The effect of tDCS targeting the left inferior frontal gyrus on fear extinction

98 

Abstract Submission 

Yuanbo Ma^1,2, Fatemeh Yavari¹, Fujia Jiao^1,3, Michael Nitsche^1,4

¹Psychology and neurosciences, Leibniz Research Centre for working environment and human factors, Dortmund, Germany, ²Neuropsychology, Institute of Cognitive Neuroscience, Faculty of Psychology, Ruhr University Bochum, Bochum, Germany, ³Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China, ⁴Bielefeld University, University Hospital OWL, Protestant Hospital of Bethel Foundation, University Clinic of Psychiatry and Psychotherapy, and University Clinic of Child and Adolescent Psychiatry and Psychotherapy, Bielefeld, Germany

Yuanbo Ma  
Psychology and neurosciences, Leibniz Research Centre for working environment and human factors|Neuropsychology, Institute of Cognitive Neuroscience, Faculty of Psychology, Ruhr University Bochum
Dortmund, Germany|Bochum, Germany

Fatemeh Yavari  
Psychology and neurosciences, Leibniz Research Centre for working environment and human factors
Dortmund, Germany

Fujia Jiao  
Psychology and neurosciences, Leibniz Research Centre for working environment and human factors|Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport
Dortmund, Germany|Shanghai, China

Michael Nitsche  
Psychology and neurosciences, Leibniz Research Centre for working environment and human factors|Bielefeld University, University Hospital OWL, Protestant Hospital of Bethel Foundation, University Clinic of Psychiatry and Psychotherapy, and University Clinic of Child and Adolescent Psychiatry and Psychotherapy
Dortmund, Germany|Bielefeld, Germany

Impaired fear extinction is an essential factor contributing into several anxiety disorders, such as post-traumatic stress disorder (PTSD) and phobias [1]. Based on the fear extinction model, exposure therapy is considered as an effective treatment method for anxiety disorders. However, some patients experience reappearance of fear in real-life contexts after treatment, indicating the crucial role of contextual factors in the efficiency of fear extinction (renewal effect). A recent fMRI study has shown activation of the left inferior frontal gyrus (LiFG) during the extinction phase of a predictive learning task, implying the correlational involvement of LiFG in context processing during extinction learning [2]. In this study, we aimed to investigate the suggested causal role of LiFG in the context-dependency of fear extinction learning via non-invasive transcranial direct current stimulation (tDCS), which alters cortical excitability, to target this area.

180 healthy subjects (92 females) were recruited and randomly assigned to 9 groups (3 tDCS types (anodal, cathodal, and sham) × 3 context combinations (AAA, ABA, and ABB)). The fear conditioning task was conducted over three consecutive days: acquisition, the first extinction, and the second extinction phases. tDCS (2 mA, 10 min) was administered during the first extinction phase to the LiFG using a 4-electrode montage. Skin conductance response (SCR) data was collected and analyzed using a mixed-model ANOVA, Bonferroni comparisons were performed when results appeared significant.

During the extinction phase, subjects who received anodal tDCS showed a significantly higher fear response compared to the cathodal and sham conditions, and this effect was stable till the 2nd extinction phase. Cathodal tDCS caused a significant decrease in the difference of the response to the threat and safety cues during the 2nd extinction phase compared to anodal and sham conditions. An interaction between tDCS and context was only observed during the extinction phase.

Our results do not support the causal role of LiFG in the context-dependency of fear extinction learning, though anodal tDCS led to augmented fear responses independent of the context. It has been previously indicated that in fear conditioning, a positive prediction error (PPE) can update and increase fear responses to the threat cues, and increased activation of the LiFG has been observed to be associated with PPE [3]. This is in line with our results, as hyperactivation of LiFG by anodal tDCS could have evoked a positive prediction error which increases fear responses. Furthermore, previous fMRI data have shown that the LiFG is activated when participants are asked to increase their negative emotions in response to aversive images [4]. Increasing the activity of the LiFG by tDCS in our study might therefore elevate the negative interpretation of the fear stimulus (CS+), leading to increased fear responses and deteriorate fear extinction learning.

TDCS ¹

Emotional Learning ²

Affective Disorders

Anxiety

Cognition

Cortex

ELECTROPHYSIOLOGY

Emotions

Learning

Memory

Other - Transcranial Direct Current Stimulation