Neuronal networks

…Many features of brain-wide neuronal networks have been identified in mammals using noninvasive methods that lack cellular information. Here, we performed whole-brain calcium imaging in zebrafish larvae to investigate the structural and genetic basis of functional connectivity (FC) at single-cell resolution. Neural activity from $\sim$50,000 neurons was recorded in head-restrained transgenic larvae expressing a pan-neuronal calcium sensor, while monitoring their tail movem

Activity-dependent structural plasticity plays a pivotal role in the self-organization of neuronal networks. Emerging activity continuously feeds back into the growth process, regulating connectivity and activity homeostatically towards an optimal functional dynamic range. Transferred into cell culture, neurons follow the same homeostatic principles. They migrate and regrow neurites to establish synaptic connectivity and spontaneous network activity. Despite of homeostatic regulation, the resulting network structure and activity dynamics exhibit considerable variability across and within studi

The analysis of effective connectivity in neuronal networks has become an essential tool for understanding the underlying mechanisms of information transfer in neural circuits. However, its interpretation is not always straightforward, and it can be masked by the presence of artifacts.We scrutinized calcium imaged data from in vitro neuronal cultures grown of PDMS-engineered patterns using a transfer entropy algorithm [1]. Initial analyses revealed the presence of spurious correlations which hampered the actual underlying network. The origin of these artifacts lays on the delicate interplay be

Neuronal networks are at the core of the brain's vast computational capacities. Different strategies have each brought deep insights into their architecture. Yet, each method is limited in its capacity to resolve even simple subnetworks of single cells, due to the current compromise between throughput, resolution, and coverage. Viral projection tracing helps establish regional connectomes of mammalian brains. In combination with additional modification, the method can reveal cell-type-specific projection patterns. However, these maps lack single-neuron resolution. Monosynaptic connectivity tra

…become a prominent method for studying neuronal network properties, establishing human neuronal cultures with mature electrophysiological features compatible with MEAs has posed a significant challenge. The aim of this study was to establish a reliable protocol for generating human-derived neuronal networks on High Density Microelectrode Arrays (HD-MEA) and to characterize their electrophysiological features for potential applications in disease modeling and therapeutic testing. Human-induced pluripotent stem cel

…These neuronal networks seem to be dependant of individual expertise. Although the scientific literature seems to agree for a reduced and focused brain activity as expertise increases, a few investigated complex whole-body movements because MI is usually studied through standardized common tasks (e.g., keyboard sequences).

…a subset of neurons within intricate networks. In response to these challenges, we adopt a bottom-up approach to engineer low-density neuronal networks with defined architectures. Human induc

…the CNS react to this injury and shape neuronal activity ex vivo. To this end, we investigated microglial phenotypes and contribution to network organisation and functioning in acute brain slices. The comprehensive assesment of microglial states in acute brain slices demonstrated time-dependent microglial phenotype changes that

…namely in the modulation of synapses, neuronal networks, and behavior, proving that these are more than mere supportive cells. Indeed, astrocytes gained recognition as the third active element of a synapse. In this tripartite synapse concept, while interacting closely with neurons, these cells can modulate neuronal activity by sensing, processing, integrating, and responding to synaptic transmission. Astrocytes were shown to sense glutamate, the most abundant excitatory neurotransmitter in the brain, which occurs by acti

Neuronal development and function is regulated by a complex interplay between neurons and glial cells. Microglia are the tissue-resident immune cells of the central nervous system bridging immunological and neuronal activity. In recent years, the involvement of microglia in a variety of neurological and psychiatric disorders has been increasingly highlighted. However, understanding microglia-specific contributions to neuronal activity in humans remains challenging. A promising tool to gain mechanistic insight into how microglial cells shape neuronal networks and their activity is combining mic

Gliomas are brain tumors formed by networks of connected tumor cells, nested in and interacting with neuronal networks. Neuronal activities interfere with tumor growth and occurrence of seizures affects glioma prognosis, while the developing tumor triggers seizures in the infiltrated cortex. Oncometabolites produced by tumor cells and neurotransmitters affect both the generation of epileptic activities by neurons and the growth of glioma cells through synaptic-related mechanisms, involving both GABAergic / Chloride pathways and glutamatergic signaling. From a clinical sight, epilepsy occurrenc

…neurons through synapses into neural networks or circuits is essential for brain organization. Neuronal networks are sculpted and refined throughout life by constant adjustment of the strength of synaptic communication by neuronal activity, a process known as synaptic plasticity. Deficits in the development or plasticity of synapses underlie various neuropsychiatric disorders, including autism, schizophrenia and intellectual disability. The

…the ability of astrocytes to "sense" neuronal communication and release gliotransmitters, an attractive hypothesis is emerging stating that the effects of antidepressants on brain function could be, at

…Similarly, spiking neural networks are also gaining traction in machine learning with the promise that neuromorphic hardware will eventually make them much more energy efficient than classical ANNs. In this session, we will present the GeNN (GPU-enhanced Neuronal Networks) framework, which aims to facilitate the use of graphics accelerators for computational models of large-scale spiking neuronal networks to address the challenge

Understanding how the brain can store and process information is one of the biggest challenges we are currently facing in the field of neuroscience. It is possible to study the brain as a whole. However, such approaches tend to only recover neural activity from a sparse subset. To counteract this problem, we are using a bottom-up neuroscience paradigm, where neurons are cultured on top of a multi-electrode array (MEA). The MEA can be used to stimulate and record neural activity. To further reduce the complexity, we culture neurons inside of a polydimethylsiloxane (PDMS) microstructure, which e

…the properties of single neurons and networks of such neurons. Answering this question requires theoretical advances that shine light into the ‘black box’ of neuronal networks. In this talk, I will demonstrate theoretical approaches that help describe how cognitive and behavioral task implementations emerge from structure in neural populations and from biologically plausible learning rules. First, I will introduce an analytic theory that connects geometric structures that arise from neural res

In our everyday lives, we form connections and build up social networks that allow us to function successfully as individuals and as a society. Our social networks tend to include well-connected individuals who link us to other groups of people that we might otherwise have limited access to. In addition, we are more likely to befriend individuals who a) live nearby and b) have mutual friends. Interestingly, neurons tend to do the same…until development is perturbed. Just like social networks, neuronal networks require highly connected hubs to elicit efficient communication at minimal cost (you

Simply put, the goal of my research is to describe the neuronal circuitry of the retina. The organization of the mammalian retina is certainly complex but it is not chaotic. Although there are many cell types, most adhere to a relatively constant morphology and they are distributed in non-random mosaics. Furthermore, each cell type ramifies at a characteristic depth in the retina and makes a stereotyped set of synaptic connections. In other words, these neurons form a series of local circuits across the retina. The next step is to identify the simplest and commonest of these repeating neural c

…functional and structural changes of neuronal synapses. In recent years, however, myelin plasticity has emerged as a potential modulator of neuronal networks. Myelination of previously unmyelinated axons and changes in the structure on already-myelinated axons can have large effects on the function of neuronal networks. Yet myelination has been mostly studied in relation to its functional and metabolic activity. Myelin modifications are increasingly being implicated as a mechanism for sensory-motor learning and unpublished data f

Major depressive disorder (MDD) is a sexually dimorphic disease. This sexual dimorphism is believed to result from sex-specific molecular alterations affecting functional pathways regulating the capacity of men and women to cope with daily life stress differently. Transcriptional changes associated with epigenetic alterations have been observed in the brain of men and women with depression and similar changes have been reported in different animal models of stress-induced depressive-like behaviors. In fact, most of our knowledge of the biological basis of MDD is derived from studies of chronic

…algorithm, which we used to train neuronal networks on the mixed-signal neuromorphic platform Br