ИСТИНА

The brain activity of human or animal subjects in a resting state is often interpreted in terms of background replay of acquired neural networks of prior experience. However, classical non-invasive neuroimaging lacks the cellular resolution required to relate such activity to the content of subjective experience. To overcome this limitation, we started a project on cellular imaging neuronal resting state networks of the mouse brain and relating their activity to animal’s past experiences. First, we characterized resting state activity of 104 structures by means of c-Fos cellular mapping. We made an estimate of the activation level for each of the analyzed brain areas based on amount of c-Fos positive cells in all the experimental animals. Based on the level of resting state activity structures were divided into four groups: 59 brain areas were non-active, 14 – low, 29 – medium, and 8 – were highly active. There was no direct relationship between anatomical attributes of examined areas and the level of their activity. We also showed that resting state networks identified by c-Fos expression were stable and reproducible in all the animals. Next, we selected 38 areas to characterize the major components and analyze functional connectivity of the resting state network. Based on the activity of selected brain areas and using Pearson correlation we plotted networks with varying correlation coefficients and compared these experimentally identified networks with random, scale free and small world networks. Our analysis suggests that the resting state network of the mouse brain is scale free with local clusters. In addition, we identified several major groups of functionally connected areas in the resting state network of mouse: a cluster of medial prefrontal cortex and other associative areas, a cluster of visual areas, a tightly linked cluster of sensorimotor areas and basal nuclei, and an entirely isolated cluster of auditory areas. Importantly, activity of amygdala and hippocampus, known for their relationship to threat learning, was not correlated and did not comprise any special functional group. This high variability in the activity of fear-related structures will be used at the next stage of the project to examine changes in the cellular activity of the resting state network in relation to the engram of threat experience previously labelled in the same mouse brain. Supported by RSF 16-15-00300, 14-15-00685.