Gamma tACS over the temporal lobe increases the occurrence of Eureka! moments

Abstract

The solution to a problem might manifest itself as a burst of unexpected, unpredictable clarity. Such Eureka! events, or Insight moments, are among the most fascinating mysteries of human cognition, whose neurophysiological substrate seems to include a role for oscillatory activity within the α and γ bands in the right parietal and temporal brain regions. We tested this hypothesis on thirty-one healthy participants using transcranial Alternating Current Stimulation (tACS) to externally amplify α (10 Hz) and γ (40 Hz) activity in the right parietal and temporal lobes, respectively. During γ-tACS over the right temporal lobe, we observed an increase in accuracy on a verbal insight task. Furthermore, electroencephalography (EEG) data revealed an increase in γ spectral power over bilateral temporal lobes after stimulation. Additionally, resting-state functional MRI data acquired before the stimulation session suggested a correlation between behavioral response to right temporal lobe tACS and functional connectivity of bilateral temporal lobes, in line with the bilateral increase in γ band revealed by EEG. Overall, results suggest the possibility of enhancing the probability of generating Eureka! moments in humans by means of frequency-specific noninvasive brain stimulation.

TDCS to the right anterior temporal lobe facilitates insight problem-solving

“…Using HD tDCS we identified a causal relationship between active rATL stimulation and increased insight problem-solving. Consistent with the recent results obtained by Santarnecchi and colleagues 24 , our results indicate that inducing insight can be achieved using non-invasive brain stimulation to the rATL. Our study design considered several flaws in previous studies using non-invasive brain stimulation during insight problem-solving, by including increasing statistical power and by having two control conditions.…”

“…Other brain areas besides the rATL and the lFPC may be preferentially involved in solving other types of problems via insight or solving similar problems when insight solutions are not required. For example, Santarnecchi and colleagues' results were significant only for CRA problems but not for Rebus puzzles 24 . Thus, future research needs to address if the tDCS effect is limited only to CRA problems or can be extended to a different class of problems (i.e., Rebus puzzles).…”

“…Despite the key role assigned to the rATL in facilitating the processing of distant semantic associate relationships, and specifically insight problem-solving 22,24 , only a few studies have attempted to investigate the causal role of this brain network node using transcranial Direct Current Stimulation (tDCS) [32][33][34][35] . TDCS applies a constant, low current (1-2 mA) to the brain area of interest via electrodes on the scalp.…”

Oculometric signature of switch into awareness? Pupil size predicts sudden insight whereas microsaccades predict problem-solving via analysis

“…Afterward, the problem words were erased and participants had to report, via button press, whether they had solved the problem via insight or analysis. Self-reports for insight and analytic solving have been established in numerous behavioral and neuroimaging studies (e.g., Cristofori et al, 2018 ; Jung-Beeman et al, 2004 ; Kounios et al, 2006 ; Laukkonen and Tangen, 2018 ; Salvi et al, 2018 ; Salvi et al, 2016a ,b; Santarnecchi et al, 2019 ; Salvi et al, 2020 ; Salvi and Bowden, 2019 ). No feedback was given to participants regarding whether the solution they had provided was correct.…”

The Effect of Dopaminergic Replacement Therapy on Creative Thinking and Insight Problem-Solving in Parkinson's Disease Patients

“…For this study, CRA problems consisted of 40 trials per session (for a total of 120 Italian CRA problems, taken from Salvi et al, 2015b ). The CRA problems have been used specifically for investigating the neural bases of insight problem-solving (see e.g., Jung-Beeman et al, 2004 ; Bowden et al, 2005 ; Kounios et al, 2006 ; Salvi et al, 2015a , 2020a , c ; Sprugnoli et al, 2017 ; Santarnecchi et al, 2019 ; Becker et al, 2020b ) and other cognitive and social factors associated with it (e.g., Salvi et al, 2016a , b , 2020b ; Cristofori et al, 2018 ; Salvi and Bowden, 2019 ; Threadgold et al, 2019 ).…”