Just like a master chef creating a masterpiece, computational neuroscientists are using an advanced neural simulator called ANNarchy to create multi-scale network models that simulate various measurable signals at different spatial and temporal scales. These models are like a symphony orchestra playing different instruments, with each signal representing a musician. One important signal is the blood-oxygen-level-dependent (BOLD) signal, which can provide insights into brain activity. The researchers in this study implemented a BOLD monitor within ANNarchy, allowing them to compute simulated BOLD signals in real-time. They also explored the coupling between neural processes, cerebral blood flow, and cerebral metabolic rate of oxygen by testing different hypotheses and analyzing how these couplings affect the simulated BOLD signals. By providing this tool, ANNarchy enables modelers to relate their network models to experimental MRI data and deepens our understanding of neural processes in humans. It’s like having a new pair of glasses that reveals hidden details in a painting! If you’re curious about the intricate workings of the brain and want to dive into the research behind these fascinating simulations, check out the full article!

Multi-scale network models that simultaneously simulate different measurable signals at different spatial and temporal scales, such as membrane potentials of single neurons, population firing rates, local field potentials, and blood-oxygen-level-dependent (BOLD) signals, are becoming increasingly popular in computational neuroscience. The transformation of the underlying simulated neuronal activity of these models to simulated non-invasive measurements, such as BOLD signals, is particularly relevant. The present work describes the implementation of a BOLD monitor within the neural simulator ANNarchy to allow an on-line computation of simulated BOLD signals from neural network models. An active research topic regarding the simulation of BOLD signals is the coupling of neural processes to cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2). The flexibility of ANNarchy allows users to define this coupling with a high degree of freedom and thus, not only allows to relate mesoscopic network models of populations of spiking neurons to experimental BOLD data, but also to investigate different hypotheses regarding the coupling between neural processes, CBF and CMRO2 with these models. In this study, we demonstrate how simulated BOLD signals can be obtained from a network model consisting of multiple spiking neuron populations. We first demonstrate the use of the Balloon model, the predominant model for simulating BOLD signals, as well as the possibility of using novel user-defined models, such as a variant of the Balloon model with separately driven CBF and CMRO2 signals. We emphasize how different hypotheses about the coupling between neural processes, CBF and CMRO2 can be implemented and how these different couplings affect the simulated BOLD signals. With the BOLD monitor presented here, ANNarchy provides a tool for modelers who want to relate their network models to experimental MRI data and for scientists who want to extend their studies of the coupling between neural processes and the BOLD signal by using modeling approaches. This facilitates the investigation and model-based analysis of experimental BOLD data and thus improves multi-scale understanding of neural processes in humans.

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