A major challenge of cognitive neuroscience is to understand how the brain as a network gives rise to our cognition. Simultaneous [18F]-fluorodeoxyglucose positron emission tomography functional magnetic resonance imaging (FDG-PET/fMRI) provides the opportunity to investigate brain connectivity not only via spatially distant, synchronous cerebrovascular hemodynamic responses (functional connectivity), but also glucose metabolism (metabolic connectivity). However, how these two modalities of brain connectivity differ in their relation to cognition is unknown. In this webinar, Dr Katharina Voigt will discuss recent findings demonstrating the advantage of simultaneous FDG-PET/fMRI in providing a more complete picture of the neural mechanisms underlying cognition, that calls for a combination of both modalities in future cognitive neuroscience. Dr Katharina Voigt is a Research Fellow within the Turner Institute for Brain and Mental Health, Monash University. Her research interests include systems neuroscience, simultaneous PET-MRI, and decision-making.

Work in my laboratory is based on the assumptions that we do not know yet how all physiological functions are regulated and that mouse genetics by allowing to identify novel inter-organ communications is the most efficient ways to identify novel regulation of physiological functions. We test these two contention through the study of bone which is the organ my lab has studied since its inception. Based on precise cell biological and clinical reasons that will be presented during the seminar we hypothesized that bone should be a regulator of energy metabolism and reproduction and identified a bone-derived hormone termed osteocalcin that is responsible of these regulatory events. The study of this hormone revealed that in addition to its predicted functions it also regulates brain size, hippocampus development, prevents anxiety and depression and favors spatial learning and memory by signaling through a specific receptor we characterized. As will be presented, we elucidated some of the molecular events accounting for the influence of osteocalcin on brain and showed that maternal osteocalcin is the pool of this hormone that affects brain development. Subsequently and looking at all the physiological functions regulated by osteocalcin, i.e., memory, the ability to exercise, glucose metabolism, the regulation of testosterone biosynthesis, we realized that are all need or regulated in the case of danger. In other words it suggested that osteocalcin is an hormone needed to sense and overcome acute danger. Consonant with this hypothesis we next showed this led us to demonstrate that bone via osteocalcin is needed to mount an acute stress response through molecular and cellular mechanisms that will be presented during the seminar. overall, an evolutionary appraisal of bone biology, this body of work and experiments ongoing in the lab concur to suggest 1] the appearance of bone during evolution has changed how physiological functions as diverse as memory, the acute stress response but also exercise and glucose metabolism are regulated and 2] identified bone and osteocalcin as its molecular vector, as an organ needed to sense and response to danger.

Cross-sectional and longitudinal multimodal brain imaging studies using positron emission tomography (PET) and magnetic resonance imaging (MRI) have provided detailed insight into the pathophysiological progression of Alzheimer’s disease. It starts at an asymptomatic stage with widespread gradual accumulation of beta-amyloid and spread of pathological tau deposits. Subsequently changes of functional connectivity and glucose metabolism associated with mild cognitive impairment and brain atrophy may develop. However, the rate of progression to a symptomatic stage and ultimately dementia varies considerably between individuals. Mathematical models have been developed to describe disease progression, which may be used to identify markers that determine the current stage and likely rate of progression. Both are very important to improve the efficacy of clinical trials. In this lecture, I will provide an overview on current research and future perspectives in this area.

The Ca2+ modulated pulsatile secretions of glucagon and insulin by pancreatic α and β cells play a key role in glucose metabolism and homeostasis. However, how different types of cells in the islet couple and coordinate to give rise to various Ca2+ oscillation patterns and how these patterns are being tuned by paracrine regulation are still elusive. Here we developed a microfluidic device to facilitate long-term recording of islet Ca2+ activity at single cell level and found that islets show heterogeneous but intrinsic oscillation patterns. The α and β cells in an islet oscillate in antiphase and are globally phase locked to display a variety of oscillation modes. A mathematical model of islet oscillation maps out the dependence of the oscillation modes on the paracrine interactions between α and β cells. Our study reveals the origin of the islet oscillation patterns and highlights the role of paracrine regulation in tuning them.