Polarity-specific high-definition transcranial direct current stimulation of the anterior and posterior default mode network improves remote memory retrieval

Abstract

Background: Previous studies show that activity in the posterior default mode network (pDMN), including the posterior cingulate cortex and the precuneus, is correlated with the success of long-term episodic memory retrieval. However, the role of the anterior DMN (aDMN) including the medial prefrontal cortex is still unclear. Some studies show that activating the medial prefrontal cortex improves memory retrieval while other studies show deactivation of the medial prefrontal cortex in successful retrieval of episodic memories, suggesting a possible functional dissociation between the aDMN and pDMN.Objective: In the current study, we aim to causally explore this probable dissociation using highdefinition transcranial direct current stimulation (HD-tDCS). Methods: We perform a randomised double-blinded two-visit placebo-controlled study with 84 healthy young adults. During Visit 1 they learn 75 Swahili-English word-associations. Seven days later, they randomly receive either anodal, cathodal or sham HD-tDCS targeting the pDMN or aDMN while they recall what they have previously learned. Results: We demonstrate that anodal stimulation of the pDMN and cathodal stimulation of the aDMN, equally improve the percentage of Swahili-English word-associations recalled 7 days after learning. Conclusions: Modulating the activity in the aDMN and pDMN causally affect memory retrieval performance. HD-tDCS of the aDMN and pDMN shows that anodal stimulation of the pDMN and cathodal stimulation of the aDMN increases memory retrieval performance one week after the learning phase. Given consistent evidence, it is highly likely that we are increasing the activity in the pDMN with anodal pDMN stimulation. However, it is not clear if cathodal HD-tDCS targetting aDMN works via decoupling from the pDMN or via indirectly disinhibit pDMN.

Transcranial Electrical Stimulation for Associative Memory Enhancement: State-of-the-Art from Basic to Clinical Research

“…However, the positioning of the return electrode/s was highly inconsistent, resulting in a diverse set of montages used in the experiments. Moreover, a few studies targeted other brain areas, including the temporal cortex (e.g., [ 28 ]) and occipital nerve [ 58 ], or used unique montages targeting various brain areas at once [ 54 ]. Some versions of standard AM tasks (source memory and tasks where participants had to pair words and/or pictures) were used in all papers, along with standard outcome measures of cued recall (19 studies) or recognition (14 studies).…”

“…Specifically, 18 out of 29 studies found positive tES effects on AM, 7 studies presented evidence of tES decreasing AM performance, while 4 studies reported null effects on all AM outcomes. There is no apparent relationship between the AM effects and the type of tES protocol applied, as positive effects were reported following anodal tDCS [ 32 , 33 , 44 , 47 , 49 , 52 , 53 , 57 ], tACS [ 58 , 59 ], otDCS [ 52 , 59 ], HD-tDCS [ 54 ], HD-tACS [ 48 ] and even cathodal tDCS [ 51 ].…”

“…The effects of frontal stimulation were much more mixed—some experiments showed AM improvement [ 32 , 33 , 37 , 45 , 48 , 50 , 53 ], while others showed null [ 38 , 40 , 41 , 42 , 45 , 51 , 56 ] or negative effects [ 36 , 42 , 43 ]. Two-thirds of the studies that applied tES during the encoding (online protocol) showed neuromodulatory effects, while only 3 out of 7 studies that applied tES during the retrieval stage showed positive effects on AM [ 34 , 45 , 54 ]. When it comes to studies that applied tES prior to AM task (offline protocol), all but one showed a facilitatory effect.…”

Applications of open-source software ROAST in clinical studies: A review

“…In addition, many studies run the models on the example head included with ROAST or an individual sample from the investigators. These work cover various clinical applications including: attention-deficit hyperactivity disorder [ 61 , 62 ], aging [ 63 ], associative memory [ 64 , 65 ], attention [ 66 – 68 ], body awareness [ 69 ], cognitive control and function [ 70 ]; Fusco et al [ 125 ]; [ 71 , 72 ], connectivity [ 73 ], decision making [ 74 – 77 ]; Schulreich and Schwabe [ 126 ], declarative learning [ 78 ], depressive disorder [ 79 ], electroencephalography (EEG) research [ 80 – 83 ], imitation [ 84 ], memory retrieval [ 85 – 87 ], mind wandering [ 88 , 89 ], motor learning [ 90 – 95 ], motor skills [ 96 – 98 ], neurorehabilitation [ 60 ], neurovascular coupling [ 99 ], obsessive-compulsive disorder [ 100 ], phantom limb pain [ 101 ], post-anoxic leukoencephalopathy [ 102 ], reading speed [ 103 ], schizophrenia [ 104 ], social anxiety disorder [ 105 ], stroke [ 106 ], visual perception [ 107 , 108 ], and working memory [ 109 – 115 ].…”

Establishing a causal role for left ventrolateral prefrontal cortex in value-directed memory encoding with high-definition transcranial direct current stimulation

“…Thus, our final dataset consists of 63 participants’ data, with 21 in the left-anode group ( M age = 20.4, SD = 1.17), 20 in the right-anode group ( M age = 19.7, SD = 1.22), and 22 in the sham group (11 left-sham and 11 right-sham, M age = 20.6, SD = 3.27). We considered this sample size acceptable given that similar or smaller sample sizes have been used in prior studies investigating tDCS modulation of memory (Huang et al, 2021).…”