Transcranial Direct Current Stimulation (tDCS) of the Right Inferior Frontal Gyrus Attenuates Skin Conductance Responses to Unpredictable Threat Conditions

• Published in: Frontiers in human neuroscience Vol. 10; p. 352
• Main Authors: Herrmann, Martin J, Beier, Jennifer S, Simons, Bibiane, Polak, Thomas
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Research Foundation 12-07-2016; Frontiers Media S.A
• Subjects: Anxiety; Attention deficit hyperactivity disorder; Cardiovascular disease; Conductance; Electrical stimulation of the brain; Electrodes; emotional regulation; Emotions; ESB; Fear; Frontal gyrus; Neuroscience; NPU; Panic attacks; Post traumatic stress disorder; right inferior frontal gyrus; Skin conductance response; Studies; sustained fear; transcranial direct current stimulation; NPU; emotional regulation; sustained fear; right inferior frontal gyrus; transcranial direct current stimulation
• ISSN: 1662-5161; 1662-5161
• DOI: 10.3389/fnhum.2016.00352

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.