Modulation of creativity by transcranial direct current stimulation

Teach a Man to Fish: Hyper-brain Evidence on Scaffolding Strategy Enhancing Creativity Acquisition and Transfer

Creativity is an indispensable competency in today's innovation-driven society. Yet, the influences of instructional strategy, a key determinant of educational outcomes, on the creativity-fostering process remains an unresolved mystery. We proposed that instructional strategy affects creativity cultivation and further investigated the intricate neural mechanisms underlying this relationship. In a naturalistic laboratory setting, 66 instructor-learner dyads were randomized into three groups (scaffolding, explanation, and control), with divergent thinking instructions separately. Functional near-infrared spectroscopy (fNIRS) hyperscanning simultaneously collected brain signals in the prefrontal cortex and temporal-parietal junction regions. Results indicated that learners instructed with a scaffolding strategy demonstrated superior creative performance both in acquisition (direct learning) and transfer (use in a novel context) of creativity skills, compared to pretest levels. In contrast, the control and explanation groups did not exhibit such effects. Notably, we also observed remarkable interbrain neural synchronization (INS) between instructors and learners in the left superior frontal cortex in the scaffolding group, but not in the explanation or control groups. Furthermore, INS positively predicted enhancements in creativity performance (acquisition and transfer), indicating that it is a crucial neural mechanism in the creativity-fostering process. These findings reveal that scaffolding facilitates the acquisition and transfer of creativity and deepen our understanding of the neural mechanisms underlying the process of creativity-fostering. The current study provides valuable insights for implementing teaching strategies to fostering creativity.

Neurobiological Effects of Transcranial Direct Current Stimulation over the Inferior Frontal Gyrus: A Systematic Review on Cognitive Enhancement in Healthy and Neurological Adults

The neurobiological effects of transcranial direct current stimulation (tDCS) have still not been unequivocally clarified. Some studies have suggested that the application of tDCS over the inferior frontal gyrus (IFG) enhances different aspects of cognition in healthy and neurological individuals, exerting neural changes over the target area and its neural surroundings. In this systematic review, randomized sham-controlled trials in healthy and neurological adults were selected through a database search to explore whether tDCS over the IFG combined with cognitive training modulates functional connectivity or neural changes. Twenty studies were finally included, among which twelve measured tDCS effects through functional magnetic resonance (fMRI), two through functional near-infrared spectroscopy (fNIRS), and six through electroencephalography (EEG). Due to the high heterogeneity observed across studies, data were qualitatively described and compared to assess reliability. Overall, studies that combined fMRI and tDCS showed widespread changes in functional connectivity at both local and distant brain regions. The findings also suggested that tDCS may also modulate electrophysiological changes underlying the targeted area. However, these outcomes were not always accompanied by corresponding significant behavioral results. This work raises the question concerning the general efficacy of tDCS, the implications of which extend to the steadily increasing tDCS literature.

Impaired creative cognition after surgery for an IDH-mutated glioma: A proof-of-concept study

Assessment of high cognitive functions, such as creativity, is often overlooked in medical practice. However, it is crucial to understand the impact of brain tumors, specifically low-grade gliomas, on creative cognition, as these tumors predominantly affect brain regions associated with cognitive creativity. In this study, we investigated creative cognition using the Alternative Uses Task (AUT) and the Combination of Associates Task (CAT) in a cohort of 29 patients who underwent brain surgery for a low-grade glioma, along with 27 control participants. While the group of patients did not exhibit deficits in clinical neuropsychological assessments, our results revealed significant impairment in generating original and creative ideas compared to the control group. Furthermore, when analyzing the specific brain regions affected by the tumors, patients with lesions overlapping the left rostro-lateral prefrontal cortex, a critical region for creativity, displayed more pronounced impairments in the CAT compared to patients with lesions outside this region. These findings provide proof of concept that patients can experience impaired creative cognition following surgery for low-grade glioma, highlighting the importance of assessing higher-order cognitive functions, including creativity, in neurosurgical patients. Moreover, beyond its clinical relevance, our study contributes to advancing our understanding of the neuroscience of creativity.

Divergent thinking benefits from functional antagonism of the left IFG and right TPJ: a transcranial direct current stimulation study

Divergent thinking is assumed to benefit from releasing the constraint of existing knowledge (i.e. top-down control) and enriching free association (i.e. bottom-up processing). However, whether functional antagonism between top-down control-related and bottom-up processing-related brain structures is conducive to generating original ideas is largely unknown. This study was designed to investigate the effect of functional antagonism between the left inferior frontal gyrus and the right temporoparietal junction on divergent thinking performance. A within-subjects design was adopted for three experiments. A total of 114 participants performed divergent thinking tasks after receiving transcranial direct current stimulation over target regions. In particular, cathodal stimulation over the left inferior frontal gyrus and anodal stimulation over the right inferior frontal gyrus (Experiment 1), anodal stimulation over the right temporoparietal junction (Experiment 2), and both cathodal stimulation over the left inferior frontal gyrus and anodal stimulation over the right temporoparietal junction (Experiment 3) were manipulated. Compared with sham stimulation, the combination of hyperpolarization of the left inferior frontal gyrus and depolarization of the right temporoparietal junction comprehensively promoted the fluency, flexibility, and originality of divergent thinking without decreasing the rationality of generated ideas. Functional antagonism between the left inferior frontal gyrus (hyperpolarization) and right temporoparietal junction (depolarization) has a "1 + 1 > 2" superposition effect on divergent thinking.

Individual differences and creative ideation: neuromodulatory signatures of mindset and response inhibition

This study addresses the modulatory role of individual mindset in explaining the relationship between response inhibition (RI) and divergent thinking (DT) using transcranial direct current stimulation (tDCS). Forty undergraduate students (22 male and 18 female), aged between 18 and 23 years (average age = 19 years, SD = 1.48), were recruited. Participants received either anodal tDCS of the right IFG coupled with cathodal tDCS of the left IFG (R + L-; N = 19) or the opposite coupling (R-L+; N = 21). We tested DT performance using the alternative uses task (AUT), measuring participants' fluency, originality, and flexibility in the response production, as well as participants' mindsets. Furthermore, we applied a go-no-go task to examine the role of RI before and after stimulating the inferior frontal gyrus (IFG) using tDCS. The results showed that the mindset levels acted as moderators on stimulation conditions and enhanced RI on AUT fluency and flexibility but not originality. Intriguingly, growth mindsets have opposite moderating effects on the change in DT, resulting from the tDCS stimulation of the left and the right IFG, with reduced fluency but enhanced flexibility. Our findings imply that understanding neural modulatory signatures of ideational processes with tDCS strongly benefits from evaluating cognitive status and control functions.

Preventing prefrontal dysfunction by tDCS modulates stress-induced creativity impairment in women: an fNIRS study

Stress is a major external factor threatening creative activity. The study explored whether left-lateralized activation in the dorsolateral prefrontal cortex manipulated through transcranial direct current stimulation could alleviate stress-induced impairment in creativity. Functional near-infrared spectroscopy was used to explore the underlying neural mechanisms. Ninety female participants were randomly assigned to three groups that received stress induction with sham stimulation, stress induction with true stimulation (anode over the left and cathode over the right dorsolateral prefrontal cortex), and control manipulation with sham stimulation, respectively. Participants underwent the stress or control task after the transcranial direct current stimulation manipulation, and then completed the Alternative Uses Task to measure creativity. Behavioral results showed that transcranial direct current stimulation reduced stress responses in heart rate and anxiety. The functional near-infrared spectroscopy results revealed that transcranial direct current stimulation alleviated dysfunction of the prefrontal cortex under stress, as evidenced by higher activation of the dorsolateral prefrontal cortex and frontopolar cortex, as well as stronger inter-hemispheric and intra-hemispheric functional connectivity within the prefrontal cortex. Further analysis demonstrated that the cortical regulatory effect prevented creativity impairment induced by stress. The findings validated the hemispheric asymmetry hypothesis regarding stress and highlighted the potential for brain stimulation to alleviate stress-related mental disorders and enhance creativity.

The Mystery of Mental Integrity: Clarifying Its Relevance to Neurotechnologies

The concept of mental integrity is currently a significant topic in discussions concerning the regulation of neurotechnologies. Technologies such as deep brain stimulation and brain-computer interfaces are believed to pose a unique threat to mental integrity, and some authors have advocated for a legal right to protect it. Despite this, there remains uncertainty about what mental integrity entails and why it is important. Various interpretations of the concept have been proposed, but the literature on the subject is inconclusive. Here we consider a number of possible interpretations and argue that the most plausible one concerns neurotechnologies that bypass one's reasoning capacities, and do so specifically in ways that reliably lead to alienation from one's mental states. This narrows the scope of what constitutes a threat to mental integrity and offers a more precise role for the concept to play in the ethical evaluation of neurotechnologies.

Comparing transcranial direct current stimulation and transcranial random noise stimulation over left dorsolateral prefrontal cortex and left inferior frontal gyrus: Effects on divergent and convergent thinking

The essential role of creativity has been highlighted in several human knowledge areas. Regarding the neural underpinnings of creativity, there is evidence about the role of left dorsolateral prefrontal cortex (DLPFC) and left inferior frontal gyrus (IFG) on divergent thinking (DT) and convergent thinking (CT). Transcranial stimulation studies suggest that the left DLPFC is associated with both DT and CT, whereas left IFG is more related to DT. However, none of the previous studies have targeted both hubs simultaneously and compared transcranial direct current stimulation (tDCS) and random noise stimulation (tRNS). Additionally, given the relationship between cognitive flexibility and creativity, we included it in order to check if the improvement in creativity may be mediated by cognitive flexibility. In this double-blind, between-subjects study, 66 healthy participants were randomly assigned to one of three groups (N = 22) that received a transcranial direct current stimulation (tDCS), transcranial random noise stimulation (tRNS), or sham for 20 min. The tDCS group received 1.5 mA with the anode over the left DLPFC and cathode over the left IFG. Locations in tRNS group were the same and they received 1.5 mA of high frequency tRNS (100–500 Hz). Divergent thinking was assessed before (baseline) and during stimulation with unusual uses (UU) and picture completion (PC) subtests from Torrance Creative thinking Test, whereas convergent thinking was evaluated with the remote association test (RAT). Stroop test was included to assess cognitive flexibility. ANCOVA results of performance under stimulation (controlling for baseline performance) showed that there were significant differences in PC (F = 3.35, p = 0.042, np2 = 0.10) but not in UU (F = 0.61, p = 0.546) and RAT (F = 2.65, p = 0.079) scores. Post-hoc analyses showed that tRNS group had significantly higher scores compared to sham (p = 0.004) in PC. More specifically, tRNS showed higher performance in fluency (p = 0.012) and originality (p = 0.021) dimensions of PC compared to sham. Regarding cognitive flexibility, we did not find any significant effect of any of the stimulation groups (F = 0.34, p = 0.711). Therefore, no further mediation analyses were performed. Finally, the group that received tDCS reported more adverse effects than sham group (F = 3.46, p = 0.035). Altogether, these results suggest that tRNS may have some advantages over tDCS in DT.

Non-invasive brain stimulation and neuroenhancement

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The available data frame with a wide parameter space of tES does not allow an overarching protocol recommendation.

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Established engineering risk-management procedures with regard to manufacturing should be followed.

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Consensus among experts is that tES for neuroenhancement is safe as long as tested protocols are followed.

Attempts to enhance human memory and learning ability have a long tradition in science. This topic has recently gained substantial attention because of the increasing percentage of older individuals worldwide and the predicted rise of age-associated cognitive decline in brain functions. Transcranial brain stimulation methods, such as transcranial magnetic (TMS) and transcranial electric (tES) stimulation, have been extensively used in an effort to improve cognitive functions in humans.

Here we summarize the available data on low-intensity tES for this purpose, in comparison to repetitive TMS and some pharmacological agents, such as caffeine and nicotine. There is no single area in the brain stimulation field in which only positive outcomes have been reported. For self-directed tES devices, how to restrict variability with regard to efficacy is an essential aspect of device design and function. As with any technique, reproducible outcomes depend on the equipment and how well this is matched to the experience and skill of the operator. For self-administered non-invasive brain stimulation, this requires device designs that rigorously incorporate human operator factors. The wide parameter space of non-invasive brain stimulation, including dose (e.g., duration, intensity (current density), number of repetitions), inclusion/exclusion (e.g., subject’s age), and homeostatic effects, administration of tasks before and during stimulation, and, most importantly, placebo or nocebo effects, have to be taken into account. The outcomes of stimulation are expected to depend on these parameters and should be strictly controlled. The consensus among experts is that low-intensity tES is safe as long as tested and accepted protocols (including, for example, dose, inclusion/exclusion) are followed and devices are used which follow established engineering risk-management procedures. Devices and protocols that allow stimulation outside these parameters cannot claim to be “safe” where they are applying stimulation beyond that examined in published studies that also investigated potential side effects.

Brain stimulation devices marketed for consumer use are distinct from medical devices because they do not make medical claims and are therefore not necessarily subject to the same level of regulation as medical devices (i.e., by government agencies tasked with regulating medical devices). Manufacturers must follow ethical and best practices in marketing tES stimulators, including not misleading users by referencing effects from human trials using devices and protocols not similar to theirs.

Effects of theta transcranial alternating current stimulation (tACS) on exploration and exploitation during uncertain decision-making

Exploring ones surroundings may yield unexpected rewards, but is associated with uncertainty and risk. Alternatively, exploitation of certain outcomes is related to low risk, yet potentially better outcomes remain unexamined. As such, risk-taking behavior depends on perceived uncertainty and a trade-off between exploration-exploitation. Previously, it has been suggested that risk-taking may relate to theta activity in the prefrontal cortex. Furthermore, previous studies hinted at a relationship between a right-hemispheric bias in frontal theta asymmetry and risky behavior. In the present double-blind sham-controlled within-subject study, we applied bifrontal transcranial alternating current stimulation (tACS) at the theta frequency (5 Hz) on eighteen healthy volunteers during a gambling task. Two tACS montages with either left-right or posterior-anterior current flow were employed at an intensity of 1 mA. Results showed that, compared to sham, theta tACS increased perceived uncertainty irrespective of current flow direction. Despite this observation, no direct effect of tACS on exploration behavior and general risk-taking was observed. Furthermore, frontal theta asymmetry was more right-hemispherically biased after posterior-anterior tACS, compared to sham. Finally, we used electric field simulation to identify which regions were targeted by the tACS montages as an overlap in regions may explain why the two montages resulted in comparable outcomes. Our findings provide a first step towards understanding the relationship between frontal theta oscillations and different features of risk-taking.

Synchronised neural signature of creative mental imagery in reality and augmented reality

Creativity, transforming imaginative thinking into reality, is a mental imagery simulation in essence. It can be incorporeal, concerns sophisticated and/or substantial thinking, and involves objects. In the present study, a mental imagery task consisting of creating a scene using familiar (FA) or abstract (AB) physical or virtual objects in real (RMI) and augmented reality (VMI) environments, and an execution task involving effectively creating a scene in augmented reality (VE), were utilised. The beta and gamma neural oscillations of healthy participants were recorded via a 32 channel wireless 10/20 international EGG system. In real and augmented environments and for both the mental imagery and execution tasks, the participants displayed a similar cortico-cortical neural signature essentially based on synchronous vs asynchronous beta and gamma oscillatory activities between anterior (i.e. frontal) and posterior (i.e. parietal, occipito-parietal and occipito-temporal) areas bilaterally. The findings revealed a transient synchronised neural architecture that appears to be consistent with the hypothesis according to which, creativity, because of its inherent complexity, cannot be confined to a single brain area but engages various interconnected networks.

Adjunctive multi-session transcranial direct current stimulation for neurocognitive dysfunction in schizophrenia: A meta-analysis

Findings of multi-session transcranial direct current stimulation (tDCS) as an adjunctive treatment of neurocognitive dysfunction in schizophrenia have been inconsistent. This meta-analysis of randomized controlled trials (RCTs) investigated the neurocognitive effects of adjunctive multi-session tDCS for schizophrenia. Twelve RCTs covering 418 schizophrenia patients were included and analyzed in this meta-analysis. The RevMan software (Version 5.3) was used to calculate risk ratios (RRs) and standardized mean differences (SMDs) with their 95% confidence intervals (CIs). Adjunctive tDCS outperformed the comparator in improving working memory deficits (SMD = 0.34, 95% CI: 0.03, 0.65; I² = 52%; p = 0.03), but no significant effects were found in other cognitive domains. No group differences were found with regard to total psychopathology measured by the Brief Psychiatric Rating Scale and the Positive and Negative Symptom Scale (SMD =-0.29, 95%CI: -0.61, 0.03; I² = 50%, p = 0.07) and discontinuation due to any reason (RR=0.80, 95%CI: 0.39, 1.66; I² = 9%, p = 0.56). Adjunctive tDCS appears to have a significant therapeutic effect improving the working memory deficits in schizophrenia.

Transcranial direct current stimulation of bilateral dorsolateral prefrontal cortex eliminates creativity impairment induced by acute stress

The creativity impairment under acute stress may be closely related to the down-regulation of the prefrontal cortex function caused by stress-related neurotransmitters and hormones. In the current study, we explored whether transcranial direct current stimulation (tDCS) over bilateral dorsolateral prefrontal cortex (DLPFC) eliminated stress-induced creativity impairment and the potential mechanism from the perspective of stress response recovery. Seventy participants were randomly allocated to a group undergoing the activation of right DLPFC and the deactivation of left DLPFC (R+L-; N = 35), and a group of sham stimulation (sham; N = 35). Participants received tDCS after the stress induction, and then completed the Alternative Uses Task (AUT) and the Remote Association Task (RAT) during the stimulation. The stress response was indicated using heart rate, cortisol, and emotion changes. Results showed that R+L- stimulation facilitated the recovery of anxious state compared to sham stimulation. We also found that the decreased value of AUT scores after stress in the R+L- group was significantly lower than that in the sham group. Moreover, further analysis revealed state anxiety mediated the effect of tDCS on the flexibility component of the AUT. We concluded that bilateral tDCS over the DLPFC is efficient in alleviating stress-induced creativity impairment, which may correlate with greater recovery of state anxiety. Our findings provide causal evidence for the neurophysiological mechanisms by which stress affects creativity, as well as clinical suggestions for stress-related psychiatric disorders prevention and intervention.

Paternalistic Leadership, Polychronicity, and Life Satisfaction of Nurses: The Role of Work-Family Conflict and Family-Work Conflict in Public Sector Hospitals

Based on the leadership literature, this study investigates how paternalistic leadership (PL) and polychronicity (PC) affect the life satisfaction (LS) of nurses, specifically in public hospitals. Moreover, the mediating role of work-family conflict (WFC) and family-work conflict (FWC) is also assessed the relationships among PL, PC, and LS. The cross-sectional study design is used in this study due to its cost benefits and the convenience of data collection at a single point in time. A survey questionnaire is used to collect data from 226 nurses, and the Partial least squares structural equation modeling (PLS-SEM) technique is used to investigate the proposed model. The findings of this study confirmed that PL and PC have a positive relationship with LS. Furthermore, WFC partially mediated the relationships among PL, PC, and LS. In addition, FWC partially mediated the relationship between PL and LS; the role of FWC in mediating the relationship between PC and LS has been found to be insignificant. Employees with high PC and those whose supervisors show PL behavior become more satisfied with their lives and have relatively low WFC and FWC. In addition, the theoretical and practical implications have also been discussed.

Simultaneously stimulating both brain hemispheres by rTMS in patients with unilateral brain lesions decreases interhemispheric asymmetry

BACKGROUND

Interhemispheric asymmetry caused by brain lesions is an adverse factor in the recovery of patients with neurological deficits. Repetitive transcranial magnetic stimulation (rTMS) has been shown to modulate cortical oscillation and proposed as an approach to rebalance the symmetry, which has not been documented well.

OBJECTIVE

In this study, we investigated the influence of repetitive transcranial magnetic stimulation (rTMS) on EEG power in patients with unilateral brain lesions by simultaneously stimulating both brain hemispheres and to elucidate asymmetrical changes in rTMS-induced neurophysiological activity.

METHODS

Fourteen patients with unilateral brain lesions were treated with one active and one sham session of 10 Hz rTMS over the vertex (Cz position). Resting-state EEGs were recorded before and immediately after rTMS. The brain symmetry index (BSI), calculated from a fast Fourier transform, was employed to quantify the power asymmetry in both hemispheres and paired channels over the entire range and five frequency bands (delta, theta, alpha, beta and gamma bands).

RESULTS

Comparison between active and sham sessions demonstrated rTMS-induced EEG after-effects. rTMS in the active session significantly reduced the BSI in patients with unilateral brain lesions over the entire frequency range (t = 2.767, P = 0.016). Among the five frequency bands, rTMS only induced a noticeable decrease in the BSI in the delta band (t = 2.254, P = 0.042). Furthermore, analysis of different brain regions showed that significant changes in the BSI of the alpha band were only demonstrated in the posterior parietal lobe. In addition, EEG topographic mapping showed a decreased power of delta oscillations in the ipsilesional hemisphere, whereas distinct cortical oscillations were observed in the alpha band around the parietal-occipital lobe in the contralesional hemisphere.

CONCLUSIONS

When both brain hemispheres were simultaneously activated, rTMS decreased interhemispheric asymmetry primarily via reducing the delta band in the lesioned hemisphere.

Baseline Differences in Anxiety Affect Attention and tDCS-Mediated Learning

Variable responses to transcranial direct current stimulation (tDCS) protocols across individuals are widely reported, but the reasons behind this variation are unclear. This includes tDCS protocols meant to improve attention. Attentional control is impacted by top-down and bottom-up processes, and this relationship is affected by state characteristics such as anxiety. According to Attentional Control Theory, anxiety biases attention towards bottom-up and stimulus-driven processing. The goal of this study was to explore the extent to which differences in state anxiety and related measures affect visual attention and category learning, both with and without the influence of tDCS. Using discovery learning, participants were trained to classify pictures of European streets into two categories while receiving 30 min of 2.0 mA anodal, cathodal, or sham tDCS over the rVLPFC. The pictures were classifiable according to two separate rules, one stimulus and one hypothesis-driven. The Remote Associates Test (RAT), Profile of Mood States, and Attention Networks Task (ANT) were used to understand the effects of individual differences at baseline on subsequent tDCS-mediated learning. Multinomial logistic regression was fit to predict rule learning based on the baseline measures, with subjects classified according to whether they used the stimulus-driven or hypothesis-driven rule to classify the pictures. The overall model showed a classification accuracy of 74.1%. The type of tDCS stimulation applied, attentional orienting score, and self-reported mood were significant predictors of different categories of rule learning. These results indicate that anxiety can influence the quality of subjects' attention at the onset of the task and that these attentional differences can influence tDCS-mediated category learning during the rapid assessment of visual scenes. These findings have implications for understanding the complex interactions that give rise to the variability in response to tDCS.

A Systematic Review of Creativity-Related Studies Applying the Remote Associates Test From 2000 to 2019

The study examines how the remote associates test (RAT) has been used to examine theories of creativity through a review of recent studies on creativity. Creativity-related studies published between 2000 and 2019 were retrieved from the SCOPUS database. A total of 172 papers were chosen for further analysis. Content analysis shows that research on creativity using RAT mainly concerns remote association, insight problem-solving, general creative process, test development, individual difference, effect of treatment, clinical case, social interaction effect, and predictor or criterion. The study constructs a theoretical framework based on the 4P (Product–Person–Process–Place) model and demonstrates how empirical studies using the RAT explore the individual differences, internal processes, and external influences of creative thinking. In addition, the most commonly used version of the RAT is the Compound Remote Associates Problems (Bowden and Jung-Beeman, 2003a). Current research shows a trend whereby the creative thinking process has been receiving greater attention. In particular, a growing number of studies in this field have been carried out using cognitive neuroscience technologies. These findings suggest that the RAT provides researchers with a way to deepen their understanding of different levels of creativity.

Effects of Transcranial Direct Current Stimulation on Brain Networks Related to Creative Thinking

Human creative thinking is unique and capable of generating novel and valuable ideas. Recent research has clarified the contribution of different brain networks (default mode network, DN; executive control network; salience network) to creative thinking. However, the effects of brain stimulation on brain networks during creative thinking and on creative performance have not been clarified. The present study was designed to examine the changes in functional connectivity (FC) and effective connectivity (EC) of the large-scale brain network, and the ensuing changes in creative performance, induced by transcranial direct current stimulation (tDCS). Fourteen healthy male students underwent two tDCS sessions, one with actual stimulation and one with sham stimulation, on two separate days. Participants underwent tDCS (anode over the left dorsolateral prefrontal cortex, DLPFC; cathode over the right inferior parietal lobule, IPL) for 20 min. Before and after the tDCS session, electroencephalography signals were acquired from 32 electrodes over the whole head during the creative thinking task. On FC analysis, the delta band FC between the posterior cingulate cortex and IPL significantly increased only after real stimulation. We also found that the change of flexibility score was significantly correlated with the change in: (i) delta band FC between mPFC and left lateral temporal cortex (LTC) and (ii) alpha band FC between IPL and right LTC. On EC analysis, decreased flow within the DN (from left LTC to right IPL) was observed. Our results reveal that tDCS could affect brain networks, particularly the DN, during creative thinking and modulate key FC in the generation of flexible creative ideas.

Creativity on demand - Hacking into creative problem solving

How can creative problem solving be enhanced? The paper identifies and examines modulatory approaches from the cognitive and neuroscientific literature that have been made to make creative problem solving better. We review neuromodulatory approaches of both global and local effects. Through a 2-process model of creative problem solving that involves both automatic and controlled processes, we demonstrate how these approaches could be used and what potential they may have for enhancing creative problem solving. We conclude that direct neuromodulation will be best used in unison with behavioral manipulations of cognition, and that better understanding of these manipulations should inform and guide research on direct neuromodulatory procedures.

Anodal and cathodal tDCS modulate neural activity and selectively affect GABA and glutamate syntheses in the visual cortex of cats

KEY POINTS

The present study showed that anodal and cathodal transcranial direct current stimulation (tDCS) can respectively increase and decrease the amplitude of visually evoked field potentials in the stimulated visual cortex of cats, with the effect lasting for ∼60-70 min. We directly measured tDCS-induced changes in the concentration of inhibitory and excitatory neurotransmitters in the visual cortex using the enzyme-linked immunosorbent assay method and showed that anodal and cathodal tDCS can selectively decrease the concentration of GABA and glutamate in the stimulated cortical area. Anodal and cathodal tDCS can selectively inhibit the synthesis of GABA and glutamate by suppressing the expression of GABA- and glutamate-synthesizing enzymes, respectively.

ABSTRACT

Transcranial direct current stimulation (tDCS) evokes long-lasting neuronal excitability in the target brain region. The underlying neural mechanisms remain poorly understood. The present study examined tDCS-induced alterations in neuronal activities, as well as the concentration and synthesis of GABA and glutamate (GLU), in area 21a (A21a) of cat visual cortex. Our analysis showed that anodal and cathodal tDCS respectively enhanced and suppressed neuronal activities in A21a, as indicated by a significantly increased and decreased amplitude of visually evoked field potentials (VEPs). The tDCS-induced effect lasted for ∼60-70 min. By contrast, sham tDCS had no significant impact on the VEPs in A21a. On the other hand, the concentration of GABA, but not that of GLU, in A21a significantly decreased after anodal tDCS relative to sham tDCS, whereas the concentration of GLU, but not that of GABA, in A21a significantly decreased after cathodal tDCS relative to sham tDCS. Furthermore, the expression of GABA-synthesizing enzymes GAD65 and GAD67 in A21a significantly decreased in terms of both mRNA and protein concentrations after anodal tDCS relative to sham tDCS, whereas that of GLU-synthesizing enzyme glutaminase (GLS) did not change significantly after anodal tDCS. By contrast, both mRNA and protein concentrations of GLS in A21a significantly decreased after cathodal tDCS relative to sham tDCS, whereas those of GAD65/GAD67 showed no significant change after cathodal tDCS. Taken together, these results indicate that anodal and cathodal tDCS may selectively reduce GABA and GLU syntheses and thus respectively enhance and suppress neuronal excitability in the stimulated brain area.