Precision neuroengineering allows complex brain functions to be reproduced in vitro

Precision neuroengineering allows complex brain functions to be reproduced in vitro https://i1.wp.com/www.eresviral.com/wp-content/uploads/2018/11/La-neuroingeniería-de-precisión-permite-reproducir-in-vitro-funciones-cerebrales-complejas.jpg?fit=146%2C146&ssl=1

Precision neuroengineering allows complex brain functions to be reproduced in vitro





Precision neuroengineering allows complex brain functions to be reproduced in vitro


One of the most important and surprising features of the brain is its ability to dynamically reconfigure connections in order to process stimuli and respond correctly to them. Researchers from the University of Tohoku (Sendai, Japan) and the University of Barcelona (Catalunya, Spain), using neuroengineering tools, have designed in vitro neural circuits that reproduce the capacity for segregation and integration of brain circuits and that they allow us to understand the keys of the dynamic reconfiguration of the brain. The study has been published in the journal Science Advances.



Dynamic reconfiguration is understood as the reinforcement or weakening of bonds through an increase or decrease in neuronal activity. When the reconfiguration leads to a greater cohesion between different neuronal circuits of the brain, it is said that it is integrated, and when the cohesion decreases, it is said to be segregated. «This study demonstrates the importance of modular organization to maximize the flexibility of a neural circuit. It also illustrates the potential of in vitro tools and biophysical models to advance in the understanding of collective phenomena in a complex system as fascinating and rich as the brain, "explains Jordi Soriano, researcher at the Institute of Complex Systems of the UB (UBICS). co-author of the work.



Integration is associated with the rapid exchange of information between very distant and different circuits, while segregation is associated with the processing of information in localized circuits. What makes the brain unique is that it continually moves from a segregated state to an integrated one according to the nature and strength of the stimuli. This dynamic reconfiguration avoids creating and destroying physical connections continuously, a strategy that is as inefficient as it is costly. Thus, for example, the stimuli that reach us through sight, hearing and smell are processed in a segregated manner in the cerebral cortex and then partially or totally integrated according to the needs. While we are watching a movie, we integrate images and sounds, ignoring smells and other stimuli. But when we notice burnt smell, the brain is alerted to integrate and analyze all possible information and make urgent decisions.







Despite the importance of integration and segregation, the biophysical mechanisms linked to dynamic reconfiguration were still not well understood. Furthermore, it was not understood to what extent the integration-segregation capacity is sensitive to the number of physical connections between brain regions.



The in vitro brain model developed by the researchers consists of four interconnected modules, each of which represents a specialized neuronal circuit (for example, in sight or in the ear). The four modules are coated with adhesive proteins and nutrients where neurons develop, which connect between them within a module and with other neurons in distant modules. Precision neuroengineering allows controlling how many connections pass from one module to another and, therefore, allows adjusting the degree of physical coupling between modules. In this model the stimuli correspond to spontaneous activations of neurons.



Using calcium fluorescence microscopy to detect neuronal activations, researchers have studied the ability of the circuit to integrate or segregate spontaneously according to the degree of connectivity between the modules, among other factors. "What we have observed is that the circuit is permanently integrated or segregated when the number of connections between modules is too large or too small. The optimal circuit is one in which the four modules have a connectivity just below the minimum to be integrated, so that the pulses of neuronal activity are sufficient to punctually reinforce the connections and complete the integration. In practice, this optimally activated circuit spontaneously works in a regime where integration and segregation coexist, "says Hideaki Yamamoto, a researcher at Tohoku University. The expert points out that "the observed dynamics is still very far from the complexity of the real brain, but we have been able to obtain details about the fundamental mechanisms that outline the dynamics of the brain". (Source: U. Barcelona)

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