LAUSR

The basolateral amygdala (BLA) forms a triad with the medial prefrontal cortex (mPFC) and the hippocampus (HPC) to process incoming stimuli and orchestrate emotional responses [1]. In post-traumatic stress disorder (PTSD), a dysfunction in this triad is characterized by a deficit of mPFC inhibition of the BLA [2]. As a result, metabolic hyperactivity of the BLA characterize symptomatic episodes in PTSD patients [3]. We are using deep brain stimulation (DBS) in PTSD subjects to modulate the activity of the BLA and promote fear extinction [4]. Targeted focal neuromodulation offers a unique opportunity to gain new insights into the circuitry of emotion in PTSD patients. In this study, we included two patients with refractory PTSD who underwent bilateral BLA-DBS as part of our clinical trial with the aim of mapping the behavioral responses to acute amygdala stimulation. Unlike rodent or non-human primate models, patients can effectively communicate their feelings and emotions in real-time allowing us to link a psychological percept to a specific focal stimulation. All procedures were performed under approval of the institutional board review of the VAGLAHS. Patients provided informed consent for all parts of the study including surgery and data collection. To identify the behavioral responses of stimulation of the amygdala, we tested each of the four contacts of the DBS electrode increasing the amplitude to a maximum of 5V (66 stimulation trials in the two patients). The stimulated region encompassed the BLA (basal, basal accessory, and lateral nucleus of the amygdala), central nucleus of the amygdala, and HPC. Since the behavioral responses in PTSD patients can have unique features, these were captured by an experienced psychiatrist who monitored the patients while they underwent telemetry and video-EEG monitoring one month after implantation. These responses were categorized as positive (including happiness, euphoria, relaxation, or any other positive states), negative (anxiety, anger, or any other distressing responses), and autonomic symptoms. The anxiety was rated in