Imaging Techniques
imaging techniques
Massimo Sartori
The Neuro-Mechanical Modeling and Engineering Lab (NMLab) at the University of Twente invites applications for a 3-year postdoctoral position funded by the ERC Consolidator Grant ROBOREACTOR. This is an exciting opportunity to join a cutting-edge team at the intersection of neurophysiology, biomechanics, and rehabilitation robotics. As a postdoctoral researcher in this project, you will work on breakthrough technology for non-invasive biopsies of skeletal muscles, specifically targeting the lower limbs. You will employ high-density electromyography (HD-EMG) and ultrasonography, combined with advanced statistical and machine learning techniques, to characterize muscle properties at multiple scales. Key focuses include motor unit phenotype distribution, 3D muscle fascicle morphology, and muscle inflammation levels. You will validate these non-invasive measurements against invasive biopsy samples and advanced imaging techniques, working with both healthy individuals and post-stroke survivors in the context of rehabilitation robotics and regenerative robotics technologies.
Inducing short to medium neuroplastic effects with Transcranial Ultrasound Stimulation
Sound waves can be used to modify brain activity safely and transiently with unprecedented precision even deep in the brain - unlike traditional brain stimulation methods. In a series of studies in humans and non-human primates, I will show that Transcranial Ultrasound Stimulation (TUS) can have medium- to long-lasting effects. Multiple read-outs allow us to conclude that TUS can perturb neuronal tissues up to 2h after intervention, including changes in local and distributed brain network configurations, behavioural changes, task-related neuronal changes and chemical changes in the sonicated focal volume. Combined with multiple neuroimaging techniques (resting state functional Magnetic Resonance Imaging [rsfMRI], Spectroscopy [MRS] and task-related fMRI changes), this talk will focus on recent human TUS studies.
How AI is advancing Clinical Neuropsychology and Cognitive Neuroscience
This talk aims to highlight the immense potential of Artificial Intelligence (AI) in advancing the field of psychology and cognitive neuroscience. Through the integration of machine learning algorithms, big data analytics, and neuroimaging techniques, AI has the potential to revolutionize the way we study human cognition and brain characteristics. In this talk, I will highlight our latest scientific advancements in utilizing AI to gain deeper insights into variations in cognitive performance across the lifespan and along the continuum from healthy to pathological functioning. The presentation will showcase cutting-edge examples of AI-driven applications, such as deep learning for automated scoring of neuropsychological tests, natural language processing to characeterize semantic coherence of patients with psychosis, and other application to diagnose and treat psychiatric and neurological disorders. Furthermore, the talk will address the challenges and ethical considerations associated with using AI in psychological research, such as data privacy, bias, and interpretability. Finally, the talk will discuss future directions and opportunities for further advancements in this dynamic field.
Development and evolution of neuronal connectivity
In most animal species including humans, commissural axons connect neurons on the left and right side of the nervous system. In humans, abnormal axon midline crossing during development causes a whole range of neurological disorders ranging from congenital mirror movements, horizontal gaze palsy, scoliosis or binocular vision deficits. The mechanisms which guide axons across the CNS midline were thought to be evolutionary conserved but our recent results suggesting that they differ across vertebrates. I will discuss the evolution of visual projection laterality during vertebrate evolution. In most vertebrates, camera-style eyes contain retinal ganglion cell (RGC) neurons projecting to visual centers on both sides of the brain. However, in fish, RGCs are thought to only innervate the contralateral side. Using 3D imaging and tissue clearing we found that bilateral visual projections exist in non-teleost fishes. We also found that the developmental program specifying visual system laterality differs between fishes and mammals. We are currently using various strategies to discover genes controlling the development of visual projections. I will also present ongoing work using 3D imaging techniques to study the development of the visual system in human embryo.
The glymphatic system in motor neurone disease
Neurodegenerative diseases are chronic and inexorable conditions characterised by the presence of insoluble aggregates of abnormally ubiquinated and phosphorylated proteins. Recent evidence also suggests that protein misfolding can propagate throughout the body in a prion-like fashion via the interstitial or cerebrospinal fluids (CSF). As protein aggregation occurs well before the onset of brain damage and symptoms, new biomarkers sensitive to early pathology, together with therapeutic strategies that include eliminating seed proteins and blocking cell-to-cell spread, are of vital importance. The glymphatic system, which facilitates the continuous exchange of CSF and interstitial fluid to clear the brain of waste, presents as a potential biomarker of disease severity, therapeutic target, and drug delivery system. In this webinar, Associate Professor David Wright from the Department of Neuroscience, Monash University, will outline recent advances in using MRI to investigate the glymphatic system. He will also present some of his lab’s recent work investigating glymphatic clearance in preclinical models of motor neurone disease. Associate Professor David Wright is an NHMRC Emerging Leadership Fellow and the Director of Preclinical Imaging in the Department of Neuroscience, Monash University and the Alfred Research Alliance, Alfred Health. His research encompasses the development, application and analysis of advanced magnetic resonance imaging techniques for the study of disease, with a particular emphasis on neurodegenerative disorders. Although less than three years post PhD, he has published over 60 peer-reviewed journal articles in leading neuroscience journals such as Nature Medicine, Brain, and Cerebral Cortex.
Translation at the Synapse
The complex morphology of neurons, with synapses located hundreds of microns from the cell body, necessitates the localization of important cell biological machines, including ribosomes, within dendrites and axons. Local translation of mRNAs is important for the function and plasticity of synapses. Using advanced sequencing and imaging techniques we have updated our understanding of the local transcriptome and identified the local translatome- identifying over 800 transcripts for which local translation is the dominant source of protein. In addition, we have explored the unique mechanisms neurons use to meet protein demands at synapses, identifying surprising features of neuronal and synaptic protein synthesis.
Computational modelling of neurotransmitter release
Synaptic transmission provides the basis for neuronal communication. When an action-potential propagates through the axonal arbour, it activates voltage-gated Ca2+ channels located in the vicinity of release-ready synaptic vesicles docked at the presynaptic active zone. Ca2+ ions enter the presynaptic terminal and activate the vesicular Ca2+ sensor, thereby triggering neurotransmitter release. This whole process occurs on a timescale of a few milliseconds. In addition to fast, synchronous release, which keeps pace with action potentials, many synapses also exhibit delayed asynchronous release that persists for tens to hundreds of milliseconds. In this talk I will demonstrate how experimentally constrained computational modelling of underlying biological processes can complement laboratory studies (using electrophysiology and imaging techniques) and provide insights into the mechanisms of synaptic transmission.
Functional Divergence at the Mouse Bipolar Cell Terminal
Research in our lab focuses on the circuit mechanisms underlying sensory computation. We use the mouse retina as a model system because it allows us to stimulate the circuit precisely with its natural input, patterns of light, and record its natural output, the spike trains of retinal ganglion cells. We harness the power of genetic manipulations and detailed information about cell types to uncover new circuits and discover their role in visual processing. Our methods include electrophysiology, computational modeling, and circuit tracing using a variety of imaging techniques.
How bilingualism modulates the neural mechanisms of selective attention
Learning and using multiple languages places considerable demands on our cognitive system, and has been shown to modulate the mechanisms of selective attention in both children and adults. Yet the nature of these adaptive changes is still not entirely clear. One possibility is that bilingualism boosts the capacity for selective attention; another is that it leads to a different distribution of this finite resource, aimed at supporting optimal performance under the increased processing demands. I will present a series of studies investigating the nature of modifications of selective attention in bilingualism. Using behavioural and neuroimaging techniques, our data confirm that bilingualism modifies the neural mechanisms of selective attention even in the absence of behavioural differences between monolinguals and bilinguals. They further suggest that, instead of enhanced attentional capacity, these neuroadaptive modifications appear to reflect its redistribution, arguably aimed at economising the available resources to support optimal behavioural performance.
Hard x-ray imaging of biological soft tissues
The aim of this half day virtual meeting is to consider what is currently achievable with existing techniques and to explore where advancements can be made in the short and medium term. Leading scientists in the field will highlight the questions currently being addressed using hard X-ray imaging techniques, volume electron microscopy and their combination with other imaging modalities, with a forward look to areas of opportunity becoming accessible as a result of the recent and upcoming synchrotron upgrades. We expect an exciting day filled with science focused talks and lively discussions on how the field will develop over the next few years.
Visualizing the multi-scale complexity of the brain
The brain is complex over multiple length-scales, from many protein molecules forming intricate nano-machines in a synapse to many neurons forming interconnected networks across the brain. Unraveling this multi-scale complexity is fundamental to our understanding of brain function and disease. In this lecture, I will introduce advances in visualizing the complex, multi-scale structures in the brain. Emphasis will be on new imaging techniques, including cryo electron tomography and correlative light-electron microscopy that enabled revealing in situ organization of synaptic molecules, and ultra-high speed volumetric imaging method VISoR developed to map brain-wide circuits at subcellular resolution. I will also discuss challenges and opportunities for interdisciplinary research collaboration to analyze and understand the enormous data generated by these cutting-edge technologies.
Advances in Computational Psychiatry: Understanding (cognitive) control as a network process
The human brain is a complex organ characterized by heterogeneous patterns of interconnections. Non-invasive imaging techniques now allow for these patterns to be carefully and comprehensively mapped in individual humans, paving the way for a better understanding of how wiring supports cognitive processes. While a large body of work now focuses on descriptive statistics to characterize these wiring patterns, a critical open question lies in how the organization of these networks constrains the potential repertoire of brain dynamics. In this talk, I will describe an approach for understanding how perturbations to brain dynamics propagate through complex wiring patterns, driving the brain into new states of activity. Drawing on a range of disciplinary tools – from graph theory to network control theory and optimization – I will identify control points in brain networks and characterize trajectories of brain activity states following perturbation to those points. Finally, I will describe how these computational tools and approaches can be used to better understand the brain's intrinsic control mechanisms and their alterations in psychiatric conditions.
Generative models of the human connectome
The human brain is a complex network of neuronal connections. The precise arrangement of these connections, otherwise known as the topology of the network, is crucial to its functioning. Recent efforts to understand how the complex topology of the brain has emerged have used generative mathematical models, which grow synthetic networks according to specific wiring rules. Evidence suggests that a wiring rule which emulates a trade-off between connection costs and functional benefits can produce networks that capture essential topological properties of brain networks. In this webinar, Professor Alex Fornito and Dr Stuart Oldham will discuss these previous findings, as well as their own efforts in creating more physiologically constrained generative models. Professor Alex Fornito is Head of the Brain Mapping and Modelling Research Program at the Turner Institute for Brain and Mental Health. His research focuses on developing new imaging techniques for mapping human brain connectivity and applying these methods to shed light on brain function in health and disease. Dr Stuart Oldham is a Research Fellow at the Turner Institute for Brain and Mental Health and a Research Officer at the Murdoch Children’s Research Institute. He is interested in characterising the organisation of human brain networks, with particular focus on how this organisation develops, using neuroimaging and computational tools.
The life of a mucosalivary droplet: Lessons from synthetic breaths and sneezes
The main transmission mode of the COVID-19 disease is through virus-laden aerosols and droplets generated by expiratory events, such as breathing and sneezing. Patients with respiratory diseases are typically treated with oxygenation devices in hospitals, homes, and other settings where they increase the risk of spreading the disease to caregivers and first responders. Here, I will discuss a systematic study of aerosol and droplet dispersal through the air and their final deposition on surfaces. Through laser and fluorescent imaging techniques, we measure the volumetric spatial-temporal dynamics of droplet dispersal while varying rheological properties of the mucosaliva. We then demonstrate that a standard nose and mouth mask reduces the amount of mucosaliva dispersed by a factor of at least a hundred. Our ongoing collaborations with doctors and respiratory therapists from the Baystate Medical Hospital are developing new guidelines to help mitigate disease spread in a hospital setting.
Mapping the brain’s remaining terra incognita
In this webinar, Dr Ye Tian and A/Prof Andrew Zalesky will present new research on mapping the functional architecture of the human subcortex. They used 3T and 7T functional MRI from more than 1000 people to map one of the most detailed functional atlases of the human subcortex to date. Comprising four hierarchical scales, the new atlas reveals the complex topographic organisation of the subcortex, which dynamically adapts to changing cognitive demands. The atlas enables whole-brain mapping of connectomes and has been used to optimise targeting of deep brain stimulation. This joint work with Professors Michael Breakspear and Daniel Margulies was recently published in Nature Neuroscience. In the second part of the webinar, Dr Ye Tian will present her current research on the biological ageing of different body systems, including the human brain, in health and degenerative conditions. Conducted in more than 30,000 individuals, this research reveals associations between the biological ageing of different body systems. She will show the impact of lifestyle factors on ageing and how advanced ageing can predict the risk of mortality. Associate Professor Andrew Zalesky is a Principal Researcher with a joint appointment between the Faculties of Engineering and Medicine at The University of Melbourne. He currently holds a NHMRC Senior Research Fellowship and serves as Associate Editor for Brain Topography, Neuroimage Clinical and Network Neuroscience. Dr Zalesky is recognised for the novel tools that he has developed to analyse brain networks and their application to the study of neuropsychiatric disorders. Dr Ye Tian is a postdoctoral researcher at the Department of Psychiatry, University of Melbourne. She received her PhD from the University of Melbourne in 2020, during which she established the Melbourne Subcortex Atlas. Dr Tian is interested in understanding brain organisation and using brain imaging techniques to unveil neuropathology underpinning neuropsychiatric disorders.
Neuron-glia interactions in synapse degeneration in Alzheimer's disease
Tara Spires-Jones’ research focuses on the mechanisms and reversibility of neurodegeneration in Alzheimer’s disease, other degenerative brain diseases, and ageing. The objective of her research group is to understand why synapses and neurons become dysfunctional and die in these diseases in order to develop effective therapeutic strategies. Her work has shown that soluble forms of the pathological proteins amyloid beta and tau contribute to synapse degeneration, and that lowering levels of these proteins can prevent and reverse phenotypes in model systems. Further, she has pioneered high-resolution imaging techniques in human post-mortem brain and found evidence that these proteins accumulate in synapses in human disease.
Neurobiology of Social Behavior
Social interactions are central to the human experience, yet it is also one of the faculty of the brain that is the most impaired by mental illness. Similarly, social interactions are essential for animals to survive, reproduce, and raise their young. Over the years, my lab has attempted to decipher the unique characteristics of social recognition: what are the unique cues that trigger distinct social behaviors, what is the nature and identity of social behavior circuits, how is the function of these circuits different in males and females and how are they modulated by the animal physiological status? In this lecture, I will describe our recent progress in using genetic, imaging, molecular and behavioral approaches to understand how the brain controls specific social behaviors in both males and females, and how areas throughout the brain participate in the positive and negative controls of specific social interactions. I will also describe how new approaches of single cell transcriptomics have enabled us to uncover specific cell populations involved in distinct social behaviors and the basis of their activity modulation according to the animal state.
Misplaced and misconnected: circuit-level defects in malformations of cortical development
During histogenesis of the cerebral cortex, a proper laminar placement of defined numbers of specific cellular types is necessary to ensure proper functional connectivity patterns. There is a wide range of cortical malformations causing epilepsy and intellectual disability in humans, characterized with various degrees of neuronal misplacement, aberrant circuit organization or abnormal folding patterns. Although progress in human neurogenetics and brain imaging techniques have considerably advanced the identification of their causative genes, the pathophysiological mechanisms associated with defective cerebral cortex development remain poorly understood. In my presentation, I will outline some of our recent works in rodent models illustrating how misplaced neurons forming grey matter heterotopia, a cortical malformation subtype, interfere with the proper development of cortical circuits, and induce both local and distant circuitry changes associated with the subsequent emergence of epilepsy.