Biology subjects

Kay, L. M.

Publications and source records attributed to Kay, L. M..

4 recordsLinked to original sources

bioRxiv2026

Recurrent beta-gamma interactions between olfactory bulb and piriform cortex support cross-sniff perceptual continuity in humans

Olfactory perception relies on active sampling, with successive inhalations providing discrete sensory inputs that in humans can be separated by several seconds. Yet odors are perceived as continuous and stable, raising the question of how the brain integrates sensory information across these temporal gaps. Here, we used electrobulbogram (EBG) recordings in 48 participants to demonstrate that successive sniffs are not processed independently but are linked through recurrent oscillatory dynamics between the olfactory bulb (OB) and piriform cortex (PC). Specifically, first-sniff alpha/beta activity in the OB and OB-PC functional connectivity predicted second-sniff gamma power, while transfer entropy indicated a directional temporal dependence from first-sniff alpha/beta to second-sniff gamma dynamics. In parallel, second-sniff gamma activity selectively tracked subjective odor valence prior to inhalation onset. At the network level, the PC exhibited stronger alpha/beta-band connectivity with orbitofrontal, insular, and prefrontal regions during the first sniff than during the second, suggesting that early evaluative processing provides a contextual signal that is carried forward to shape subsequent sensory representations. These results demonstrate that the human OB-PC circuit carries evaluative information across inhalations through directed alpha/beta-to-gamma interactions, providing a mechanism for maintaining perceptual continuity in a sensory system defined by temporally discrete sampling.

neuroscience↗

bioRxiv2024

Sex differences in olfactory behavior and neurophysiology in Long Evans Rats

In many species, olfactory abilities in females are more sensitive than those in males. Studies in humans show that women have lower olfactory thresholds and are better able to discriminate and identify odors than men. In mice, odorants elicit faster activation from a larger number of olfactory sensory neurons in females than males. Our study explores sex differences in olfaction in Long Evans rats from a behavioral and electrophysiological perspective. Local field potentials (LFPs) in the olfactory bulb (OB) represent the coordinated activity of bulbar neurons. Olfactory gamma (65-120 Hz) and beta (15-30 Hz) oscillations have been functionally linked to odor perception. Spontaneous and odor-evoked OB LFPs were recorded from awake rats at the same time for 12 days. Odors used included urine of both sexes and monomolecular odorants characterized previously for correlation of volatility with behavior and OB oscillations. Sampling duration, baseline gamma and beta power, and odor-elicited beta and gamma power were analyzed. We find that females sample odorants for a shorter duration than males (close to 1s difference). While baseline gamma and beta power do not show significant differences between the two sexes, odor-elicited gamma and beta power in females is significantly lower than in males. Neither sampling duration nor beta and gamma power in females varied systematically with day of estrus. We further verify that variance of these behavioral and physiological measures is not different across sexes, adding to growing evidence that researchers need not be concerned about often- claimed additional variance in female subjects. New and NoteworthyOlfaction plays a large role in evolutionary processes. However, we know little about sex differences in olfactory bulb neurophysiology, and many scientists believe that females are more variable due to estrus. We show that female rats sniff odors for shorter durations than males and have lower power in neural oscillations related to cognition. Estrus was not related to variance in any measures. Finally, males and females show equal variance on these behavioral and physiological processes.

neuroscience↗

bioRxiv2021

ODOR IDENTITY CAN BE EXTRACTED FROM THE RECIPROCAL CONNECTIVITY BETWEEN OLFACTORY BULB AND PIRIFORM CORTEX IN HUMANS

Neuronal oscillations route external and internal information across brain regions. In the olfactory system, the two central nodes--the olfactory bulb (OB) and the piriform cortex (PC)--communicate with each other via neural oscillations to shape the olfactory percept. Communication between these nodes have been well characterized in non-human animals but less is known about their role in the human olfactory system. Using a recently developed and validated EEG-based method to extract signals from the OB and PC sources, we show in healthy human participants that there is a bottom-up information flow from the OB to the PC in the beta and gamma frequency bands, while top-down information from the PC to the OB is facilitated by delta and theta oscillations. Importantly, we demonstrate that there was enough information to decipher odor identity above chance from the low gamma in the OB-PC oscillatory circuit as early as 100ms after odor onset. These data further our understanding of the critical role of bidirectional information flow in human sensory systems to produce perception. However, future studies are needed to determine what specific odor information is extracted and communicated in the information exchange.

neuroscience↗

bioRxiv2017

Pharmacological manipulation of olfactory bulb granule cell excitability modulates beta oscillations: Testing a model

The mammalian olfactory bulb (OB) generates gamma (40 - 100 Hz) and beta (15 - 30 Hz) oscillations of the local field potential (LFP). Gamma oscillations arise at the peak of inhalation supported by dendrodendritic interactions between glutamatergic mitral cells (MCs) and GABAergic granule cells (GCs). Beta oscillations occur in response to odorants in learning or odor sensitization paradigms, but their generation mechanism and function are still poorly understood. When centrifugal inputs to the OB are blocked, beta oscillations disappear, but gamma oscillations persist. Centrifugal input targets primarily GABAergic interneurons in the GC layer (GCL) and regulates GC excitability, which suggests a causal link between beta oscillations and GC excitability. Previous modeling work from our laboratory predicted that convergence of excitatory/inhibitory inputs onto MCs and centrifugal inputs onto GCs can increase GC excitability sufficiently to drive beta oscillations primarily through voltage dependent calcium channel (VDCC) mediated GABA release, independently of NMDA channels. We test this model by examining the influence of NMDA and muscarinic acetylcholine receptors on GC excitability and beta oscillations. Intrabulbar scopolamine (muscarinic antagonist) infusion decreased or completely suppressed odor-evoked beta in response to a strong stimulus, but increased beta power in response to a weak stimulus, as predicted by our model. Piriform cortex (PC) beta power was unchanged. Oxotremorine (muscarinic agonist) tended to suppress all oscillations, probably from over-inhibition. APV, an NMDA receptor antagonist, suppressed gamma oscillations selectively (in OB and PC), lending support to the models prediction that beta oscillations can be supported by VDCC mediated currents.\n\nNew and NoteworthyO_LIOlfactory bulb beta oscillations rely on granule cell excitability.\nC_LIO_LIReducing granule cell excitability with scopolamine reduces high volatilityinduced beta power but increases low volatility-induced beta power.\nC_LIO_LIPiriform cortex beta oscillations maintain power when olfactory bulb beta power is low, and the system maintains beta band coherence.\nC_LI

neuroscience↗