Evidence-based psychotherapy, such as prolonged exposure (PE) or cognitive processing therapy, is the first-line therapy for post-traumatic stress disorder (PTSD). However, patients with PTSD often drop out from those psychotherapies. To prevent dropout, combining these psychotherapies with pharmacotherapy may be useful. Understanding the underlying neurobiological mechanisms of drug action is necessary for proper pharmacotherapy. It has been reported that brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) are involved in the enhancement of fear extinction, which is considered a basic theoretical model for PE across species. Recently, a selective TrkB agonist, 7,8-dihydroxyflavone (7,8-DHF), that can pass through the blood-brain barrier has been developed. Therefore, this review summarizes the role of BDNF-TrkB signaling in fear extinction and drugs targeting BDNF-TrkB signaling.
Mirror writing refers to writing as if the script was reflected in a mirror. This study describes the case of a patient who exhibited mirror writing with her left hand after suffering thalamic hemorrhage. Before the stroke, she was right-handed, but became unable to write with her right hand due to severe paralysis. Afterwards, she began writing with her left hand and mirror writing emerged. Interestingly, her mirror writing occurred frequently, even six months after the stroke. In addition, these features influenced the writing direction. There are more frequently emerged leftward and vertical directions. The reason why the feature of the phenomenon is characteristics of the movement to write a letter with left hand, and the role of the right hemisphere for writing.
Functional near-infrared spectroscopy (fNIRS) is an optical neuroimaging method for recording cerebral hemodynamics. Tolerance of motion is considered an advantage of fNIRS when compared with other imaging techniques. However, fNIRS signals are often contaminated by scalp blood flow (SBF) signals due to motion of the subject. In the present study, we recorded changes in the concentrations of oxygenated and deoxygenated hemoglobin by multidistance source-detector probes during whole body tilting with the head and trunk fixed, and demonstrated that the change in body direction against gravity causes SBF signal contamination. Non-negligible parallel changes in oxygenated and deoxygenated hemoglobin during trunk tilt were observed in long-distance channels (conventional 30 mm), as well as those in short-distance channels (15 mm) reflecting SBF changes. Because the tilt angle-dependent changes in the long channels were correlated highly with those in the short channels, the fluctuation caused by the trunk tilt could be considered SBF signal contamination. The contamination was successfully removed by a multidistance method and by a hemodynamic modality separation method.