Connectomics data from animal models provide an invaluable opportunity to reveal the complex interplay between structure and function in the mammalian brain. In this work, we investigate the relationship between structural and functional connectivity in the rat brain cortex using a directed anatomical network generated from a carefully curated meta-analysis of published tracing data, along with resting-state functional MRI data obtained from a group of 14 anesthetized Wistar rats. We found a high correspondence between the strength of functional connections, measured as blood oxygen level dependent (BOLD) signal correlations between cortical regions, and the weight of the corresponding anatomical links in the connectome graph (maximum Spearman rank-order correlation ρ = 0.48). At the network-level, regions belonging to the same functionally defined community tend to form more mutual weighted connections between each other compared to regions located in different communities. We further found that functional communities in resting-state networks are enriched in densely connected anatomical motifs. Importantly, these higher-order structural subgraphs cannot be explained by lower-order topological properties, suggesting that dense structural patterns support functional associations in the resting brain. Simulations of brain-wide resting-state activity based on neural mass models implemented on the empirical rat anatomical connectome demonstrated high correlation between the simulated and the measured functional connectivity (maximum Pearson correlation ρ = 0.53), further suggesting that the topology of structural connections plays an important role in shaping functional cortical networks.

Choroid plexus papillomas (CPPs) are rare, benign tumors that can arise in young children. Most pediatric patients present with signs of hydrocephalus and require immediate treatment. The natural history of choroid plexus tumors in children without hydrocephalus is poorly defined. In this report, the authors present the very rare case of a child without hydrocephalus but with two intraventricular choroid plexus tumors discovered shortly after birth. Initial imaging had been performed for seizures and showed agenesis of the corpus callosum and enhancing tumors in the third and left lateral ventricles. Sequential imaging demonstrated rapid growth of both tumors. The lateral tumor was removed when the child was 3 months of age. A histological examination of the specimen showed benign features with an elevated mitotic rate. Given the patient’s age of under 3 years, the diagnosis was WHO grade I CPP. The third ventricle tumor grew rapidly. A second surgery was performed and this tumor was resected. Again, the pathological diagnosis was WHO grade I CPP. The authors present this rare case and discuss the current relevant literature.

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Background and Hypothesis:  In neuroimaging, functional connectivity (FC), defined as the correlation between the functional MRI signals of two brain grey matter regions of interest (ROIs), is thought to reflect communication between ROIs. Changes in whole brain FC networks have been detected in Alzheimer’s disease (AD); however, traditional FC networks generated using the entire length of an fMRI scan could miss cognitively relevant fluctuations in FC. Analyzing dynamic patterns of FC within subsets of fMRI scans is hypothesized to enable greater sensitivity to deficits of information transfer and processing in AD compared to static FC.  Project Methods:  Functional MRI data of 58 participants with either subjective cognitive decline (SCD), mild cognitive impairment (MCI), AD, or controls were divided into time windows; the FC within each window provides sequential dynamic FC networks (dFC). Each dFC network was partitioned into subnetworks, e.g. visual or motor, whose member ROIs are strongly interconnected, and the functional flexibility of an ROI was estimated by the number of times it switches subnetworks in a scan.  Results:  The flexibility of the left inferior parietal lobule, right rostral lateral orbitofrontal cortex, and right amyglada/parahippocampal gyrus showed the highest correlations with Montreal Cognitive Assessment scores: r = 0.2516, 0.2480, and 2421, respectively. Although no correlations reached conventional significance (p = 0.0568, 0.0605, and 0.0671, uncorrected), this may reflect low power that should be increased with a planned larger sample.  Potential Impact:  Dynamic FC analyses may help clarify the neurophysiological mechanisms underlying cognitive decline, but methodological refinements and higher resolution data are likely needed to realize this potential.