Brain Stimulation for Improving Working Memory

(TravelingTES Trial)

Overseen By Alexander Opitz, PhD

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of Minnesota

Disqualifiers: Neurological disorder, Metal implant, Head injuries, Chronic condition, Pregnancy, Addiction

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 2

Duration: 20 minutes per session

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores how transcranial alternating current stimulation (tACS), a type of brain stimulation, might improve working memory. It uses low-level electrical currents on specific brain areas to test if memory skills can be enhanced. Researchers are testing four different stimulation techniques. This trial may suit adults who are fluent in English and have no neurological conditions or head injuries. As an unphased trial, it offers a unique opportunity to contribute to cutting-edge research in brain stimulation and memory enhancement.

Do I have to stop taking my current medications?

Yes, you must stop taking your current medications because the trial excludes anyone with a medical condition that requires ongoing pharmacological treatment.

Will I have to stop taking my current medications?

Yes, you will need to stop taking your current medications, as the trial excludes anyone with a medical condition that requires ongoing treatment with drugs.

What prior data suggests that transcranial alternating current stimulation (tACS) is safe for improving working memory?

Research has shown that transcranial alternating current stimulation (tACS) is generally safe and well-tolerated. In a study involving young people with a specific genetic condition, participants tolerated tACS well, experiencing no major problems during treatment. Another review highlighted that tACS is safer compared to other similar methods, making it a promising option for boosting brain function. These findings suggest that tACS is a safe treatment option for improving working memory in adults. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about using transcranial alternating current stimulation (tACS) to improve working memory because it offers a non-invasive approach that directly targets brain regions involved in memory processing. Most traditional treatments rely on medications that affect neurotransmitter levels or cognitive training exercises. In contrast, tACS uses electrical currents to create specific brain wave patterns, like the parietofrontal or frontoparietal theta waves at different frequencies, which could enhance communication between brain areas critical for memory. This technique could provide a faster, more targeted way to boost cognitive function without the side effects associated with medication.

What evidence suggests that this trial's treatments could be effective for improving working memory?

Research has shown that transcranial alternating current stimulation (tACS) can improve working memory in healthy individuals. This trial will explore various types of tACS, including Parietofrontal Slow Theta Stimulation, Parietofrontal Fast Theta Stimulation, Frontoparietal Slow Theta Stimulation, and Frontoparietal Fast Theta Stimulation. Studies have found that real tACS, compared to a placebo, can sometimes enhance working memory, but results vary. Some studies discovered that a specific type, theta tACS, did not significantly improve working memory. The results depend on the exact frequency used and the targeted brain areas. Overall, while tACS shows promise, its effectiveness in boosting working memory is not guaranteed and can vary among individuals. ^{4 6 7 8 9}

Who Is on the Research Team?

Ivan Alekseichuk, PhD

Principal Investigator

University of Minnesota

Are You a Good Fit for This Trial?

This trial is for adults aged 18-45 with a good grasp of English. It's not suitable for those with chronic neurological or mental disorders, head injuries causing unconsciousness, ongoing medical conditions needing drugs, pregnant or breastfeeding individuals, substance addicts, or people with metal/electric implants in the upper body.

Inclusion Criteria

Confident level of English language

Exclusion Criteria

Pregnancy or breast-feeding

History or evidence of chronic neurological or mental disorder

Alcohol or drug addiction

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive transcranial alternating current stimulation (tACS) to assess its impact on working memory performance

20 minutes per session

1 visit (in-person)

Follow-up

Participants are monitored for changes in EEG connectivity and reaction time post-stimulation

5 minutes

1 visit (in-person)

What Are the Treatments Tested in This Trial?

Interventions

• Transcranial Alternating Current Stimulation (tACS)

Trial Overview The study is testing how traveling-wave transcranial electric stimulation (tACS), a non-invasive brain stimulation technique, affects working memory performance in healthy adults.

How Is the Trial Designed?

Group I: Parietofrontal Slow Theta Stimulation Experimental Treatment 1 Intervention

Participants will receive multi-electrode transcranial alternating current stimulation over the prefrontal and parietal brain regions that induces parietal-to-frontal traveling wave at the frequency of 4 Hz with the intensity of up to 2 mA and duration up to 20 min.

Group II: Parietofrontal Fast Theta Stimulation Experimental Treatment 1 Intervention

Participants will receive multi-electrode transcranial alternating current stimulation over the prefrontal and parietal brain regions that induces parietal-to-frontal traveling wave at the frequency of 7 Hz with the intensity of up to 2 mA and duration up to 20 min.

Group III: Frontoparietal Slow Theta Stimulation Experimental Treatment 1 Intervention

Participants will receive multi-electrode transcranial alternating current stimulation over the prefrontal and parietal brain regions that induces frontal-to-parietal traveling wave at the frequency of 4 Hz with the intensity of up to 2 mA and duration up to 20 min.

Group IV: Frontoparietal Fast Theta Stimulation Experimental Treatment 1 Intervention

Participants will receive multi-electrode transcranial alternating current stimulation over the prefrontal and parietal brain regions that induces frontal-to-parietal traveling wave at the frequency of 7 Hz with the intensity of up to 2 mA and duration up to 20 min.

Who Is Running the Clinical Trial?

University of Minnesota

Lead Sponsor

Trials

1,459

Recruited

1,623,000+

Brain & Behavior Research Foundation

Collaborator

Trials

63

Recruited

2,900+

Published Research Related to This Trial

In a study with 20 healthy participants, high gamma-band transcranial alternating current stimulation (tACS) at 80 Hz significantly improved working memory capacity, while low gamma tACS at 40 Hz did not show a significant effect.

This research is the first to demonstrate that high gamma tACS can enhance working memory across both visual hemifields, suggesting its potential as a neurorehabilitation method to improve cognitive functions by facilitating communication between brain regions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

80 Hz but not 40 Hz, transcranial alternating current stimulation of 80 Hz over right intraparietal sulcus increases visuospatial working memory capacity. Park, J., Lee, C., Lee, S., et al.[2022]

Transcranial alternating current stimulation (tACS) at beta frequency (20 Hz) significantly improved the forward digit span memory in young adults, indicating a potential method to enhance short-term memory capacity.

The study found that the benefits of beta-tACS were age-dependent, with younger individuals showing greater improvements compared to midlife adults, suggesting that this technique may be more effective in enhancing memory in younger populations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Frequency-specific insight into short-term memory capacity. Feurra, M., Galli, G., Pavone, EF., et al.[2018]

In a study involving 38 healthy adults, temporal interference transcranial alternating current stimulation (TI-tACS) was found to be safe, with no significant adverse effects reported after active stimulation at 2 mA for 30 minutes.

The study showed no significant differences in neurological and neuropsychological measurements between the active TI-tACS group and the sham group, indicating that TI-tACS does not negatively impact brain function under the tested conditions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety Evaluation of Employing Temporal Interference Transcranial Alternating Current Stimulation in Human Studies. Piao, Y., Ma, R., Weng, Y., et al.[2022]

Transcranial alternating-current stimulation (tACS) is a promising non-invasive brain stimulation technique that may enhance working memory (WM) performance, particularly in older adults and individuals with cognitive deficits, due to its superior safety and tolerability compared to repetitive transcranial magnetic stimulation (rTMS).

Research indicates that tACS can effectively manipulate brain oscillations associated with WM, suggesting its potential as a non-pharmacological tool for cognitive rehabilitation in aging populations and those with conditions like dementia and depression.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Working Memory and Transcranial-Alternating Current Stimulation-State of the Art: Findings, Missing, and Challenges. Al Qasem, W., Abubaker, M., Kvašňák, E.[2023]

Transcranial direct current stimulation (tDCS) is generally considered safe, with most adverse effects being mild and temporary; however, some cases of persistent skin lesions and rare instances of mania or hypomania have been reported, particularly in patients with depression.

Transcranial alternating current stimulation (tACS) has fewer reported adverse events, and no persistent effects have been documented, but more research is needed to fully establish its safety compared to tDCS.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Adverse events of tDCS and tACS: A review. Matsumoto, H., Ugawa, Y.[2020]

In a study involving 20 participants with mild cognitive impairment due to Alzheimer's disease, γ-tACS significantly improved memory performance, as shown by increased scores on the Rey auditory verbal learning test and face-name associations, compared to sham stimulation.

The γ-tACS also enhanced cholinergic transmission, indicated by increased short latency afferent inhibition measured with TMS, suggesting a potential mechanism for its memory-enhancing effects.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Exposure to gamma tACS in Alzheimer's disease: A randomized, double-blind, sham-controlled, crossover, pilot study. Benussi, A., Cantoni, V., Cotelli, MS., et al.[2021]

Transcranial Alternating Current Stimulation (tACS) has shown a small-to-medium effect on improving both working memory (WM) and long-term memory (LTM) in healthy adults, based on a systematic review of 104 studies.

Specific tACS parameters, such as posterior theta-tACS for WM and anterior gamma-tACS for LTM, were found to effectively modulate memory performance, with results correlating with brain oscillatory activity measured by EEG and MEG.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effects of transcranial alternating current stimulation on memory performance in healthy adults: A systematic review. Booth, SJ., Taylor, JR., Brown, LJE., et al.[2022]

In a randomized crossover study involving 43 participants (22 with major depression and 21 healthy volunteers), gamma transcranial alternating current stimulation (tACS) did not improve working memory performance during a computerized task, regardless of whether the stimulation was active or sham.

The study highlights the need for standardized methodologies in gamma tACS research, as the lack of cognitive improvement aligns with previous inconsistent findings in the field.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Single session gamma transcranial alternating stimulation does not modulate working memory in depressed patients and healthy controls. Palm, U., Baumgartner, C., Hoffmann, L., et al.[2022]

In a study involving 30 participants, transcranial alternating current stimulation (TACS) at 6 Hz was found to significantly improve working memory performance compared to transcranial direct current stimulation (TDCS), suggesting TACS may be more effective for enhancing cognitive function.

Despite the overall improvements in reaction times due to practice effects, the results indicate that TACS could be a promising method for optimizing working memory performance, warranting further research into its application.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Modulation of Working Memory Using Transcranial Electrical Stimulation: A Direct Comparison Between TACS and TDCS. Röhner, F., Breitling, C., Rufener, KS., et al.[2020]

Transcranial alternating current stimulation (tACS) at a frequency tailored to individual brain activity (Tuned condition) significantly improved visuospatial working memory (vsWM) and mental rotation tasks in 20 adults, compared to a sham stimulation.

The improvement in performance was linked to increased synchrony in the fronto-parietal brain network, suggesting that targeted stimulation can enhance specific cognitive functions related to spatial abilities.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Individually tuned theta HD-tACS improves spatial performance. Zhang, DW., Moraidis, A., Klingberg, T.[2023]

Transcranial alternating current stimulation (tACS) is a promising non-invasive technique that may help improve cognitive deficits by targeting and enhancing cortical network synchronization.

Current research suggests that tACS could clarify the causal relationship between specific brain activity patterns and cognitive abilities, paving the way for new treatment options for cognitive impairments in psychiatric illnesses.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Targeting the neurophysiology of cognitive systems with transcranial alternating current stimulation. Fröhlich, F., Sellers, KK., Cordle, AL.[2018]

Citations

1. frontiersin.org frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2023.1265600/full

Fronto-parietal theta high-definition transcranial alternating ... This study aimed to investigate the immediate effects of fronto-parietal θ HD-tACS on a dual task of working memory-postural control.

2. biorxiv.org biorxiv.org/content/10.1101/2024.03.20.585954v2.full-text

Theta transcranial alternating current stimulation is not ... Taken together, our results demonstrate that theta frequency tACS applied at the midline is not an effective method for enhancing WM.

3. nature.com nature.com/articles/s41539-022-00152-9

A meta-analysis showing improved cognitive performance ... This systematic review and meta-analysis investigated the effects of tACS protocols on cognitive functions in healthy young adults.

4. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC12417929/

Effect of theta-transcranial alternating current stimulation ... Core Tip: In this meta-analysis, we evaluated theta-band transcranial alternating current stimulation for working memory enhancement in healthy adults. Although ...

5. sciencedirect.com sciencedirect.com/science/article/pii/S1094715923000090

Efficacy of Transcranial Alternating Current Stimulation in ... Active tACS enhances working memory performance in healthy individuals compared to sham, with a moderate effect size (Cohen’s d = 0.5).

6. sciencedirect.com sciencedirect.com/science/article/pii/S0165178124001203

A randomized double-blind sham-controlled study Transcranial alternating current stimulation (tACS) was well-tolerated among young individuals with 22q11.2 deletion syndrome (22q11.2DS).

7. frontiersin.org frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2022.822545/full

Working Memory and Transcranial-Alternating Current ... Compared to rTMS, tACS demonstrates superior cost, tolerability, portability, and safety profile, making it an attractive potential tool for ...

8. translationalneurodegeneration.biomedcentral.com translationalneurodegeneration.biomedcentral.com/articles/10.1186/s40035-024-00423-y

Transcranial alternating current stimulation (tACS) at gamma ... We outline the current knowledge concerning the clinical efficacy, safety, ease-of-use and cost-effectiveness of tACS on early and advanced AD.

9. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10257732/

Efficacy of tACS in the enhancement of working memory ... In contrast, transcranial alternating current stimulation (tACS) is a form of NIBS that safely and painlessly alters cortical oscillations, rhythmic patterns of ...