activations across fMRI and EEG studies.•Need for a consensus around validated insight tasks to be used for EEG/fMRI studies.•Future studies should test for causal role of brain areas by modulating brain oscillations.
The ability to flexibly manipulate memory representations is embedded in visual working memory (VWM) and can be tested using paradigms with retrospective cues. Although valid retrospective cues often ...facilitate memory recall, invalid ones may or may not result in performance costs. We investigated individual differences in utilising retrospective cues and evaluated how these individual differences are associated with brain oscillatory activity at rest. At the behavioural level, we operationalised flexibility as the ability to make effective use of retrospective cues or disregard them if required. At the neural level, we tested whether individual differences in such flexibility were associated with properties of resting‐state alpha oscillatory activity (8–12 Hz). To capture distinct aspects of these brain oscillations, we evaluated their power spectral density and temporal dynamics using long‐range temporal correlations (LRTCs). In addition, we performed multivariate patterns analysis (MVPA) to classify individuals' level of behavioural flexibility based on these neural measures. We observed that alpha power alone (magnitude) at rest was not associated with flexibility. However, we found that the participants' ability to manipulate VWM representations was correlated with alpha LRTC and could be decoded using MVPA on patterns of alpha power. Our findings suggest that alpha LRTC and multivariate patterns of alpha power at rest may underlie some of the individual differences in using retrospective cues in working memory tasks.
We used alpha oscillatory activity at rest to investigate flexibility in visual working memory (VWM), indexed by valid, invalid and neutral retrospective cues. Invalid retro‐cue processing could result in a cost or no‐cost performance. No‐cost performance, reflecting flexible manipulation of VWM representations, was associated with alpha long‐range temporal correlation (LRTC) and distinguished from cost performance using multivariate patterns analysis (MVPA) of alpha power and LRTC.
Background: Depression presents with altered energy regulation and neural plasticity. Previous electroencephalography (EEG) studies showed that practice in learning tasks increases power in beta ...range (13–30 Hz) in healthy subjects but not in those with impaired plasticity. Here, we ascertain whether depression presents with alterations of spectral activity and connectivity before and after a learning task. Methods: We used publicly available resting-state EEG recordings (64 electrodes) from 122 subjects. Based on Beck Depression Inventory (BDI) scores, they were assigned to either a high BDI (hBDI, BDI > 13, N = 46) or a control (CTL, BDI < 7, N = 75) group. We analyzed spectral activity, theta–beta, and theta–gamma phase–amplitude coupling (PAC) of EEG recorded at rest before and after a learning task. Results: At baseline, compared to CTL, hBDI exhibited greater power in beta over fronto-parietal regions and in gamma over the right parieto-occipital area. At post task, power increased in all frequency ranges only in CTL. Theta–beta and theta–gamma PAC were greater in hBDI at baseline but not after the task. Conclusions: The lack of substantial post-task growth of beta power in depressed subjects likely represents power saturation due to greater baseline values. We speculate that inhibitory/excitatory imbalance, altered plasticity mechanisms, and energy dysregulation present in depression may contribute to this phenomenon.
Movement is associated with power changes over sensory-motor areas in different frequency ranges, including beta (15-30 Hz). In fact, beta power starts decreasing before the movement onset ...(event-related desynchronization, ERD) and rebounds after its end (event-related synchronization, ERS). There is increasing evidence that beta modulation depth (measured as ERD-ERS difference) increases with practice in a planar reaching task, suggesting that this measure may reflect plasticity processes. In the present work, we analyzed beta ERD, ERS and modulation depth in healthy subjects to determine their changes over three regions of interest (ROIs): right and left sensorimotor and frontal areas, during a reaching task with the right arm. We found that ERD, ERS and modulation depth increased with practice with lower values over the right sensory-motor area. Timing of peak ERD and ERS were similar across ROIs, with ERS peak occurring earlier in later sets. Finally, we found that beta ERS of the frontal ROI involved higher beta range (23-29 Hz) than the sensory-motor ROIs (15-18 Hz). Altogether these results suggest that practice in a reaching task is associated with modification of beta power and timing. Additionally, beta ERS may have different functional meaning in the three ROIs, as suggested by the involvement of upper and lower beta bands in the frontal and sensorimotor ROIs, respectively.
In this article we investigate the trade-off between the compression ratio and distortion of a recently published compression technique specifically devised for multichannel electroencephalograph ...(EEG) signals. In our previous paper, we proved that, when singular value decomposition (SVD) is already performed for denoising or removing unwanted artifacts, it is possible to exploit the same SVD for compression purpose by achieving a compression ratio in the order of 10 and a percentage root mean square distortion in the order of 0.01 %. In this article, we successfully demonstrate how, with a negligible increase in the computational cost of the algorithm, it is possible to further improve the compression ratio by about 10 % by maintaining the same distortion level or, alternatively, to improve the compression ratio by about 50 % by still maintaining the distortion level below the 0.1 %.
Violence is a major problem in our society and therefore research into the neural underpinnings of aggression has grown exponentially. Although in the past decade the biological underpinnings of ...aggressive behavior have been examined, research on neural oscillations in violent offenders during resting-state electroencephalography (rsEEG) remains scarce. In this study we aimed to investigate the effect of high-definition transcranial direct current stimulation (HD-tDCS) on frontal theta, alpha and beta frequency power, asymmetrical frontal activity, and frontal synchronicity in violent offenders.
Fifty male violent forensic patients diagnosed with a substance dependence were included in a double-blind sham-controlled randomized study. The patients received 20 minutes of HD-tDCS two times a day on five consecutive days. Before and after the intervention, the patients underwent a rsEEG task.
Results showed no effect of HD-tDCS on the power in the different frequency bands. Also, no increase in asymmetrical activity was found. However, we found increased synchronicity in frontal regions in the alpha and beta frequency bands indicating enhanced connectivity in frontal brain regions as a result of the HD-tDCS-intervention.
This study has enhanced our understanding of the neural underpinnings of aggression and violence, pointing to the importance of alpha and beta frequency bands and their connectivity in frontal brain regions. Although future studies should further investigate the complex neural underpinnings of aggression in different populations and using whole-brain connectivity, it can be suggested with caution, that HD-tDCS could be an innovative method to regain frontal synchronicity in neurorehabilitation.
Movement is accompanied by modulation of oscillatory activity in different ranges over the sensorimotor areas. This increase is more evident in normal subjects and less in patients with Parkinson's ...Disease (PD), a disorder associated with deficits in the formation of new motor skills. Here, we investigated whether such EEG changes improved in a group of PD patients, after two different treatments and whether this relates to performance. Subjects underwent either a session of 5 Hz repetitive Transcranial Magnetic Stimulation (rTMS) over the right posterior parietal cortex or a 4-week Multidisciplinary Intensive Rehabilitation Treatment (MIRT). We used a reaching task with visuo-motor adaptation to a rotated display in incremental 10° steps up to 60°. Retention of the learned rotation was tested before and after either intervention over two consecutive days. High-density EEG was recorded throughout the testing. We found that patients adapted their movements to the rotated display similarly to controls, although retention was poorer. Both rTMS and MIRT lead to improvement in retention of the learned rotation. Mean beta modulation levels changed significantly after MIRT and not after rTMS. These results suggest that rTMS produced local improvement reflected in enhanced short-term skill retention; on the other hand, MIRT determined changes across the contralateral sensorimotor area, reflected in beta EEG changes.
Lake Geneva is one of the largest European lakes with a surface area of 580 km². Its catchment area covers 7400 km², of which ~20% is arable land. Monitoring campaigns have been carried out in 2004 ...and 2005 to determine the contamination of the lake by pesticides. The results highlight the widespread presence of herbicides in water, the measured concentrations for most substances remaining constant in 2004 and 2005. However, for some individual herbicides the concentrations increased drastically (e.g., the herbicide foramsulfuron). We assessed the environmental risk of the herbicides detected in the lake using water quality criteria recently determined for the Swiss environmental protection agency. Furthermore, we assessed the risk of herbicide mixtures, grouped based upon their mode of action. Generally, the risk estimated for all single substances is low, except for some sulfonylurea compounds. For these substances, the measured concentrations are higher than the predicted no-effect concentration. Impact on the flora of the lake can therefore not be excluded. When mixtures of pesticides with similar mode of action are taken into account, the risk remains lower than the mixture water quality criteria for all groups, but can reach as high as one third of this quality criteria. A further step would therefore be to assess the risk of the total pesticide mixture, including similar and dissimilar modes of action.
Purpose: The objective of this study is to discuss the implications of product loss rates in terms of the environmental performance of bottled wine. Wine loss refers to loss occurring when the ...consumer does not consume the wine contained in the bottle and disposes of it because of taste alteration, which is caused by inadequate product protection rendering the wine unpalatable to a knowledgeable consumer. The decision of whether or not to drink the wine in such cases is guided by subjective consumer taste perception and wine quality expectation (drinking the bottle or disposing of the wine down the drain and replacing it with a new bottle). This study aims to illustrate the importance of accurately defining system boundaries related to wine packaging systems. Methods: The environmental impacts resulting from wine loss rates as related to two types of wine bottle closures—natural cork stoppers and screw caps—have been estimated based on literature review data and compared to the impact of the respective closure system. The system studied relates to the functional unit “a 750 mL bottle of drinkable wine” and includes bottled wine, bottle and closure production, wine production, wine loss and wine poured down the drain. Results: The range of wine alteration rates due to corked wine is estimated to be 2–5% based on interviews with wine experts. Consumer behavior was assessed through a sensitivity study on replacement rates. When the increase in loss rate with the cork stopper is higher than 1.2% (corresponding to 3.5% corked wine multiplied by a consumer replacement rate of 35%), the influence of losses on the impact results is higher than that of the closure material itself. The different closures and associated wine losses represent less than 5% of the total life cycle impact of bottled wine.
In this paper, we investigate performance of a re-cently proposed near-lossless compression algorithm specifically devised for multichannel electroencephalograph (EEG) signals. The algorithm exploits ...the fact that singular value decomposition (SVD) is usually performed on EEG signals for denoising and removing unwanted artifacts and that the same SVD can be used for compression purpose. In this paper, we derived an analytical expression for the expected compression ratio and an upper bound for the maximum distortion introduced by the algorithm after reconstruction. Moreover, performances of the algorithm have been investigated on an extended dataset containing real EEG signals related to subjects performing different sensorimotor tasks. Both analytical and experimental results reported in this paper show that the algorithm is able to attain a compression ratio proportional to the number of EEG channels by achieving a percentage root mean square distortion (PRD) in the order of 0.01 %. In particular, the achieved PRD is very low if compared with other state-of-the-art compression algorithms with similar complexity. Moreover, the algorithm allows the desired maximum absolute error to be fixed a priori. Therefore, we can consider this algorithm as an efficient tool for reducing the amount of memory necessary to record data and, at the same time, preserving actual clinical information of the signals besides compression.
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