title: Transcranial Direct Current Stimulation (tDCS) of the Right Inferior Frontal Gyrus Attenuates Skin Conductance Responses to Unpredictable Threat Conditions.
abstract: Patients with panic and post-traumatic stress disorders seem to show increased psychophysiological reactions to conditions of unpredictable (U) threat, which has been discussed as a neurobiological marker of elevated levels of sustained fear in these disorders. Interestingly, a recent study found that the right inferior frontal gyrus (rIFG) is correlated to the successful regulation of sustained fear during U threat. Therefore this study aimed to examine the potential use of non-invasive brain stimulation to foster the rIFG by means of anodal transcranial direct current stimulation (tDCS) in order to reduce psychophysiological reactions to U threat. Twenty six participants were randomly assigned into an anodal and sham stimulation group in a double-blinded manner. Anodal and cathodal electrodes (7 * 5 cm) were positioned right frontal to target the rIFG. Stimulation intensity was I = 2 mA applied for 20 min during a task including U threat conditions (NPU-task). The effects of the NPU paradigm were measured by assessing the emotional startle modulation and the skin conductance response (SCR) at the outset of the different conditions. We found a significant interaction effect of condition × tDCS for the SCR (F (2,48) = 6.3, p < 0.01) without main effects of condition and tDCS. Post hoc tests revealed that the increase in SCR from neutral (N) to U condition was significantly reduced in verum compared to the sham tDCS group (t (24) = 3.84, p < 0.001). Our results emphasize the causal role of rIFG for emotional regulation and the potential use of tDCS to reduce apprehension during U threat conditions and therefore as a treatment for anxiety disorders.
authors.affiliation: Laboratory for Psychophysiology and Functional Imaging, Department of Psychiatry, Psychosomatics and Psychotherapy, University Clinics of Würzburg Würzburg, Germany.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Herrmann
authors.affiliation: Laboratory for Psychophysiology and Functional Imaging, Department of Psychiatry, Psychosomatics and Psychotherapy, University Clinics of Würzburg Würzburg, Germany.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Beier
authors.affiliation: Laboratory for Psychophysiology and Functional Imaging, Department of Psychiatry, Psychosomatics and Psychotherapy, University Clinics of Würzburg Würzburg, Germany.
authors.forename: Bibiane
authors.initials: B
authors.lastname: Simons
authors.affiliation: Laboratory for Psychophysiology and Functional Imaging, Department of Psychiatry, Psychosomatics and Psychotherapy, University Clinics of Würzburg Würzburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Polak
keywords: NPU; emotional regulation; right inferior frontal gyrus; sustained fear; transcranial direct current stimulation