Transcranial Direct Current Stimulation of the Left Dorsolateral Prefrontal Cortex Shifts Preference of Moral Judgments

tDCS modified moral behavior! By ‘utilitarian’ I believe the researchers mean that the subject was less likely to ‘save the many’ by (actively participating in) sacrificing the few.

Accordingly, during anodal stimulation of the left DLPFC participants rated the utilitarian actions as more inappropriate than they did during sham and cathodal stimulation. Thus, anodal tDCS of the left DLPFC resulted in a shift of preference from an utilitarian, active decisions (i.e. to actively hazard another person’s life to rescue the lives of several people) to non-utilitarian, passive decisions (i.e. to avoid harming another person, but in consequence to accept the harm to several people.

For context, you might want to examine The Trolley Problem!

Transcranial Direct Current Stimulation of Frontal Cortex Decreases Performance on the WAIS-IV Intelligence Test, Sellers 2015

[Update 5/15/15 More or less debunked, at least a much better understanding of the anomalies of this particular study, from Nathan Whitmore’s rebuttal.] Would only now like to see this replicated with tDCS applied during testing. i.e. In this study tDCS was administered prior to the test (‘offline’ as opposed to ‘online’). But for those of us who are looking to tDCS for potential cognitive enhancement, this is a significant study. Posted to Reddit by Gwern!

Transcranial direct current stimulation (tDCS) modulates excitability of motor cortex. However, there is conflicting evidence about the efficacy of this non-invasive brain stimulation modality to modulate performance on cognitive tasks. Previous work has tested the effect of tDCS on specific facets of cognition and executive processing. However, no randomized, double-blind, sham-controlled study has looked at the effects of tDCS on a comprehensive battery of cognitive processes. The objective of this study was to test if tDCS had an effect on performance on a comprehensive assay of cognitive processes, a standardized intelligence quotient (IQ) test. The study consisted of two substudies and followed a double-blind, between-subjects, sham-controlled design. In total, 41 healthy adult participants completed the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV) as a baseline measure. At least one week later, participants in substudy 1 received either bilateral tDCS (anodes over both F4 and F3, cathode over Cz, 2mA at each anode for 20 minutes) or active sham tDCS (2mA for 40 seconds), and participants in substudy 2 received either right or left tDCS (anode over either F4 or F3, cathode over Cz, 2mA for 20 minutes). In both studies, the WAIS-IV was immediately administered following stimulation to assess for performance differences induced by bilateral and unilateral tDCS. Compared to sham stimulation, right, left, and bilateral tDCS reduced improvement between sessions on Full Scale IQ and the Perceptual Reasoning Index. This demonstration that frontal tDCS selectively degraded improvement on specific metrics of the WAIS-IV raises important questions about the often proposed role of tDCS in cognitive enhancement.

Source: “Transcranial Direct Current Stimulation of Frontal Cortex Decreases Performance on the WAIS-IV Intelligence Test”, Sellers 2015 : tDCS

My brain on electricity: A 130 day tDCS experiment

Reddit user ADifferentDrum posted the results of his informal long term dual n back/tDCS training research project. Links below to full article.

In an informal experiment aimed at improving memory and attention, I stimulated various regions of my brain using tDCS therapy for 130 sessions over 135 days while simultaneously completing the working memory task dual n back. Each session lasted about 30 minutes. I found that my scores significantly improved both during “live” tDCS treatment and also during intermittent “off” stimulation memory task sessions. I had previously done the dual n back task thousands of trials over the course of two years so the improvement in performance cannot be attributed to practice effects alone. Just as some of the literature suggests, I found that tDCS can improve a very specific skill (in this case “brain game” performance), but the jury is still out as to what benefits, if any does tDCS have in improving other skills outside of training…

130 day stimulation schedule

EEG Position Description Duration
P4 Right Parietal 15 days
P3 Left Parietal 15 days
F3 Left Dorsolateral Prefrontal Cortex 30 days
FP2 Right Frontal Pole 15 days
FP1 Left Frontal Pole 15 days
F3/FP1 (revisiting regions) Left DLPFC/Left Poles 10 days
T4 Right Temporal Lobe 15 days
T3 Left Temporal Lobe 15 days

via My brain on electricity: A 130 day tDCS experiment.

Keep Calm and Carry On: Improved Frustration Tolerance and Processing Speed by Transcranial Direct Current Stimulation (tDCS) | PLOS ONE

tdcsKeepCalmCC stands for cognitive control. In this study 28 participants took a PASAT test (try one yourself online the better you do the harder it gets). They also reported their state of mind, (PANAS) both before and after the PASAT test. Participants who received tDCS to dlPFC (dorsalateral prefrontal cortext) showed increased cognitive control and less stress from the test itself.

With this study, we provide first evidence that the enhancement of activity in the left prefrontal cortex by anodal tDCS during an adaptively challenging attention task improves performance parallel to, and in correlation with the suppression of specific task-induced negative affect. These data can be interpreted as a tDCS-supported shift of processing resources towards task-oriented performance away from preoccupation with task-related negative affect and cognition. Thereby they extend the notion of enhanced CC by prefrontal activation to internally generated distress-related distractors. More specifically, by demonstrating that tDCS-induced higher performance is associated with a lesser degree of feeling ‘upset’ with the task, these data may exemplify a subjective, experiential aspect of enhanced CC in challenging operations. Not least, these findings substantially support the concept of a tDCS-enhanced CC training as a new pathophysiology-based treatment approach of disorders associated with dysfunctional CC

tDCS seems to be (they say ‘might’), allowing our focus network to overpower the feedback network thereby shutting out the negative feedback (those self-doubting voices).

Since processing in the brain is highly competitive with different pathways mediating different aspects of information, the winners are those with the strongest sources of support [11]. Accordingly, increased activation of the dlPFC by anodal tDCS might strengthen its function to avert attention from affective reactions induced by performance errors and thus maintain goal-directed processing.

via PLOS ONE: Keep Calm and Carry On: Improved Frustration Tolerance and Processing Speed by Transcranial Direct Current Stimulation (tDCS).