Brainstem Circuits for Locomotion

Locomotion is a universal motor behavior that is expressed as the output of many integrated brain functions. Locomotion is organized at several levels of the nervous system, with brainstem circuits acting as the gate between brain areas regulating innate, emotional, or motivational locomotion and executive spinal circuits. Here we review recent advances on brainstem circuits involved in controlling locomotion. We describe how delineated command circuits govern the start, speed, stop, and steering of locomotion. We also discuss how these pathways interface between executive circuits in the spinal cord and diverse brain areas important for context-specific selection of locomotion. A recurrent theme is the need to establish a functional connectome to and from brainstem command circuits. Finally, we point to unresolved issues concerning the integrated function of locomotor control. Expected final online publication date for the Annual Review of Neuroscience, Volume 45 is July 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Association between aerobic fitness and the functional connectome in patients with schizophrenia

Schizophrenia is accompanied by widespread alterations in static functional connectivity associated with symptom severity and cognitive deficits. Improvements in aerobic fitness have been demonstrated to ameliorate symptomatology and cognition in people with schizophrenia, but the intermediary role of macroscale connectivity patterns remains unknown. Therefore, we aim to explore the relation between aerobic fitness and the functional connectome in individuals with schizophrenia. Further, we investigate clinical and cognitive relevance of the identified fitness-connectivity links. 58 patients with schizophrenia were included in the resting-state fMRI analysis. Multilevel Bayesian partial correlations between aerobic fitness and functional connections across the whole brain as well as between static functional connectivity patterns and clinical and cognitive outcome were performed. Preliminary causal inferences were enabled based on a mediation analysis. Static functional connectivity between the subcortical nuclei and the cerebellum as well as between temporal seeds mediated the attenuating impact of aerobic fitness on total symptom severity. Functional connections between cerebellar seeds affected the positive link between aerobic fitness and global cognition, while the functional interplay between central and limbic seeds drove the beneficial relation between aerobic fitness and emotion recognition. The current study provides first insights into the interactions between aerobic fitness, the functional connectome and clinical and cognitive outcome in people with schizophrenia, but results have to be interpreted carefully. Further interventional aerobic exercise studies are needed in order to replicate the current findings and to enable conclusive causal inferences.

Mapping Consistent, Reproducible, and Transcriptionally Relevant Connectome Hubs of the Human Brain

Macroscopic functional connectomic analyses have identified sets of densely connected regions in the human brain, known as connectome hubs, which play a vital role in understanding network communication, cognitive processing, and brain disorders. However, anatomical locations of functional connectome hubs are largely inconsistent and less reproducible among extant reports, partly due to inadequate sample size and differences in image processing and network analysis. Moreover, the genetic signatures underlying the robust connectome hubs remain unknown. Here, we conduct the first worldwide voxelwise meta-connectomic analysis by pooling resting-state functional MRI data of 5,212 healthy young adults across 61 independent international cohorts with harmonized image processing and network analysis protocols. We identify highly consistent and reproducible functional connectome hubs that are spatially distributed in multiple heteromodal and unimodal regions, with the most robust findings mainly located in lateral parietal regions. These connectome hubs show unique, heterogeneous connectivity profiles and are critical for both intra- and inter-network communications. Using transcriptome data from the Allen Human Brain Atlas and BrainSpan Atlas as well as machine learning, we demonstrate that these robust hubs are significantly associated with a transcriptomic pattern dominated by genes involved in the neuropeptide signaling pathway, neurodevelopmental processes, and cellular metabolic processes. This pattern represents microstructural and metabolic substrates underlying the development and functioning of brain hubs. Together, these results highlight robustness of macroscopic connectome hubs of the human brain and their potential cellular and molecular underpinnings and have implications for understanding how brain hubs support the connectome organization in health and disease.

Predicting multilingual effects on executive function and individual connectomes in children: An ABCD study

While there is a substantial amount of work studying multilingualism’s effect on cognitive functions, little is known about how the multilingual experience modulates the brain as a whole. In this study, we analyzed data of over 1,000 children from the Adolescent Brain Cognitive Development (ABCD) Study to examine whether monolinguals and multilinguals differ in executive function, functional brain connectivity, and brain–behavior associations. We observed significantly better performance from multilingual children than monolinguals in working-memory tasks. In one finding, we were able to classify multilinguals from monolinguals using only their whole-brain functional connectome at rest and during an emotional n-back task. Compared to monolinguals, the multilingual group had different functional connectivity mainly in the occipital lobe and subcortical areas during the emotional n-back task and in the occipital lobe and prefrontal cortex at rest. In contrast, we did not find any differences in behavioral performance and functional connectivity when performing a stop-signal task. As a second finding, we investigated the degree to which behavior is reflected in the brain by implementing a connectome-based behavior prediction approach. The multilingual group showed a significant correlation between observed and connectome-predicted individual working-memory performance scores, while the monolingual group did not show any correlations. Overall, our observations suggest that multilingualism enhances executive function and reliably modulates the corresponding brain functional connectome, distinguishing multilinguals from monolinguals even at the developmental stage.