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Coppola DM, Reisert J. The Role of the Stimulus in Olfactory Plasticity. Brain Sci 2023; 13:1553. [PMID: 38002512 PMCID: PMC10669894 DOI: 10.3390/brainsci13111553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/02/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
Plasticity, the term we use to describe the ability of a nervous system to change with experience, is the evolutionary adaptation that freed animal behavior from the confines of genetic determinism. This capacity, which increases with brain complexity, is nowhere more evident than in vertebrates, especially mammals. Though the scientific study of brain plasticity dates back at least to the mid-19th century, the last several decades have seen unprecedented advances in the field afforded by new technologies. Olfaction is one system that has garnered particular attention in this realm because it is the only sensory modality with a lifelong supply of new neurons, from two niches no less! Here, we review some of the classical and contemporary literature dealing with the role of the stimulus or lack thereof in olfactory plasticity. We have restricted our comments to studies in mammals that have used dual tools of the field: stimulus deprivation and stimulus enrichment. The former manipulation has been implemented most frequently by unilateral naris occlusion and, thus, we have limited our comments to research using this technique. The work reviewed on deprivation provides substantial evidence of activity-dependent processes in both developing and adult mammals at multiple levels of the system from olfactory sensory neurons through to olfactory cortical areas. However, more recent evidence on the effects of deprivation also establishes several compensatory processes with mechanisms at every level of the system, whose function seems to be the restoration of information flow in the face of an impoverished signal. The results of sensory enrichment are more tentative, not least because of the actual manipulation: What odor or odors? At what concentrations? On what schedule? All of these have frequently not been sufficiently rationalized or characterized. Perhaps it is not surprising, then, that discrepant results are common in sensory enrichment studies. Despite this problem, evidence has accumulated that even passively encountered odors can "teach" olfactory cortical areas to better detect, discriminate, and more efficiently encode them for future encounters. We discuss these and other less-established roles for the stimulus in olfactory plasticity, culminating in our recommended "aspirations" for the field going forward.
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Affiliation(s)
- David M. Coppola
- Biology Department, Randolph-Macon College, Ashland, VA 23005, USA
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2
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Shen J, Li M, Long C, Yang L, Jiang J. Altered Odor-Evoked Electrophysiological Responses in the Anterior Piriform Cortex of Conscious APP/PS1 Mice. J Alzheimers Dis 2022; 90:1277-1289. [DOI: 10.3233/jad-220694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background: Olfactory decline is an indicator of early-stage Alzheimer’s disease (AD). Although the anterior piriform cortex (aPC) is an important brain area involved in processing olfactory input, little is known about how its neuronal activity is affected in early-stage AD. Objective: To elucidate whether odor-induced electrophysiological responses are altered in the aPC of 3-5-month-old APP/PS1 mice. Methods: Using head-fixed multi-channel recording techniques in APP/PS1 AD mouse model to uncover potential aberrance of the aPC neuronal firing and local field potential (LFP) in response to vanillin. Results: We show that the firing rate of aPC neurons evoked by vanillin is significantly reduced in conscious APP/PS1 mice. LFP analysis demonstrates reduced low- and high-gamma (γ low, γ high) oscillations during both the baseline and odor stimulation periods in APP/PS1 mice. Moreover, according to spike-field coherence (SFC) analysis, APP/PS1 mice show decreased coherence between odor-evoked spikes and γ low rhythms, while the coherence with γ high rhythms and the ΔSFC of the oscillations is unaffected. Furthermore, APP/PS1 mice show reduced phase-locking strength in the baseline period, such that there is no difference between baseline and odor-stimulation conditions. This contrasts markedly with wild type mice, where phase-locking strength decreases on stimulation. Conclusion: The abnormalities in both the neuronal and oscillatory activities of the aPC may serve as electrophysiological indicators of underlying olfactory decline in early AD.
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Affiliation(s)
- Jialun Shen
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Meng Li
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Cheng Long
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Li Yang
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Jinxiang Jiang
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, China
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3
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Stensola T, Stensola H. Understanding Categorical Learning in Neural Circuits Through the Primary Olfactory Cortex. Front Cell Neurosci 2022; 16:920334. [PMID: 35813505 PMCID: PMC9263292 DOI: 10.3389/fncel.2022.920334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 05/30/2022] [Indexed: 11/25/2022] Open
Abstract
Knowing which elements in the environment are associated with various opportunities and dangers is advantageous. A major role of mammalian sensory systems is to provide information about the identity of such elements which can then be used for adaptive action planning by the animal. Identity-tuned sensory representations are categorical, invariant to nuances in the sensory stream and depend on associative learning. Although categorical representations are well documented across several sensory modalities, these tend to situate synaptically far from the sensory organs which reduces experimenter control over input-output transformations. The formation of such representations is a fundamental neural computation that remains poorly understood. Odor representations in the primary olfactory cortex have several characteristics that qualify them as categorical and identity-tuned, situated only two synapses away from the sensory epithelium. The formation of categorical representations is likely critically dependent on—and dynamically controlled by—recurrent circuitry within the primary olfactory cortex itself. Experiments suggest that the concerted activity of several neuromodulatory systems plays a decisive role in shaping categorical learning through complex interactions with recurrent activity and plasticity in primary olfactory cortex circuits. In this perspective we discuss missing pieces of the categorical learning puzzle, and why several features of olfaction make it an attractive model system for this challenge.
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Endo K, Kazama H. Central organization of a high-dimensional odor space. Curr Opin Neurobiol 2022; 73:102528. [DOI: 10.1016/j.conb.2022.102528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/17/2022] [Accepted: 02/24/2022] [Indexed: 11/03/2022]
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Coureaud G, Thomas-Danguin T, Sandoz JC, Wilson DA. Biological constraints on configural odour mixture perception. J Exp Biol 2022; 225:274695. [PMID: 35285471 PMCID: PMC8996812 DOI: 10.1242/jeb.242274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Animals, including humans, detect odours and use this information to behave efficiently in the environment. Frequently, odours consist of complex mixtures of odorants rather than single odorants, and mixtures are often perceived as configural wholes, i.e. as odour objects (e.g. food, partners). The biological rules governing this 'configural perception' (as opposed to the elemental perception of mixtures through their components) remain weakly understood. Here, we first review examples of configural mixture processing in diverse species involving species-specific biological signals. Then, we present the original hypothesis that at least certain mixtures can be processed configurally across species. Indeed, experiments conducted in human adults, newborn rabbits and, more recently, in rodents and honeybees show that these species process some mixtures in a remarkably similar fashion. Strikingly, a mixture AB (A, ethyl isobutyrate; B, ethyl maltol) induces configural processing in humans, who perceive a mixture odour quality (pineapple) distinct from the component qualities (A, strawberry; B, caramel). The same mixture is weakly configurally processed in rabbit neonates, which perceive a particular odour for the mixture in addition to the component odours. Mice and honeybees also perceive the AB mixture configurally, as they respond differently to the mixture compared with its components. Based on these results and others, including neurophysiological approaches, we propose that certain mixtures are convergently perceived across various species of vertebrates/invertebrates, possibly as a result of a similar anatomical organization of their olfactory systems and the common necessity to simplify the environment's chemical complexity in order to display adaptive behaviours.
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Affiliation(s)
- Gérard Coureaud
- Centre de Recherche en Neurosciences de Lyon, Team Sensory Neuroethology (ENES), CNRS/INSERM/UCBL1/UJM, 69500 Lyon, France
| | - Thierry Thomas-Danguin
- Centre des Sciences du Goût et de l'Alimentation, Team Flavor, Food Oral Processing and Perception, INRAE, CNRS, Institut Agro Dijon, Université Bourgogne Franche-Comté, 21000 Dijon, France
| | - Jean-Christophe Sandoz
- Evolution, Genomes, Behavior and Ecology, CNRS, Université Paris-Saclay, IRD, 91190 Gif-sur-Yvette, France
| | - Donald A Wilson
- Department of Child & Adolescent Psychiatry, New York University Langone School of Medicine and Nathan S. Kline Institute for Psychiatric Research, New York, NY 10016, USA
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6
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Lebovich L, Yunerman M, Scaiewicz V, Loewenstein Y, Rokni D. Paradoxical relationship between speed and accuracy in olfactory figure-background segregation. PLoS Comput Biol 2021; 17:e1009674. [PMID: 34871306 PMCID: PMC8675919 DOI: 10.1371/journal.pcbi.1009674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 12/16/2021] [Accepted: 11/20/2021] [Indexed: 11/19/2022] Open
Abstract
In natural settings, many stimuli impinge on our sensory organs simultaneously. Parsing these sensory stimuli into perceptual objects is a fundamental task faced by all sensory systems. Similar to other sensory modalities, increased odor backgrounds decrease the detectability of target odors by the olfactory system. The mechanisms by which background odors interfere with the detection and identification of target odors are unknown. Here we utilized the framework of the Drift Diffusion Model (DDM) to consider possible interference mechanisms in an odor detection task. We first considered pure effects of background odors on either signal or noise in the decision-making dynamics and showed that these produce different predictions about decision accuracy and speed. To test these predictions, we trained mice to detect target odors that are embedded in random background mixtures in a two-alternative choice task. In this task, the inter-trial interval was independent of behavioral reaction times to avoid motivating rapid responses. We found that increased backgrounds reduce mouse performance but paradoxically also decrease reaction times, suggesting that noise in the decision making process is increased by backgrounds. We further assessed the contributions of background effects on both noise and signal by fitting the DDM to the behavioral data. The models showed that background odors affect both the signal and the noise, but that the paradoxical relationship between trial difficulty and reaction time is caused by the added noise. Sensory systems are constantly stimulated by signals from many objects in the environment. Segmentation of important signals from the cluttered background is therefore a task that is faced by all sensory systems. For many mammalians, the sense of smell is the primary sense that guides many daily behaviors. As such, the olfactory system must be able to detect and identify odors of interest against varying and dynamic backgrounds. Here we studied how background odors interfere with the detection of target odors. We trained mice on a task in which they are presented with odor mixtures and are required to report whether they include either of two target odors. We analyze the behavioral data using a common model of sensory-guided decision-making—the drift-diffusion-model. In this model, decisions are influenced by two elements: a drift which is the signal produced by the stimulus, and noise. We show that the addition of background odors has a dual effect—a reduction in the drift, as well as an increase in the noise. The increased noise also causes more rapid decisions, thereby producing a paradoxical relationship between trial difficulty and decision speed; mice make faster decisions on more difficult trials.
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Affiliation(s)
- Lior Lebovich
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, Jerusalem, Israel
| | - Michael Yunerman
- Department of Medical Neurobiology, School of Medicine and IMRIC, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Viviana Scaiewicz
- Department of Medical Neurobiology, School of Medicine and IMRIC, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yonatan Loewenstein
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University, Jerusalem, Israel
- The Alexander Silberman Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
- Department of Cognitive Sciences and The Federmann Center for the Study of Rationality, The Hebrew University, Jerusalem, Israel
| | - Dan Rokni
- Department of Medical Neurobiology, School of Medicine and IMRIC, The Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail:
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7
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Samuelsen CL, Vincis R. Cortical Hub for Flavor Sensation in Rodents. Front Syst Neurosci 2021; 15:772286. [PMID: 34867223 PMCID: PMC8636119 DOI: 10.3389/fnsys.2021.772286] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/21/2021] [Indexed: 01/05/2023] Open
Abstract
The experience of eating is inherently multimodal, combining intraoral gustatory, olfactory, and somatosensory signals into a single percept called flavor. As foods and beverages enter the mouth, movements associated with chewing and swallowing activate somatosensory receptors in the oral cavity, dissolve tastants in the saliva to activate taste receptors, and release volatile odorant molecules to retronasally activate olfactory receptors in the nasal epithelium. Human studies indicate that sensory cortical areas are important for intraoral multimodal processing, yet their circuit-level mechanisms remain unclear. Animal models allow for detailed analyses of neural circuits due to the large number of molecular tools available for tracing and neuronal manipulations. In this review, we concentrate on the anatomical and neurophysiological evidence from rodent models toward a better understanding of the circuit-level mechanisms underlying the cortical processing of flavor. While more work is needed, the emerging view pertaining to the multimodal processing of food and beverages is that the piriform, gustatory, and somatosensory cortical regions do not function solely as independent areas. Rather they act as an intraoral cortical hub, simultaneously receiving and processing multimodal sensory information from the mouth to produce the rich and complex flavor experience that guides consummatory behavior.
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Affiliation(s)
- Chad L Samuelsen
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, United States
| | - Roberto Vincis
- Department of Biological Science and Program in Neuroscience, Florida State University, Tallahassee, FL, United States
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8
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Shanahan LK, Bhutani S, Kahnt T. Olfactory perceptual decision-making is biased by motivational state. PLoS Biol 2021; 19:e3001374. [PMID: 34437533 PMCID: PMC8389475 DOI: 10.1371/journal.pbio.3001374] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 07/29/2021] [Indexed: 11/18/2022] Open
Abstract
Growing evidence suggests that internal factors influence how we perceive the world. However, it remains unclear whether and how motivational states, such as hunger and satiety, regulate perceptual decision-making in the olfactory domain. Here, we developed a novel behavioral task involving mixtures of food and nonfood odors (i.e., cinnamon bun and cedar; pizza and pine) to assess olfactory perceptual decision-making in humans. Participants completed the task before and after eating a meal that matched one of the food odors, allowing us to compare perception of meal-matched and non-matched odors across fasted and sated states. We found that participants were less likely to perceive meal-matched, but not non-matched, odors as food dominant in the sated state. Moreover, functional magnetic resonance imaging (fMRI) data revealed neural changes that paralleled these behavioral effects. Namely, odor-evoked fMRI responses in olfactory/limbic brain regions were altered after the meal, such that neural patterns for meal-matched odor pairs were less discriminable and less food-like than their non-matched counterparts. Our findings demonstrate that olfactory perceptual decision-making is biased by motivational state in an odor-specific manner and highlight a potential brain mechanism underlying this adaptive behavior.
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Affiliation(s)
- Laura K. Shanahan
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail: (LKS); (TK)
| | - Surabhi Bhutani
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- School of Exercise and Nutritional Sciences, College of Health and Human Services, San Diego State University, San Diego, California, United States of America
| | - Thorsten Kahnt
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- Department of Psychology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, Illinois, United States of America
- * E-mail: (LKS); (TK)
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9
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Liu CY, Lai WS. Functional neuroanatomy and neural oscillations during social eavesdropping in male golden hamsters. Horm Behav 2021; 127:104881. [PMID: 33127368 DOI: 10.1016/j.yhbeh.2020.104881] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/06/2020] [Accepted: 10/23/2020] [Indexed: 10/23/2022]
Abstract
Social eavesdropping is a low-cost learning mechanism by which individuals extract relevant social information from social interactions between conspecifics, thereby gaining subsequent advantages in information gathering and usage. The aim of this study was to take advantage of a new hamster model of social eavesdropping to investigate behavioral consequences and neural activity in male hamsters during social eavesdropping. Bystander hamsters with a defeat experience were exposed to either a fighting interaction, a neutral encounter, or control conditions for 3 days of social eavesdropping. In Experiment 1, bystanders in the fight and neutral groups displayed more information gathering behaviors and less nonsocial behavior than control hamsters. The fight group displayed significant increases in c-Fos-positive neurons in the anterior mid-cingulate cortex (aMCC) and the piriform cortex. A slight but not significant group difference was found in their serum cortisol levels. In vivo local field potential oscillation recordings in Experiment 2 revealed that bystanders in the fight group had more delta oscillations in the aMCC during information gathering across 3-day social eavesdropping than those in the other 2 groups. Experiment 3 confirmed that 20 min of social eavesdropping on Day 1 was sufficient to evoke differential behavioral outcomes, and the behavioral responses became more prominent after 3 days of social eavesdropping. Collectively, our study confirmed that male golden hamsters are capable of social eavesdropping and indicated the involvement of aMCC delta oscillations in social eavesdropping.
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Affiliation(s)
- Ching-Yi Liu
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Wen-Sung Lai
- Department of Psychology, National Taiwan University, Taipei, Taiwan; Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan; Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan.
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10
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Penker S, Licht T, Hofer KT, Rokni D. Mixture Coding and Segmentation in the Anterior Piriform Cortex. Front Syst Neurosci 2020; 14:604718. [PMID: 33328914 PMCID: PMC7710992 DOI: 10.3389/fnsys.2020.604718] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/02/2020] [Indexed: 12/14/2022] Open
Abstract
Coding of odorous stimuli has been mostly studied using single isolated stimuli. However, a single sniff of air in a natural environment is likely to introduce airborne chemicals emitted by multiple objects into the nose. The olfactory system is therefore faced with the task of segmenting odor mixtures to identify objects in the presence of rich and often unpredictable backgrounds. The piriform cortex is thought to be the site of object recognition and scene segmentation, yet the nature of its responses to odorant mixtures is largely unknown. In this study, we asked two related questions. (1) How are mixtures represented in the piriform cortex? And (2) Can the identity of individual mixture components be read out from mixture representations in the piriform cortex? To answer these questions, we recorded single unit activity in the piriform cortex of naïve mice while sequentially presenting single odorants and their mixtures. We find that a normalization model explains mixture responses well, both at the single neuron, and at the population level. Additionally, we show that mixture components can be identified from piriform cortical activity by pooling responses of a small population of neurons-in many cases a single neuron is sufficient. These results indicate that piriform cortical representations are well suited to perform figure-background segmentation without the need for learning.
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Affiliation(s)
| | | | | | - Dan Rokni
- Department of Medical Neurobiology, School of Medicine and IMRIC, The Hebrew University of Jerusalem, Jerusalem, Israel
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11
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Endo K, Tsuchimoto Y, Kazama H. Synthesis of Conserved Odor Object Representations in a Random, Divergent-Convergent Network. Neuron 2020; 108:367-381.e5. [PMID: 32814018 DOI: 10.1016/j.neuron.2020.07.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 03/10/2020] [Accepted: 07/24/2020] [Indexed: 01/09/2023]
Abstract
Animals are capable of recognizing mixtures and groups of odors as a unitary object. However, how odor object representations are generated in the brain remains elusive. Here, we investigate sensory transformation between the primary olfactory center and its downstream region, the mushroom body (MB), in Drosophila and show that clustered representations for mixtures and groups of odors emerge in the MB at the population and single-cell levels. Decoding analyses demonstrate that neurons selective for mixtures and groups enhance odor generalization. Responses of these neurons and those selective for individual odors all emerge in an experimentally well-constrained model implementing divergent-convergent, random connectivity between the primary center and the MB. Furthermore, we found that relative odor representations are conserved across animals despite this random connectivity. Our results show that the generation of distinct representations for individual odors and groups and mixtures of odors in the MB can be understood in a unified computational and mechanistic framework.
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Affiliation(s)
- Keita Endo
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; RIKEN CBS-KAO Collaboration Center, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Yoshiko Tsuchimoto
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Hokto Kazama
- RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; RIKEN CBS-KAO Collaboration Center, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
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12
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Odor habituation can modulate very early olfactory event-related potential. Sci Rep 2020; 10:18117. [PMID: 33093624 PMCID: PMC7582193 DOI: 10.1038/s41598-020-75263-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 10/08/2020] [Indexed: 11/08/2022] Open
Abstract
Odor habituation is a phenomenon that after repeated exposure to an odor, is characterized by decreased responses to it. The central nervous system is involved in odor habituation. To study odor habituation in humans, measurement of event-related potentials (ERPs) has been widely used in the olfactory system and other sensory systems, because of their high temporal resolution. Most previous odor habituation studies have measured the olfactory ERPs of (200-800) ms. However, several studies have shown that the odor signal is processed in the central nervous system earlier than at 200 ms. For these reasons, we studied whether when odors were habituated, olfactory ERP within 200 ms of odors could change. To this end, we performed an odor habituation behavior test and electroencephalogram experiments. In the behavior test, under habituation conditions, odor intensity was significantly decreased. We found significant differences in the negative and positive potentials within 200 ms across the conditions, which correlated significantly with the results of the behavior test. We also observed that ERP latency depended on the conditions. Our study suggests that odor habituation can involve the olfactory ERP of odors within 200 ms in the brain.
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Fleming G, Wright BA, Wilson DA. The Value of Homework: Exposure to Odors in the Home Cage Enhances Odor-Discrimination Learning in Mice. Chem Senses 2020; 44:135-143. [PMID: 30590399 DOI: 10.1093/chemse/bjy083] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Perceptual learning is an enhancement in discriminability of similar stimuli following experience with those stimuli. Here, we examined the efficacy of adding additional active training following a standard training session, compared with additional stimulus exposure in the absence of associated task performance. Mice were trained daily in an odor-discrimination task, and then, several hours later each day, received 1 of 3 different manipulations: 1) a second active-training session, 2) non-task-related odor exposure in the home cage, or 3) no second session. For home-cage exposure, odorants were presented in small tubes that mice could sniff and investigate for a similar period of time as in the active discrimination task each day. The results demonstrate that daily home-cage exposure was equivalent to active odor training in supporting improved odor discrimination. Daily home-cage exposure to odorants that did not match those used in the active task did not improve learning, yielding outcomes similar to those obtained with no second session. Piriform cortical local field potential recordings revealed that both sampling in the active learning task and investigation in the home cage evoked similar beta band oscillatory activity. Together the results suggest that odor-discrimination learning can be significantly enhanced by addition of odor exposure outside of the active training task, potentially because of the robust activity evoked in the olfactory system by both exposure paradigms. They further suggest that odorant exposure alone could enhance or maintain odor-discrimination abilities in conditions associated with olfactory impairment, such as aging or dementia.
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Affiliation(s)
- Gloria Fleming
- Emotional Brain Institute, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Beverly A Wright
- Department of Communication Sciences and Disorders, Knowles Hearing Center, Northwestern University, Evanston, IL, USA.,Center for Neural Science, New York University, New York, NY, USA
| | - Donald A Wilson
- Emotional Brain Institute, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, USA.,Center for Neural Science, New York University, New York, NY, USA.,Department of Child and Adolescent Psychiatry, New York Langone School of Medicine, New York, NY, USA
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14
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Wilson DA, Fleming G, Vervoordt SM, Coureaud G. Cortical processing of configurally perceived odor mixtures. Brain Res 2020; 1729:146617. [PMID: 31866364 PMCID: PMC6941848 DOI: 10.1016/j.brainres.2019.146617] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 12/12/2019] [Accepted: 12/17/2019] [Indexed: 02/01/2023]
Abstract
Most odors are not composed of a single volatile chemical species, but rather are mixtures of many different volatile molecules, the perception of which is dependent on the identity and relative concentrations of the components. Changing either the identity or ratio of components can lead to shifts between configural and elemental perception of the mixture. For example, a 30/70 ratio of ethyl isobutyrate (odorant A, a strawberry scent) and ethyl maltol (odorant B, a caramel scent) is perceived as pineapple by humans - a configural percept distinct from the components. In contrast, a 68/32 ratio of the same odorants is perceived elementally, and is identified as the component odors. Here, we examined single-unit responses in the anterior and posterior piriform cortex (aPCX and pPCX) of mice to these A and B mixtures. We first demonstrate that mouse behavior is consistent with a configural/elemental perceptual shift as concentration ratio varies. We then compared responses to the configural mixture to those evoked by the elemental mixture, as well as to the individual components. Hierarchical cluster analyses suggest that in the mouse aPCX, the configural mixture was coded as distinct from both components, while the elemental mixture was coded as similar to the components. In contrast, mixture perception did not predict pPCX ensemble coding. Similar electrophysiological results were also observed in rats. The results suggest similar perceptual characteristics of the AB mixture across species, and a division in the roles of aPCX and pPCX in the coding of configural and elemental odor mixtures.
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Affiliation(s)
- Donald A Wilson
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA; Child & Adolescent Psychiatry, NYU School of Medicine, New York, NY, USA.
| | - Gloria Fleming
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Samantha M Vervoordt
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Gérard Coureaud
- Lyon Neuroscience Research Center, INSERM U1028/CNRS UMR 5292/Lyon 1 University, Bron, France.
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15
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Hakim M, Battle AR, Belmer A, Bartlett SE, Johnson LR, Chehrehasa F. Pavlovian Olfactory Fear Conditioning: Its Neural Circuity and Importance for Understanding Clinical Fear-Based Disorders. Front Mol Neurosci 2019; 12:221. [PMID: 31607858 PMCID: PMC6761252 DOI: 10.3389/fnmol.2019.00221] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 09/03/2019] [Indexed: 11/13/2022] Open
Abstract
Odors have proven to be the most resilient trigger for memories of high emotional saliency. Fear associated olfactory memories pose a detrimental threat of potentially transforming into severe mental illness such as fear and anxiety-related disorders. Many studies have deliberated on auditory, visual and general contextual fear memory (CFC) processes; however, fewer studies have investigated mechanisms of olfactory fear memory. Evidence strongly suggests that the neuroanatomical representation of olfactory fear memory differs from that of auditory and visual fear memory. The aim of this review article is to revisit the literature regarding the understanding of the neurobiological process of fear conditioning and to illustrate the circuitry of olfactory fear memory.
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Affiliation(s)
- Marziah Hakim
- School of Biomedical Science, Queensland University of Technology, Brisbane, QLD, Australia.,Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia.,Mater Medical Research Institute and Queensland Health, Queensland University of Technology, The University of Queensland, Woolloongabba, QLD, Australia
| | - Andrew R Battle
- School of Biomedical Science, Queensland University of Technology, Brisbane, QLD, Australia.,Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia.,Mater Medical Research Institute and Queensland Health, Queensland University of Technology, The University of Queensland, Woolloongabba, QLD, Australia.,The University of Queensland Diamantina Institute, Translational Research Institute, Woolloongabba, QLD, Australia
| | - Arnauld Belmer
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia.,Mater Medical Research Institute and Queensland Health, Queensland University of Technology, The University of Queensland, Woolloongabba, QLD, Australia
| | - Selena E Bartlett
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia.,Mater Medical Research Institute and Queensland Health, Queensland University of Technology, The University of Queensland, Woolloongabba, QLD, Australia.,School of Clinical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Luke R Johnson
- School of Biomedical Science, Queensland University of Technology, Brisbane, QLD, Australia.,Mater Medical Research Institute and Queensland Health, Queensland University of Technology, The University of Queensland, Woolloongabba, QLD, Australia.,Division of Psychology, School of Medicine, University of Tasmania, Launceston, TAS, Australia.,Center for the Study of Traumatic Stress, School of Medicine, College of Health and Medicine, Uniformed Services University, Bethesda, MD, United States
| | - Fatemeh Chehrehasa
- School of Biomedical Science, Queensland University of Technology, Brisbane, QLD, Australia.,Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia.,Mater Medical Research Institute and Queensland Health, Queensland University of Technology, The University of Queensland, Woolloongabba, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
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16
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Kumar A, Schiff O, Barkai E, Mel BW, Poleg-Polsky A, Schiller J. NMDA spikes mediate amplification of inputs in the rat piriform cortex. eLife 2018; 7:38446. [PMID: 30575520 PMCID: PMC6333441 DOI: 10.7554/elife.38446] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 12/20/2018] [Indexed: 11/13/2022] Open
Abstract
The piriform cortex (PCx) receives direct input from the olfactory bulb (OB) and is the brain's main station for odor recognition and memory. The transformation of the odor code from OB to PCx is profound: mitral and tufted cells in olfactory glomeruli respond to individual odorant molecules, whereas pyramidal neurons (PNs) in the PCx responds to multiple, apparently random combinations of activated glomeruli. How these 'discontinuous' receptive fields are formed from OB inputs remains unknown. Counter to the prevailing view that olfactory PNs sum their inputs passively, we show for the first time that NMDA spikes within individual dendrites can both amplify OB inputs and impose combination selectivity upon them, while their ability to compartmentalize voltage signals allows different dendrites to represent different odorant combinations. Thus, the 2-layer integrative behavior of olfactory PN dendrites provides a parsimonious account for the nonlinear remapping of the odor code from bulb to cortex.
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Affiliation(s)
- Amit Kumar
- Department of Physiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Oded Schiff
- Department of Physiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Edi Barkai
- Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Bartlett W Mel
- Biomedical Engineering Department, University of Southern California, Los Angeles, United States
| | - Alon Poleg-Polsky
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, United States
| | - Jackie Schiller
- Department of Physiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
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17
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Bamji-Stocke S, Biggs BT, Samuelsen CL. Experience-dependent c-Fos expression in the primary chemosensory cortices of the rat. Brain Res 2018; 1701:189-195. [PMID: 30244018 PMCID: PMC6289795 DOI: 10.1016/j.brainres.2018.09.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/30/2018] [Accepted: 09/18/2018] [Indexed: 11/21/2022]
Abstract
Eating a new food is a unique event that guides future food choices. A key element for these choices is the perception of flavor (odor-taste associations), a multisensory process dependent upon taste and smell. The two primary cortical areas for taste and smell, gustatory cortex and piriform cortex, are thought to be crucial regions for processing and responding to odor-taste mixtures. To determine how previous experience impacts the primary chemosensory cortices, we compared the expression of the immediate early gene, c-Fos, between rats presented with a taste, an odor, or an odor-taste mixture for the first-time with rats that had many days of prior experience. Compared to rats with prior experience, we found that first-time sampling of all three chemosensory stimuli led to significantly greater c-Fos expression in gustatory cortex. In piriform cortex, only the novel chemosensory stimuli containing odors showed greater c-Fos expression. These results indicate that prior experience with taste, odor, or odor-taste stimuli habituates responses in the primary chemosensory cortices and adds further evidence supporting gustatory cortex as a fundamental node for the integration of gustatory and olfactory signals.
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Affiliation(s)
- Sanaya Bamji-Stocke
- Department of Anatomical Sciences and Neurobiology, University of Louisville, KY 40202, United States.
| | - Bradley T Biggs
- Department of Anatomical Sciences and Neurobiology, University of Louisville, KY 40202, United States
| | - Chad L Samuelsen
- Department of Anatomical Sciences and Neurobiology, University of Louisville, KY 40202, United States.
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18
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Al Koborssy D, Palouzier-Paulignan B, Canova V, Thevenet M, Fadool DA, Julliard AK. Modulation of olfactory-driven behavior by metabolic signals: role of the piriform cortex. Brain Struct Funct 2018; 224:315-336. [PMID: 30317390 DOI: 10.1007/s00429-018-1776-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/08/2018] [Indexed: 12/25/2022]
Abstract
Olfaction is one of the major sensory modalities that regulates food consumption and is in turn regulated by the feeding state. Given that the olfactory bulb has been shown to be a metabolic sensor, we explored whether the anterior piriform cortex (aPCtx)-a higher olfactory cortical processing area-had the same capacity. Using immunocytochemical approaches, we report the localization of Kv1.3 channel, glucose transporter type 4, and the insulin receptor in the lateral olfactory tract and Layers II and III of the aPCtx. In current-clamped superficial pyramidal (SP) cells, we report the presence of two populations of SP cells: glucose responsive and non-glucose responsive. Using varied glucose concentrations and a glycolysis inhibitor, we found that insulin modulation of the instantaneous and spike firing frequency are both glucose dependent and require glucose metabolism. Using a plethysmograph to record sniffing frequency, rats microinjected with insulin failed to discriminate ratiometric enantiomers; considered a difficult task. Microinjection of glucose prevented discrimination of odorants of different chain-lengths, whereas injection of margatoxin increased the rate of habituation to repeated odor stimulation and enhanced discrimination. These data suggest that metabolic signaling pathways that are present in the aPCtx are capable of neuronal modulation and changing complex olfactory behaviors in higher olfactory centers.
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Affiliation(s)
- Dolly Al Koborssy
- Program in Neuroscience, The Florida State University, Tallahassee, FL, USA.,Department of Biological Science, The Florida State University, Tallahassee, FL, USA
| | - Brigitte Palouzier-Paulignan
- Univ Lyon, Université Claude Bernard Lyon1, Centre de Recherche en Neurosciences de Lyon (CRNL), INSERM U1028/CNRS UMR5292 Team Olfaction: From Coding to Memory, 50 Av. Tony Garnier, 69366, Lyon, France
| | - Vincent Canova
- Univ Lyon, Université Claude Bernard Lyon1, Centre de Recherche en Neurosciences de Lyon (CRNL), INSERM U1028/CNRS UMR5292 Team Olfaction: From Coding to Memory, 50 Av. Tony Garnier, 69366, Lyon, France
| | - Marc Thevenet
- Univ Lyon, Université Claude Bernard Lyon1, Centre de Recherche en Neurosciences de Lyon (CRNL), INSERM U1028/CNRS UMR5292 Team Olfaction: From Coding to Memory, 50 Av. Tony Garnier, 69366, Lyon, France
| | - Debra Ann Fadool
- Program in Neuroscience, The Florida State University, Tallahassee, FL, USA.,Institute of Molecular Biophysics, The Florida State University, Tallahassee, FL, USA.,Department of Biological Science, The Florida State University, Tallahassee, FL, USA
| | - Andrée Karyn Julliard
- Univ Lyon, Université Claude Bernard Lyon1, Centre de Recherche en Neurosciences de Lyon (CRNL), INSERM U1028/CNRS UMR5292 Team Olfaction: From Coding to Memory, 50 Av. Tony Garnier, 69366, Lyon, France.
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19
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Weiss K, Vickers Z. Evaluation of omission testing as a method for identifying important odorants in a mixture. J SENS STUD 2018. [DOI: 10.1111/joss.12460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Kirsten Weiss
- Department of Food Science and Nutrition; University of Minnesota; St. Paul Minnesota
| | - Zata Vickers
- Department of Food Science and Nutrition; University of Minnesota; St. Paul Minnesota
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20
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Brooks J, Nicholas J, Robertson JJ. Task dependence of odor discrimination: choosing between speed and accuracy. J Neurophysiol 2018; 119:377-379. [PMID: 29212916 DOI: 10.1152/jn.00522.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Odor discrimination is a complex task that may be improved by increasing sampling time to facilitate evidence accumulation. However, experiments testing this phenomenon in olfaction have produced conflicting results. To resolve this disparity, Frederick et al. (Frederick DE, Brown A, Tacopina S, Mehta N, Vujovic M, Brim E, Amina T, Fixsen B, Kay LM. J Neurosci 37: 4416-4426, 2017) conducted experiments that suggest that sampling time and performance are task dependent. Their findings have implications for understanding olfactory processing and experimental design, specifically the effect of subtle differences in experimental design on study results.
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Affiliation(s)
- Jack Brooks
- Neuroscience Research Australia, University of New South Wales , Sydney , Australia
| | - Jennifer Nicholas
- Black Dog Institute, School of Psychiatry, University of New South Wales , Sydney , Australia
| | - Jennifer J Robertson
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, the Australian National University , Canberra , Australia
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21
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Jacobson GA, Rupprecht P, Friedrich RW. Experience-Dependent Plasticity of Odor Representations in the Telencephalon of Zebrafish. Curr Biol 2018; 28:1-14.e3. [DOI: 10.1016/j.cub.2017.11.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/16/2017] [Accepted: 11/01/2017] [Indexed: 11/26/2022]
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22
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23
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Zhang X, Chen W, Li S, Zhou W. Developmental Fine-tuning of Human Olfactory Discriminability. Chem Senses 2017; 42:655-662. [PMID: 28981823 DOI: 10.1093/chemse/bjx047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Unlike vision or audition, human olfaction is generally considered evolutionarily ancient and well-functioning at birth, yet there have been few empirical data on the development of olfactory acuity. The current study has assessed olfactory discriminability in children aged 3 to 6 years with 16 pairs of single-compound odorants that differ in various degrees in structure and smell. We report a significant improvement over age in young children's overall olfactory discriminability. Critically, such improvement is modulated by the degree of structural similarity between odorants independent of odor familiarity. Our findings indicate that odor representations in the olfactory system are fine-tuned during early childhood (3-6 years of age) to allow refined discrimination. Moreover, they suggest the need to take molecular similarity into consideration in the evaluation of olfactory discrimination in pediatric populations.
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Affiliation(s)
- Xiaomeng Zhang
- Institute of Psychology, CAS Key Laboratory of Behavioral Science, Chinese Academy of Sciences, Beijing 100101, China
| | - Wei Chen
- Institute of Psychology, CAS Key Laboratory of Behavioral Science, Chinese Academy of Sciences, Beijing 100101, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Beijing 100101, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Su Li
- Institute of Psychology, CAS Key Laboratory of Behavioral Science, Chinese Academy of Sciences, Beijing 100101, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wen Zhou
- Institute of Psychology, CAS Key Laboratory of Behavioral Science, Chinese Academy of Sciences, Beijing 100101, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Beijing 100101, China.,Department of Psychology, University of Chinese Academy of Sciences, Beijing 100049, China
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24
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Yang J, Litscher G, Sun Z, Tang Q, Kishi K, Oda S, Takayanagi M, Sheng Z, Liu Y, Guo W, Zhang T, Wang L, Gaischek I, Litscher D, Lippe IT, Kuroda M. Quantitative analysis of axon collaterals of single pyramidal cells of the anterior piriform cortex of the guinea pig. BMC Neurosci 2017; 18:25. [PMID: 28178946 PMCID: PMC5299671 DOI: 10.1186/s12868-017-0342-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 01/24/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The role of the piriform cortex (PC) in olfactory information processing remains largely unknown. The anterior part of the piriform cortex (APC) has been the focus of cortical-level studies of olfactory coding, and associative processes have attracted considerable attention as an important part in odor discrimination and olfactory information processing. Associational connections of pyramidal cells in the guinea pig APC were studied by direct visualization of axons stained and quantitatively analyzed by intracellular biocytin injection in vivo. RESULTS The observations illustrated that axon collaterals of the individual cells were widely and spatially distributed within the PC, and sometimes also showed a long associational projection to the olfactory bulb (OB). The data showed that long associational axons were both rostrally and caudally directed throughout the PC, and the intrinsic associational fibers of pyramidal cells in the APC are omnidirectional connections in the PC. Within the PC, associational axons typically followed rather linear trajectories and irregular bouton distributions. Quantitative data of the axon collaterals of two pyramidal cells in the APC showed that the average length of axonal collaterals was 101 mm, out of which 79 mm (78% of total length) were distributed in the PC. The average number of boutons was 8926 and 7101, respectively, with 79% of the total number of boutons being distributed in the PC. The percentage of the total area of the APC and the posterior piriform cortex occupied by the average distribution region of the axon collaterals of two superficial pyramidal (SP) cells was about 18 and 5%, respectively. CONCLUSION Our results demonstrate that omnidirectional connection of pyramidal cells in the APC provides a substrate for recurrent processes. These findings indicate that the axon collaterals of SP cells in the PC could make synaptic contacts with all granule cells in the OB. This study provides the morphological evidence for understanding the mechanisms of information processing and associative memory in the APC.
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Affiliation(s)
- Junli Yang
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.
- Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan.
| | - Gerhard Litscher
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.
- Research Unit for Complementary and Integrative Laser Medicine, Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, and TCM Research Center Graz, Medical University of Graz, 8036, Graz, Austria.
| | - Zhongren Sun
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.
| | - Qiang Tang
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China
| | - Kiyoshi Kishi
- Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan
| | - Satoko Oda
- Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan
| | - Masaaki Takayanagi
- Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan
| | - Zemin Sheng
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China
- Privatclinic Lassnitzhoehe, 8301, Lassnitzhoehe, Austria
| | - Yang Liu
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China
| | - Wenhai Guo
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China
| | - Ting Zhang
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China
| | - Lu Wang
- Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China
- Research Unit for Complementary and Integrative Laser Medicine, Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, and TCM Research Center Graz, Medical University of Graz, 8036, Graz, Austria
| | - Ingrid Gaischek
- Research Unit for Complementary and Integrative Laser Medicine, Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, and TCM Research Center Graz, Medical University of Graz, 8036, Graz, Austria
| | - Daniela Litscher
- Research Unit for Complementary and Integrative Laser Medicine, Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, and TCM Research Center Graz, Medical University of Graz, 8036, Graz, Austria
| | - Irmgard Th Lippe
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, 8036, Graz, Austria
| | - Masaru Kuroda
- Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan
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25
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Wilson DA, Best AR, Sullivan RM. Plasticity in the Olfactory System: Lessons for the Neurobiology of Memory. Neuroscientist 2016; 10:513-24. [PMID: 15534037 PMCID: PMC1868530 DOI: 10.1177/1073858404267048] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We are rapidly advancing toward an understanding of the molecular events underlying odor transduction, mechanisms of spatiotemporal central odor processing, and neural correlates of olfactory perception and cognition. A thread running through each of these broad components that define olfaction appears to be their dynamic nature. How odors are processed, at both the behavioral and neural level, is heavily dependent on past experience, current environmental context, and internal state. The neural plasticity that allows this dynamic processing is expressed nearly ubiquitously in the olfactory pathway, from olfactory receptor neurons to the higher-order cortex, and includes mechanisms ranging from changes in membrane excitability to changes in synaptic efficacy to neurogenesis and apoptosis. This review will describe recent findings regarding plasticity in the mammalian olfactory system that are believed to have general relevance for understanding the neurobiology of memory.
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Affiliation(s)
- D A Wilson
- Department of Zoology, University of Oklahoma, Norman, OK 73019, USA.
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26
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Abstract
Object recognition is a crucial component of both visual and auditory perception. It is also critical for olfaction. Most odours are composed of 10s or 100s of volatile components, yet they are perceived as unitary perceptual events against a continually shifting olfactory background (ie figure—ground segregation). We argue here that this occurs by rapid central adaptation to background odours combined with a pattern-matching system to recognise discrete sets of spatial and temporal olfactory features—an odour object. We present supporting neuropsychological, learning, and developmental evidence and then describe the neural circuitry which underpins this. The vagaries of an object-recognition approach are then discussed, with emphasis on the putative importance of memory, multimodal representations, and top—down processing.
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Affiliation(s)
| | - Donald A Wilson
- Department of Zoology, University of Oklahoma, Norman, OK 73019, USA
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27
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Fournel A, Ferdenzi C, Sezille C, Rouby C, Bensafi M. Multidimensional representation of odors in the human olfactory cortex. Hum Brain Mapp 2016; 37:2161-72. [PMID: 26991044 DOI: 10.1002/hbm.23164] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/09/2016] [Accepted: 02/18/2016] [Indexed: 11/09/2022] Open
Abstract
What is known as an odor object is an integrated representation constructed from physical features, and perceptual attributes mainly mediated by the olfactory and trigeminal systems. The aim of the present study was to comprehend how this multidimensional representation is organized, by deciphering how similarities in the physical, olfactory and trigeminal perceptual spaces of odors are represented in the human brain. To achieve this aim, we combined psychophysics, functional MRI and multivariate representational similarity analysis. Participants were asked to smell odors diffused by an fMRI-compatible olfactometer and to rate each smell along olfactory dimensions (pleasantness, intensity, familiarity and edibility) and trigeminal dimensions (irritation, coolness, warmth and pain). An event-related design was implemented, presenting different odorants. Results revealed that (i) pairwise odorant similarities in anterior piriform cortex (PC) activity correlated with pairwise odorant similarities in chemical properties (P < 0.005), (ii) similarities in posterior PC activity correlated with similarities in olfactory perceptual properties (P <0.01), and (iii) similarities in amygdala activity correlated with similarities in trigeminal perceptual properties (P < 0.01). These findings provide new evidence that extraction of physical, olfactory and trigeminal features is based on specific fine processing of similarities between odorous stimuli in a distributed manner in the olfactory system. Hum Brain Mapp 37:2161-2172, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- A Fournel
- Lyon Neuroscience Research Center, CNRS UMR5292, INSERM U1028, University Lyon, F-69000, France
| | - C Ferdenzi
- Lyon Neuroscience Research Center, CNRS UMR5292, INSERM U1028, University Lyon, F-69000, France
| | - C Sezille
- Lyon Neuroscience Research Center, CNRS UMR5292, INSERM U1028, University Lyon, F-69000, France
| | - C Rouby
- Lyon Neuroscience Research Center, CNRS UMR5292, INSERM U1028, University Lyon, F-69000, France
| | - M Bensafi
- Lyon Neuroscience Research Center, CNRS UMR5292, INSERM U1028, University Lyon, F-69000, France
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28
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Sato T, Kajiwara R, Takashima I, Iijima T. A novel method for quantifying similarities between oscillatory neural responses in wavelet time-frequency power profiles. Brain Res 2016; 1636:107-117. [PMID: 26855257 DOI: 10.1016/j.brainres.2016.01.054] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 01/16/2016] [Accepted: 01/29/2016] [Indexed: 11/29/2022]
Abstract
Quantifying similarities and differences between neural response patterns is an important step in understanding neural coding in sensory systems. It is difficult, however, to compare the degree of similarity among transient oscillatory responses. We developed a novel method of wavelet correlation analysis for quantifying similarity between transient oscillatory responses, and tested the method with olfactory cortical responses. In the anterior piriform cortex (aPC), the largest area of the primary olfactory cortex, odors induce inhibitory activities followed by transient oscillatory local field potentials (osci-LFPs). Qualitatively, the resulting time courses of osci-LFPs for identical odors were modestly different. We then compared several methods for quantifying the similarity between osci-LFPs for identical or different odors. Using fast Fourier transform band-pass filters, a conventional method demonstrated high correlations of the 0-2Hz components for both identical and different odors. None of the conventional methods tested demonstrated a clear correlation between osci-LFPs. However, wavelet correlation analysis resolved a stimulus dependency of 2-45Hz osci-LFPs in the aPC output layer, and produced experience-dependent high correlations in the input layer between some of the identical or different odors. These results suggest that redundancy in the neural representation of sensory information may change in the aPC. This wavelet correlation analysis may be useful for quantifying the similarities of transient oscillatory neural responses.
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Affiliation(s)
- Takaaki Sato
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda 563-8577, Japan.
| | - Riichi Kajiwara
- School of Science and Technology, Meiji University, Kawasaki 214-8571, Japan
| | - Ichiro Takashima
- Human Technology Research Institute, AIST, Tsukuba 305-8568, Japan
| | - Toshio Iijima
- Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
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29
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Experience shapes our odor perception but depends on the initial perceptual processing of the stimulus. Atten Percept Psychophys 2015; 77:1794-806. [PMID: 25832188 DOI: 10.3758/s13414-015-0883-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The questions of whether configural and elemental perceptions are competitive or exclusive perceptual processes and whether they rely on independent or dependent mechanisms are poorly understood. To examine these questions, we modified perceptual experience through preexposure to mixed or single odors and measured the resulting variation in the levels of configural and elemental perception of target odor mixtures. We used target mixtures that were spontaneously processed in a configural or an elemental manner. The AB binary mixture spontaneously involved the configural perception of a pineapple odor, whereas component A smelled like strawberry and component B smelled like caramel. The CD mixture produced the elemental perceptions of banana (C) and smoky (D) odors. Perceptual experience was manipulated through repeated exposure to either a mixture (AB or CD) or the components (A and B or C and D). The odor typicality rating data recorded after exposure revealed different influences of experience on odor mixtures and single-component perception, depending both on the type of exposure (components or mixture) and the mixture's initial perceptual property (configural or elemental). Although preexposure to A and B decreased the pineapple typicality of the configural AB mixture, preexposure to AB did not modify its odor quality. In contrast, preexposure to the CD elemental mixture induced a quality transfer between the components. These results emphasize the relative plasticity of odor mixture perception, which is prone to experience-induced modulations but depends on the stimulus's initial perceptual properties, suggesting that configural and elemental forms of odor mixture perception rely on rather independent processes.
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Karunanayaka PR, Wilson DA, Vasavada M, Wang J, Martinez B, Tobia MJ, Kong L, Eslinger P, Yang QX. Rapidly acquired multisensory association in the olfactory cortex. Brain Behav 2015; 5:e00390. [PMID: 26664785 PMCID: PMC4667761 DOI: 10.1002/brb3.390] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 07/31/2015] [Accepted: 08/09/2015] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The formation of an odor percept in humans is strongly associated with visual information. However, much less is known about the roles of learning and memory in shaping the multisensory nature of odor representations in the brain. METHOD The dynamics of odor and visual association in olfaction was investigated using three functional magnetic resonance imaging (fMRI) paradigms. In two paradigms, a visual cue was paired with an odor. In the third, the same visual cue was never paired with an odor. In this experimental design, if the visual cue was not influenced by odor-visual pairing, then the blood-oxygen-level-dependent (BOLD) signal elicited by subsequent visual cues should be similar across all three paradigms. Additionally, intensity, a major dimension of odor perception, was used as a modulator of associative learning which was characterized in terms of the spatiotemporal behavior of the BOLD signal in olfactory structures. RESULTS A single odor-visual pairing cue could subsequently induce primary olfactory cortex activity when only the visual cue was presented. This activity was intensity dependent and was also detected in secondary olfactory structures and hippocampus. CONCLUSION This study provides evidence for a rapid learning response in the olfactory system by a visual cue following odor and visual cue pairing. The novel data and paradigms suggest new avenues to explore the dynamics of odor learning and multisensory representations that contribute to the construction of a unified odor percept in the human brain.
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Affiliation(s)
- Prasanna R Karunanayaka
- Department of Radiology (Center for NMR Research) The Pennsylvania State University College of Medicine Hershey Pennsylvania
| | - Donald A Wilson
- Emotional Brain Institute Nathan S. Kline Institute for Psychiatric Research Orangeburg New York ; Department of Child & Adolescent Psychiatry New York University School of Medicine New York City New York
| | - Megha Vasavada
- Department of Radiology (Center for NMR Research) The Pennsylvania State University College of Medicine Hershey Pennsylvania
| | - Jianli Wang
- Department of Radiology (Center for NMR Research) The Pennsylvania State University College of Medicine Hershey Pennsylvania
| | - Brittany Martinez
- Department of Radiology (Center for NMR Research) The Pennsylvania State University College of Medicine Hershey Pennsylvania
| | - Michael J Tobia
- Department of Radiology (Center for NMR Research) The Pennsylvania State University College of Medicine Hershey Pennsylvania
| | - Lan Kong
- Department of Public Health Sciences The Pennsylvania State University College of Medicine Hershey Pennsylvania
| | - Paul Eslinger
- Department of Radiology (Center for NMR Research) The Pennsylvania State University College of Medicine Hershey Pennsylvania ; Department of Neurology The Pennsylvania State University College of Medicine Hershey Pennsylvania
| | - Qing X Yang
- Department of Radiology (Center for NMR Research) The Pennsylvania State University College of Medicine Hershey Pennsylvania ; Department of Neurosurgery The Pennsylvania State University College of Medicine Hershey Pennsylvania
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Kass MD, Guang SA, Moberly AH, McGann JP. Changes in Olfactory Sensory Neuron Physiology and Olfactory Perceptual Learning After Odorant Exposure in Adult Mice. Chem Senses 2015; 41:123-33. [PMID: 26514410 DOI: 10.1093/chemse/bjv065] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The adult olfactory system undergoes experience-dependent plasticity to adapt to the olfactory environment. This plasticity may be accompanied by perceptual changes, including improved olfactory discrimination. Here, we assessed experience-dependent changes in the perception of a homologous aldehyde pair by testing mice in a cross-habituation/dishabituation behavioral paradigm before and after a week-long ester-odorant exposure protocol. In a parallel experiment, we used optical neurophysiology to observe neurotransmitter release from olfactory sensory neuron (OSN) terminals in vivo, and thus compared primary sensory representations of the aldehydes before and after the week-long ester-odorant exposure in individual animals. Mice could not discriminate between the aldehydes during pre-exposure testing, but ester-exposed subjects spontaneously discriminated between the homologous pair after exposure, whereas home cage control mice cross-habituated. Ester exposure did not alter the spatial pattern, peak magnitude, or odorant-selectivity of aldehyde-evoked OSN input to olfactory bulb glomeruli, but did alter the temporal dynamics of that input to make the time course of OSN input more dissimilar between odorants. Together, these findings demonstrate that odor exposure can induce both physiological and perceptual changes in odor processing, and suggest that changes in the temporal patterns of OSN input to olfactory bulb glomeruli could induce differences in odor quality.
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Affiliation(s)
- Marley D Kass
- Behavioral & Systems Neuroscience Section, Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ 08854, USA
| | - Stephanie A Guang
- Behavioral & Systems Neuroscience Section, Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ 08854, USA
| | - Andrew H Moberly
- Behavioral & Systems Neuroscience Section, Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ 08854, USA
| | - John P McGann
- Behavioral & Systems Neuroscience Section, Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ 08854, USA
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Coureaud G, Thomas-Danguin T, Wilson DA, Ferreira G. Neonatal representation of odour objects: distinct memories of the whole and its parts. Proc Biol Sci 2015; 281:20133319. [PMID: 24990670 DOI: 10.1098/rspb.2013.3319] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Extraction of relevant information from highly complex environments is a prerequisite to survival. Within odour mixtures, such information is contained in the odours of specific elements or in the mixture configuration perceived as a whole unique odour. For instance, an AB mixture of the element A (ethyl isobutyrate) and the element B (ethyl maltol) generates a configural AB percept in humans and apparently in another species, the rabbit. Here, we examined whether the memory of such a configuration is distinct from the memory of the individual odorants. Taking advantage of the newborn rabbit's ability to learn odour mixtures, we combined behavioural and pharmacological tools to specifically eliminate elemental memory of A and B after conditioning to the AB mixture and evaluate consequences on configural memory of AB. The amnesic treatment suppressed responsiveness to A and B but not to AB. Two other experiments confirmed the specific perception and particular memory of the AB mixture. These data demonstrate the existence of configurations in certain odour mixtures and their representation as unique objects: after learning, animals form a configural memory of these mixtures, which coexists with, but is relatively dissociated from, memory of their elements. This capability emerges very early in life.
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Affiliation(s)
- Gérard Coureaud
- Centre des Sciences du Goût et de l'Alimentation (CSGA), UMR 6265 CNRS, UMR 1324 INRA, Université de Bourgogne, 9E Boulevard Jeanne d'Arc, 21000 Dijon, France
| | - Thierry Thomas-Danguin
- Centre des Sciences du Goût et de l'Alimentation (CSGA), UMR 6265 CNRS, UMR 1324 INRA, Université de Bourgogne, 9E Boulevard Jeanne d'Arc, 21000 Dijon, France
| | - Donald A Wilson
- Department of Child and Adolescent Psychiatry, New York University Langone School of Medicine, New York, NY 10016, USA
| | - Guillaume Ferreira
- Nutrition and Integrative Neurobiology group, INRA UMR 1286, 33000 Bordeaux, France Université de Bordeaux, 33000 Bordeaux, France
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Romagny S, Thomas-Danguin T, Coureaud G. Configural processing of odor mixture: Does the learning of elements prevent the perception of configuration in the newborn rabbit? Physiol Behav 2015; 142:161-9. [DOI: 10.1016/j.physbeh.2015.02.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/04/2015] [Accepted: 02/10/2015] [Indexed: 10/24/2022]
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Coureaud G, Thomas-Danguin T, Datiche F, Wilson DA, Ferreira G. Differential memory persistence of odor mixture and components in newborn rabbits: competition between the whole and its parts. Front Behav Neurosci 2014; 8:211. [PMID: 24982622 PMCID: PMC4059275 DOI: 10.3389/fnbeh.2014.00211] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 05/26/2014] [Indexed: 12/02/2022] Open
Abstract
Interacting with the mother during the daily nursing, newborn rabbits experience her body odor cues. In particular, the mammary pheromone (MP) contained in rabbit milk triggers the typical behavior which helps to localize and seize the nipples. It also promotes the very rapid appetitive learning of simple or complex stimuli (odorants or mixtures) through associative conditioning. We previously showed that 24 h after MP-induced conditioning to odorants A (ethyl isobutyrate) or B (ethyl maltol), newborn rabbits perceive the AB mixture in a weak configural way, i.e., they perceive the odor of the AB configuration in addition to the odors of the elements. Moreover, after conditioning to the mixture, elimination of the memories of A and B does not affect the memory of AB, suggesting independent elemental and configural memories of the mixture. Here, we evaluated whether configural memory persistence differs from elemental one. First, whereas 1 or 3-day-old pups conditioned to A or B maintained their responsiveness to the conditioned odorant for 4 days, those conditioned to AB did not respond to the mixture after the same retention period. Second, the pups conditioned to AB still responded to A and B 4 days after conditioning, which indicates stronger retention of the elements than of the configuration when all information are learned together. Third, we determined whether the memory of the elements competes with the memory of the configuration: after conditioning to AB, when the memories of A and B were erased using pharmacological treatment, the memory of the mixture was extended to day 5. Thus, newborn rabbits have access to both elemental and configural information in certain odor mixtures, and competition between these distinct representations of the mixture influences the persistence of their memories. Such effects certainly occur in the natural context of mother-pup interactions and may contribute to early acquisition of knowledge about the surroundings.
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Affiliation(s)
- Gérard Coureaud
- Centre des Sciences du Goût et de l'Alimentation (CSGA), UMR 6265 CNRS, UMR 1324 INRA, Université de Bourgogne Dijon, France
| | - Thierry Thomas-Danguin
- Centre des Sciences du Goût et de l'Alimentation (CSGA), UMR 6265 CNRS, UMR 1324 INRA, Université de Bourgogne Dijon, France
| | - Frédérique Datiche
- Centre des Sciences du Goût et de l'Alimentation (CSGA), UMR 6265 CNRS, UMR 1324 INRA, Université de Bourgogne Dijon, France
| | - Donald A Wilson
- Department of Child and Adolescent Psychiatry, New York University Langone School of Medicine New York, NY, USA
| | - Guillaume Ferreira
- Nutrition and Integrative Neurobiology Group, INRA UMR 1286 Bordeaux, France ; Université de Bordeaux Bordeaux, France
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Cellular registration without behavioral recall of olfactory sensory input under general anesthesia. Anesthesiology 2014; 120:890-905. [PMID: 24694846 DOI: 10.1097/aln.0000000000000137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Previous studies suggest that sensory information is "received" but not "perceived" under general anesthesia. Whether and to what extent the brain continues to process sensory inputs in a drug-induced unconscious state remain unclear. METHODS One hundred seven rats were randomly assigned to 12 different anesthesia and odor exposure paradigms. The immunoreactivities of the immediate early gene products c-Fos and Egr1 as neural activity markers were combined with behavioral tests to assess the integrity and relationship of cellular and behavioral responsiveness to olfactory stimuli under a surgical plane of ketamine-xylazine general anesthesia. RESULTS The olfactory sensory processing centers could distinguish the presence or absence of experimental odorants even when animals were fully anesthetized. In the anesthetized state, the c-Fos immunoreactivity in the higher olfactory cortices revealed a difference between novel and familiar odorants similar to that seen in the awake state, suggesting that the anesthetized brain functions beyond simply receiving external stimulation. Reexposing animals to odorants previously experienced only under anesthesia resulted in c-Fos immunoreactivity, which was similar to that elicited by familiar odorants, indicating that previous registration had occurred in the anesthetized brain. Despite the "cellular memory," however, odor discrimination and forced-choice odor-recognition tests showed absence of behavioral recall of the registered sensations, except for a longer latency in odor recognition tests. CONCLUSIONS Histologically distinguishable registration of sensory processing continues to occur at the cellular level under ketamine-xylazine general anesthesia despite the absence of behavioral recognition, consistent with the notion that general anesthesia causes disintegration of information processing without completely blocking cellular communications.
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Thomas-Danguin T, Sinding C, Romagny S, El Mountassir F, Atanasova B, Le Berre E, Le Bon AM, Coureaud G. The perception of odor objects in everyday life: a review on the processing of odor mixtures. Front Psychol 2014; 5:504. [PMID: 24917831 PMCID: PMC4040494 DOI: 10.3389/fpsyg.2014.00504] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 05/08/2014] [Indexed: 11/13/2022] Open
Abstract
Smelling monomolecular odors hardly ever occurs in everyday life, and the daily functioning of the sense of smell relies primarily on the processing of complex mixtures of volatiles that are present in the environment (e.g., emanating from food or conspecifics). Such processing allows for the instantaneous recognition and categorization of smells and also for the discrimination of odors among others to extract relevant information and to adapt efficiently in different contexts. The neurophysiological mechanisms underpinning this highly efficient analysis of complex mixtures of odorants is beginning to be unraveled and support the idea that olfaction, as vision and audition, relies on odor-objects encoding. This configural processing of odor mixtures, which is empirically subject to important applications in our societies (e.g., the art of perfumers, flavorists, and wine makers), has been scientifically studied only during the last decades. This processing depends on many individual factors, among which are the developmental stage, lifestyle, physiological and mood state, and cognitive skills; this processing also presents striking similarities between species. The present review gathers the recent findings, as observed in animals, healthy subjects, and/or individuals with affective disorders, supporting the perception of complex odor stimuli as odor objects. It also discusses peripheral to central processing, and cognitive and behavioral significance. Finally, this review highlights that the study of odor mixtures is an original window allowing for the investigation of daily olfaction and emphasizes the need for knowledge about the underlying biological processes, which appear to be crucial for our representation and adaptation to the chemical environment.
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Affiliation(s)
- Thierry Thomas-Danguin
- Centre des Sciences du Goût et de l'Alimentation, CNRS UMR6265, INRA UMR1324, Université de Bourgogne Dijon, France
| | - Charlotte Sinding
- Smell and Taste Clinic, Department of Otorhinolaryngoly TU Dresden, Dresden, Germany
| | - Sébastien Romagny
- Centre des Sciences du Goût et de l'Alimentation, CNRS UMR6265, INRA UMR1324, Université de Bourgogne Dijon, France
| | - Fouzia El Mountassir
- Centre des Sciences du Goût et de l'Alimentation, CNRS UMR6265, INRA UMR1324, Université de Bourgogne Dijon, France
| | | | | | - Anne-Marie Le Bon
- Centre des Sciences du Goût et de l'Alimentation, CNRS UMR6265, INRA UMR1324, Université de Bourgogne Dijon, France
| | - Gérard Coureaud
- Centre des Sciences du Goût et de l'Alimentation, CNRS UMR6265, INRA UMR1324, Université de Bourgogne Dijon, France
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Barnes DC, Wilson DA. Sleep and olfactory cortical plasticity. Front Behav Neurosci 2014; 8:134. [PMID: 24795585 PMCID: PMC4001050 DOI: 10.3389/fnbeh.2014.00134] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 04/03/2014] [Indexed: 12/21/2022] Open
Abstract
In many systems, sleep plays a vital role in memory consolidation and synaptic homeostasis. These processes together help store information of biological significance and reset synaptic circuits to facilitate acquisition of information in the future. In this review, we describe recent evidence of sleep-dependent changes in olfactory system structure and function which contribute to odor memory and perception. During slow-wave sleep, the piriform cortex becomes hypo-responsive to odor stimulation and instead displays sharp-wave activity similar to that observed within the hippocampal formation. Furthermore, the functional connectivity between the piriform cortex and other cortical and limbic regions is enhanced during slow-wave sleep compared to waking. This combination of conditions may allow odor memory consolidation to occur during a state of reduced external interference and facilitate association of odor memories with stored hedonic and contextual cues. Evidence consistent with sleep-dependent odor replay within olfactory cortical circuits is presented. These data suggest that both the strength and precision of odor memories is sleep-dependent. The work further emphasizes the critical role of synaptic plasticity and memory in not only odor memory but also basic odor perception. The work also suggests a possible link between sleep disturbances that are frequently co-morbid with a wide range of pathologies including Alzheimer's disease, schizophrenia and depression and the known olfactory impairments associated with those disorders.
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Affiliation(s)
- Dylan C. Barnes
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric ResearchOrangeburg, NY, USA
- Behavioral and Cognitive Neuroscience Program, City University of New YorkNew York, NY, USA
- Department of Biology, University of OklahomaNorman, OK, USA
| | - Donald A. Wilson
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric ResearchOrangeburg, NY, USA
- Behavioral and Cognitive Neuroscience Program, City University of New YorkNew York, NY, USA
- Department of Biology, University of OklahomaNorman, OK, USA
- Department of Child and Adolescent Psychiatry, New York University Langone School of MedicineNew York, NY, USA
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Royet JP, Plailly J, Saive AL, Veyrac A, Delon-Martin C. The impact of expertise in olfaction. Front Psychol 2013; 4:928. [PMID: 24379793 PMCID: PMC3861696 DOI: 10.3389/fpsyg.2013.00928] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 11/23/2013] [Indexed: 11/21/2022] Open
Abstract
Olfactory expertise remains poorly understood, most likely because experts in odor, such as perfumers, sommeliers, and oenologists, are much rarer than experts in other modalities, such as musicians or sportsmen. In this review, we address the specificities of odor expertise in both odor experts and in a priori untrained individuals who have undergone specific olfactory training in the frame of an experiment, such as repeated exposure to odors or associative learning. Until the 21st century, only the behavioral effects of olfactory training of untrained control individuals had been reported, revealing an improvement of olfactory performance in terms of sensitivity, discrimination, memory, and identification. Behavioral studies of odor experts have been scarce, with inconsistent or inconclusive results. Recently, the development of cerebral imaging techniques has enabled the identification of brain areas and neural networks involved in odor processing, revealing functional and structural modifications as a function of experience. The behavioral approach to odor expertise has also evolved. Researchers have particularly focused on odor mental imagery, which is characteristic of odor experts, because this ability is absent in the average person but is part of a perfumer’s professional practice. This review summarizes behavioral, functional, and structural findings on odor expertise. These data are compared with those obtained using animals subjected to prolonged olfactory exposure or to olfactory-enriched environments and are discussed in the context of functional and structural plasticity.
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Affiliation(s)
- Jean-Pierre Royet
- Olfaction: From Coding to Memory Team, Centre de Recherche en Neurosciences de Lyon, CNRS UMR 5292, INSERM U1028, Université Lyon 1 Lyon, France
| | - Jane Plailly
- Olfaction: From Coding to Memory Team, Centre de Recherche en Neurosciences de Lyon, CNRS UMR 5292, INSERM U1028, Université Lyon 1 Lyon, France
| | - Anne-Lise Saive
- Olfaction: From Coding to Memory Team, Centre de Recherche en Neurosciences de Lyon, CNRS UMR 5292, INSERM U1028, Université Lyon 1 Lyon, France
| | - Alexandra Veyrac
- Olfaction: From Coding to Memory Team, Centre de Recherche en Neurosciences de Lyon, CNRS UMR 5292, INSERM U1028, Université Lyon 1 Lyon, France
| | - Chantal Delon-Martin
- INSERM, U836, NeuroImagerie Fonctionnelle et Perfusion Cerebrale Grenoble, France ; Université Joseph Fourier, Grenoble Institut des Neurosciences Grenoble, France
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40
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Giessel AJ, Datta SR. Olfactory maps, circuits and computations. Curr Opin Neurobiol 2013; 24:120-32. [PMID: 24492088 DOI: 10.1016/j.conb.2013.09.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 09/06/2013] [Accepted: 09/20/2013] [Indexed: 11/17/2022]
Abstract
Sensory information in the visual, auditory and somatosensory systems is organized topographically, with key sensory features ordered in space across neural sheets. Despite the existence of a spatially stereotyped map of odor identity within the olfactory bulb, it is unclear whether the higher olfactory cortex uses topography to organize information about smells. Here, we review recent work on the anatomy, microcircuitry and neuromodulation of two higher-order olfactory areas: the piriform cortex and the olfactory tubercle. The piriform is an archicortical region with an extensive local associational network that constructs representations of odor identity. The olfactory tubercle is an extension of the ventral striatum that may use reward-based learning rules to encode odor valence. We argue that in contrast to brain circuits for other sensory modalities, both the piriform and the olfactory tubercle largely discard any topography present in the bulb and instead use distributive afferent connectivity, local learning rules and input from neuromodulatory centers to build behaviorally relevant representations of olfactory stimuli.
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Affiliation(s)
- Andrew J Giessel
- Harvard Medical School, Department of Neurobiology, 220 Longwood Avenue, Boston, MA 02115, United States
| | - Sandeep Robert Datta
- Harvard Medical School, Department of Neurobiology, 220 Longwood Avenue, Boston, MA 02115, United States.
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Wass C, Pizzo A, Sauce B, Kawasumi Y, Sturzoiu T, Ree F, Otto T, Matzel LD. Dopamine D1 sensitivity in the prefrontal cortex predicts general cognitive abilities and is modulated by working memory training. Learn Mem 2013; 20:617-27. [PMID: 24129098 PMCID: PMC3799419 DOI: 10.1101/lm.031971.113] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A common source of variance (i.e., “general intelligence”) underlies an individual's performance across diverse tests of cognitive ability, and evidence indicates that the processing efficacy of working memory may serve as one such source of common variance. One component of working memory, selective attention, has been reported to co-vary with general intelligence, and dopamine D1 signaling in prefrontal cortex can modulate attentional abilities. Based on their aggregate performance across five diverse tests of learning, here we characterized the general cognitive ability (GCA) of CD-1 outbred mice. In response to a D1 agonist (SKF82958, 1 mg/kg), we then assessed the relationship between GCA and activation of D1 receptor (D1R)-containing neurons in the prelimbic region of the medial prefrontal cortex, the agranular insular cortex, and the dorsomedial striatum. Increased activation of D1R-containing neurons in the prelimbic cortex (but not the agranular insular cortex or dorsomedial striatum) was observed in animals of high GCA relative to those of low GCA (quantified by c-Fos activation in response to the D1 agonist). However, a Western blot analysis revealed no differences in the density of D1Rs in the prelimbic cortex between animals of high and low GCA. Last, it was observed that working memory training promoted an increase in animals’ GCA and enhanced D1R-mediated neuronal activation in the prelimbic cortex. These results suggest that the sensitivity (but not density) of D1Rs in the prelimbic cortex may both regulate GCA and be a target for working memory training.
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Affiliation(s)
- Christopher Wass
- Department of Psychology, Rutgers University, Piscataway, New Jersey 08854, USA
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Abstract
The main olfactory system encodes information about molecules in a combinatorial fashion by distributed spatiotemporal activity patterns. As activity propagates from sensory neurons to the olfactory bulb and to higher brain areas, odor information is processed by multiple transformations of these activity patterns. This review discusses neuronal computations associated with such transformations in the olfactory system of zebrafish, a small vertebrate that offers advantages for the quantitative analysis and manipulation of neuronal activity in the intact brain. The review focuses on pattern decorrelation in the olfactory bulb and on the readout of multiplexed sensory representations in the telencephalic area Dp, the homolog of the olfactory cortex. These computations are difficult to study in larger species and may provide insights into general information-processing strategies in the brain.
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Affiliation(s)
- Rainer W Friedrich
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.
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Neurons and circuits for odor processing in the piriform cortex. Trends Neurosci 2013; 36:429-38. [PMID: 23648377 DOI: 10.1016/j.tins.2013.04.005] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 04/04/2013] [Accepted: 04/04/2013] [Indexed: 01/13/2023]
Abstract
Increased understanding of the early stages of olfaction has lead to a renewed interest in the higher brain regions responsible for forming unified 'odor images' from the chemical components detected by the nose. The piriform cortex, which is one of the first cortical destinations of olfactory information in mammals, is a primitive paleocortex that is critical for the synthetic perception of odors. Here we review recent work that examines the cellular neurophysiology of the piriform cortex. Exciting new findings have revealed how the neurons and circuits of the piriform cortex process odor information, demonstrating that, despite its superficial simplicity, the piriform cortex is a remarkably subtle and intricate neural circuit.
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Garske AK, Lawyer CR, Peterson BM, Illig KR. Adolescent changes in dopamine D1 receptor expression in orbitofrontal cortex and piriform cortex accompany an associative learning deficit. PLoS One 2013; 8:e56191. [PMID: 23437091 PMCID: PMC3578843 DOI: 10.1371/journal.pone.0056191] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 01/07/2013] [Indexed: 11/30/2022] Open
Abstract
The orbitofrontal cortex (OFC) and piriform cortex are involved in encoding the predictive value of olfactory stimuli in rats, and neural responses to olfactory stimuli in these areas change as associations are learned. This experience-dependent plasticity mirrors task-related changes previously observed in mesocortical dopamine neurons, which have been implicated in learning the predictive value of cues. Although forms of associative learning can be found at all ages, cortical dopamine projections do not mature until after postnatal day 35 in the rat. We hypothesized that these changes in dopamine circuitry during the juvenile and adolescent periods would result in age-dependent differences in learning the predictive value of environmental cues. Using an odor-guided associative learning task, we found that adolescent rats learn the association between an odor and a palatable reward significantly more slowly than either juvenile or adult rats. Further, adolescent rats displayed greater distractibility during the task than either juvenile or adult rats. Using real-time quantitative PCR and immunohistochemical methods, we observed that the behavioral deficit in adolescence coincides with a significant increase in D1 dopamine receptor expression compared to juvenile rats in both the OFC and piriform cortex. Further, we found that both the slower learning and increased distractibility exhibited in adolescence could be alleviated by experience with the association task as a juvenile, or by an acute administration of a low dose of either the dopamine D1 receptor agonist SKF-38393 or the D2 receptor antagonist eticlopride. These results suggest that dopaminergic modulation of cortical function may be important for learning the predictive value of environmental stimuli, and that developmental changes in cortical dopaminergic circuitry may underlie age-related differences in associative learning.
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Affiliation(s)
- Anna K. Garske
- Department of Biology and Program in Neuroscience, University of St. Thomas, Saint Paul, Minnesota, United States of America
| | - Chloe R. Lawyer
- Department of Biology and Program in Neuroscience, University of St. Thomas, Saint Paul, Minnesota, United States of America
| | - Brittni M. Peterson
- Department of Biology and Program in Neuroscience, University of St. Thomas, Saint Paul, Minnesota, United States of America
| | - Kurt R. Illig
- Department of Biology and Program in Neuroscience, University of St. Thomas, Saint Paul, Minnesota, United States of America
- * E-mail:
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Sugai T, Yamamoto R, Yoshimura H, Kato N. Multimodal cross-talk of olfactory and gustatory information in the endopiriform nucleus in rats. Chem Senses 2012; 37:681-8. [PMID: 22490644 DOI: 10.1093/chemse/bjs046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The endopiriform nucleus (EPN) is a large group of multipolar cells located in the depth of the piriform cortex (PC). Although many studies have suggested that the EPN plays a role in temporal lobe epilepsy, the normal function of the EPN remains to be elucidated. By using optical imaging of coronal brain slice preparations with voltage-sensitive dye, we found signal propagation from the PC or gustatory cortex (GC) to the EPN in normal medium. In our previous research, we failed to elicit a reliable signal reproducibly in the EPN by single stimulation either to the PC or GC. In our current research, we found that a double-pulse stimulation to either the PC or GC (interpulse interval: 20-100 ms) induced robust signal propagation to the EPN through excitation in the agranular division of the insular cortex (AI), with further extension to the claustrum. Finally, double site paired-pulse stimulation to the PC and GC also evoked excitation in the AI, claustrum, and EPN. These results suggest that the EPN has dual roles: 1) further processing of modality-specific olfactory and gustatory information from the PC and GC, respectively and 2) synergistic integration of PC-derived olfactory information and GC-derived gustatory information.
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Affiliation(s)
- T Sugai
- Department of Physiology, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan.
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Bensafi M. The Role of the Piriform Cortex in Human Olfactory Perception: Insights from Functional Neuroimaging Studies. CHEMOSENS PERCEPT 2011. [DOI: 10.1007/s12078-011-9110-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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47
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Fletcher ML. Analytical processing of binary mixture information by olfactory bulb glomeruli. PLoS One 2011; 6:e29360. [PMID: 22206012 PMCID: PMC3243692 DOI: 10.1371/journal.pone.0029360] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 11/27/2011] [Indexed: 11/18/2022] Open
Abstract
Odors are rarely composed of a single compound, but rather contain a large and complex variety of chemical components. Often, these mixtures are perceived as having unique qualities that can be quite different than the combination of their components. In many cases, a majority of the components of a mixture cannot be individually identified. This synthetic processing of odor information suggests that individual component representations of the mixture must interact somewhere along the olfactory pathway. The anatomical nature of sensory neuron input into segregated glomeruli with the bulb suggests that initial input of odor information into the bulb is analytic. However, a large network of interneurons within the olfactory bulb could allow for mixture interactions via mechanisms such as lateral inhibition. Currently in mammals, it is unclear if postsynaptic mitral/tufted cell glomerular mixture responses reflect the analytical mixture input, or provide the initial basis for synthetic processing with the olfactory system. To address this, olfactory bulb glomerular binary mixture representations were compared to representations of each component using transgenic mice expressing the calcium indicator G-CaMP2 in olfactory bulb mitral/tufted cells. Overall, dorsal surface mixture representations showed little mixture interaction and often appeared as a simple combination of the component representations. Based on this, it is concluded that dorsal surface glomerular mixture representations remain largely analytical with nearly all component information preserved.
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Affiliation(s)
- Max L Fletcher
- Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas, United States of America.
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Abstract
Natural odors, generally composed of many monomolecular components, are analyzed by peripheral receptors into component features and translated into spatiotemporal patterns of neural activity in the olfactory bulb. Here, we will discuss the role of the olfactory cortex in the recognition, separation and completion of those odor-evoked patterns, and how these processes contribute to odor perception. Recent findings regarding the neural architecture, physiology, and plasticity of the olfactory cortex, principally the piriform cortex, will be described in the context of how this paleocortical structure creates odor objects.
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Affiliation(s)
- Donald A Wilson
- Emotional Brain Institute, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
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Chen CFF, Barnes DC, Wilson DA. Generalized vs. stimulus-specific learned fear differentially modifies stimulus encoding in primary sensory cortex of awake rats. J Neurophysiol 2011; 106:3136-44. [PMID: 21918001 DOI: 10.1152/jn.00721.2011] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Experience shapes both central olfactory system function and odor perception. In piriform cortex, odor experience appears critical for synthetic processing of odor mixtures, which contributes to perceptual learning and perceptual acuity, as well as contributing to memory for events and/or rewards associated with odors. Here, we examined the effect of odor fear conditioning on piriform cortical single-unit responses to the learned aversive odor, as well as its effects on similar (overlapping mixtures) in freely moving rats. We found that odor-evoked fear responses were training paradigm dependent. Simple association of a condition stimulus positive (CS+) odor with foot shock (unconditioned stimulus) led to generalized fear (cue-evoked freezing) to similar odors. However, after differential conditioning, which included trials where a CS- odor (a mixture overlapping with the CS+) was not paired with shock, freezing responses were CS+ odor specific and less generalized. Pseudoconditioning led to no odor-evoked freezing. These differential levels of stimulus control over freezing were associated with different training-induced changes in single-unit odor responses in anterior piriform cortex (aPCX). Both simple and differential conditioning induced a significant decrease in aPCX single-unit spontaneous activity compared with pretraining levels while pseudoconditioning did not. Simple conditioning enhanced mean receptive field size (breadth of tuning) of the aPCX units, while differential conditioning reduced mean receptive field size. These results suggest that generalized fear is associated with an impairment of olfactory cortical discrimination. Furthermore, changes in sensory processing are dependent on the nature of training and can predict the stimulus-controlled behavioral outcome of the training.
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Affiliation(s)
- Chien-Fu F Chen
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA.
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Wilson DA, Peterson J, Basavaraj BS, Saito M. Local and regional network function in behaviorally relevant cortical circuits of adult mice following postnatal alcohol exposure. Alcohol Clin Exp Res 2011; 35:1974-84. [PMID: 21649667 DOI: 10.1111/j.1530-0277.2011.01549.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Ethanol consumption during pregnancy can lead to fetal alcohol spectrum disorder (FASD), which consists of the complete spectrum of developmental deficits including neurological dysfunction. FASD is associated with a variety of neurobehavioral disturbances dependent on the age and duration of exposure. Ethanol exposure in neonatal rodents can also induce widespread apoptotic neurodegeneration and long-lasting behavioral abnormalities similar to FASD. The developmental stage of neonatal rodent brains that are at the peak of synaptogenesis is equivalent to the third trimester of human gestation. METHODS Male and female C57BL/6By mice were injected with ethanol (20%, 2.5 g/kg, 2 s.c. injections) or an equal volume of saline (controls) on postnatal day 7 (P7). Animals were allowed to mature and at 3 months were tested on an olfactory habituation task known to be dependent on piriform cortex function, a hippocampal-dependent object place memory task, and used for electrophysiological testing of spontaneous and odor-evoked local field potential (LFP) activity in the olfactory bulb, piriform cortex, and dorsal hippocampus. RESULTS P7 ethanol induced widespread cell death within 1 day of exposure, with highest levels in the neocortex, intermediate levels in the dorsal hippocampus, and relatively low levels in the primary olfactory system. No impairment of odor investigation or odor habituation was detected in P7 ethanol-exposed 3-month-old mice compared to saline controls. However, hippocampal-dependent object place memory was significantly impaired in the P7 ethanol-treated adult mice. Odor-evoked LFP activity was enhanced throughout the olfacto-hippocampal pathway, primarily within the theta frequency band, although the hippocampus also showed elevated evoked delta frequency activity. In addition, functional coherence between the piriform cortex and olfactory bulb and between the piriform cortex and dorsal hippocampus was enhanced in the beta frequency range in P7 ethanol-treated adult mice compared to controls. CONCLUSIONS P7 ethanol induces an immediate wave of regionally selective cell death followed by long-lasting changes in local circuit and regional network function that are accompanied by changes in neurobehavioral performance. The results suggest that both the activity of local neural circuits within a brain region and the flow of information between brain regions can be modified by early alcohol exposure, which may contribute to long-lasting behavioral abnormalities known to rely on those circuits.
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Affiliation(s)
- Donald A Wilson
- Emotional Brain Institute, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA.
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