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Effects of frontal transcranial direct current stimulation on emotional state and processing in healthy humans.

Nitsche MA, Koschack J, Pohlers H, Hullemann S, Paulus W, Happe S - Front Psychiatry (2012)

Bottom Line: In healthy subjects, however, rTMS of the same areas has no major effect, and the effects of tDCS are mixed.We aimed to evaluate the effects of prefrontal tDCS on emotion and emotion-related cognitive processing in healthy humans.We conclude that tDCS of the prefrontal cortex improves emotion processing in healthy subjects, but does not influence subjective emotional state.

View Article: PubMed Central - PubMed

Affiliation: Department Clinical Neurophysiology, Georg-August-University Goettingen, Germany.

ABSTRACT
The prefrontal cortex is involved in mood and emotional processing. In patients suffering from depression, the left dorsolateral prefrontal cortex (DLPFC) is hypoactive, while activity of the right DLPFC is enhanced. Counterbalancing these pathological excitability alterations by repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) improves mood in these patients. In healthy subjects, however, rTMS of the same areas has no major effect, and the effects of tDCS are mixed. We aimed to evaluate the effects of prefrontal tDCS on emotion and emotion-related cognitive processing in healthy humans. In a first study, we administered excitability-enhancing anodal, excitability-diminishing cathodal, and placebo tDCS to the left DLPFC, combined with antagonistic stimulation of the right frontopolar cortex, and tested acute emotional changes by an adjective checklist. Subjective emotions were not influenced by tDCS. Emotional face identification, however, which was explored in a second experiment, was subtly improved by a tDCS-driven excitability modulation of the prefrontal cortex, markedly by anodal tDCS of the left DLPFC for positive emotional content. We conclude that tDCS of the prefrontal cortex improves emotion processing in healthy subjects, but does not influence subjective emotional state.

No MeSH data available.


Related in: MedlinePlus

Emotional face identification is modified by tDCS: reaction times. Baseline-standardized reaction times for the identification of the position of negative (A) or positive (B) emotional facial expressions shown on a computer screen are depicted during (d) and after (p1–3; p1 = immediately and 5 min after tDCS, p2 = 10 and 20 min after tDCS, p3 = 30 and 60 min after tDCS), anodal, cathodal, and placebo tDCS. Reaction times become faster during the course of the experiment, thus indicating learning of the task in all stimulation and emotional conditions. Under both real stimulation conditions and for both facial expressions, reaction time reductions become earlier significant than under placebo stimulation. Under anodal tDCS, positive emotional facial expressions are faster identified as compared to placebo stimulation during and after tDCS. For emotionally negative facial expressions, anodal tDCS improves perception only during tDCS as compared to placebo stimulation. A minor effect can be seen for cathodal tDCS, as compared to placebo stimulation (p2 only). Filled symbols indicate significant reaction time differences as compared to baseline values, asterisks significant differences between anodal tDCS and placebo tDCS, and hash symbols significant differences between cathodal and placebo tDCS for a given time point (paired, two-tailed t-tests, p < 0.05). Vertical bars indicate standard error of mean.
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Figure 3: Emotional face identification is modified by tDCS: reaction times. Baseline-standardized reaction times for the identification of the position of negative (A) or positive (B) emotional facial expressions shown on a computer screen are depicted during (d) and after (p1–3; p1 = immediately and 5 min after tDCS, p2 = 10 and 20 min after tDCS, p3 = 30 and 60 min after tDCS), anodal, cathodal, and placebo tDCS. Reaction times become faster during the course of the experiment, thus indicating learning of the task in all stimulation and emotional conditions. Under both real stimulation conditions and for both facial expressions, reaction time reductions become earlier significant than under placebo stimulation. Under anodal tDCS, positive emotional facial expressions are faster identified as compared to placebo stimulation during and after tDCS. For emotionally negative facial expressions, anodal tDCS improves perception only during tDCS as compared to placebo stimulation. A minor effect can be seen for cathodal tDCS, as compared to placebo stimulation (p2 only). Filled symbols indicate significant reaction time differences as compared to baseline values, asterisks significant differences between anodal tDCS and placebo tDCS, and hash symbols significant differences between cathodal and placebo tDCS for a given time point (paired, two-tailed t-tests, p < 0.05). Vertical bars indicate standard error of mean.

Mentions: The ANOVA revealed a significant main effect of time (Table 1). An additional trend for an effect of tDCS on performance was identified. As depicted in Figure 3, reaction times diminished throughout the course of the experiment in all tDCS and facial expression conditions. We conducted exploratory, subjected to confirmation, post hoct-tests despite only trend wise effects of tDCS or the interactions including tDCS in the ANOVA. These revealed significant shortenings of reaction time relative to baseline during and after anodal tDCS for positive and negative emotional expressions. For cathodal tDCS, the direction of the improvements of reaction time were similar, but somewhat smaller as compared to anodal tDCS for positive emotional expressions. Conversely, under placebo stimulation the reaction time improvements occurred later during the course of the experiment and were significant – as compared to baseline – only for the last measures. The post hoc tests additionally revealed significant reaction time differences for anodal tDCS vs placebo stimulation. Anodal tDCS reduced reaction time significantly during tDCS relative to placebo stimulation for emotionally negative faces. For emotionally positive facial expressions, this effect emerged during tDCS, and remained significant for up to 10 min after tDCS. Reaction times under cathodal tDCS did differ significantly relative to placebo stimulation only for negative facial expressions during the second measures after tDCS.


Effects of frontal transcranial direct current stimulation on emotional state and processing in healthy humans.

Nitsche MA, Koschack J, Pohlers H, Hullemann S, Paulus W, Happe S - Front Psychiatry (2012)

Emotional face identification is modified by tDCS: reaction times. Baseline-standardized reaction times for the identification of the position of negative (A) or positive (B) emotional facial expressions shown on a computer screen are depicted during (d) and after (p1–3; p1 = immediately and 5 min after tDCS, p2 = 10 and 20 min after tDCS, p3 = 30 and 60 min after tDCS), anodal, cathodal, and placebo tDCS. Reaction times become faster during the course of the experiment, thus indicating learning of the task in all stimulation and emotional conditions. Under both real stimulation conditions and for both facial expressions, reaction time reductions become earlier significant than under placebo stimulation. Under anodal tDCS, positive emotional facial expressions are faster identified as compared to placebo stimulation during and after tDCS. For emotionally negative facial expressions, anodal tDCS improves perception only during tDCS as compared to placebo stimulation. A minor effect can be seen for cathodal tDCS, as compared to placebo stimulation (p2 only). Filled symbols indicate significant reaction time differences as compared to baseline values, asterisks significant differences between anodal tDCS and placebo tDCS, and hash symbols significant differences between cathodal and placebo tDCS for a given time point (paired, two-tailed t-tests, p < 0.05). Vertical bars indicate standard error of mean.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3377009&req=5

Figure 3: Emotional face identification is modified by tDCS: reaction times. Baseline-standardized reaction times for the identification of the position of negative (A) or positive (B) emotional facial expressions shown on a computer screen are depicted during (d) and after (p1–3; p1 = immediately and 5 min after tDCS, p2 = 10 and 20 min after tDCS, p3 = 30 and 60 min after tDCS), anodal, cathodal, and placebo tDCS. Reaction times become faster during the course of the experiment, thus indicating learning of the task in all stimulation and emotional conditions. Under both real stimulation conditions and for both facial expressions, reaction time reductions become earlier significant than under placebo stimulation. Under anodal tDCS, positive emotional facial expressions are faster identified as compared to placebo stimulation during and after tDCS. For emotionally negative facial expressions, anodal tDCS improves perception only during tDCS as compared to placebo stimulation. A minor effect can be seen for cathodal tDCS, as compared to placebo stimulation (p2 only). Filled symbols indicate significant reaction time differences as compared to baseline values, asterisks significant differences between anodal tDCS and placebo tDCS, and hash symbols significant differences between cathodal and placebo tDCS for a given time point (paired, two-tailed t-tests, p < 0.05). Vertical bars indicate standard error of mean.
Mentions: The ANOVA revealed a significant main effect of time (Table 1). An additional trend for an effect of tDCS on performance was identified. As depicted in Figure 3, reaction times diminished throughout the course of the experiment in all tDCS and facial expression conditions. We conducted exploratory, subjected to confirmation, post hoct-tests despite only trend wise effects of tDCS or the interactions including tDCS in the ANOVA. These revealed significant shortenings of reaction time relative to baseline during and after anodal tDCS for positive and negative emotional expressions. For cathodal tDCS, the direction of the improvements of reaction time were similar, but somewhat smaller as compared to anodal tDCS for positive emotional expressions. Conversely, under placebo stimulation the reaction time improvements occurred later during the course of the experiment and were significant – as compared to baseline – only for the last measures. The post hoc tests additionally revealed significant reaction time differences for anodal tDCS vs placebo stimulation. Anodal tDCS reduced reaction time significantly during tDCS relative to placebo stimulation for emotionally negative faces. For emotionally positive facial expressions, this effect emerged during tDCS, and remained significant for up to 10 min after tDCS. Reaction times under cathodal tDCS did differ significantly relative to placebo stimulation only for negative facial expressions during the second measures after tDCS.

Bottom Line: In healthy subjects, however, rTMS of the same areas has no major effect, and the effects of tDCS are mixed.We aimed to evaluate the effects of prefrontal tDCS on emotion and emotion-related cognitive processing in healthy humans.We conclude that tDCS of the prefrontal cortex improves emotion processing in healthy subjects, but does not influence subjective emotional state.

View Article: PubMed Central - PubMed

Affiliation: Department Clinical Neurophysiology, Georg-August-University Goettingen, Germany.

ABSTRACT
The prefrontal cortex is involved in mood and emotional processing. In patients suffering from depression, the left dorsolateral prefrontal cortex (DLPFC) is hypoactive, while activity of the right DLPFC is enhanced. Counterbalancing these pathological excitability alterations by repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) improves mood in these patients. In healthy subjects, however, rTMS of the same areas has no major effect, and the effects of tDCS are mixed. We aimed to evaluate the effects of prefrontal tDCS on emotion and emotion-related cognitive processing in healthy humans. In a first study, we administered excitability-enhancing anodal, excitability-diminishing cathodal, and placebo tDCS to the left DLPFC, combined with antagonistic stimulation of the right frontopolar cortex, and tested acute emotional changes by an adjective checklist. Subjective emotions were not influenced by tDCS. Emotional face identification, however, which was explored in a second experiment, was subtly improved by a tDCS-driven excitability modulation of the prefrontal cortex, markedly by anodal tDCS of the left DLPFC for positive emotional content. We conclude that tDCS of the prefrontal cortex improves emotion processing in healthy subjects, but does not influence subjective emotional state.

No MeSH data available.


Related in: MedlinePlus