P184 Spontaneous oscillations and neural avalanches are linked to whisker stimulation response in the rat-barrel and thalamus circuit
Benedetta Mariani*1, Ramon Guevara Erra1,2, Mattia Tambaro3,4, Marta Maschietto3, Alessandro Leparulo3,5, Stefano Vassanelli3, Samir Suweis1,2
1Padova Neuroscience Center, University of Padova, Padova, Italy
2Department of Physics and Astronomy, University of Padova, Padova, Italy
3Department of Biomedical Sciences, University of Padova, Padova, Italy
4Department of Physics, University of Milano Bicocca, Milan, Italy
5Department of Neuroscience, University of Padova, Padova, Italy
*Email: benedetta.mariani@unipd.it
Introduction
The cerebral cortex operates in a state of restless activity, even in the absence of external stimuli [1,2]. Collective neuronal activities, such as neural avalanches[3] and collective oscillations[4], are also found under resting conditions, and these features have been suggested to support sensory processing and brain readiness for rapid responses [2]. However, most of these results are supported by theoretical models rather than experimental observations. The rat barrel cortex and thalamus circuit, with its somatotopic organization for processing whisker movements, provides a powerful system to explore the interplay between spontaneous and evoked activities.
Methods
To characterize the resting state circuits, we perform multi-electrode recordings in both rats' barrel cortex and thalamus through a neural probe, both during spontaneous activity and activity after controlled whisker stimulation. We decompose the LFP signals into their frequency contents through Empirical Mode Decomposition, a tool that is suited to analyze non-linear and non-stationary oscillations. We also analyze avalanches distributions by detecting events in MUAs activity and grouping them by temporal proximity. We then employ a mesoscopic firing rate model, fitted on real data [5], to understand the observed phenomomenology. It receives as input the experimental thalamic firing rate.
Results
During spontaneous activity, we find 10-15 Hz oscillations in the barrel cortex concomitantly with slow 1-4 Hz oscillations, as well as power-law distributed avalanches. The slow oscillations are also present in the thalamus, while the 10-15 Hz one is lacking. We find that the phase of the slow oscillation modulates the higher frequency amplitude, as well as avalanche occurrences. We then record neural activity during controlled whisker movements to confirm that the 10-15 Hz barrel circuit is amplified after whisker stimulation.We finally show how the thalamic-driven firing rate model can describe the entire phenomenology observed and predict the response to whisker stimulations.
Discussion
Our results show that even during spontaneous activity the rat barrel cortex displays a rich dynamical state that includes avalanches and oscillations, which are coupled through the slow oscillation. The 10-15 Hz oscillation is amplified after the whisker stimulation, suggesting that spontaneous neural activity primes the rat cortex for the whisker response. These facts are confirmed by our model, that is able to reproduce the resting state phenomenology and the amplification of oscillations after stimulation, thanks to the thalamic input to the cortex. Moreover, the barrel cortex oscillatory behavior may allow a flexible synchronization mechanism for the perception of stimuli.
Acknowledgements
Work by B.M and S.S. is supported by #NEXTGENERATIONEU (NGEU) and funded by the Ministry of University and Research (MUR), National Recovery and Resilience Plan (NRRP), project MNESYS (PE0000006) –(DN. 1553 11.10.2022). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
References
[1] Raichle M. E. (2011),https://doi.org/10.1089/brain.2011.0019
[2]Smith, S. M., et al (2009),https://doi.org/10.1073/pnas.0905267106
[3]Beggs, J. M., & Plenz, D. (2003),https://doi.org/10.1523/JNEUROSCI.23-35-11167.2003
[4] Singer W. (2018),https://doi.org/10.1111/ejn.13796
[5]Pinto, D. et al (1996),https://doi.org/10.1007/BF00161134
