Biology subjects

Rigolli, N.

Publications and source records attributed to Rigolli, N..

5 recordsLinked to original sources

bioRxiv2025

Mice navigate scent trails using predictive policies

Many terrestrial animals accurately follow odor trails, but their navigation strategies remain unclear. We presented mice with dynamic, non-repeating odor trails using a paper treadmill, and found that they rapidly learned to track trails effectively. Odor detections by one or both nostrils during inhalation evoked rapid, stereotyped motor responses. Blocking one nostril led to biased tracking, while disconnecting interhemispheric neural communication disrupted tracking almost entirely. We found that trail tracking is more than a reflex, with mice adapting their movements according to a memory of recently encountered trail geometry. A Bayesian model captures these behaviors, suggesting mice combine bilateral olfactory input with short-term memory to guide navigation actively. Functional perturbations and neural recordings from behaving animals implicate an early olfactory cortical region in trail tracking. These results lay the groundwork to uncover the computational architecture of sensorimotor integration in naturalistic tasks.

neuroscience↗

bioRxiv2024

The spiking output of the mouse olfactory bulb encodes large-scale temporal features of natural odor environments

In natural odor environments, odor travels in plumes. Odor concentration dynamics change in characteristic ways across the width and length of a plume. Thus, spatiotemporal dynamics of plumes have informative features for animals navigating to an odor source. Population activity in the olfactory bulb (OB) has been shown to follow odor concentration across plumes to a moderate degree (Lewis et al., 2021). However, it is unknown whether the ability to follow plume dynamics is driven by individual cells or whether it emerges at the population level. Previous research has explored the responses of individual OB cells to isolated features of plumes, but it is difficult to adequately sample the full feature space of plumes as it is still undetermined which features navigating mice employ during olfactory guided search. Here we released odor from an upwind odor source and simultaneously recorded both odor concentration dynamics and cellular response dynamics in awake, head-fixed mice. We found that longer timescale features of odor concentration dynamics were encoded at both the cellular and population level. At the cellular level, responses were elicited at the beginning of the plume for each trial, signaling plume onset. Plumes with high odor concentration elicited responses at the end of the plume, signaling plume offset. Although cellular level tracking of plume dynamics was observed to be weak, we found that at the population level, OB activity distinguished whiffs and blanks (accurately detected odor presence versus absence) throughout the duration of a plume. Even [~]20 OB cells were enough to accurately discern odor presence throughout a plume. Our findings indicate that the full range of odor concentration dynamics and high frequency fluctuations are not encoded by OB spiking activity. Instead, relatively lower-frequency temporal features of plumes, such as plume onset, plume offset, whiffs, and blanks, are represented in the OB.

neuroscience↗

bioRxiv2023

Reconstitution of ORP-mediated lipid exchange process coupled to PI(4)P metabolism

Lipid distribution in the eukaryotic cells depends on tight couplings between lipid transfer and lipid metabolism. Yet these couplings remain poorly described. Notably, it is unclear to what extent lipid exchangers of the OSBP-related proteins (ORPs) family, coupled to PI(4)P metabolism, contribute to the formation of sterol and phosphatidylserine gradient between the endoplasmic reticulum (ER) and other cell regions. To address this question, we have examined in vitro the activity of Osh4p, a representative ORP, between Golgi mimetic membranes in which PI(4)P is produced by a PI 4-kinase and ER mimetic membranes in which PI(4)P is hydrolyzed by the phosphatase Sac1p. Using quantitative, real-time assays, we demonstrate that Osh4p creates a sterol gradient between the two membranes by sterol/PI(4)P exchange as soon as a PI(4)P gradient is generated at this interface following ATP addition, and define how much PI(4)P must be synthesized for this process. Then, using a kinetic model supported by our in vitro data, we estimate to what extent PI(4)P metabolism can drive lipid transfer in cells. Finally, we show that Sec14p, by transferring phosphatidylinositol between membranes, can support the synthesis of PI(4)P and the creation of a sterol gradient by Osh4p. These results indicate to what extent ORPs, under the control of PI(4)P metabolism, can distribute lipids in the cell.

biochemistry↗

bioRxiv2021

Alternation emerges as a multi-modal strategy for turbulent odor navigation

Foraging mammals exhibit a familiar yet poorly characterized phenomenon, "alternation", a momentary pause to sniff in the air often preceded by the animal rearing on its hind legs or raising its head. Intriguingly, rodents executing an olfactory search task spontaneously exhibit alternation in the presence of airflow, suggesting that alternation may serve an important role during turbulent plume-tracking. To test this hypothesis, we combine fully-resolved numerical simulations of turbulent odor transport and Bellman optimization methods for decision-making under partial observability. We show that an agent trained to minimize search time in a realistic odor plume exhibits extensive alternation together with the characteristic cast-and-surge behavior commonly observed in flying insects. Alternation is tightly linked with casting and occurs more frequently when the agent is far downwind of the source, where the likelihood of detecting airborne cues is higher relative to cues close to the ground. Casting and alternation emerge as complementary tools for effective exploration when cues are sparse. We develop a model based on marginal value theory to capture the interplay between casting, surging and alternation. More generally, we show how multiple sensorimotor modalities can be fruitfully integrated during complex goal-directed behavior.

animal behavior and cognition↗

bioRxiv2020

Plume dynamics structure the spatiotemporal activity of glomerular networks in the mouse olfactory bulb

Although mice locate resources using turbulent airborne odor plumes, the stochasticity and intermittency of fluctuating plumes create challenges for interpreting odor cues in natural environments. Population activity within the olfactory bulb (OB), is thought to process this complex spatial and temporal information, but how plume dynamics impact odor representation in this early stage of the mouse olfactory system is not known. Limitations in odor detection technology have made it impossible to measure plume fluctuations while simultaneously recording from the mouses brain. Thus, previous studies have measured OB activity following controlled odor pulses of varying profiles or frequencies, but this approach only captures a subset of features found within olfactory plumes. Adequately sampling this feature space is difficult given a lack of knowledge regarding which features the brain extracts during exposure to natural olfactory scenes. Here we measured OB responses to naturally fluctuating odor plumes using a miniature, adapted odor sensor combined with wide-field GCaMP6f signaling from the dendrites of mitral and tufted (MT) cells imaged in olfactory glomeruli of head-fixed mice. We precisely tracked plume dynamics and imaged glomerular responses to this fluctuating input, while varying flow conditions across a range of ethologically-relevant values. We found that a consistent portion of MT activity in glomeruli follows odor concentration dynamics, and the strongest responding glomeruli are the best at following fluctuations within odor plumes. Further, the reliability and average response magnitude of glomerular populations of MT cells are affected by the flow condition in which the animal samples the plume, with the fidelity of plume following by MT cells increasing in conditions of higher flow velocity where odor dynamics result in intermittent whiffs of stronger concentration. Thus, the flow environment in which an animal encounters an odor has a large-scale impact on the temporal representation of an odor plume in the OB. Additionally, across flow conditions odor dynamics are a major driver of activity in many glomerular networks. Taken together, these data demonstrate that plume dynamics structure olfactory representations in the first stage of odor processing in the mouse olfactory system.

neuroscience↗