Faculty Opinions recommendation of Obesity-associated variants within FTO form long-range functional connections with IRX3.

Brain function depends on segregation and integration of information processing in brain networks often separated by long-range anatomical connections. Neuronal oscillations orchestrate such distributed processing through transient amplitude and phase coupling; however, little is known about local network properties facilitating these functional connections. Here, we test whether criticality—a dynamical state characterized by scale-free oscillations—optimizes the capacity of neuronal networks to couple through amplitude or phase, and transfer information. We coupled in silico networks with varying excitatory and inhibitory connectivity, and found that phase coupling emerges at criticality, and that amplitude coupling, as well as information transfer, are maximal when networks are critical. Our data support the idea that criticality is important for local and global information processing and may help explain why brain disorders characterized by local alterations in criticality also exhibit impaired long-range synchrony, even prior to degeneration of physical connections.

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Long-range connections mirror and link microarchitectural and cognitive hierarchies in the human brain

10.1101/2021.10.25.465692 ◽

2021 ◽

Author(s):

Yezhou Wang ◽

Jessica Royer ◽

Bo-yong Park ◽

Reinder Vos de Wael ◽

Sara Lariviere ◽

...

Keyword(s):

Long Range ◽

Cognitive Processing ◽

Social Cognitive ◽

Geodesic Distance ◽

Meta Analysis ◽

Resting State Fmri ◽

Association Cortex ◽

Functional Connections ◽

Cognitive Hierarchies

Core features of higher-order cognition are hypothesized to be implemented via distributed cortical networks that are linked via long-range connections. However, these connections are biologically expensive, and it is unknown how the computational advantages long-range connections provide overcome the associated wiring costs. Our study investigated this question by exploring the relationship between long-range functional connections and local cortical microarchitecture. Specifically, our work (i) profiled distant cortical connectivity using resting-state fMRI and cortico-cortical geodesic distance mapping, (ii) assessed how long-range connections reflect local brain microarchitecture, and (iii) studied the microarchitectural similarity of regions connected through long-range connections. Analysis of two independent datasets indicated that sensory and motor areas had more clustered short-range connectivity patterns, while transmodal association cortices, including regions of the default mode network, were characterized by distributed, long-range connections. Confirmatory meta-analysis suggested that this topographical difference mirrored a shift in cognitive function, from perception/action towards emotional and social cognitive processing. Analysis of myelin-sensitive in vivo MRI in the same participants as well as post mortem histology and gene expression established that gradients in functional connectivity distance are paralleled by those present in cortical microarchitecture. Moreover, long-range connections were found to link together spatially remote regions of association cortex with an unexpectedly similar microarchitecture. These findings provide novel insights into how the organization of distributed functional networks in transmodal association cortex contribute to cognition, because they suggest that long-range connections link together distant islands of association cortex with similar microstructural features.

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Long-Range Inhibition Within the Zebra Finch Song Nucleus RA Can Coordinate the Firing of Multiple Projection Neurons

Journal of Neurophysiology ◽

10.1152/jn.1999.81.6.3007 ◽

1999 ◽

Vol 81 (6) ◽

pp. 3007-3020 ◽

Cited By ~ 104

Author(s):

John E. Spiro ◽

Matthew B. Dalva ◽

Richard Mooney

Keyword(s):

Long Range ◽

Zebra Finch ◽

Feedback Inhibition ◽

Brain Slices ◽

Acid Decarboxylase ◽

Projection Neurons ◽

Current Frequency ◽

Functional Connections ◽

Local Inhibition ◽

Zebra Finch Song

Long-range inhibition within the zebra finch song nucleus RA can coordinate the firing of multiple projection neurons. The zebra finch forebrain song control nucleus RA (robust nucleus of the archistriatum) generates a phasic and temporally precise neural signal that drives vocal and respiratory motoneurons during singing. RA’s output during singing predicts individual notes, even though afferent drive to RA from the song nucleus HVc is more tonic, and predicts song syllables, independent of the particular notes that comprise the syllable. Therefore RA’s intrinsic circuitry transforms neural activity from HVc into a highly precise premotor output. To understand how RA’s intrinsic circuitry effects this transformation, we characterized RA interneurons and projection neurons using intracellular recordings in brain slices. RA interneurons fired fast action potentials with steep current-frequency relationships and had small somata with thin aspinous processes that extended throughout large portions of the nucleus; the similarity of their fine processes to those labeled with a glutamic acid decarboxylase (GAD) antibody strongly suggests that these interneurons are GABAergic. Electrical stimulation revealed that RA interneurons receive excitatory inputs from RA’s afferents, the lateral magnocellular nucleus of the anterior neostriatum (LMAN) and HVc, and from local axon collaterals of RA projection neurons. To map the functional connections that RA interneurons make onto RA projection neurons, we focally uncaged glutamate, revealing long-range inhibitory connections in RA. Thus these interneurons provide fast feed-forward and feedback inhibition to RA projection neurons and could help create the phasic pattern of bursts and pauses that characterizes RA output during singing. Furthermore, selectively activating the inhibitory network phase locks the firing of otherwise unconnected pairs of projection neurons, suggesting that local inhibition could coordinate RA output during singing.

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