An international and multidisciplinary team of researchers, including scientists from IFISC (UIB-CSIC), has published a paper in which they analyzed the role of the transmission delays and frequency detuning in the regulation of the information flow between brain regions. The research, published in the journal PLoS Computational Biology, shows through numerical simulations and analytical arguments that the amount of information transfer between two oscillating neural populations could be determined by their connection delay and the mismatch in their oscillation frequencies.
Understanding how information is routed and processed within the brain is fundamental to understand its operation. However, this is not a simple task since the brain is an amazingly complex organ containing billions of neurons, each with its own connection and internal dynamics. The flow of information between neuron populations is possible thanks to the synaptic interactions, which bring out correlations between the activity of different populations that oscillate collectively. Nevertheless, it is well known that in networks of coupled dynamical systems there are certain delays that are inherent to the complexity with which the elements of the system are connected. These delays in the brain are quite heterogeneous and can range from a few milliseconds to tens of milliseconds. It is only relatively recently that the role of these delays in synaptic dynamics has begun to be studied.
In order to test the role of the delay and frequency detuning in the communication effectivity, the researchers varied the interaction delay and mismatch of the natural oscillation frequencies between two coupled neural populations.
The study concludes that for small delays the information encoded in the population with higher frequency is transmitted to the other population. On the other hand, while when the information is encoded in the population oscillating at a lower frequency, the other population is unable to receive the information. Yet, the manuscript states that the degree and the direction of the effective communication between two populations depend, in addition to the frequency of oscillation, on the interaction delay. This enables the researchers to forecast how the efficient communication between two coupled oscillators varies as the delay and frequency mismatch shift.
The results highlight the role of the collective phase response curve of the oscillating neural populations for the efficacy of signal transmission and the quality of the information transfer in brain networks. This applies to the two classical approaches in brain information processing: rate and time coding of the information.
Pariz, A., Fischer, I., Valizadeh, A. and Mirasso, C. (2021). Transmission delays and frequency detuning can regulate information flow between brain regions. PLoS Computational Biology 17(4), e1008129. Doi: 10.1371/journal.pcbi.1008129