Stefens, C. | bioRxiv Science

bioRxiv2026

Insulin controls olfactory gain at the first central synapse by regulating periglomerular neuron excitability

Sensory processing is dynamically tuned by internal state, yet how metabolic signals reshape the earliest stages of sensory circuits remains poorly understood. Here we identify a circuit mechanism by which satiety suppresses olfactory sensitivity at the first central synapse in the mouse olfactory bulb. Using a within-animal paradigm modelling fasted and glucose-induced sated states, we show that satiety impairs food-finding behaviour and reduces olfactory receptor neuron input to the olfactory bulb. Periglomerular (PG) cells, which co-express insulin receptors and the potassium channel Kv1.3, mediate this effect: insulin inhibits the low-voltage-activated Kv1.3 current in PG cells, increasing their spontaneous and odour-evoked activity. This heightened PG cell activity drives enhanced presynaptic inhibition of olfactory receptor neuron terminals, dampening sensory input before it reaches mitral cells. These findings establish insulin-dependent presynaptic inhibition of PG cells as a key locus of state-dependent sensory gain control.

neuroscience↗

bioRxiv2025

Synergy mediates Long-Range Correlations in the Visual Cortex Near Criticality

Long-range correlations are a key signature of systems operating near criticality, indicating spatially-extended interactions across large distances. These extended dependencies underlie other emergent properties of critical dynamics, such as high susceptibility and multi-scale coordination. In the brain, along with other signatures of criticality, long-range correlations have been observed across various spatial scales, suggesting that the brain may operate near a critical point to optimise information processing and adaptability. However, the mechanisms underlying these long-range correlations remain poorly understood. Here, we investigate the role of synergistic interactions in mediating long-range correlations in the visual cortex of awake mice. We leverage recent advances in mesoscale two-photon calcium imaging to analyse the activity of thousands of neurons across a wide field of view, allowing us to confirm the presence of long-range correlations at the level of neuronal populations. By applying the Partial Information Decomposition (PID) framework, we decompose the correlations into synergistic and redundant information interactions. Our results reveal that the increase in long-range correlations during visual stimulation is accompanied by a significant increase in synergistic rather than redundant interactions among neurons. Furthermore, we analyse a combined network formed by the union of synergistic and redundant interaction networks, and find that both types of interactions complement each other to facilitate efficient information processing across long distances. This complementarity is further enhanced during the visual stimulation. These findings provide new insights into the computational mechanisms that give rise to long-range correlations in neural systems and highlight the importance of considering different types of information interactions in understanding correlations in the brain.

neuroscience↗