Cortical Mechanisms of Single-Pulse Transcranial Magnetic Stimulation in Migraine

Single-pulse transcranial magnetic stimulation (sTMS) of the occipital cortex is an effective migraine treatment. However, its mechanism of action and cortical effects of sTMS in migraine are yet to be elucidated. Using calcium imaging and GCaMP-expressing mice, sTMS did not depolarise neurons and had no effect on vascular tone. Pre-treatment with sTMS, however, significantly affected some characteristics of the cortical spreading depression (CSD) wave, the correlate of migraine aura. sTMS inhibited spontaneous neuronal firing in the visual cortex in a dose-dependent manner and attenuated l-glutamate-evoked firing, but not in the presence of GABA_A/B antagonists. In the CSD model, sTMS increased the CSD electrical threshold, but not in the presence of GABA_A/B antagonists. We first report here that sTMS at intensities similar to those used in the treatment of migraine, unlike traditional sTMS applied in other neurological fields, does not excite cortical neurons but it reduces spontaneous cortical neuronal activity and suppresses the migraine aura biological substrate, potentially by interacting with GABAergic circuits.Electronic supplementary materialThe online version of this article (10.1007/s13311-020-00879-6) contains supplementary material, which is available to authorized users.Key Words: Migraine, transcranial magnetic stimulation, GABA, glutamate, cortex     

Validation of the Expressions of Moral Injury Scale‐Military version‐Short Form

Military personnel may encounter morally injurious events that lead to emotional, social, and spiritual suffering that transcend and/or overlap with mental health diagnoses (e.g., post‐traumatic stress disorder [PTSD]). Advancement of scientific research and potential clinical innovation for moral injury (MI) requires a diversity of measurement approaches. Drawing on results from the bifactor model in Currier et al.'s (2017) psychometric evaluation of the Expressions of Moral Injury Scale‐Military version (EMIS‐M), this study validated a four‐item short form of the instrument with two samples of veterans with a history of war‐zone service. Namely, despite the reduced number of items, the EMIS‐M‐Short Form (SF) yielded favourable internal consistency and comparable levels of convergent validity with theoretically related constructs (e.g., PTSD and struggles with morality and ultimate meaning) as the full‐length version. Notwithstanding the possible utility of distinguishing between self‐ and other‐directed forms of MI, factor analytic results further revealed that the EMIS‐M‐SF was best conceptualized with a unidimensional factorial model that might allow for a general assessment of MI‐related outcomes. Overall, these initial results suggest that the EMIS‐M‐SF may hold promise as a short, reliable, and valid assessment of overall outcomes related to a possible MI.     

Overexpression of striatal D2 receptors reduces motivation thereby decreasing food anticipatory activity

Dopamine has been implicated in circadian timing underlying the food entrainable oscillator (FEO) circuitry and overexpression of the dopamine D2 receptor (D2R) in the striatum has been reported to reduce motivation to obtain food rewards in operant tasks. In the present study, we explored both of these mechanisms by examining food anticipatory activity (FAA) in dopamine D2 receptor‐overexpressing (D2R‐OE) mice under various durations of food availability. First, we noted that at baseline, there were no differences between D2R‐OE mice and their littermates in activity level, food intake, and body weight or in circadian activity. Under conditions of very restricted food availability (4 or 6 hr), both genotypes displayed FAA. In contrast, under 8‐hr food availability, control mice showed FAA, but D2R‐OE mice did not. Normalization of D2R by administration of doxycycline, a tetracycline analogue, rescued FAA under 8‐hr restricted food. We next tested for circadian regulation of FAA. When given ad libitum access to food, neither D2R‐OE nor controls were active during the daytime. However, after an interval of food restriction, all mice showed elevated locomotor activity at the time of previous food availability in the day, indicating circadian timing of anticipatory activity. In summary, motivation is reduced in D2R‐OE mice but circadian timing behavior is not affected. We conclude that an increase in striatal D2R reduces FAA by modulating motivation and not by acting on a clock mechanism.     

The Association of Helicobacter pylori,Eradication, and Early Complications of Laparoscopic Sleeve Gastrectomy

Obesity Surgery - Laparoscopic sleeve gastrectomy (SG) is a common and effective bariatric surgery, with low postoperative complication rates. It is important to define modifiable risk factors for...