Investigating the Neural Correlates in Memory Retrieval After HD-tDCS

The overall objective of this study is to investigate the neural correlate in retrieval memory task.

The aim of the study is to understand the undergoing changes in late positive ERP component during retrieval memory task when stimulating the posterior cingulate cortex (PCC) with High Definition Transcranial Direct Current Stimulation (HD-tDCS).

Study Overview

• Status: Completed
• Conditions: Healthy Adults
• Intervention / Treatment: Device: active anodal HD-tDCS; Device: sham HD-tDCS; Device: active cathodal HD-tDCS

Detailed Description

Retrieval memory is supported by distinct retrieval process known as recollection and familiarity. These two process have been associated with distinct event related potentials (ERPs). At the time of retrieval, familiarity is associated with modulation of the FN400, an enhanced positivity for old items relative to new items observed from approximately 400-600ms post stimulus onset. The FN400 tends to have mid-frontal scalp distribution which can extend to left and right frontal areas and central midline regions. In contrast, recollection has been linked with modulation of positive going waveform that emerges approximately 600ms post stimulus and is typically maximal over parietal sites and referred to as late positive component (LPC). In addition, FN400 is found to increase gradually as a function of item retrieval confidence whereas LPC is limited to high confidence retrieval response.

High Definition transcranial Direct Current Stimulation (HD-tDCS ) is a non-invasive neuromodulation technique. Compared to the standard bipolar montage used by the conventional tDCS, it uses arrays of smaller, specially designed electrodes to deliver a constant and low current directly to the cortical brain areas to increase the spatial focality. Studies show that the cortical area undergoing stimulation with HD-tDCS is more restricted compared to the standard bipolar montage of conventional tDCS. Moreover, tDCS has been proposed as a therapeutic procedure in various diseases and tDCS in healthy adults have demonstrated to improve cognitive and memory performance, but information regarding the effects of HD-tDCS targeting the PCC and its impact on memory retrieval is scarce. By targeting the PCC area by HD-tDCS, we want to introduce a safer, easier-to-use and more accurate non-invasive neuromodulation procedure. The dysfunctions of posterior cingulate cortex hav been linked to a range of psychiatric and neurological condition such as Alzheimer's disease, schizophrenia, autism, depression and attention deficit hyperactivity disorder, as well as aging. It shows increased activity when subject retrieve autobiographical memories suggests its internal orientated function. PET and ERP combined studies have shown greater blood flow medial temporal lobe with a brief late positive ERP component in PCC. Therefore, in this study we aim to understand whether HD-tDCS targeting the PCC can modulate the late positive ERP component.

• Study Type: Interventional
• Enrollment (Actual): 45
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Texas
    • Richardson, Texas, United States, 75080
      • University of Texas at Dallas

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Native English Speaker
• Currently not using any medication
• Capable of understanding and signing an informed consent

Exclusion Criteria:

• Severe disease
• Mental illness
• Cardiac history
• History of severe head injuries
• History of epileptic seizures
• Any implanted devices such as pacemaker, neurostimulator
• Pregnancy

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: active anodal HD-tDCS; Active anodal HD-tDCS stimulation applied during memory task	Device: active anodal HD-tDCS; 1) active anodal HD-tDCS with memory task
Sham Comparator: sham HD-tDCS; Sham HD-tDCS stimulation during memory task for comparison	Device: sham HD-tDCS; 2) sham HD-tDCS with memory task
Experimental: active cathodal HD-tDCS; Active cathodal HD-tDCS stimulation applied during memory task	Device: active cathodal HD-tDCS; 3) active cathodal HD-tDCS with memory task

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Recognition Memory Assessed by a Retrieval Memory Experiment	Participants had to learn an association between a face and a name. The face-name association memory task was divided into (1) an encoding phase, (2) a consolidation phase, and (3) a retrieval phase. During the encoding phase, participants studied 60 successively presented face-name pairs. Participants were instructed to assess the gender of each face shown to keep participants focused on the task. The encoding phase lasted approximately 5 minutes. This is followed by a consolidation phase where participants were instructed to "sit still, relax, and think about nothing in particular" for 10 minutes. During the retrieval phase, participants were presented with 60 old and 60 new faces and were instructed to assess whether they had seen this face during the encoding phase, or if it was a 'new' face. Participants received active or sham transcranial direct current stimulation targetting the posterior cingulate cortex during retrieval. The outcome is correctly recalled old faces.	Retrieval Memory is assessed after 90 seconds break following the recognition phase.

Collaborators and Investigators

• Sponsor: The University of Texas at Dallas

Study record dates

Study Major Dates

• Study Start (Actual): September 18, 2017
• Primary Completion (Actual): January 1, 2020
• Study Completion (Actual): January 30, 2020

Study Registration Dates

• First Submitted: October 18, 2017
• First Submitted That Met QC Criteria: October 18, 2017
• First Posted (Actual): October 24, 2017

Study Record Updates

• Last Update Posted (Actual): August 26, 2020
• Last Update Submitted That Met QC Criteria: August 24, 2020
• Last Verified: August 1, 2020

More Information

Terms related to this study

• Other Study ID Numbers: 18-01 (National Center for Advancing Translational Sciences (NCATS))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes