Biology subjects

Belenya, R.

Publications and source records attributed to Belenya, R..

3 recordsLinked to original sources

bioRxiv2026

Directed cortical connectivity inferred from neural energy metabolism

Complex cognition depends on directed communication between brain regions. Yet, resting functional MRI resolves only undirected associations, and inferring the direction of signalling has proven difficult across the whole brain. Because synaptic transmission is metabolically asymmetric, with the postsynaptic neuron bearing most of the energetic cost, regional energy demand carries a physical signature of the direction of communication. Here, we show that this signature organizes the human cortex into a reproducible directed hierarchy, in which sensory and attentional systems preferentially drive higher-order networks, while the default mode and control networks act as principal receivers. Critically, the inferred directionality is independently predicted by two cellular markers of neuronal energy demand, regional mitochondrial density and laminar cytoarchitecture, linking macroscale information flow to its cellular substrate. The directed architecture recapitulates the known feedforward and feedback organization of visual pathways and, using an average CMRGlc template, extends to functional MRI acquired without PET. By grounding communication direction in energy metabolism, Metabolic Connectivity Mapping bridges correlative and effective connectivity and offers a scalable, biologically interpretable framework for mapping directed communication across the human brain.

neuroscience↗

bioRxiv2024

Simultaneous quantification of oxygen and glucose consumption during visual stimulation in the human cortex

The brain is fueled by oxidative glucose metabolism, yet activation may uncouple oxygen and glucose consumption. Because the two have never been measured simultaneously in humans across conditions, we combined multiparametric quantitative BOLD (mqBOLD) imaging with functional PET (fPET) during rest and visual stimulation. Participants (n = 12 with complete data) were scanned on an integrated PET/MR system during alternating six-minute blocks of checkerboard stimulation and fixation, with continuous arterial sampling. Cerebral metabolic rates of oxygen (CMRO2) and glucose (CMRglc), and cerebral blood flow (CBF) were quantified per condition and combined into the oxygen-to-glucose index (OGI = CMRO2/CMRglc), where six indicates fully oxidative glucose use. At rest, OGI was 4.6-5.0 in task-responsive visual regions and 4.9 elsewhere. Stimulation increased CMRglc (12-26%) and CBF (10-22%) more than CMRO2; (3-10%, not significant), lowering OGI by 12% in metabolically defined visual regions. Beyond the visual cortex, OGI fell 8%, significantly in 47% of cortical regions. The mechanisms differed, however: glycolytic upregulation in visual cortex (CBF, CMRglc up) versus oxidative downregulation elsewhere (CBF, CMRO2; down; CMRglc unchanged). Simultaneous imaging thus shows that focal activation shifts metabolism toward glycolysis across the cortex, with consequences for interpreting metabolic contrasts outside engaged regions.

neuroscience↗

bioRxiv2023

An energy costly architecture of neuromodulators for human brain evolution and cognition

Humans spend more energy on the brain than any other species. However, the high energy demand cannot be fully explained by brain size scaling alone. We hypothesized that energy-demanding signaling strategies may have contributed to human cognitive development. We measured the energy distribution along signaling pathways using multimodal brain imaging and found that evolutionarily novel connections have up to 67% higher energetic costs of signaling than sensory-motor pathways. Additionally, histology, transcriptomic data, and molecular imaging independently reveal an upregulation of signaling at G-protein coupled receptors in energy-demanding regions. We found that neuromodulators are predominantly involved in complex cognition such as reading or memory processing. Our study suggests that the upregulation of neuromodulator activity, alongside increased brain size, is a crucial aspect of human brain evolution.

neuroscience↗