D-9-tetrahydrocannabinol (D-9-THC) and Cannabidiol (CBD), the two main ingredients of the Cannabis sativa plant have distinct symptomatic and behavioral effects. We used functional magnetic resonance imaging (fMRI) in healthy volunteers to examine whether D-9-THC and CBD had opposite effects on regional brain function. We then assessed whether pretreatment with CBD can prevent the acute psychotic symptoms induced by D-9-THC. Fifteen healthy men with minimal earlier exposure to cannabis were scanned while performing a verbal memory task, a response inhibition task, a sensory processing task, and when viewing fearful faces. Subjects were scanned on three occasions, each preceded by oral administration of D-9-THC, CBD, or placebo. BOLD responses were measured using fMRI. In a second experiment, six healthy volunteers were administered D-9-THC intravenously on two occasions, after placebo or CBD pretreatment to examine whether CBD could block the psychotic symptoms induced by D-9-THC. D-9-THC and CBD had opposite effects on activation relative to placebo in the striatum during verbal recall, in the hippocampus during the response inhibition task, in the amygdala when subjects viewed fearful faces, in the superior temporal cortex when subjects listened to speech, and in the occipital cortex during visual processing. In the second experiment, pretreatment with CBD prevented the acute induction of psychotic symptoms by D-9-tetrahydrocannabinol. D-9-THC and CBD can have opposite effects on regional brain function, which may underlie their different symptomatic and behavioral effects, and CBD's ability to block the psychotogenic effects of D-9-THC.

There is growing interest in the complex topology of human brain functional networks, often measured using resting-state functional MRI (fMRI). Here, we used a meta-analysis of the large primary literature that used fMRI or PET to measure task-related activation (>1,600 studies; 1985–2010). We estimated the similarity (Jaccard index) of the activation patterns across experimental tasks between each pair of 638 brain regions. This continuous coactivation matrix was used to build a weighted graph to characterize network topology. The coactivation network was modular, with occipital, central, and default-mode modules predominantly coactivated by specific cognitive domains (perception, action, and emotion, respectively). It also included a rich club of hub nodes, located in parietal and prefrontal cortex and often connected over long distances, which were coactivated by a diverse range of experimental tasks. Investigating the topological role of edges between a deactivated and an activated node, we found that such competitive interactions were most frequent between nodes in different modules or between an activated rich-club node and a deactivated peripheral node. Many aspects of the coactivation network were convergent with a connectivity network derived from resting state fMRI data ( n = 27, healthy volunteers); although the connectivity network was more parsimoniously connected and differed in the anatomical locations of some hubs. We conclude that the community structure of human brain networks is relevant to cognitive function. Deactivations may play a role in flexible reconfiguration of the network according to cognitive demand, varying the integration between modules, and between the periphery and a central rich club.

The purpose of this research is to determine the impact of working during the early stage of the COVID‐19 pandemic on the well‐being of staff at one 600‐bed acute hospital in metropolitan Melbourne, Australia. This exploratory study is part of a larger mixed methods survey project, reporting the qualitative data from an on‐line survey of clinical staff working at one acute hospital between April 16th and May 13th, 2020 during the COVID‐19 pandemic. Responses to five free‐text questions were analysed using inductive content analysis. 321 medical, nursing, allied health and non‐clinical staff responded to the survey. Respondents reported anxiety, fear and uncertainty related to the pandemic, from the perspectives of work, home, family and community. They reported feeling confused by inconsistent messages received from government, hospital executive, managers and media. Seven themes were identified: (i) worrying about patient care, (ii) changed working conditions, (iii) working in the changed hospital environment, (iv) impact of the pandemic, (v) personal isolation and uncertainty, (vi) leadership and management and (vii) additional support needed for staff. Despite the pandemic being comparatively well‐controlled in Australia, all disciplines reported a high degree of anticipatory anxiety. Staff working in healthcare require both managerial and psychological support to minimise anxiety and promote well‐being and resilience in order to deal with the health crisis. Regular unambiguous communication directing the way forward is crucial.

Objective: To examine psychological distress in healthcare workers (HCWs) during the COVID-19 pandemic in April–May 2020. Methods: A cross-sectional survey examining demographic, employment and mental health characteristics of HCWs in a large metropolitan hospital in Australia. Results: HCWs showed significant symptoms of moderate-severe level depression (21%), anxiety (20%) and posttraumatic stress disorder (PTSD; 29%), associated with burnout, prior psychiatric history, profession and resilience. Conclusion: Despite low levels of COVID contact, moderate to high levels of psychological distress were reported. Continued monitoring and support for HCWs’ mental well-being is warranted as the COVID-19 pandemic develops.