Article

Olfactory perceptual stability and discrimination

Neurobehavioral Institute, Department of Zoology, University of Oklahoma, 730 Van Vleet Oval, Norman, Oklahoma 73019, USA.
Nature Neuroscience (Impact Factor: 16.1). 01/2009; 11(12):1378-80. DOI: 10.1038/nn.2217
Source: PubMed

ABSTRACT

No two roses smell exactly alike, but our brain accurately bundles these variations into a single percept 'rose'. We found that ensembles of rat olfactory bulb neurons decorrelate complex mixtures that vary by as little as a single missing component, whereas olfactory (piriform) cortical neural ensembles perform pattern completion in response to an absent component, essentially filling in the missing information and allowing perceptual stability. This piriform cortical ensemble activity predicts olfactory perception.

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    • "Each program was repeated four times in sequential repeating order for every recording analyzed with at least a 60-s inter-stimulus interval to avoid odor habituation (Wilson, 1998a,b). Odor stimuli included variants of a 10-component (10c) mixture as previously described (Barnes et al., 2008; Chapuis and Wilson, 2012; Lovitz et al., 2012), with individual cells primarily tested with a single mixture. "
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    ABSTRACT: Olfactory information is synthesized within the olfactory cortex to provide not only an odor percept, but also a contextual significance that supports appropriate behavioral response to specific odor cues. The piriform cortex serves as a communication hub within this circuit by sharing reciprocal connectivity with higher processing regions, such as the lateral entorhinal cortex and amygdala. The functional significance of these descending inputs on piriform cortical processing of odorants is currently not well understood. We have employed optogenetic methods to selectively stimulate lateral and basolateral amygdala (BLA) afferent fibers innervating the posterior piriform cortex (pPCX) to quantify BLA modulation of pPCX odor-evoked activity. Single unit odor-evoked activity of anaesthetized BLA-infected animals was significantly modulated compared with control animal recordings, with individual cells displaying either enhancement or suppression of odor-driven spiking. In addition, BLA activation induced a decorrelation of odor-evoked pPCX ensemble activity relative to odor alone. Together these results indicate a modulatory role in pPCX odor processing for the BLA complex, which could contribute to learned changes in PCX activity following associative conditioning.
    Full-text · Article · Dec 2015 · Frontiers in Neural Circuits
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    • "In rodents, odor mixtures are processed differently by the olfactory bulb and primary olfactory (piriform) cortex (Wilson and Sullivan, 2011). For example, the activity of olfactory bulb mitral/tufted cell neural ensembles is strongly consistent with pattern separation processing– responding uniquely to even minor changes in mixture elements (Barnes et al., 2008; Chapuis and Wilson, 2011; Sahay et al., 2011). Thus, it has been hypothesized that olfactory bulb neural ensembles respond to odor mixture features or components, rather than to the mixture configuration. "

    Full-text · Dataset · Oct 2015
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    • "The animals were allowed to recover for at least 2 weeks, and then began training with odour mixture discrimination. For mixture discrimination training, animals were presented with two overlapping 10 component odorant mixtures, which have been described in detail elsewhere (Barnes et al. 2008; Chen et al. 2011; Chapuis & Wilson, 2012; Lovitz et al. 2012). The full 10 component mixture (10 c) included the monomolecular odorants: isoamyl acetate (100 p. "
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    ABSTRACT: Bilateral cortical circuits are not necessarily symmetrical. Asymmetry, or cerebral lateralization, allows functional specialization of bilateral brain regions and has been described in humans for such diverse functions as perception, memory and emotion. There is also evidence for asymmetry in the human olfactory system, though evidence in non-human animal models is lacking. Here, we took advantage of the known changes in olfactory cortical local field potentials that occur over the course of odor discrimination training to test for functional asymmetry in piriform cortical activity during learning. Both the right and left piriform cortex local field potential activities were recorded. The results demonstrate robust inter-hemispheric asymmetry in anterior piriform cortex activity that emerges during specific stages of odor discrimination learning, with a transient bias toward the left hemisphere. This asymmetry is not apparent during error trials. Furthermore, functional connectivity (coherence) between the bilateral anterior piriform cortices is learning- and context-dependent. Steady-state inter-hemispheric anterior piriform cortex coherence is reduced during initial stages of learning and then recovers as animals acquire competent performance. The decrease in coherence is seen relative to bilateral coherence expressed in the home cage, which remains stable across conditioning days. Similarly, transient, trial-related inter-hemispheric coherence increases with task competence. Together the results demonstrate transient asymmetry in piriform cortical function during odor discrimination learning until mastery, and suggests that each PCX may contribute something unique to odor memory.This article is protected by copyright. All rights reserved
    Full-text · Article · Jan 2015 · The Journal of Physiology
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