Presentation Details
| Phasic Locus Coeruleus Activation Transforms Cortical Taste Representations Across Distinct Stimulus Dimensions Will Fan, Natale R.Sciolino. University of Connecticut, Storrs, CT, USA |
Abstract
Norepinephrine neurons in the locus coeruleus (LC) modulate sensory responses across the brain, yet how their diverse cellular effects regulate ensemble encoding of specific sensory attributes remains unclear. To address this, we examined the influences of LC activation on the primary gustatory cortex (GC), a system rarely studied in neuromodulation. Using miniscope calcium imaging, we recorded GC excitatory neurons in mice during intraoral tastant delivery, with brief optogenetic LC activation preceding half the trials. We tested three sets of taste stimuli, each varying in a specific sensory attribute: palatability (sweet > salty > sour > bitter), mixture composition (four sucrose–NaCl ratios), and intensity (four sucrose concentrations). Across conditions, LC activation either enhanced or suppressed the responses of a subset of GC neurons, with no neuron showing both effects across stimuli. Principal component analysis revealed that LC activation increased the separation of population responses along dimensions relevant to palatability and mixture composition. Further, LC activation rotated the coding axis for mixture composition, but not for palatability or intensity, suggesting greater invariance of the latter attributes. Scaling and rotation of coding axes were driven primarily by LC-enhanced neurons, although LC-suppressed neurons may also contribute. LC’s distinct effects across conditions are partially attributable to the prevalence of additive, multiplicative, and stimulus-specific modulations at the single-neuron level. Together, our findings highlight the complexity of neuromodulatory influences on cortical coding and motivate future investigations into their underlying mechanisms and behavioral consequences.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.