Seminars

The Group Iterative Multiple Model Estimation (GIMME) framework has emerged as a promising method for characterizing connections between brain regions in functional neuroimaging data. Two of the most appealing features of this framework are its ability to estimate the directionality of connections between network nodes and its ability to determine whether those connections apply to everyone in a sample (group-level) or just to one person (individual-level). However, there are outstanding questions about the validity and stability of these estimates, including: 1) how recovery of connection directionality is affected by features of data sets such as scan length and autoregressive effects, which may be strong in some imaging modalities (resting state fMRI, fNIRS) but weaker in others (task fMRI); and 2) whether inferences about directionality at the group and individual levels are stable across time. This talk will provide an overview of the GIMME framework and describe relevant results from a large-scale simulation study that assesses directionality recovery under various conditions and a separate project that investigates the temporal stability of GIMME’s inferences in the Human Connectome Project data set. Analyses from these projects demonstrate that estimates of directionality are most precise when autoregressive and cross-lagged relations in the data are relatively strong, and that inferences about the directionality of group-level connections, specifically, appear to be stable across time. Implications of these findings for the interpretation of directional connectivity estimates in different types of neuroimaging data will be discussed.

Sylvia Serfaty studies the many-particle limit of systems driven by Coulomb or Riesz interactions through gradient flows or analogous conservative dynamics, possibly with added random diffusion. The Riesz interaction has inverse-distance exponent s between d−2 and d in dimension d. The talk presents convergence, as the number of particles tends to infinity, to the expected mean-field evolution. It also discusses deriving the Vlasov–Poisson equation from Newtonian dynamics in the monokinetic case and related results for Ginzburg–Landau vortex dynamics.

The nervous system and the immune system share the common ability to exert gatekeeper roles at the interfaces between internal and external environment. Although interaction between these two evolutionarily highly conserved systems is long recognized, the pathophysiological mechanisms regulating their reciprocal crosstalk in cardiovascular diseases became object of investigation only more recently. In the last years, our group elucidated how the autonomic nervous system controls the splenic immunity recruited by hypertensive challenges. In my talk, I will focus on the molecular mechanisms that regulate the neuro-immune crosstalk in hypertension. I will elaborate on the mechanistic insights into this brain-spleen axis led us uncover a new molecular pathway mediating the neuroimmune interaction established by noradrenergic-mediated release in the spleen of placental growth factor (PlGF), an angiogenic growth factor potentially targetable with pharmacological approaches.

Research tools are paramount for scientific development, they enable researchers to observe and manipulate natural phenomena, learn their principles, make predictions and develop new technologies, treatments and improve living standards. Due to their costs and the geographical distribution of manufacturing companies access to them is not widely available, hindering the pace of research, the ability of many communities to contribute to science and education and reap its benefits. One possible solution for this issue is to create research tools under the open source ethos, where all documentation about them (including their designs, building and operating instructions) are made freely available. Dubbed Open Science Hardware (OSH), this production method follows the established and successful principles of open source software and brings many advantages over traditional creation methods such as: economic savings (see Pearce 2020 for potential economic savings in developing open source research tools), distributed manufacturing, repairability, and higher customizability. This development method has been greatly facilitated by recent technological developments in fast prototyping tools, Internet infrastructure, documentation platforms and lower costs of electronic off-the-shelf components. Taken together these benefits have the potential to make research more inclusive, equitable, distributed and most importantly, more reliable and reproducible, as - 1) researchers can know their tools inner workings in minute detail - 2) they can calibrate their tools before every experiment and having them running in optimal condition everytime - 3) given their lower price point, a)students can be trained/taught with hands on classes, b) several copies of the same instrument can be built leading to a parallelization of data collection and the creation of more robust datasets. - 4) Labs across the world can share the exact same type of instruments and create collaborative projects with standardized data collection and sharing.

Recent findings have revealed that mRNAs have a much more dynamic behaviour than initially described. This is particularly true in neurons, where mRNAs are transported to specific axonal and dendritic areas. The seminar will present our most recent findings unveiling complex mRNA processing dynamics driven by splicing proteins in developing axons.

What are the things that draw us to a particular field of science and what is it that keeps us there? For Dr. Bahia, there was a particular attraction to sensory nerves; the monitors of the worlds inside and outside of our bodies. In this talk, Dr. Bahia will outline her career path as a neuroscientist resulting in the title of Research Associate. She will also talk about the longest project she has participated in, 'exploring the role of ion channels in sensory nerves' (rupress.org/jgp/article/147/6/451/43495/The-exceptionally-high-reactivity-of-Cys-621-is)

tbc

A key question for basic biology and regenerative medicine concerns the way in which evolution exploits physics toward adaptive form and function. While genomes specify the molecular hardware of cells, what algorithms enable cellular collectives to reliably build specific, complex, target morphologies? Our lab studies the way in which all cells, not just neurons, communicate as electrical networks that enable scaling of single-cell properties into collective intelligences that solve problems in anatomical feature space. By learning to read, interpret, and write bioelectrical information in vivo, we have identified some novel controls of growth and form that enable incredible plasticity and robustness in anatomical homeostasis. In this talk, I will describe the fundamental knowledge gaps with respect to anatomical plasticity and pattern control beyond emergence, and discuss our efforts to understand large-scale morphological control circuits. I will show examples in embryogenesis, regeneration, cancer, and synthetic living machines. I will also discuss the implications of this work for not only regenerative medicine, but also for fundamental understanding of the origin of bodyplans and the relationship between genomes and functional anatomy.

In the Learning Salon, we will discuss the similarities and differences between biological and machine learning, including individuals with diverse perspectives and backgrounds, so we can all learn from one another.

Constraints on control-dependent processing have become a fundamental concept in general theories of cognition that explain human behavior in terms of rational adaptations to these constraints. However, theories miss a rationale for why such constraints would exist in the first place. Recent work suggests that constraints on the allocation of control facilitate flexible task switching at the expense of the stability needed to support goal-directed behavior in face of distraction. We formulate this problem in a dynamical system, in which control signals are represented as attractors and in which constraints on control allocation limit the depth of these attractors. We derive formal expressions of the stability-flexibility tradeoff, showing that constraints on control allocation improve cognitive flexibility but impair cognitive stability. We provide evidence that human participants adapt higher constraints on the allocation of control as the demand for flexibility increases but that participants deviate from optimal constraints. In continuing work, we are investigating how collaborative performance of a group of individuals can benefit from individual differences defined in terms of balance between cognitive stability and flexibility.

The symposium will start with A/Prof Jenny Gunnersen who will present “New insights into mechanisms of excitatory synapse development”. Then, Dr Tommas Ellender will deal with the “Embryonic neural progenitor pools and the generation of fine-scale neural circuits” and Dr Thomas Marissal will talk about “Parvalbumin interneurons: the missing link between the micro and macroscopic alterations related to neurodevelopmental disorders?"”.

The cognitive neuroscience of conscious perception has seen considerable growth over the past few decades. Confirming an influential hypothesis driven by earlier studies of neuropsychological patients, we have found that the lateral and polar prefrontal cortices play important causal roles in the generation of subjective experiences. However, this basic empirical finding has been hotly contested by researchers with different theoretical commitments, and the differences are at times difficult to resolve. To address the controversies, I suggest one alternative venue may be to look for clinical applications derived from current theories. I outline an example in which we used closed-loop fMRI combined with machine learning to nonconsciously manipulate the physiological responses to threatening stimuli, such as spiders or snakes. A clinical trial involving patients with phobia is currently taking place. I also outline how this theoretical framework may be extended to other diseases. Ultimately, a truly meaningful understanding of the fundamental nature of our mental existence should lead to useful insights for our colleagues on the clinical frontlines. If we use this as a yardstick, whoever loses the esoteric theoretical debates, both science and the patients will always win.