Leslie M. Kay

University of Chicago | UC · Department of Psychology

In many species, olfactory abilities in females are more acute 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 bulb glomeruli in females than males. Our study explores s...

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 explo...

Prior attempts at forming theoretical predictions regarding the quality of binary odor mixtures have failed to find any consistent predictor for overshadowing of one component in a binary mixture by the other. We test here the hypothesis that trigeminality contributes to overshadowing effects in binary mixture perception. Most odorants stimulate th...

Circadian rhythms provide daily temporal structure to cellular and organismal biological processes, ranging from gene expression to cognition. Higher-frequency (intradaily) ultradian rhythms are similarly ubiquitous but have garnered far less empirical study, in part because of the properties that define them-multimodal periods, non-stationarity, c...

Olfactory dysfunction is a hallmark symptom of COVID-19 disease resulting from the SARS-CoV-2 virus. The cause of the sudden and usually temporary anosmia that most people suffer from COVID-19 is likely entirely peripheral - inflammation and other damage caused by the virus in the sensory epithelium inside the upper recesses of the nasal cavity can...

Biological organisms learn from interactions with their environment throughout their lifetime. For artificial systems to successfully act and adapt in the real world, it is desirable to similarly be able to learn on a continual basis. This challenge is known as lifelong learning, and remains to a large extent unsolved. In this Perspective article,...

Neural oscillations can couple networks of brain regions, especially at lower frequencies. The nasal respiratory rhythm, which elicits robust olfactory bulb oscillations, has been linked to episodic memory, locomotion, and exploration, along with widespread oscillatory coherence. The piriform cortex is implicated in propagating the olfactory-bulb-d...

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 animal...

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 animal...

While orthonasal odorants are often associated with the external environment, retronasal odorants are accompanied by consummatory behaviors and indicate an internal state of an animal. Our study aimed to examine whether the same odorants may generate a consistent perceptual experience when two olfactory routes potentiate variations in concentration...

The mammalian olfactory bulb displays a prominent respiratory rhythm, linked to the sniff cycle and driven by sensory input from olfactory receptors in the nasal sensory epithelium. In rats and mice, respiratory frequencies occupy the same band as the hippocampal theta rhythm, which has been shown to be a key player in memory processes. Hippocampal...

The mammalian olfactory bulb (OB) generates gamma (40 - 100 Hz) and beta (15 - 30 Hz) local field potential (LFP) oscillations. Gamma oscillations arise at the peak of inhalation supported by dendrodendritic interactions between glutamatergic mitral cells (MCs) and GABAergic granule cells (GCs). Beta oscillations are induced by odorants in learning...

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 odorant...

Differing results in olfactory-based decision-making research regarding the amount of time that rats and mice use to identify odors have led to some disagreements about odor processing mechanics, including whether or not rodents use temporal integration (i.e., sniffing longer to identify odors better). Reported differences in behavioral strategies...

Unlabelled: Olfactory system beta (15-35 Hz) and gamma (40-110 Hz) oscillations of the local field potential in mammals have both been linked to odor learning and discrimination. Gamma oscillations represent the activity of a local network within the olfactory bulb, and beta oscillations represent engagement of a systemwide network. Here, we test...

Odors evoke gamma (40 - 100 Hz) and beta (20 - 30 Hz) oscillations in the local field potential (LFP) of the mammalian olfactory bulb (OB). Gamma (and possibly beta) oscillations arise from interactions in the dendrodendritic microcircuit between excitatory mitral cells (MCs) and inhibitory granule cells (GCs). When cortical descending inputs to th...

The effect of circadian rhythm (CR) disruption on immune function depends on the method by which CRs are disrupted. Behavioral and thermoregulatory responses induced by lipopolysaccharide (LPS) treatment were assessed in female Siberian hamsters in which circadian locomotor activity (LMA) rhythms were eliminated by exposure to a disruptive phase-sh...

Odors evoke gamma (60 - 100 Hz) and beta (20 - 30 Hz) oscillations in the local field potential (LFP) of the rat olfactory bulb (OB). These oscillations arise from activity in the dendrodendritic microcircuit between excitatory mitral cells (MCs) and inhibitory granule cells (GCs) [1]. When cortical feedback inputs to the OB are blocked, beta oscil...

Sensory perception is accomplished by means of active behaviors that help to extract information from the external environment. These behaviors become a part of the percept and also constrain the perceptual task. In olfactory perception, sniffing is the means by which individuals acquire olfactory stimuli from the environment. Rats sniff at 8–10 Hz...

Neural oscillations are ubiquitous in olfactory systems of mammals, insects and molluscs. Neurophysiological and computational investigations point to common mechanisms for gamma or odor associated oscillations across phyla (40-100Hz in mammals, 20-30Hz in insects, 0.5-1.5Hz in molluscs), engaging the reciprocal dendrodendritic synapse between exci...

Sensory-motor relationships are part of the normal operation of sensory systems. Sensing occurs in the context of active sensor movement, which in turn influences sensory processing. We address such a process in the rat olfactory system. Through recordings of the diaphragm electromyogram (EMG), we monitored the motor output of the respiratory circu...

Olfactory system neural oscillations as seen in the local field potential have been studied for many decades. Recent research has shown that there is a functional role for the most studied gamma oscillations (40-100Hz in rats and mice, and 20Hz in insects), without which fine odor discrimination is poor. When these oscillations are increased artifi...

Current antidepressants must be administered for several weeks to produce therapeutic effects. We show that selective serotonin 2C (5-HT2C) antagonists exert antidepressant actions with a faster-onset (5 days) than that of current antidepressants (14 days) in mice. Subchronic (5 days) treatment with 5-HT2C antagonists induced antidepressant behavio...

Olfactory perception spans multiple time scales, from sub-millisecond and millisecond generation and timing of action potentials to developmental time. In this paper I review recent research addressing the mesoscopic scale and interactions with events that occur on longer time scales. Oscillatory local field potential frequency and coherence patter...

For decades it has been known that the olfactory sensory epithelium can act like a chromatograph, separating odorants based on their air-mucus sorptive properties (Mozell and Jagodowicz, 1973). It has been hypothesized that animals could take advantage of this property, modulating sniffing behavior to manipulate airflow and thereby directing odoran...

Newborn feeding, maternal, bonding, growth and wellbeing depend upon intact odor recognition in the early postnatal period. Antenatal stress may affect postnatal odor recognition. We investigated the exact role of a neurotransmitter, nitric oxide (NO), in newborn olfactory function. We hypothesized that olfactory neuron activity depended on NO gene...

Stimulating arbitrary collections of as few as 300 neurons in the primary olfactory cortex of mice suffices for associative learning independent of any odor stimulation. Thus, programmed spatial relationships may not exist in piriform cortex, making flexible random associations the rule.

The local field potential from the mammalian olfactory system displays several oscillatory modes. Gamma oscillations (40–100 Hz) are associated with odor stimulation in the olfactory bulb (OB) and are enhanced with odor discrimination learning in a 2-alternative choice task when odors are very similar. Beta oscillations (15–30 Hz) are associated wi...

To elucidate the cognitive structures of animals, neuroscientists use several behavioral tasks. Therefore, it is imperative to have a firm understanding of each task's behavioral parameters in order to parse out possible task effects. We compare two operant discrimination tasks (Go/No-Go: GNG; Two-Alternative Choice: TAC) that are commonly used in...

Previous studies in waking animals have shown that the frequency structure of olfactory bulb (OB) local field potential oscillations is very similar across the OB, but large low-impedance surface electrodes may have favored highly coherent events, averaging out local inhomogeneities. We tested the hypothesis that OB oscillations represent spatially...

We previously showed that in a two-alternative choice (2AC) task, olfactory bulb (OB) gamma oscillations (approximately 70 Hz in rats) were enhanced during discrimination of structurally similar odorants (fine discrimination) versus discrimination of dissimilar odorants (coarse discrimination). In other studies (mostly employing go/no-go tasks) in...

The hippocampus and olfactory regions are anatomically close, and both play a major role in memory formation. However, the way they interact during odor processing is still unclear. In both areas, strong oscillations of the local field potential (LFP) can be recorded, and are modulated by behavior. In particular, in the olfactory system, the beta r...

Gamma oscillations in the olfactory bulb can be produced as an interaction of subthreshold oscillations (STOs) in the mitral cells (MCs) with inhibitory granule cells (GCs). The mechanism does not require that the GCs spike, and we work in a regime in which the MCs fire at rates lower than the fast gamma rhythm they create. The frequency of the net...

The overlap hypothesis of mixture perception is based on the observation that mixtures of perceptually similar odorants tend to smell different from their components (configural), whereas mixtures of dissimilar odorants smell like their components (elemental). Because input patterns of perceptually similar odorants tend to overlap more than dissimi...

Olfactory system oscillations play out with beautiful temporal and behavioral regularity on the oscilloscope and seem to scream 'meaning'. Always there is the fear that, although attractive, these symbols of dynamic regularity might be just seductive epiphenomena. There are now many studies that have isolated some of the neural mechanisms involved...

Surgical removal of the olfactory bulb alters several aspects of immunological activity. This study investigated the role of the olfactory bulbs in the control of behavioral responses to simulated infection, and the environmental modulation of sickness behaviors by changes in day length. Adult male Siberian hamsters (Phodopus sungorus) were subject...

DefinitionThis characterizes the lowest level of sound that a listener can reliably detect and is sometimes referred to as threshold of audibility. The units are typically reported in dB sound pressure level (SPL).Psychoacoustics

In reproductively photoperiodic Syrian hamsters, removal of the olfactory bulbs (OBx) leads to a marked and sustained increase in gonadotrophin secretion which prevents normal testicular regression in short photoperiods. In contrast, among reproductively nonphotoperiodic laboratory strains of rats and mice, bulbectomy unmasks reproductive responses...

The mammalian olfactory system shows many types of sensory and perceptual processing accompanied by oscillations at the level of the local field potential, and much is already known about the cellular and synaptic origins of these markers of coherent population activity. Complex, but chemotopic input patterns describe the qualitative similarity of...

Oscillatory phenomena have been a focus of dynamical systems research since the time of the classical studies on the pendulum by Galileo. Fast cortical oscillations also have a long and storied history in neurophysiology, and olfactory oscillations have led the way with a depth of explanation not present in the literature of most other cortical sys...

Odor mixtures can produce several qualitatively different percepts; it is not known at which stage of processing these are determined. We asked if activity within the first stage of olfactory processing, the glomerular layer of the olfactory bulb, predicts odor mixture perception. We characterized how mice respond to components after training to fi...

The present study tested the hypothesis that seasonal intervals of exposure to modest changes in photoperiod, typical of those experienced by humans living in temperate latitudes (10-14 h light/day), engage changes in emotional behaviour of Wistar rats, a commonly-used animal model for investigations of affective physiology. Short day lengths (<or=...

Annual variations in day length (photoperiod) trigger changes in the immune and reproductive system of seasonally-breeding animals. The purpose of this study was to determine whether photoperiodic changes in immunity depend on concurrent photoperiodic responses in the reproductive system, or whether immunological responses to photoperiod occur inde...

Several studies have shown that memory consolidation relies partly on interactions between sensory and limbic areas. The functional loop formed by the olfactory system and the hippocampus represents an experimentally tractable model that can provide insight into this question. It had been shown previously that odor-learning associated beta band osc...

Fast oscillations in neural assemblies have been proposed as a mechanism to facilitate stimulus representation in a variety of sensory systems across animal species. In the olfactory system, intervention studies suggest that oscillations in the gamma frequency range play a role in fine odor discrimination. However, there is still no direct evidence...

Recent studies have pointed to olfactory system beta oscillations of the local field potential (15-30 Hz) and their roles both in learning and as specific responses to predator odors. To describe odorant physical properties, resultant behavioral responses and changes in the central olfactory system that may induce these oscillations without associa...

Despite widespread interest in the evolutionary implications of human olfactory communication, the mechanisms underlying human odor production are still poorly understood. Previous studies have demonstrated that human odor cues are related to variations in the major histocompatibility complex, but it is unclear whether odors are associated with ove...

The mammalian olfactory system is unique in that sensory receptors synapse directly into the olfactory bulb of the forebrain without the thalamic relay that is common to all other sensory pathways. We argue that the olfactory bulb has an equivalent role to the thalamus, because the two regions have very similar structures and functions. Both the th...

In this issue of Neuron, Rinberg et al. show that mice use a speed-accuracy tradeoff in odor discrimination. Shorter sampling results in high performance for easy problems, and enforced longer sampling results in higher accuracy for difficult problems, but mice freely choose intermediate sampling durations and accuracy varies with difficulty. Rewar...

Insects and vertebrates separately evolved remarkably similar mechanisms to process olfactory information. Odors are sampled by huge numbers of receptor neurons, which converge type-wise upon a much smaller number of principal neurons within glomeruli. There, odor information is transformed by inhibitory interneuron-mediated, cross-glomerular circu...

Recent studies show that some features of odor perception are predicted by olfactory receptor biophysics and olfactory bulb physiology. Those studies used a behavioral assay in which rodents dig in a dish of scented cage bedding after pretraining to associate a buried reward with an odorant. The advantage of the digging task is an intensity measure...

Odor mixtures are perceived as different from (configural) or the same as (elemental) their components. Recent studies (L. M. Kay, C. A. Lowry, & H. A. Jacobs, 2003; C. Wiltrout, S. Dogra, & C. Linster, 2003) propose that component structural or perceptual similarities predict configural properties of binary mixtures. The authors evaluated this in...

Performance and cognitive effort in humans have recently been related to amplitude and multisite coherence of alpha (7-12 Hz) and theta (4-7 Hz) band electroencephalogram oscillations. I examined this phenomenon in rats by using theta band oscillations of the local field potential to signify sniffing as a sensorimotor process. Olfactory bulb (OB) t...

It has long been suggested that synchronous fast oscillations in central sensory systems facilitate formation of neural assemblies that represent sensory objects. This hypothesis derives from the olfactory system, where odor-evoked fast oscillations of 40 Hz and above in the local field potential of the mammalian olfactory bulb (OB) were first repo...

Brain hermeneutics and chaotic itinerancy proposed by Tsuda are attractive characterizations of perceptual dynamics in the mammalian olfactory system. This theory proposes that perception occurs at the interface between itinerant neural representation and interaction with the environment. Quantifiable application of these dynamics has been hampered...

Odor mixture perception can be configural (the mixture is qualitatively different from the components) or elemental (the components are recognizable). Some have argued that configural properties are dependent on chemical similarity and possible overlap at the receptor level. The authors show that a binary mixture in which both components activate t...

Gamma oscillations (40-100 Hz), originally seen in the olfactory bulb (OB), have long been a defining characteristic of sensory coding in the olfactory system. This study proposes that gamma oscillations are of two types, associated with different behavioral features and synaptic origins within the OB. Local field potentials were recorded from rat...

Synchronized neural activity is believed to be essential for many CNS functions, including neuronal development, sensory perception, and memory formation. In several brain areas GABAA receptor-mediated synaptic inhibition is thought to be important for the generation of synchronous network activity. We have used GABAA receptor β3 subunit deficient...

Chaotic itinerancy is useful for illustrating transitions in attractor dynamics seen in the olfactory system. Cantor coding is a good model for information processing, but so far it lacks perceptual proof. The theories presented provide a large step toward bridging the use of chaos as an interpretive tool and hard examination of chaotic neural acti...

The projections and odor responses of mammalian olfactory receptor neurons, as well as the physiology of the bulb's principal neurons-the mitral cells (MCs)-are known from studies in slices and anesthetized animals. In behaving rats trained to discriminate between two odors associated with different reinforcers, we examined MC responses following a...

The projections and odor responses of mammalian olfactory receptor neurons, as well as the physiology of the bulb's principal neurons—the mitral cells (MCs)—are known from studies in slices and anesthetized animals. In behaving rats trained to discriminate between two odors associated with different reinforcers, we examined MC responses following a...

Field potentials were recorded simultaneously from the olfactory bulb (OB), prepyriform cortex (PPC), entorhinal cortex (EC), and dentate gyrus (DG) of rats trained to respond to appetitively reinforced odors. Preafferent anticipatory events in the beta band (12-35 Hz) suggest transmission from EC to OB before the odorant stimulus. Gamma band (35-1...

Field potentials were recorded simultaneously from the olfactory bulb (OB), prepyriform cortex (PPC), entorhinal cortex (EC), and dentate gyrus (DG) of rats trained to respond to appetitively reinforced odors. Preafferent anticipatory events in the beta band (12–35 Hz) suggest transmission from EC to OB before the odorant stimulus. Gamma band (35–1...

Olfactory bulb activity has been postulated to be chaotic, as measured in the EEG, and to be subject to an attractor with many "wings" enabling classification of different learned odor classes. Two parallel questions are thus addressed by the work presented here: (1) what is the evidence for attractors in the olfactory system, which can mediate lea...

Olfactory bulb activity has been postulated to be chaotic, as measured in the EEG, and to be subject to an attractor with many “wings” enabling classification of different learned odor classes. Two parallel questions are thus addressed by the work presented here: (1) what is the evidence for attractors in the olfactory system, which can mediate lea...

We approach the question of how the brain may expect a known olfactory stimulus. EEG data were recorded from rats simultaneously from the olfactory bulb (OB), prepiriform cortex (PPC), entorhinal cortex (EC), and dentate gyms (DG) of the hippocampus. The animals were trained in a classical paradigm to identify two odors. The problem of nonstationar...

The so-called “spontaneous,” background, or “basal” time series of electroencephalographic (EEG) data from rat olfactory cortex are compared with those generated by a model of the ol-factory system, denoted KIII, composed of nonlinear coupled second order ODEs with feedback delay. Each ODE (KO) represents a neural mass having either excitatory or i...