See our lab's presentations at upcoming conferences and learn about our latest research:
Annual Meeting Canadian Pain Society, Montreal, 2018
Organization of the Human Brain Mapping, Singapore, 2018
Symposium talk: Prediction bias in perceptual experience and decision making
Trainee Poster: Brain connectivity states predict participant engagement in web-based behavioral training
The 8th International Workshop on Pattern Recognition in Neuroimaging, Singapore, 2018
Christos Papadelis from Boston Children’s and Harvard Medical School to speak at BIOTIC on August 3rd, at 11:00 am. Title: Advanced Multimodal Neuroimaging for Studying Prevalent Neurological Pediatric Disorders.
Congratulations Tareq Yousef on receiving the Graduate Student Stipend Award from the Department of Anesthesia, Pain Management and Perioperative Medicine!
Three spectacular candidates have been shortlisted for the Postdoc position and will be giving talks to our group for the final selection.
NetPhysJC resumed last week. We discussed a paper from Tim Behren’s group (Boorman et al., 2016, Neuron). Great discussion on information theory and Bayesian frameworks ensued. Mathematical modelling was discussed. Follow us on twitter @netphys1 #netphysJC
Poster presented at GENEVA OHBM 2016!
Dexmedetomidine disrupts local and global communication in large-scale brain networks
Javeria A Hashmi, Marco Loggia, Sheraz Khan, Rafael Vazquez, Jim Rhee, Emery N Brown, Oluwaseun Akeju
Large-scale networks formed by synchronized fluctuations in functional MRI (fMRI) signals show a distinct architecture when observed from the vantage point of complex network analysis and graph theory . Spatial correlations in fMRI signal can be represented by several clusters of connected brain regions representing ‘local networks’. These clusters are in turn connected to each other to form a ‘global network’ primarily though connections between hubs that have both inter and intra-cluster connections. The configuration of these networks is a putative mechanism to explain information dissemination in the brain.
A more precise understanding of the functional roles of these large-scale brain networks may be obtained by studying how network topology changes during altered states of arousal. General anesthetic and sedative drugs are routinely used in the clinical settings to manipulate arousal states, and provide a scientifically valid and clinically relevant approach to study the functional role of topology in large scale brain networks . In a previous study, we have demonstrated how dexmedetomidine, an alpha-2 adrenergic agonist, alters functional connectivity between the thalamus and the default mode network . However, the effects of dexmedetomidine on global brain networks have not been investigated. Here we tested how dexmedetomidine effects brain network capacity for efficient information transfer within local and global networks. We hypothesized that anesthesia-induced sedation reduces the local and global efficiency of large-scale brain networks.
Using resting state functional MRI, we imaged the brain of 14 healthy subjects during baseline (awake), dexmedetomidine-induced sedation, and recovery from the dexmedetomidine-induced states . Using a whole-brain network approach, networks were constructed at 6 different network density thresholds from a 131-ROI parcellation . We used the Brain Connectivity Toolbox and custom codes written in MATLAB . Graph metrics were compared with paired t-tests and results were corrected for multiple comparison using FDR (p<0.05).
Our investigations showed that neural communication mediated by synchronizations in slow rsfMRI signals were disrupted during dexmedetomidine-induced sedation. In particular, we found significantly reduced capacity for efficient information transfer within the brain at both a local and a global level in weighted networks during the sedated state. The topological changes were associated with reduced strength of connections (nodal strength) at a global mean level during the sedated state (p<0.05 for all network density thresholds). Importantly, we did not find significant changes in number of connections at a nodal level (degree distribution). As previously reported with sedatives and anesthetics, we also observed reduced connectivity in thalamic , attention networks  and default-mode networks, however, our global network approach also showed reduced functional connectivity within and between all resting state networks. The most robust change was observed for subcortical connections with multimodal networks, and for sensory connections with language/memory processing networks.
Our findings are the first to demonstrate that sedation induced with dexmedetomidine significantly disrupts the capacity for efficient information transfer at a local and a global scale. By using a global network approach, we have found that the effects of dexmedetomidine are not specific to a particular network; instead, connectivity was reduced both within and between several resting state networks.
DAL PAIN NETWORK MEETING 2016
As part of Dal Pain Day, the NetPhys Lab presented a poster and attended talks by Dr. Irene Tracey from Oxford University. We had a lovely and informative day from 7am Grand Rounds to an informal dinner at the end of the night.
Taking a look at some research at the poster presentation session during Dal Pain Day.