Biology subjects

Winter, A. L.

Publications and source records attributed to Winter, A. L..

3 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↗

bioRxiv2025

Limited Effects of Isolated Congenital Anosmia on Cerebral White Matter Morphology

Lack of sensory input is associated with alterations in brain morphology; mainly in or near cerebral regions normally devoted to processing of the missing sense. We have in multiple studies demonstrated that the only consistent morphological finding within the gray matter of individuals born without the sense of smell (isolated congenital anosmia; ICA), are changes in or near the olfactory sulcus. For the connecting tissue of the brain, the white matter (WM), previous studies have yielded inconsistent findings. Here, we show that individuals with ICA (n=49) exhibit alterations in WM volume as compared to age- and sex-matched controls. Consistent evidence from both voxel-based morphometry and multi-voxel pattern analysis shows that individuals with ICA show decreased WM in areas surrounding the olfactory sulcus. Importantly, no WM alterations were found in areas surrounding the olfactory (piriform) cortex. In contrast to congenital sensory loss in other systems, we show that morphological alterations due to lifelong olfactory deprivation are limited. Alterations are primarily localized around the olfactory sulcus and likely due to the absence of olfactory bulbs. A possible explanation for the lack of major morphological alterations in individuals with congenital anosmia is that the olfactory regions may be recruited for non-olfactory functions.

neuroscience↗

bioRxiv2023

The how, when, and what of odor valence communication between the olfactory bulb and piriform cortex

A core function of the olfactory system is to determine an odors valence. The central processing of odor valence is initiated in the olfactory bulb, but the neural mechanisms by which this important information is communicated to, and from, the olfactory cortex (piriform cortex) in humans are not known. To assess communication between the two nodes, we simultaneously measured odor-dependent neural activity in the olfactory bulb and piriform cortex from human participants while obtaining trial-by-trial valence ratings. We determined when valence information was communicated, what kind of information was transferred, and how the information was transferred (i.e., in which frequency band). Support vector machine learning on the coherence spectrum and frequency-resolved Granger causality were used to identify valence-dependent differences in functional and effective connectivity between the olfactory bulb and piriform cortex. We found that the olfactory bulb communicates odor valence to the piriform cortex in the gamma band shortly after odor onset, while the piriform cortex subsequently feeds valence-related information back to the olfactory bulb in the beta band. Decoding accuracy was better for negative than positive valence, suggesting negative valence superiority. Critically, we replicated these findings in an independent dataset using other odors across a larger perceived valence range. Combined, these results demonstrate that the olfactory bulb and piriform cortex communicate levels of odor pleasantness across multiple frequencies, at specific time-points and in a direction-dependent pattern in accordance with the two-stage model of odor processing. It also provides further evidence that odor valence should be viewed as two perceptual dimensions and not one continuous.

neuroscience↗