Prefrontal engrams of long-term fear memory perpetuate pain perception.

A painful episode can lead to a life-long increase in an individual's experience of pain. Fearful anticipation of imminent pain could play a role in this phenomenon, but the neurobiological underpinnings are unclear because fear can both suppress and enhance pain. Here, we show in mice that long-term associative fear memory stored in neuronal engrams in the prefrontal cortex determines whether a painful episode shapes pain experience later in life. Furthermore, under conditions of inflammatory and neuropathic pain, prefrontal fear engrams expand to encompass neurons representing nociception and tactile sensation, leading to pronounced changes in prefrontal connectivity to fear-relevant brain areas. Conversely, silencing prefrontal fear engrams reverses chronically established hyperalgesia and allodynia. These results reveal that a discrete subset of prefrontal cortex neurons can account for the debilitating comorbidity of fear and chronic pain and show that attenuating the fear memory of pain can alleviate chronic pain itself.

Quality contract 'prevention of postoperative delirium in the care of elderly patients' study protocol: a non-randomised, pre-post, monocentric, prospective trial.

INTRODUCTION: Postoperative delirium (POD) is seen in approximately 15% of elderly patients and is related to poorer outcomes. In 2017, the Federal Joint Committee (Gemeinsamer Bundesausschuss) introduced a 'quality contract' (QC) as a new instrument to improve healthcare in Germany. One of the four areas for improvement of in-patient care is the 'Prevention of POD in the care of elderly patients' (QC-POD), as a means to reduce the risk of developing POD and its complications.The Institute for Quality Assurance and Transparency in Health Care identified gaps in the in-patient care of elderly patients related to the prevention, screening and treatment of POD, as required by consensus-based and evidence-based delirium guidelines. This paper introduces the QC-POD protocol, which aims to implement these guidelines into the clinical routine. There is an urgent need for well-structured, standardised and interdisciplinary pathways that enable the reliable screening and treatment of POD. Along with effective preventive measures, these concepts have a considerable potential to improve the care of elderly patients. METHODS AND ANALYSIS: The QC-POD study is a non-randomised, pre-post, monocentric, prospective trial with an interventional concept following a baseline control period. The QC-POD trial was initiated on 1 April 2020 between Charité-Universitätsmedizin Berlin and the German health insurance company BARMER and will end on 30 June 2023. INCLUSION CRITERIA: patients 70 years of age or older that are scheduled for a surgical procedure requiring anaesthesia and insurance with the QC partner (BARMER). Exclusion criteria included patients with a language barrier, moribund patients and those unwilling or unable to provide informed consent. The QC-POD protocol provides perioperative intervention at least two times per day, with delirium screening and non-pharmacological preventive measures. ETHICS AND DISSEMINATION: This protocol was approved by the ethics committee of the Charité-Universitätsmedizin, Berlin, Germany (EA1/054/20). The results will be published in a peer-reviewed scientific journal and presented at national and international conferences. TRIAL REGISTRATION NUMBER: NCT04355195.

Gamma oscillations in somatosensory cortex recruit prefrontal and descending serotonergic pathways in aversion and nociception.

In humans, gamma-band oscillations in the primary somatosensory cortex (S1) correlate with subjective pain perception. However, functional contributions to pain and the nature of underlying circuits are unclear. Here we report that gamma oscillations, but not other rhythms, are specifically strengthened independently of any motor component in the S1 cortex of mice during nociception. Moreover, mice with inflammatory pain show elevated resting gamma and alpha activity and increased gamma power in response to sub-threshold stimuli, in association with behavioral nociceptive hypersensitivity. Inducing gamma oscillations via optogenetic activation of parvalbumin-expressing inhibitory interneurons in the S1 cortex enhances nociceptive sensitivity and induces aversive avoidance behavior. Activity mapping identified a network of prefrontal cortical and subcortical centers whilst morphological tracing and pharmacological studies demonstrate the requirement of descending serotonergic facilitatory pathways in these pain-related behaviors. This study thus describes a mechanistic framework for modulation of pain by specific activity patterns in the S1 cortex.