Effects of transcranial alternating current stimulation over right-DLPFC on vigilance tasks depend on the arousal level

AbstractCurrent theoretical accounts on the oscillatory nature of sustained attention predict that entrainment via transcranial alternating current stimulation (tACS) at alpha and theta frequencies on specific areas of the prefrontal cortex could prevent the drops in vigilance across time-on-task. Nonetheless, most previous studies have neglected both the fact that vigilance comprises two dissociable components (i.e., arousal and executive vigilance) and the potential role of differences in arousal levels. We examined the effects of theta- and alpha-tACS over the right dorsolateral prefrontal cortex in both components of vigilance and in participants who differed in arousal level according to their chronotype and time of testing. Intermediate-types performed the vigilance tasks when their arousal level was optimal, whereas evening-types performed the vigilance tasks when their arousal levels were non-optimal. Both theta- and alpha-tACS improved arousal vigilance in the psychomotor vigilance task (PVT), whereas alpha-tACS, but not theta-tACS, improved executive vigilance in the sustained attention to response task (SART), and counteracted the typical vigilance decrement usually observed in this task. Importantly, these stimulation effects were only found when arousal was low (i.e., with evening-types performing the tasks at their non-optimal time of day). The results support the multicomponent view of vigilance, the relevance of heeding individual differences in arousal, and the role of alpha oscillations as a long-range cortical scale synchronization mechanism that compensates the decrements in performance as a function of time-on-task by exerting and maintaining cognitive control attributed to activation of the right dorsolateral prefrontal cortex.

Download Full-text

Alpha and Theta Transcranial Alternating Current Stimulation Over the Right Dorsolateral Prefrontal Cortex Modulates Vigilance Performance, but Only When Arousal Levels Are Non-optimal

10.21203/rs.3.rs-753599/v1 ◽

2021 ◽

Author(s):

Víctor Martínez-Pérez ◽

Miriam Tortajada ◽

Lucía B. Palmero ◽

Guillermo Campoy ◽

Luis J. Fuentes

Keyword(s):

Prefrontal Cortex ◽

Dorsolateral Prefrontal Cortex ◽

Alternating Current ◽

Time Of Day ◽

Time On Task ◽

Frontoparietal Network ◽

Dorsolateral Prefrontal ◽

Transcranial Alternating Current Stimulation ◽

The Right

Abstract BackgroundCurrent theoretical accounts on the oscillatory nature of sustained attention predict that entrainment via transcranial alternating current stimulation (tACS) at alpha and theta frequencies on the frontoparietal network could prevent the drops in vigilance across time-on-task. Nonetheless, most previous studies have neglected both the fact that vigilance comprises two dissociable components (i.e. arousal and executive vigilance) and the potential role of differences in arousal baseline. MethodWe examined the effects of theta- and alpha-tACS over the right dorsolateral prefrontal cortex on both components of vigilance and on participants that differed in arousal baseline according to their chronotype and the time of testing. Intermediate-types performed the vigilance tasks when their arousal baseline was at the optimal level, whereas evening-types performed the vigilance tasks when their arousal baseline was at non-optimal levels. ResultsBoth theta- and alpha-tACS improved arousal vigilance, whereas alpha-tACS, but not theta-tACS, improved accuracy and attenuated the typical vigilance decrement in the executive vigilance task. Importantly, these stimulation effects were only found when arousal baseline was low (i.e., with evening-types performing the tasks at their non-optimal time of day).ConclusionThe results support the multicomponent view of vigilance, the relevance of heeding individual differences in arousal baseline, and the role of alpha oscillations as a long-range cortical scale synchronization mechanism that compensates the decrements in performance as a function of time-on-task by exerting and maintaining cognitive control attributed to activation of the frontoparietal network.

Download Full-text

Reducing future fears by suppressing the brain mechanisms underlying episodic simulation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1606604114 ◽

2016 ◽

Vol 113 (52) ◽

pp. E8492-E8501 ◽

Cited By ~ 21

Author(s):

Roland G. Benoit ◽

Daniel J. Davies ◽

Michael C. Anderson

Keyword(s):

Prefrontal Cortex ◽

Dorsolateral Prefrontal Cortex ◽

Ventromedial Prefrontal Cortex ◽

Episodic Simulation ◽

Dorsolateral Prefrontal ◽

Future Events ◽

The Right ◽

Development Of Anxiety ◽

The Brain

Imagining future events conveys adaptive benefits, yet recurrent simulations of feared situations may help to maintain anxiety. In two studies, we tested the hypothesis that people can attenuate future fears by suppressing anticipatory simulations of dreaded events. Participants repeatedly imagined upsetting episodes that they feared might happen to them and suppressed imaginings of other such events. Suppressing imagination engaged the right dorsolateral prefrontal cortex, which modulated activation in the hippocampus and in the ventromedial prefrontal cortex (vmPFC). Consistent with the role of the vmPFC in providing access to details that are typical for an event, stronger inhibition of this region was associated with greater forgetting of such details. Suppression further hindered participants’ ability to later freely envision suppressed episodes. Critically, it also reduced feelings of apprehensiveness about the feared scenario, and individuals who were particularly successful at down-regulating fears were also less trait-anxious. Attenuating apprehensiveness by suppressing simulations of feared events may thus be an effective coping strategy, suggesting that a deficiency in this mechanism could contribute to the development of anxiety.

Download Full-text

Causal Role of the Dorsolateral Prefrontal Cortex in Belief Updating under Uncertainty

Cerebral Cortex ◽

10.1093/cercor/bhaa219 ◽

2020 ◽

Vol 31 (1) ◽

pp. 184-200

Author(s):

Stefan Schulreich ◽

Lars Schwabe

Keyword(s):

Prefrontal Cortex ◽

Dorsolateral Prefrontal Cortex ◽

Causal Role ◽

Uncertain Environments ◽

Belief Updating ◽

Frontoparietal Network ◽

Dorsolateral Prefrontal ◽

The Right ◽

Normative Value

Abstract Adaptive performance in uncertain environments depends on the ability to continuously update internal beliefs about environmental states. Recent correlative evidence suggests that a frontoparietal network including the dorsolateral prefrontal cortex (dlPFC) supports belief updating under uncertainty, but whether the dlPFC serves a “causal” role in this process is currently not clear. To elucidate its contribution, we leveraged transcranial direct current stimulation (tDCS) over the right dlPFC, while 91 participants performed an incentivized belief-updating task. Participants also underwent a psychosocial stress or control manipulation to investigate the role of stress, which is known to modulate dlPFC functioning. We observed enhanced monetary value updating after anodal tDCS when it was normatively expected from a Bayesian perspective. A model-based analysis indicates that this effect was driven by belief updating. However, we also observed enhanced non-normative value updating, which might have been driven instead by expectancy violation. Enhanced normative and non-normative value updating reflected increased vs. decreased Bayesian rationality, respectively. Furthermore, cortisol increases were associated with enhanced positive, but not with negative, value updating. The present study thereby sheds light on the causal role of the right dlPFC in the remarkable human ability to navigate uncertain environments by continuously updating prior knowledge following new evidence.

Download Full-text

Enhancing memory performance with rTMS in healthy subjects and individuals with Mild Cognitive Impairment: the role of the right dorsolateral prefrontal cortex

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2012.00062 ◽

2012 ◽

Vol 6 ◽

Cited By ~ 50

Author(s):

Patrizia Turriziani ◽

Daniela Smirni ◽

Giuseppe Zappalà ◽

Giuseppa R. Mangano ◽

Massimiliano Oliveri ◽

...

Keyword(s):

Cognitive Impairment ◽

Prefrontal Cortex ◽

Mild Cognitive Impairment ◽

Healthy Subjects ◽

Dorsolateral Prefrontal Cortex ◽

Memory Performance ◽

Dorsolateral Prefrontal ◽

The Right

Download Full-text

The role of the right dorsolateral prefrontal cortex in the Tower of London task performance: repetitive transcranial magnetic stimulation study in patients with Parkinson’s disease

Experimental Brain Research ◽

10.1007/s00221-012-3255-9 ◽

2012 ◽

Vol 223 (2) ◽

pp. 251-257 ◽

Cited By ~ 23

Author(s):

H. Srovnalova ◽

R. Marecek ◽

R. Kubikova ◽

I. Rektorova

Keyword(s):

Prefrontal Cortex ◽

Transcranial Magnetic Stimulation ◽

Task Performance ◽

Magnetic Stimulation ◽

Dorsolateral Prefrontal Cortex ◽

Repetitive Transcranial Magnetic Stimulation ◽

Tower Of London ◽

Dorsolateral Prefrontal ◽

The Right

Download Full-text

T54. EFFECTS OF GAMMA TRANSCRANIAL ALTERNATING CURRENT STIMULATION TO THE LEFT DORSOLATERAL PREFRONTAL CORTEX ON WORKING MEMORY IN SCHIZOPHRENIA PATIENTS

Schizophrenia Bulletin ◽

10.1093/schbul/sbaa029.614 ◽

2020 ◽

Vol 46 (Supplement_1) ◽

pp. S251-S252

Author(s):

Irina Papazova ◽

Wolfgang Strube ◽

Lina Hoffmann ◽

Tobias Schwippel ◽

Frank Padberg ◽

...

Keyword(s):

Working Memory ◽

Prefrontal Cortex ◽

Cognitive Load ◽

Dorsolateral Prefrontal Cortex ◽

Reaction Times ◽

Alternating Current ◽

Primary Study ◽

Dorsolateral Prefrontal ◽

Transcranial Alternating Current Stimulation ◽

Healthy Participants

Abstract Background Working memory (WM) impairment is characteristic for schizophrenia patients, lowering their occupational status and quality of life. Recent research suggests that non-invasive brain stimulation could have the potential to treat such cognitive deficits. One novel and promising approach is the transcranial alternating current stimulation (tACS) that could entrain the endogenous gamma oscillations in the dorsolateral prefrontal cortex (DLPFC), previously shown to be abnormal in schizophrenia patients and associated with WM deficits. Indeed, first studies demonstrated WM improvement in healthy participants following tACS at the gamma frequency (γ-tACS) to the DLPFC in healthy participants. However, till date, there is only one pilot study with ten schizophrenia patients, where cognitive enhancement was not evident. Here, we aimed to investigate the efficacy and feasibility of γ-tACS on simultaneous WM performance in schizophrenia patients with a bigger study sample and in regard of cognitive load Methods A total of fifteen patients with schizophrenia (N = 15, 8 female) participated in the current study. They underwent a pre-stimulation baseline, an active γ-tACS and a sham single-session in a double-blind, cross-over design. Stimulation was administered over the left DLPFC (F3, anode) and the contralateral region (F4, cathode) at a current of -1mA to 1mA (peek-to-peek) at 40 Hz for 20 min (48000 cycles). We assessed WM during stimulation using a verbal n-back task with three cognitive loads (1- to 3-back). Reaction times and discriminability index d prime served as primary study outcomes. Using several RM-ANOVAs, we compared working memory performance during γ-tACS and sham across all cognitive loads. Results Data analysis showed no significant main effect of γ-tACS compared to sham on both d prime values (p = .269) and reaction times (p = .166). However, we observed a significant stimulation x load interaction effect on reaction times (p = .043), suggesting that with increasing cognitive load participants responded slightly slower during active than during sham γ-tACS. Discussion The current work is one of the first to investigate the effects of γ-tACS to the DLPFC on simultaneous WM performance in schizophrenia patients. In line with previous research, we did not find any significant changes in cognition due to stimulation. Surprisingly, we observed a slight decrease in WM speed with higher cognitive load during active compared to sham tACS. Results are discussed in line of study protocol and tACS feasibility and emphasize the need for future research on the specific study design parameters.

Download Full-text