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Lafont, C.

Publications and source records attributed to Lafont, C..

2 recordsLinked to original sources
bioRxiv2026

Population geometry reveals directed coupling and transient bistability in spontaneous pituitary secretion

The pituitary gland operates as an organized signaling network in which endocrine cell populations coordinate hormone secretion, through homotypic and heterotypic interactions, yet the contribution of spontaneous intrinsic activity in shaping population-level dynamics remains poorly understood. Using geometric analysis of population trajectories -- including subspace alignment, manifold separation, and directed coupling metrics -- we identified two classes of spontaneous oscillatory signals associated with distinct cell populations exhibiting asymmetric geometric dominance and a reproducible temporal lag. Our results support that spontaneous activity generates a self-sustained oscillator exhibiting transient bistability, linked to increased physiological demand, with slow oscillations reflecting the properties of an excitatory resonator capable of self-oscillating dynamics without external drive. A low-rank recurrent neural network model recapitulated the empirical geometric landscape under three coupling conditions, confirming that directed population coupling underlies the observed coordination. These findings suggest that intrinsic population dynamics play a central role in coordinating pituitary secretion, with implications for understanding hormonal dysregulation in secretory adenomas and other pituitary disorders. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/716480v3_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@f5e32borg.highwire.dtl.DTLVardef@1151f9eorg.highwire.dtl.DTLVardef@1cefc2corg.highwire.dtl.DTLVardef@ddac4_HPS_FORMAT_FIGEXP M_FIG C_FIG Structural and functional distinctions between homotypic and heterotypic interactions have been widely described in the pituitary endocrine system. However, whether functional differences in intrinsic calcium time-series dynamics are relevant to pulsatile hormone secretion remains unexplored. Here, we classify the spontaneous activity underlying both homotypic and heterotypic interactions and characterise their synchrony. We find that heterotypic interactions exhibit transient bistability, consistent with a Hopf-type oscillator regime, in which slow oscillations drive secretory output according to physiological demand.

neuroscience↗
bioRxiv2025

Non-Invasive Photoacoustic Imaging of Cerebral Oxygenation and Hemoglobin Content in Awake Mice

IntroductionInvestigating cerebral oxygen saturation dynamics in awake animal models remains technically challenging due to motion artifacts and anesthesia-related biases. Here, we introduce a novel high-resolution ultrasound-photoacoustic (PA) imaging approach enabling real-time, non-invasive monitoring of deep cerebrovascular oxygenation dynamics in awake mice with intact skulls. Materials and MethodsSwiss male and female mice (n = 5-6) were head-fixed using a customized holder adapted to the Neurotar Mobile HomeCage floating platform. High-resolution ultrasound combined with PA imaging (VevoLAZR-X, VisualSonics) was used to discriminate oxyhemoglobin, deoxyhemoglobin, and total hemoglobin in multiple brain regions. Cerebrovascular responses were assessed under three paradigms: (i) baseline awake state vs. 2% isoflurane anesthesia, and (ii) right whisker stimulation to probe sensory-driven hemodynamics. ResultsPA imaging successfully resolved deep-brain oxygenation in awake, intact-skull mice. Under isoflurane anesthesia, we observed a rapid and transient increase in cerebrovascular sO{square} (p < 0.01). During whisker stimulation, we detected robust, region-specific increases in total hemoglobin, reflecting localized neurovascular coupling in awake mice. ConclusionsThis study establishes high-resolution PA imaging as a powerful, non-invasive tool to monitor cerebrovascular oxygenation dynamics in awake mice. By integrating baseline, anesthetic, and sensory paradigms, we demonstrate its potential to dissect neurovascular physiology without the confounding effects of anesthesia. These findings provide new opportunities for preclinical neuroscience research and translational applications investigating cerebral oxygen metabolism.

neuroscience↗