Evidence for the temporal processing of odor mixtures in humans

Laing, David G.; Eddy, Andrew; Francis, Gregory; Stephens, Larry M.

doi:10.1016/0006-8993(94)90712-9

Cited by 59 publications

(31 citation statements)

References 17 publications

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“…The composition and ratio of these notes endow the perfume with a signature scent (52). Human psychophysical studies have shown that odorants in a mixture are processed and perceived in series (53). As shown by our PID measurements (Fig.…”

Section: Resultsmentioning

confidence: 55%

Temporal coding of odor mixtures in an olfactory receptor neuron

Martelli

Emonet

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Most natural odors are mixtures and often elicit percepts distinct from those elicited by their constituents. This emergence of a unique odor quality has long been attributed to central processing. Here we show that sophisticated integration of olfactory information begins in olfactory receptor neurons (ORNs) in Drosophila. Odor mixtures are encoded in the temporal dynamics as well as in the magnitudes of ORN responses. ORNs can respond to an inhibitory odorant with different durations depending on the level of background excitation. ORNs respond to mixtures with distinctive temporal dynamics that reflect the physicochemical properties of the constituent odorants. The insect repellent DEET (N,N-diethyl-m-toluamide), which attenuates odor responses of multiple ORNs, differs from an ORNspecific inhibitor in its effects on temporal dynamics. Our analysis reveals a means by which integration of information from odor mixtures begins in ORNs and provides insight into the contribution of inhibitory stimuli to sensory coding.A fascinating aspect of the sense of smell is that odor mixtures often have distinctive emergent qualities, and their individual constituents are difficult to identify (1). How the emergent quality of an odor mixture arises is unknown. It is believed to originate mainly from information processing in the central nervous system, as in the insect antennal lobe (2-4) and the vertebrate olfactory bulb (5, 6). However, olfactory receptor neurons (ORNs) also contribute to the integration of olfactory information. For example, some individual rat ORNs respond to a binary odor mixture with response magnitudes, i.e., firing frequencies, that cannot be predicted simply from the responses to its components (7,8). In addition, studies in moths (9-14) and beetles (15) have provided evidence that information about odorants in a mixture can be integrated in the periphery. However, little is known about how information is processed in ORNs. It is unclear, for example, whether individual ORNs are capable of integrating information via means other than simple alterations of their response magnitudes.Equally intriguing in sensory coding is the role of inhibitory stimuli. In taste, certain stimuli inhibit vertebrate sweet receptors (16,17). In olfaction, inhibitory odorants have been identified for olfactory receptors of vertebrates (18-21) and invertebrates (13,(22)(23)(24)(25)(26). When delivered as a monomolecular odor stimulus, inhibitors reduce the spontaneous activity of ORNs. However, the low spontaneous activities of most ORNs (13,22,23,27) limit the dynamic range of inhibition, and inhibitory odorants may have greater functional significance when paired with excitatory odorants. Indeed, an inhibitory odorant reduced the intensity of a concurrent excitatory odor stimulus in a human psychophysical study (28), and odorants that inhibited CO 2 -sensing neurons prevented CO 2 -mediated avoidance behaviors in Drosophila (24). However, it is not clear whether a binary mixture of an excitatory stimulus and an inhibito...

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Section: Resultsmentioning

confidence: 55%

Temporal coding of odor mixtures in an olfactory receptor neuron

Martelli

Emonet

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Slow scale (seconds) temporal patterning in stimulus characteristics shapes central neuronal (present results;Heinbockel et al 1999;Sobel et al 2000) and perceptual (Goyert et al 2005;Laing et al 1994) odor responses. These slow scale patterns can lead to higher-order processing such as figureground separation as suggested here.…”

Section: Analysis or Synthesis?mentioning

confidence: 48%

“…This filtering effect could allow temporal separation of odorants based on differences in onset or inhalation time or potentially based on differences in absorption and transduction time across the olfactory epithelium. In fact, work by Laing and colleagues (Jinks and Laing 1999;Laing et al 1994) has demonstrated that identification of odorants within complex mixtures can be facilitated in humans when the odorants vary in onset or diffusion characteristics. The time factor that affected odor identification in those studies (Ͻ1 s) was substantially shorter than the time scale here, although it suggests that further investigation at the physiological level is warranted.…”

Section: Discussionmentioning

confidence: 99%

Olfactory Cortical Adaptation Facilitates Detection of Odors Against Background

Kadohisa

Wilson²

2006

Journal of Neurophysiology

115

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“…In this study, as a mixture becomes familiar and more distinctive (7), aPCX neuronal encoding of the mixture becomes more distinct from its components. That is, familiar mixtures come to be identified as odor objects distinct from their components (25), an effect that may contribute to the relatively poor ability to identify components within complex mixtures (23,26). In contrast, pPCX neurons may encode odor quality (fruity, spicy, etc.…”

Section: Discussionmentioning

confidence: 99%

Separate encoding of identity and similarity of complex familiar odors in piriform cortex

Kadohisa

Wilson

2006

Proc. Natl. Acad. Sci. U.S.A.

151

132

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Piriform cortical circuits are hypothesized to form perceptions from responses to specific odorant features, but the anterior piriform cortex (aPCX) and posterior piriform cortex (pPCX) differ markedly in their anatomical organization, differences that could lead to distinct roles in odor encoding. Here, we tested whether experience with a complex odorant mixture would modify encoding of the mixture and its components in aPCX and pPCX. Rats were exposed to an odorant mixture and its components in a go͞no-go rewarded odor discrimination task. After reaching behavioral performance criterion, single-unit recordings were made from the aPCX and pPCX in these rats and in odor-naïve, control, urethaneanesthetized rats. After odor experience, aPCX neurons were more narrowly tuned to the test odorants, and there was a decorrelation in aPCX population responses to the mixture and its components, suggesting a more distinct encoding of the familiar mixture from its components. In contrast, pPCX neurons were more broadly tuned to the familiar odorants, and pPCX population responses to the mixture and its components became more highly correlated, suggesting a pPCX encoding of similarity between familiar stimuli. The results suggest aPCX and pPCX play different roles in the processing of familiar odors and are consistent with an experiencedependent encoding (perceptual learning) of synthetic odorant identity in aPCX and an experience-dependent encoding of odor similarity or odor quality in pPCX.memory ͉ olfactory discrimination ͉ perceptual learning ͉ odorant mixture ͉ odor encoding

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Evidence for the temporal processing of odor mixtures in humans

Cited by 59 publications

References 17 publications

Temporal coding of odor mixtures in an olfactory receptor neuron

Temporal coding of odor mixtures in an olfactory receptor neuron

Olfactory Cortical Adaptation Facilitates Detection of Odors Against Background

Separate encoding of identity and similarity of complex familiar odors in piriform cortex

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