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Sullivan RM, Opendak M. Defining Immediate Effects of Sensitive Periods on Infant Neurobehavioral Function. Curr Opin Behav Sci 2020; 36:106-114. [PMID: 33043102 PMCID: PMC7543993 DOI: 10.1016/j.cobeha.2020.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
During a sensitive period associated with attachment, the infant brain has unique circuitry that enables the specialized adaptive behaviors required for survival in infancy. This infant brain is not an immature version of the adult brain. Within the attachment relationship, the infant remains close (proximity seeking) to the caregiver for nurturing and survival needs, but the caregiver also provides the immature infant with the physiological regulation interaction needed before self-regulation matures. Here we provide examples from the human and animal literature that illustrate some of these regulatory functions during sensitive periods, recent advances demonstrating the supporting transient neural mechanisms, and how these systems go awry in the absence of species-expected caregiving.
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Affiliation(s)
- Regina M. Sullivan
- Emotional Brain Institute, Nathan Kline Institute, Child and Adolescent Psychiatry, New York University Langone Medical Center New York, NY USA
| | - Maya Opendak
- Emotional Brain Institute, Nathan Kline Institute, Child and Adolescent Psychiatry, New York University Langone Medical Center New York, NY USA
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2
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Direct Comparison of Odor Responses of Homologous Glomeruli in the Medial and Lateral Maps of the Mouse Olfactory Bulb. eNeuro 2020; 7:ENEURO.0449-19.2020. [PMID: 31974110 PMCID: PMC7073388 DOI: 10.1523/eneuro.0449-19.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/31/2019] [Accepted: 01/10/2020] [Indexed: 11/29/2022] Open
Abstract
Olfactory sensory neurons (OSNs) expressing same-type odorant receptors typically project to a pair of glomeruli in the medial and lateral sides of the olfactory bulbs (OBs) in rodents. This multiple glomerular representation of homologous inputs is considered to have more important functional roles for odor information processing than the redundant backup system. However, a consensus idea is lacking and this hinders interpretation of the phenomenon. In addition, the shared and unique odorant response properties of the homologous glomeruli remain unclear because the majority of medial glomeruli are hidden in the septal OB, and thus it is difficult to directly compare them. OSNs, which express trace amine-associated odorant receptors (TAARs), were recently identified that project to a pair of glomeruli uniquely located in the dorsal OB. In this study, we measured the odorant-induced calcium responses of homologous pairs of TAAR glomeruli simultaneously in anesthetized mice and directly compared their response patterns. We found that they exhibited similar temporal response patterns and could not find differences in onset latency, rise time, decay time, or response amplitude. However, the medial glomeruli had significantly larger respiration-locked calcium fluctuations than the lateral glomeruli. This trend was observed with/without odorant stimulation in postsynaptic neurons of GABAergic, dopaminergic, and mitral/tufted cells, but not in presynaptic olfactory sensory axon terminals. This indicates that, at least in these TAAR glomeruli, the medial rather than the lateral OB map enhances the respiration-locked rhythm and transfers this information to higher brain centers.
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Learning-Dependent and -Independent Enhancement of Mitral/Tufted Cell Glomerular Odor Responses Following Olfactory Fear Conditioning in Awake Mice. J Neurosci 2018; 38:4623-4640. [PMID: 29669746 DOI: 10.1523/jneurosci.3559-17.2018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/02/2018] [Accepted: 04/10/2018] [Indexed: 01/25/2023] Open
Abstract
Associative fear learning produces fear toward the conditioned stimulus (CS) and often generalization, the expansion of fear from the CS to similar, unlearned stimuli. However, how fear learning affects early sensory processing of learned and unlearned stimuli in relation to behavioral fear responses to these stimuli remains unclear. We subjected male and female mice expressing the fluorescent calcium indicator GCaMP3 in olfactory bulb mitral and tufted cells to a classical olfactory fear conditioning paradigm. We then used awake, in vivo calcium imaging to quantify learning-induced changes in glomerular odor responses, which constitute the first site of olfactory processing in the brain. The results demonstrate that odor-shock pairing nonspecifically enhances glomerular odor representations in a learning-dependent manner and increases representational similarity between the CS and nonconditioned odors, potentially priming the system toward generalization of learned fear. Additionally, CS-specific glomerular enhancements remain even when associative learning is blocked, suggesting two separate mechanisms lead to enhanced glomerular responses following odor-shock pairings.SIGNIFICANCE STATEMENT In the olfactory bulb (OB), odors are uniquely coded in a spatial map that represents odor identity, making the OB a unique model system for investigating how learned fear alters sensory processing. Classical fear conditioning causes fear of the conditioned stimulus (CS) and of neutral stimuli, known as generalization. Combining fear conditioning with fluorescent calcium imaging of OB glomeruli, we found enhanced glomerular responses of the CS as well as neutral stimuli in awake mice, which mirrors fear generalization. We report that CS and neutral stimuli enhancements are, respectively, learning-independent and learning-dependent. Together, these results reveal distinct mechanisms leading to enhanced OB processing of fear-inducing stimuli and provide important implications for altered sensory processing in fear generalization.
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Tong J, Okutani F, Murata Y, Taniguchi M, Namba T, Wang YJ, Kaba H. Tunicamycin impairs olfactory learning and synaptic plasticity in the olfactory bulb. Neuroscience 2017; 344:371-379. [PMID: 28087337 DOI: 10.1016/j.neuroscience.2017.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 11/25/2016] [Accepted: 01/02/2017] [Indexed: 01/05/2023]
Abstract
Tunicamycin (TM) induces endoplasmic reticulum (ER) stress and inhibits N-glycosylation in cells. ER stress is associated with neuronal death in neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease, and most patients complain of the impairment of olfactory recognition. Here we examined the effects of TM on aversive olfactory learning and the underlying synaptic plasticity in the main olfactory bulb (MOB). Behavioral experiments demonstrated that the intrabulbar infusion of TM disabled aversive olfactory learning without affecting short-term memory. Histological analyses revealed that TM infusion upregulated C/EBP homologous protein (CHOP), a marker of ER stress, in the mitral and granule cell layers of MOB. Electrophysiological data indicated that TM inhibited tetanus-induced long-term potentiation (LTP) at the dendrodendritic excitatory synapse from mitral to granule cells. A low dose of TM (250nM) abolished the late phase of LTP, and a high dose (1μM) inhibited the early and late phases of LTP. Further, high-dose, but not low-dose, TM reduced the paired-pulse facilitation ratio, suggesting that the inhibitory effects of TM on LTP are partially mediated through the presynaptic machinery. Thus, our results support the hypothesis that TM-induced ER stress impairs olfactory learning by inhibiting synaptic plasticity via presynaptic and postsynaptic mechanisms in MOB.
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Affiliation(s)
- Jia Tong
- Department of Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
| | - Fumino Okutani
- Department of Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan; Department of Occupational Health, Kochi Medical School, Nankoku, Kochi 783-8505, Japan.
| | - Yoshihiro Murata
- Department of Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
| | - Mutsuo Taniguchi
- Department of Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
| | - Toshiharu Namba
- Department of Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
| | - Yu-Jie Wang
- Department of Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
| | - Hideto Kaba
- Department of Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
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5
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Abstract
Altricial infants (i.e., requiring parental care for survival), such as humans and rats, form an attachment to their caregiver and receive the nurturing and protections needed for survival. Learning has a strong role in attachment, as is illustrated by strong attachment formed to non-biological caregivers of either sex. Here we summarize and integrate results from animal and human infant attachment research that highlights the important role of social buffering (social presence) of the stress response by the attachment figure and its effect on infant processing of threat and fear through modulation of the amygdala. Indeed, this work suggests the caregiver switches off amygdala function in rodents, although recent human research suggests a similar process in humans and nonhuman primates. This cross-species analysis helps provide insight and unique understanding of attachment and its role in the neurobiology of infant behavior within attachment.
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Affiliation(s)
- Regina M Sullivan
- Emotional Brain Institute, The Nathan Kline Institute for Psychiatric Research, Child Study Center, Child and Adolescent Psychiatry, New York University Langone Medical Center
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6
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Boulanger Bertolus J, Mouly AM, Sullivan RM. Ecologically relevant neurobehavioral assessment of the development of threat learning. Learn Mem 2016; 23:556-66. [PMID: 27634146 PMCID: PMC5026204 DOI: 10.1101/lm.042218.116] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 06/02/2016] [Indexed: 11/24/2022]
Abstract
As altricial infants gradually transition to adults, their proximate environment changes. In three short weeks, pups transition from a small world with the caregiver and siblings to a complex milieu rich in dangers as their environment expands. Such contrasting environments require different learning abilities and lead to distinct responses throughout development. Here, we will review some of the learned fear conditioned responses to threats in rats during their ontogeny, including behavioral and physiological measures that permit the assessment of learning and its supporting neurobiology from infancy through adulthood. In adulthood, odor-shock conditioning produces robust fear learning to the odor that depends upon the amygdala and related circuitry. Paradoxically, this conditioning in young pups fails to support fear learning and supports approach learning to the odor previously paired with shock. This approach learning is mediated by the infant attachment network that does not include the amygdala. During the age range when pups transition from the infant to the adult circuit (10-15 d old), pups have access to both networks: odor-shock conditioning in maternal presence uses the attachment circuit but the adult amygdala-dependent circuit when alone. However, throughout development (as young as 5 d old) the attachment associated learning can be overridden and amygdala-dependent fear learning supported, if the mother expresses fear in the presence of the pup. This social modulation of the fear permits the expression of defense reactions in life threatening situations informed by the caregiver but prevents the learning of the caregiver itself as a threat.
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Affiliation(s)
| | - Anne-Marie Mouly
- Lyon Neuroscience Research Center, INSERM U1028; CNRS UMR5292; University Lyon1, Lyon, France
| | - Regina M Sullivan
- Emotional Brain Institute, Nathan Kline Institute, Child and Adolescent Psychiatry, New York University School of Medicine, New York, New York 10010, USA
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Abstract
Stress is a powerful modulator of brain structure and function. While stress is beneficial for survival, inappropriate stress dramatically increases the risk of physical and mental health problems, particularly when experienced during early developmental periods. Here we focus on the neurobiology of the infant rat's odor learning system that enables neonates to learn and approach the maternal odor and describe the unique role of the stress hormone corticosterone in modulating this odor approach learning across development. During the first nine postnatal days, this odor approach learning of infant rats is supported by a wide range of sensory stimuli and ensures attachment to the mother's odor, even when interactions with her are occasionally associated with pain. With maturation and the emergence of a stress- or pain-induced corticosterone response, this odor approach learning terminates and a more adult-like amygdala-dependent fear/avoidance learning emerges. Strikingly, the odor approach and attenuated fear learning of older pups can be re-established by the presence of the mother, due to her ability to suppress her pups' corticosterone release and amygdala activity. This suggests that developmental changes in stress responsiveness and the stimuli that produce a stress response might be critically involved in optimally adapting the pup's attachment system to its respective ecological niche.
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Fletcher ML, Bendahmane M. Visualizing olfactory learning functional imaging of experience-induced olfactory bulb changes. PROGRESS IN BRAIN RESEARCH 2014; 208:89-113. [PMID: 24767480 DOI: 10.1016/b978-0-444-63350-7.00004-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The anatomical organization of sensory neuron input allows odor information to be transformed into odorant-specific spatial maps of mitral/tufted cell glomerular activity. In other sensory systems, neuronal representations of sensory stimuli can be reorganized or enhanced following learning or experience. Similarly, several studies have demonstrated both structural and physiological experience-induced changes throughout the olfactory system. As experience-induced changes within this circuit likely serve as an initial site for odor memory formation, the olfactory bulb is an ideal site for optical imaging studies of olfactory learning, as they allow for the visualization of experience-induced changes in the glomerular circuit following learning and how these changes impact of odor representations with the bulb. Presently, optical imaging techniques have been used to visualize experience-induced changes in glomerular odor representations in a variety of paradigms in short-term habituation, chronic odor exposure, and olfactory associative conditioning.
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Affiliation(s)
- Max L Fletcher
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, USA.
| | - Mounir Bendahmane
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, USA
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Rincón-Cortés M, Sullivan RM. Early life trauma and attachment: immediate and enduring effects on neurobehavioral and stress axis development. Front Endocrinol (Lausanne) 2014; 5:33. [PMID: 24711804 PMCID: PMC3968754 DOI: 10.3389/fendo.2014.00033] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 03/05/2014] [Indexed: 01/22/2023] Open
Abstract
Over half a century of converging clinical and animal research indicates that early life experiences induce enduring neuroplasticity of the HPA-axis and the developing brain. This experience-induced neuroplasticity is due to alterations in the frequency and intensity of stimulation of pups' sensory systems (i.e., olfactory, somatosensory, gustatory) embedded in mother-infant interactions. This stimulation provides "hidden regulators" of pups' behavioral, physiological, and neural responses that have both immediate and enduring consequences, including those involving the stress response. While variation in stimulation can produce individual differences and adaptive behaviors, pathological early life experiences can induce maladaptive behaviors, initiate a pathway to pathology, and increase risk for later-life psychopathologies, such as mood and affective disorders, suggesting that infant-attachment relationships program later-life neurobehavioral function. Recent evidence suggests that the effects of maternal presence or absence during this sensory stimulation provide a major modulatory role in neural and endocrine system responses, which have minimal impact on pups' immediate neurobehavior but a robust impact on neurobehavioral development. This concept is reviewed here using two complementary rodent models of infant trauma within attachment: infant paired-odor-shock conditioning (mimicking maternal odor attachment learning) and rearing with an abusive mother that converge in producing a similar behavioral phenotype in later-life including depressive-like behavior as well as disrupted HPA-axis and amygdala function. The importance of maternal social presence on pups' immediate and enduring brain and behavior suggests unique processing of sensory stimuli in early life that could provide insight into the development of novel strategies for prevention and therapeutic interventions for trauma experienced with the abusive caregiver.
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Affiliation(s)
- Millie Rincón-Cortés
- Department of Neuroscience and Physiology, Sackler Institute for Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, New York, NY, USA
- New York University Child Study Center, Department of Child and Adolescent Psychiatry, New York University School of Medicine, New York, NY, USA
- *Correspondence: Millie Rincón-Cortés, Sullivan Laboratory, New York University Child Study Center, Department of Child and Adolescent Psychiatry, New York University School of Medicine, 1 Park Avenue, New York, NY 10016, USA e-mail:
| | - Regina M. Sullivan
- Department of Neuroscience and Physiology, Sackler Institute for Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, New York, NY, USA
- New York University Child Study Center, Department of Child and Adolescent Psychiatry, New York University School of Medicine, New York, NY, USA
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10
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Yuan Q, Shakhawat AMD, Harley CW. Mechanisms underlying early odor preference learning in rats. PROGRESS IN BRAIN RESEARCH 2014; 208:115-56. [PMID: 24767481 DOI: 10.1016/b978-0-444-63350-7.00005-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Early odor preference training in rat pups produces behavioral preferences that last from hours to lifetimes. Here, we discuss the molecular and circuitry changes we have observed in the olfactory bulb (OB) and in the anterior piriform cortex (aPC) following odor training. For normal preference learning, both structures are necessary, but learned behavior can be initiated by initiating local circuit change in either structure. Our evidence relates dynamic molecular and circuit changes to memory duration and storage localization. Results using this developmental model are consistent with biological memory theories implicating N-methyl-D-aspartate (NMDA) receptors and β-adrenoceptors, and their associated cascades, in memory induction and consolidation. Finally, our examination of the odor preference model reveals a primary role for increases in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor synaptic strength, and in network strength, in the creation and maintenance of preference memory in both olfactory structures.
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Affiliation(s)
- Qi Yuan
- Biomedical Sciences, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada.
| | - Amin M D Shakhawat
- Biomedical Sciences, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Carolyn W Harley
- Department of Psychology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada.
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11
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Delaere F, Akaoka H, De Vadder F, Duchampt A, Mithieux G. Portal glucose influences the sensory, cortical and reward systems in rats. Eur J Neurosci 2013; 38:3476-86. [DOI: 10.1111/ejn.12354] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/06/2013] [Accepted: 08/08/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Fabien Delaere
- Institut National de la Santé et de la Recherche Médicale; U855; Lyon France
- Université Lyon 1; Villeurbanne France
- Université de Lyon; Lyon France
- AgroParisTech; ENGREF; Paris France
| | - Hideo Akaoka
- Université Lyon 1; Villeurbanne France
- Université de Lyon; Lyon France
- Lyon Neuroscience Research Center; INSERM U1028-CNRS UMR 5292; Lyon France
| | - Filipe De Vadder
- Institut National de la Santé et de la Recherche Médicale; U855; Lyon France
- Université Lyon 1; Villeurbanne France
- Université de Lyon; Lyon France
| | - Adeline Duchampt
- Institut National de la Santé et de la Recherche Médicale; U855; Lyon France
- Université Lyon 1; Villeurbanne France
- Université de Lyon; Lyon France
| | - Gilles Mithieux
- Institut National de la Santé et de la Recherche Médicale; U855; Lyon France
- Université Lyon 1; Villeurbanne France
- Université de Lyon; Lyon France
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12
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Auffarth B. Understanding smell—The olfactory stimulus problem. Neurosci Biobehav Rev 2013; 37:1667-79. [DOI: 10.1016/j.neubiorev.2013.06.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 05/09/2013] [Accepted: 06/13/2013] [Indexed: 01/30/2023]
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Khodosevich K, Lazarini F, von Engelhardt J, Kaneko H, Lledo PM, Monyer H. Connective tissue growth factor regulates interneuron survival and information processing in the olfactory bulb. Neuron 2013; 79:1136-51. [PMID: 23993699 DOI: 10.1016/j.neuron.2013.07.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2013] [Indexed: 12/27/2022]
Abstract
Neurogenesis underlies plastic changes in defined neuronal circuits in the postnatal and adult brain. Here we identify connective tissue growth factor (CTGF) as a critical factor in the mouse olfactory bulb (OB) in determining the efficiency of incorporation of postnatally born inhibitory neurons, thus gating the output of glomeruli, the first relay station of olfactory processing in the brain. In the OB, CTGF expression was restricted to prenatally born external tufted cells. CTGF enhanced the proapoptotic activity of glial-derived TGF-β2, decreasing the survival of periglomerular inhibitory neurons. Changes in CTGF expression levels in the OB led to modifications in local neuronal circuitry and olfactory behaviors. We show that the odorant-specific recruitment of distinct glomeruli resulted in enhanced local CTGF expression levels in the activated glomeruli. Collectively our data reveal a molecular mechanism controlling the survival of defined postnatally born neurons, thus adapting neuronal integration to the sensory experiences.
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Affiliation(s)
- Konstantin Khodosevich
- Department of Clinical Neurobiology, Heidelberg University Medical Center, 69120 Heidelberg, Germany; Department of Clinical Neurobiology/A230, German Center for Cancer Research (DKFZ), 69120 Heidelberg, Germany
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14
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Charra R, Datiche F, Gigot V, Schaal B, Coureaud G. Pheromone-induced odor learning modifies Fos expression in the newborn rabbit brain. Behav Brain Res 2012; 237:129-40. [PMID: 23000352 DOI: 10.1016/j.bbr.2012.09.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 09/08/2012] [Accepted: 09/13/2012] [Indexed: 12/24/2022]
Abstract
Associative learning contributes crucially to adjust the behavior of neonates to the permanently changing environment. In the European rabbit, the mammary pheromone (MP) excreted in milk triggers sucking behavior in newborns, and additionally promotes very rapid learning of initially neutral odor cues. Such stimuli become then as active as the MP itself to elicit the orocephalic motor responses involved in suckling. In this context, the rabbit is an interesting model to address the question of brain circuits early engaged by learning and memory. Here, we evaluated the brain activation (olfactory bulb and central regions) induced in 4-day-old pups by an odorant (ethyl acetoacetate, EAA) after single pairing with the MP and its subsequent acquired ability to elicit sucking-related behavior (conditioned group) or after mere exposure to EAA alone (unconditioned group). The brain-wide mapping of c-Fos expression was used to compare neural activation patterns in both groups. Evidence of high immunostaining to odorant EAA occurred in the mitral+granule cells layer of the main olfactory bulb in pups previously exposed to EAA in association with the MP. These pups also showed higher expression of Fos in the piriform cortex, the hypothalamic lateral preoptic area and the amygdala (cortical and basal nuclei). Thus, MP-induced odor learning induces rapid brain modifications in rabbit neonates. The cerebral framework supporting the acquisition appears however different compared to the circuit involved in the processing of the MP itself.
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Affiliation(s)
- R Charra
- Developmental Ethology and Cognitive Psychology Group and Brain, Sensoriality and Metabolism Group, Centre des Sciences du Goût et de l'Alimentation, UMR 6265 CNRS, 1324 INRA, Université de Bourgogne, Dijon, France
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15
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Landers MS, Sullivan RM. The development and neurobiology of infant attachment and fear. Dev Neurosci 2012; 34:101-14. [PMID: 22571921 DOI: 10.1159/000336732] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 01/17/2012] [Indexed: 11/19/2022] Open
Abstract
Survival of altricial infants depends on attachment to the caregiver - a process that requires infants to identify, learn, remember, and approach their attachment figure. Here we review the neurobiology of attachment in infant rats where learning about the caregiver is supported by a specialized attachment neural circuitry to promote the infant-caregiver relationship. Specifically, the attachment circuit relies on infants acquiring learned preferences to the maternal odor, and this behavior is supported by the hyperfunctioning locus coeruleus and generous amounts of norepinephrine to produce experience-induced changes in the olfactory bulb and anterior piriform cortex. Infants also possess a reduced ability to acquire learned aversions or fear, and this behavior is facilitated through attenuated amygdala plasticity to block fear learning. Presumably, this attachment circuitry constrains the infant animal to express only learned preferences regardless of the quality of care received. As pups mature, and begin to travel in and out of the nest, the specialized attachment learning becomes contextually confined to when pups are with the mother. Thus, when outside the nest, these older pups show learning more typical of adult learning, presumably to prepare for independent life outside the nest. The quality of attachment can alter this circuitry, with early life stress prematurely terminating the pups' access to the attachment system through premature functional activation of the amygdala. Overall, the attachment circuit appears to have a dual function: to keep pups close to the caregiver but also to shape pups' behavior to match the environment and define long-term emotion and cognition.
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Affiliation(s)
- Margo S Landers
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, N.Y., USA
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Lethbridge R, Hou Q, Harley CW, Yuan Q. Olfactory bulb glomerular NMDA receptors mediate olfactory nerve potentiation and odor preference learning in the neonate rat. PLoS One 2012; 7:e35024. [PMID: 22496886 PMCID: PMC3319620 DOI: 10.1371/journal.pone.0035024] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Accepted: 03/12/2012] [Indexed: 01/23/2023] Open
Abstract
Rat pup odor preference learning follows pairing of bulbar beta-adrenoceptor activation with olfactory input. We hypothesize that NMDA receptor (NMDAR)-mediated olfactory input to mitral cells is enhanced during training, such that increased calcium facilitates and shapes the critical cAMP pattern. Here, we demonstrate, in vitro, that olfactory nerve stimulation, at sniffing frequencies, paired with beta-adrenoceptor activation, potentiates olfactory nerve-evoked mitral cell firing. This potentiation is blocked by a NMDAR antagonist and by increased inhibition. Glomerular disinhibition also induces NMDAR-sensitive potentiation. In vivo, in parallel, behavioral learning is prevented by glomerular infusion of an NMDAR antagonist or a GABA(A) receptor agonist. A glomerular GABA(A) receptor antagonist paired with odor can induce NMDAR-dependent learning. The NMDA GluN1 subunit is phosphorylated in odor-specific glomeruli within 5 min of training suggesting early activation, and enhanced calcium entry, during acquisition. The GluN1 subunit is down-regulated 3 h after learning; and at 24 h post-training the GluN2B subunit is down-regulated. These events may assist memory stability. Ex vivo experiments using bulbs from trained rat pups reveal an increase in the AMPA/NMDA EPSC ratio post-training, consistent with an increase in AMPA receptor insertion and/or the decrease in NMDAR subunits. These results support a model of a cAMP/NMDA interaction in generating rat pup odor preference learning.
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Affiliation(s)
- Rebecca Lethbridge
- Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada
| | - Qinlong Hou
- Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada
| | - Carolyn W. Harley
- Department of Psychology, Faculty of Science, Memorial University of Newfoundland, St. John’s, Canada
| | - Qi Yuan
- Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada
- * E-mail:
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Fletcher ML. Olfactory aversive conditioning alters olfactory bulb mitral/tufted cell glomerular odor responses. Front Syst Neurosci 2012; 6:16. [PMID: 22461771 PMCID: PMC3309973 DOI: 10.3389/fnsys.2012.00016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 03/05/2012] [Indexed: 11/23/2022] Open
Abstract
The anatomical organization of receptor neuron input into the olfactory bulb (OB) allows odor information to be transformed into an odorant-specific spatial map of mitral/tufted (M/T) cell glomerular activity at the upper level of the OB. In other sensory systems, neuronal representations of stimuli can be reorganized or enhanced following learning. While the mammalian OB has been shown to undergo experience-dependent plasticity at the glomerular level, it is still unclear if similar representational change occurs within (M/T) cell glomerular odor representations following learning. To address this, odorant-evoked glomerular activity patterns were imaged in mice expressing a GFP-based calcium indicator (GCaMP2) in OB (M/T) cells. Glomerular odor responses were imaged before and after olfactory associative conditioning to aversive foot shock. Following conditioning, we found no overall reorganization of the glomerular representation. Training, however, did significantly alter the amplitudes of individual glomeruli within the representation in mice in which the odor was presented together with foot shock. Further, the specific pairing of foot shock with odor presentations lead to increased responses primarily in initially weakly activated glomeruli. Overall, these results suggest that associative conditioning can enhance the initial representation of odors within the OB by enhancing responses to the learned odor in some glomeruli.
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Affiliation(s)
- Max L Fletcher
- Department of Neurobiology and Anatomy, University of Texas Medical School, Houston TX, USA
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Fletcher ML, Chen WR. Neural correlates of olfactory learning: Critical role of centrifugal neuromodulation. Learn Mem 2010; 17:561-70. [PMID: 20980444 DOI: 10.1101/lm.941510] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The mammalian olfactory system is well established for its remarkable capability of undergoing experience-dependent plasticity. Although this process involves changes at multiple stages throughout the central olfactory pathway, even the early stages of processing, such as the olfactory bulb and piriform cortex, can display a high degree of plasticity. As in other sensory systems, this plasticity can be controlled by centrifugal inputs from brain regions known to be involved in attention and learning processes. Specifically, both the bulb and cortex receive heavy inputs from cholinergic, noradrenergic, and serotonergic modulatory systems. These neuromodulators are shown to have profound effects on both odor processing and odor memory by acting on both inhibitory local interneurons and output neurons in both regions.
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Affiliation(s)
- Max L Fletcher
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
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Raineki C, Pickenhagen A, Roth TL, Babstock DM, McLean JH, Harley CW, Lucion AB, Sullivan RM. The neurobiology of infant maternal odor learning. Braz J Med Biol Res 2010; 43:914-9. [PMID: 20835686 DOI: 10.1590/s0100-879x2010007500090] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 08/24/2010] [Indexed: 02/04/2023] Open
Abstract
Infant rats must learn to identify their mother's diet-dependent odor. Once learned, maternal odor controls pups' approach to the mother, their social behavior and nipple attachment. Here we present a review of the research from four different laboratories, which suggests that neural and behavioral responses to the natural maternal odor and neonatal learned odors are similar. Together, these data indicate that pups have a unique learning circuit relying on the olfactory bulb for neural plasticity and on the hyperfunctioning noradrenergic locus coeruleus flooding the olfactory bulb with norepinephrine to support the neural changes. Another important factor making this system unique is the inability of the amygdala to become incorporated into the infant learning circuit. Thus, infant rats appear to be primed in early life to learn odors that will evoke approach responses supporting attachment to the caregiver.
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Affiliation(s)
- C Raineki
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
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Developing a neurobehavioral animal model of infant attachment to an abusive caregiver. Biol Psychiatry 2010; 67:1137-45. [PMID: 20163787 PMCID: PMC3929962 DOI: 10.1016/j.biopsych.2009.12.019] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 12/13/2009] [Accepted: 12/14/2009] [Indexed: 01/06/2023]
Abstract
BACKGROUND Both abused and well cared for infants show attachment to their caregivers, although the quality of that attachment differs. Moreover, the infant's attachment to the abusive caregiver is associated with compromised mental health, especially under stress. In an attempt to better understand how abuse by the caregiver can compromise mental health, we explore the neural basis of attachment in both typical and abusive environments using infant rats, which form attachments to the mother through learning her odor. Here, we hypothesize that the neural circuitry for infant attachment differs based on the quality of the attachment, which can be uncovered during stressful situations. METHODS We used infant rats to compare infant attachment social behaviors and supporting neurobiology using natural maternal odor, as well as two odor-learning attachment paradigms: odor-stroke (mimics typical attachment) and odor-.5 mA shock conditioning (mimics abusive attachment). Next, to uncover differences in behavior and brain, these pups were injected with systemic corticosterone. Finally, pups were reared with an abusive mother to determine ecological relevance. RESULTS Our results suggest that the natural and learned attachment odors indistinguishably control social behavior in infancy (approach to the odor and interactions with the mother). However, with corticosterone injection, pups with an abusive attachment show disrupted infant social behavior with the mother and engagement of the amygdala. CONCLUSIONS This animal model of attachment accommodates both abusive and typical attachment and suggests that pups' social behavior and underlying neural circuitry may provide clues to understanding attachment in children with various conditions of care.
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Sullivan RM, Holman PJ. Transitions in sensitive period attachment learning in infancy: the role of corticosterone. Neurosci Biobehav Rev 2010; 34:835-44. [PMID: 19931556 PMCID: PMC2848912 DOI: 10.1016/j.neubiorev.2009.11.010] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 11/06/2009] [Accepted: 11/10/2009] [Indexed: 11/15/2022]
Abstract
Survival of altricial infants, including humans and rats, depends on attachment to the caregiver - a process that requires infants to recognize, learn, and remember their attachment figure. The demands of a dynamic environment combined with a maturing organism require frequent neurobehavioral reorganization. This restructuring of behavior and its supporting neural circuitry can be viewed through the unique lens of attachment learning in rats in which preference learning is enhanced and aversion learning is attenuated. Behavioral restructuring is well adapted to securing the crucial infant-caregiver relationship regardless of the quality of care. With maturation and the end of the infant-caregiver attachment learning period, the complex interplay of neural structures, hormones, and social behavior coordinates the developing rat's eventual transition to life outside of the nest. Nevertheless, early-life environmental and physiological stressors can alter the resilient nature of this system, particularly with respect to the amygdala, and these changes may provide important clues to understanding the lasting effects of early stress.
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Affiliation(s)
- Regina M Sullivan
- Emotional Brain Institute, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
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22
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Yuan Q. Theta bursts in the olfactory nerve paired with beta-adrenoceptor activation induce calcium elevation in mitral cells: a mechanism for odor preference learning in the neonate rat. Learn Mem 2009; 16:676-81. [PMID: 19858361 DOI: 10.1101/lm.1569309] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Odor preference learning in the neonate rat follows pairing of odor input and noradrenergic activation of beta-adrenoceptors. Odor learning is hypothesized to be supported by enhanced mitral cell activation. Here a mechanism for enhanced mitral cell signaling is described. Theta bursts in the olfactory nerve (ON) produce long-term potentiation (LTP) of glomerular excitatory postsynaptic potentials (EPSPs) and of excitatory postsynaptic currents (EPSCs) in the periglomerular (PG) and external tufted (ET) cells. Theta bursts paired with beta-adrenoceptor activation significantly elevate mitral cell (MC) calcium. Juxtaglomerular inhibitory network depression by beta-adrenoceptor activation appears to increase calcium in MCs in response to theta burst stimulation.
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Affiliation(s)
- Qi Yuan
- University of California at San Diego, La Jolla, California 92093, USA.
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Johnson BA, Xu Z, Ali SS, Leon M. Spatial representations of odorants in olfactory bulbs of rats and mice: similarities and differences in chemotopic organization. J Comp Neurol 2009; 514:658-73. [PMID: 19363812 DOI: 10.1002/cne.22046] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In previous studies, we mapped glomerular layer 2-deoxyglucose uptake evoked by hundreds of both systematically related and chemically distinct odorants in rat olfactory bulbs. To determine which principles of chemotopic organization revealed in these studies may be more fundamental and which may be more species typical, we now have characterized patterns of responses to 30 of these odorants in mice. We found that only a few odorants evoked their multiple foci of peak activity in exactly the same locations in the two species. In mice, as in rats, odorants that shared molecular features evoked overlapping patterns, but the locations of the feature-responsive domains often differed in rats and mice. In rats, increasing carbon number within a homologous series of aliphatic odorants is generally associated with rostral and ventral progressions of activity within domains responding to odorant functional group and/or hydrocarbon backbone. Such chemotopic progressions were not obvious in mice, which instead showed more abrupt differences in activated glomeruli within the domains for odorants differing by a single methylene group. Despite the differences, quantitative relationships between overall uptake patterns exhibited a similar organization with respect to odorant chemistry for the two species, probably as a result of partial overlaps of peak domains and more extensive overlaps in large, low-activity areas for rats and mice. We conclude that clustering responses to shared odorant features may be a general strategy for odor coding but that the specific locations of high-activity domains may be unique to a species.
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Affiliation(s)
- Brett A Johnson
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697-4550, USA.
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24
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Sanchez-Andrade G, Kendrick KM. The main olfactory system and social learning in mammals. Behav Brain Res 2009; 200:323-35. [DOI: 10.1016/j.bbr.2008.12.021] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 12/11/2008] [Accepted: 12/12/2008] [Indexed: 12/26/2022]
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Expression of EGR-1 in a subset of olfactory bulb dopaminergic cells. J Mol Histol 2009; 40:151-5. [PMID: 19387849 DOI: 10.1007/s10735-009-9217-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 04/05/2009] [Indexed: 10/20/2022]
Abstract
In the adrenal medulla, binding of the immediate early gene (IEG) proteins, EGR-1 (ZIF-268/KROX-24/NGFI-A) and AP-1, to the tyrosine hydroxylase (Th) proximal promoter mediate inducible Th expression. The current study investigated the potential role of EGR-1 in inducible Th expression in the olfactory bulb (OB) since IEGs bound to the AP-1 site in the Th proximal promoter are also necessary for activity-dependent OB TH expression. Immunohistochemical analysis of a naris-occluded mouse model of odor deprivation revealed weak EGR-1 expression levels in the OB glomerular layer that were activity-dependent. Immunofluorescence analysis indicated that a majority of glomerular cells expressing EGR-1 also co-expressed TH, but only small subset of TH-expressing cells contained EGR-1. By contrast, granule cells, which lack TH, exhibited EGR-1 expression levels that were unchanged by naris closure. Together, these finding suggest that EGR-1 mediates activity-dependent TH expression in a subset of OB dopaminergic neurons, and that there is differential regulation of EGR-1 in periglomerular and granule cells.
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Youngentob SL, Molina JC, Spear NE, Youngentob LM. The effect of gestational ethanol exposure on voluntary ethanol intake in early postnatal and adult rats. Behav Neurosci 2008; 121:1306-15. [PMID: 18085883 DOI: 10.1037/0735-7044.121.6.1306] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Clinical and epidemiological studies provide strong data for a relationship between prenatal ethanol exposure and the risk for abuse in adolescent and young adult humans. However, drug-acceptance results in response to fetal exposure have differed by study, age at evaluation, and experimental animal. In the present study, the authors tested whether voluntary ethanol intake was enhanced in both the infantile and adult rat (15 and 90 days of age, respectively), as a consequence of chronic fetal drug experience. Experimental rats were exposed in utero by administering ethanol to a pregnant dam in a liquid diet during gestational Days 6-20. Compared with those for isocaloric pair-fed and ad lib chow control animals, the results for experimental animals demonstrated that fetal exposure significantly increased infantile affinity for ethanol ingestion without affecting intake patterns of an alternative fluid (water). Heightened affinity for ethanol was absent in adulthood. Moreover, the results argue against malnutrition as a principal factor underlying the infantile phenomenon. These data add to a growing literature indicative of heightened early postnatal acceptance patterns resulting from maternal use or abuse of ethanol during pregnancy.
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Affiliation(s)
- Steven L Youngentob
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
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27
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Youngentob SL, Kent PF, Sheehe PR, Molina JC, Spear NE, Youngentob LM. Experience-induced fetal plasticity: the effect of gestational ethanol exposure on the behavioral and neurophysiologic olfactory response to ethanol odor in early postnatal and adult rats. Behav Neurosci 2008; 121:1293-305. [PMID: 18085882 DOI: 10.1037/0735-7044.121.6.1293] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Human fetal ethanol exposure is strongly associated with ethanol avidity during adolescence. Evidence that intrauterine olfactory experience influences chemosensory-guided postnatal behaviors suggests that an altered response to ethanol odor resulting from fetal exposure may contribute to later abuse risk. Using behavioral and neurophysiological methods, the authors tested whether ethanol exposure via the dam's diet resulted in an altered responsiveness to ethanol odor in infant and adult rats. Compared with controls, (a) fetal exposure tuned the neurophysiologic response of the olfactory epithelium to ethanol odor at some expense to its responsiveness to other odorants in infantile rats--this effect was absent in adults; (b) the neural effect in infantile rats was paralleled by an altered behavioral response to ethanol odor that was specific to this odorant--this effect was also absent in adults; and (c) a significant component of the infantile behavioral effect was attributable to ethanol's effect on the olfactory neural modality. These data provide evidence for an important relationship between prenatal ethanol experience and postnatal behavioral responsiveness to the drug that is modulated or determined by olfactory function.
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Affiliation(s)
- Steven L Youngentob
- Department of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
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28
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Sevelinges Y, Moriceau S, Holman P, Miner C, Muzny K, Gervais R, Mouly AM, Sullivan RM. Enduring effects of infant memories: infant odor-shock conditioning attenuates amygdala activity and adult fear conditioning. Biol Psychiatry 2007; 62:1070-9. [PMID: 17826749 DOI: 10.1016/j.biopsych.2007.04.025] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Revised: 04/11/2007] [Accepted: 04/16/2007] [Indexed: 11/24/2022]
Abstract
BACKGROUND Early life adverse experience alters adult emotional and cognitive development. Here we assess early life learning about adverse experience and its consequences on adult fear conditioning and amygdala activity. METHODS Neonatal rats were conditioned daily from 8-12 days-old with paired odor (conditioned stimulus, CS) .5mA shock, unpaired, odor-only, or naive (no infant conditioning). In adulthood, each infant training group was divided into three adult training groups: paired, unpaired or odor-only, using either the same infant CS odor, or a novel adult CS odor without or with the infant CS present as context. Adults were cue tested for freezing (odor in novel environment), with amygdala (14)C 2-DG autoradiography and electrophysiology assessment. RESULTS Infant paired odor-shock conditioning attenuated adult fear conditioning, but only if the same infant CS odor was used. The (14)C 2-DG activity correlated with infant paired odor-shock conditioning produced attenuated amygdala but heightened olfactory bulb activity. Electrophysiological amygdala assessment further suggests early experience causes changes in amygdala processing as revealed by increased paired-pulse facilitation in adulthood. CONCLUSIONS This suggests some enduring effects of early life adversity (shock) are under CS control and dependent upon learning for their impact on later adult fear learning.
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Affiliation(s)
- Yannick Sevelinges
- Institut des Sciences Cognitives, Université Claude Bernard Lyon 1, France
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29
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Illig KR. Developmental changes in odor-evoked activity in rat piriform cortex. Neuroscience 2007; 145:370-6. [PMID: 17204372 PMCID: PMC1810345 DOI: 10.1016/j.neuroscience.2006.11.049] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 11/13/2006] [Accepted: 11/27/2006] [Indexed: 11/19/2022]
Abstract
In adult rats, odor-evoked Fos protein expression is found in rostrocaudally-oriented bands of cells in anterior piriform cortex (APC), likely indicating functionally distinct subregions, while activated cells in posterior piriform cortex (PPC) lack apparent spatial organization. To determine whether these patterns are present during early postnatal life, and whether they change during development, Fos expression was assessed following acute exposure to single aliphatic acid odors in developing rats beginning at postnatal day 3 (P3). In the olfactory bulb, Fos-immunoreactive cells were present in the granule cell, mitral cell and glomerular layers at the earliest ages examined. Cells immunopositive for Fos were clustered in areas previously reported as active in response to these odors. In piriform cortex, activation in layers II/III shared some features with that seen in the adult; in APC, rostro-caudally oriented bands of Fos-positive cells alternated with bands relatively free of label, while labeled cells were found dispersed throughout PPC. However, in P3-P7 animals, Fos-positive cells in APC were found in a central rostro-caudally oriented band that was flanked by two bands relatively free of Fos-positive cells. This contrasted with the adult pattern, a central cell-poor band flanked by cell-rich bands, which was observed beginning at P10. These results suggest that subregions of APC visualized by odor-evoked Fos expression are active and functionally distinct shortly after birth. Changes in activity within these subregions during early postnatal development coincide with a shift toward adult-like olfactory learning behavior in the second postnatal week, and may play a role in this behavioral shift.
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Affiliation(s)
- K R Illig
- Department of Psychology, University of Virginia, 102 Gilmer Hall, PO Box 400400, Charlottesville, VA 22904-4400, USA.
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30
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Woo CC, Hingco EE, Johnson BA, Leon M. Broad activation of the glomerular layer enhances subsequent olfactory responses. Chem Senses 2006; 32:51-5. [PMID: 17071941 PMCID: PMC2213453 DOI: 10.1093/chemse/bjl035] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Early olfactory experience with a specific odorant enhances the subsequent response of the glomerular layer of the rat olfactory bulb to that same odorant. Because different odorants activate different glomerular layer regions, it seemed plausible that experience with a large number of odorants might result in enhanced glomerular activation during subsequent exposure to both the previously experienced odorants and the novel odorants evoking activity in regions that overlapped with those previously stimulated by different odorants. To this end, 7 odorants were selected using our glomerular response data archive that together stimulated much of the glomerular layer (alpha-phellandrene, benzaldehyde, L-carvone, decanal, pentanol, santalol, and valeric acid). Young rats were exposed to a different odorant each day for 7 days, and this cycle was repeated 3 times from postnatal days 1-21. The [(14)C]2-deoxyglucose technique was used to measure neural activity in response to both previously experienced and novel odorants. The 2 novel odorants (alpha-ionone and L-menthone) activate regions of the glomerular layer that overlap with those stimulated by the 7 enrichment odorants. Our results indicate that early experience with multiple odorants results in increased responsiveness both to previously experienced odorants and to novel odorants that stimulate previously activated regions of the bulb.
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Affiliation(s)
- Cynthia C Woo
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-4550, USA.
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31
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Woo CC, Hingco EE, Taylor GE, Leon M. Exposure to a broad range of odorants decreases cell mortality in the olfactory bulb. Neuroreport 2006; 17:817-21. [PMID: 16708021 PMCID: PMC2231406 DOI: 10.1097/01.wnr.0000215780.84226.2d] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Experience with multiple odorants during early postnatal development increases the number of cells in the olfactory bulb of rats. In this study, we asked whether at least part of this increase was due to decreased cell death. We selected 30 natural odorants or synthetic odorant mixtures to stimulate a broad area of the bulb during postnatal days 1-15, and counted the number of cells with DNA damage associated with cell death in both the glomerular and the granule cell layers of the main olfactory bulb. Early olfactory enrichment significantly decreased cell death in both bulbar laminae. Thus, olfactory enrichment can spare bulbar cells during early development, possibly leading to increased efficacy in bulb function and enhanced bulbar responses.
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Affiliation(s)
- Cynthia C Woo
- Department of Neurobiology and Behavior, University of California, Irvine, California 92697-4550, USA.
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32
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Peele P, Ditzen M, Menzel R, Galizia CG. Appetitive odor learning does not change olfactory coding in a subpopulation of honeybee antennal lobe neurons. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2006; 192:1083-103. [PMID: 16865372 DOI: 10.1007/s00359-006-0152-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 06/13/2006] [Accepted: 06/16/2006] [Indexed: 10/24/2022]
Abstract
Odors elicit spatio-temporal patterns of activity in the olfactory bulb of vertebrates and the antennal lobe of insects. There have been several reports of changes in these patterns following olfactory learning. These studies pose a conundrum: how can an animal learn to efficiently respond to a particular odor with an adequate response, if its primary representation already changes during this process? In this study, we offer a possible solution for this problem. We measured odor-evoked calcium responses in a subpopulation of uniglomerular AL output neurons in honeybees. We show that their responses to odors are remarkably resistant to plasticity following a variety of appetitive olfactory learning paradigms. There was no significant difference in the changes of odor-evoked activity between single and multiple trial forward or backward conditioning, differential conditioning, or unrewarded successive odor stimulation. In a behavioral learning experiment we show that these neurons are necessary for conditioned odor responses. We conclude that these uniglomerular projection neurons are necessary for reliable odor coding and are not modified by learning in this paradigm. The role that other projection neurons play in olfactory learning remains to be investigated.
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Affiliation(s)
- P Peele
- Institute of Neurobiology, Freie Universität Berlin, 14195, Berlin, Germany
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Bernabeu R, Thiriet N, Zwiller J, Di Scala G. Lesion of the lateral entorhinal cortex amplifies odor-induced expression of c-fos, junB, and zif 268 mRNA in rat brain. Synapse 2006; 59:135-43. [PMID: 16342059 DOI: 10.1002/syn.20224] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Paradoxical facilitation of olfactory learning following entorhinal cortex (EC) lesion has been described, which may result from widespread functional alterations taking place within the olfactory system. To test this hypothesis, expression of the immediate early genes c-fos, junB, and zif 268 was studied in response to an olfactory stimulation in several brain areas in control and in EC-lesioned rats. Olfactory stimulation in control rats induced the expression of the three genes in the granular/mitral and glomerular layers of the olfactory bulb, as well as c-fos and junB expression in the piriform cortex. However EC lesion was devoid of effects in nonstimulated animals; it significantly amplified the odor-induced expression of the three genes in these areas, as well as in the amygdala, hippocampus, and parietal-temporal cortices. The data suggest that EC lesion modifies the neural processing of odor by suppressing an inhibitory influence on brain areas connected to this cortex.
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Affiliation(s)
- Ramón Bernabeu
- Laboratoire de Neurosciences Comportementales et Cognitives, UMR 7521, Université Louis Pasteur/CNRS, Strasbourg 67000, France
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Kerr MA, Belluscio L. Olfactory experience accelerates glomerular refinement in the mammalian olfactory bulb. Nat Neurosci 2006; 9:484-6. [PMID: 16547509 DOI: 10.1038/nn1673] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 02/27/2006] [Indexed: 11/09/2022]
Abstract
Primary olfactory sensory neurons (OSNs) impart both molecular and functional organization to the olfactory bulb. Because OSNs can be selectively activated by odorants in vivo, we sought to determine whether odorant experience alters the cellular dynamics of specific OSNs or their axonal projections. Using mice, we found that odorant stimulation associated with behavioral conditioning influenced OSN wiring by accelerating glomerular refinement independent of OSN number; furthermore, this wiring was strongly associated with olfactory learning.
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Affiliation(s)
- Mariel A Kerr
- Developmental Neural Plasticity Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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Salcedo E, Zhang C, Kronberg E, Restrepo D. Analysis of training-induced changes in ethyl acetate odor maps using a new computational tool to map the glomerular layer of the olfactory bulb. Chem Senses 2005; 30:615-26. [PMID: 16141292 DOI: 10.1093/chemse/bji055] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Odor quality is thought to be encoded by the activation of partially overlapping subsets of glomeruli in the olfactory bulb (odor maps). Mouse genetic studies have demonstrated that olfactory sensory neurons (OSNs) expressing a particular olfactory receptor target their axons to a few individual glomeruli in the bulb. While the specific targeting of OSN axons provides a molecular underpinning for the odor maps, much remains to be understood about the relationship between the functional and molecular maps. In this article, we ask the question whether intensive training of mice in a go/no-go operant conditioning odor discrimination task affects odor maps measured by determining c-fos up-regulation in periglomerular cells. Data analysis is performed using a newly developed suite of computational tools designed to systematically map functional and molecular features of glomeruli in the adult mouse olfactory bulb. This suite provides the necessary tools to process high-resolution digital images, map labeled glomeruli, visualize odor maps, and facilitate statistical analysis of patterns of identified glomeruli in the olfactory bulb. The software generates odor maps (density plots) based on glomerular activity, density, or area. We find that training up-regulates the number of glomeruli that become c-fos positive after stimulation with ethyl acetate.
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Affiliation(s)
- Ernesto Salcedo
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Mail Stop 8108 PO Box 6511, Aurora, CO 80045, USA.
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Gómez C, Briñón JG, Barbado MV, Weruaga E, Valero J, Alonso JR. Heterogeneous targeting of centrifugal inputs to the glomerular layer of the main olfactory bulb. J Chem Neuroanat 2005; 29:238-54. [PMID: 15927786 DOI: 10.1016/j.jchemneu.2005.01.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Revised: 01/29/2005] [Accepted: 01/29/2005] [Indexed: 11/26/2022]
Abstract
The centrifugal systems innervating the olfactory bulb are important elements in the functional regulation of the olfactory pathway. In this study, the selective innervation of specific glomeruli by serotonergic, noradrenergic and cholinergic centrifugal axons was analyzed. Thus, the morphology, distribution and density of positive axons were studied in the glomerular layer of the main olfactory bulb of the rat, using serotonin-, serotonin transporter- and dopamine-beta-hydroxylase-immunohistochemistry and acetylcholinesterase histochemistry in serial sections. Serotonin-, serotonin transporter-immunostaining and acetylcholinesterase-staining revealed a higher heterogeneity in the glomerular layer of the main olfactory bulb than previously reported. In this sense, four types of glomeruli could be identified according to their serotonergic innervation. The main distinctive feature of these four types of glomeruli was their serotonergic fibre density, although they also differed in their size, morphology and relative position throughout the rostro-caudal main olfactory bulb. In this sense, some specific regions of the glomerular layer were occupied by glomeruli with a particular morphology and a characteristic serotonergic innervation pattern that was consistent from animal to animal. Regarding the cholinergic system, we offer a new subclassification of glomeruli based on the distribution of cholinergic fibres in the glomerular structure. Finally, the serotonergic and cholinergic innervation patterns were compared in the glomerular layer. Sexual differences concerning the density of serotonergic fibres were observed in the atypical glomeruli (characterized by their strong cholinergic innervation). The present report provides new data on the heterogeneity of the centrifugal innervation of the glomerular layer that constitutes the morphological substrate supporting the existence of differential modulatory levels among the entire glomerular population.
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Affiliation(s)
- C Gómez
- Lab. Plasticidad neuronal y neurorreparación, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Spain
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Johnson BA, Farahbod H, Saber S, Leon M. Effects of functional group position on spatial representations of aliphatic odorants in the rat olfactory bulb. J Comp Neurol 2005; 483:192-204. [PMID: 15678475 PMCID: PMC2222918 DOI: 10.1002/cne.20415] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Principles of olfactory coding can be clarified by studying the olfactory bulb activity patterns that are evoked by odorants differing systematically in chemical structure. In the present study, we used series of aliphatic esters, ketones, and alcohols (27 odorants total) to determine the effects of functional group position on glomerular-layer activity patterns. These patterns were measured as uptake of [(14)C]2-deoxyglucose and were mapped into standardized data matrices for statistical comparison across different rats. The magnitude of the effect of position differed greatly for the different functional groups. For ketones, there was little or no effect of position on evoked patterns. For esters, uptake in individual glomerular modules increased, whereas uptake in others decreased with changing group position, yet the overall patterns remained similar. For alcohols, group position had a profound effect on evoked activity patterns. For example, moving the hydroxyl group in either heptanol or nonanol from the first to the fourth carbon changed the activity patterns so greatly that the major areas of response did not overlap. Within every functional group series, however, responses were globally chemotopic, such that pairs of odorants with the smallest difference in functional group position evoked the most similar patterns. These results help to define further the specificities of glomeruli within previously described glomerular modules, and they show that functional group position can be an important feature in encoding an odorant molecule.
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Affiliation(s)
- Brett A Johnson
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA 92697-4550, USA.
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38
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Roth TL, Sullivan RM. Memory of early maltreatment: neonatal behavioral and neural correlates of maternal maltreatment within the context of classical conditioning. Biol Psychiatry 2005; 57:823-31. [PMID: 15820702 DOI: 10.1016/j.biopsych.2005.01.032] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Revised: 12/15/2004] [Accepted: 01/13/2005] [Indexed: 01/20/2023]
Abstract
BACKGROUND While children form an attachment to their abusive caregiver, they are susceptible to mental illness and brain abnormalities. To understand this important clinical issue, we have developed a rat animal model of abusive attachment where odor paired with shock paradoxically produces an odor preference. Here, we extend this model to a seminaturalistic paradigm using a stressed, "abusive" mother during an odor presentation and assess the underlying learning neural circuit. METHODS We used a classical conditioning paradigm pairing a novel odor with a stressed mother that predominantly abused pups to assess olfactory learning in a seminaturalistic environment. Additionally, we used Fos protein immunohistochemistry to assess brain areas involved in learning this pain-induced odor preference within a more controlled maltreatment environment (odor-shock conditioning). RESULTS Odor-maternal maltreatment pairings within a seminatural setting and odor-shock pairings both resulted in paradoxical odor preferences. Learning-induced gene expression was altered in the olfactory bulb and anterior piriform cortex (part of olfactory cortex) but not the amygdala. CONCLUSIONS Infants appear to use a unique brain circuit that optimizes learned odor preferences necessary for attachment. A fuller understanding of infant brain function may provide insight into why early maltreatment affects psychiatric well-being.
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Affiliation(s)
- Tania L Roth
- Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
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39
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Abstract
Recently, modern neuroscience has made considerable progress in understanding how the brain perceives, discriminates, and recognizes odorant molecules. This growing knowledge took over when the sense of smell was no longer considered only as a matter for poetry or the perfume industry. Over the last decades, chemical senses captured the attention of scientists who started to investigate the different stages of olfactory pathways. Distinct fields such as genetic, biochemistry, cellular biology, neurophysiology, and behavior have contributed to provide a picture of how odor information is processed in the olfactory system as it moves from the periphery to higher areas of the brain. So far, the combination of these approaches has been most effective at the cellular level, but there are already signs, and even greater hope, that the same is gradually happening at the systems level. This review summarizes the current ideas concerning the cellular mechanisms and organizational strategies used by the olfactory system to process olfactory information. We present findings that exemplified the high degree of olfactory plasticity, with special emphasis on the first central relay of the olfactory system. Recent observations supporting the necessity of such plasticity for adult brain functions are also discussed. Due to space constraints, this review focuses mainly on the olfactory systems of vertebrates, and primarily those of mammals.
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40
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Mirich JM, Illig KR, Brunjes PC. Experience-dependent activation of extracellular signal-related kinase (ERK) in the olfactory bulb. J Comp Neurol 2004; 479:234-41. [PMID: 15452854 DOI: 10.1002/cne.20325] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Protein kinase-mediated signaling cascades play a fundamental role in translating extracellular signals into cellular responses in CNS neurons. The mitogen-activated protein kinase / extracellular signal-regulated kinase (MAPK/ERK) pathway participates in regulating diverse neuronal processes such as proliferation, differentiation, survival, synaptic efficacy, and long-term potentiation by inducing cAMP-response element (CRE)-mediated gene transcription. Central olfactory structures show plasticity throughout the lifespan, but the role of the MAPK/ERK pathway in odor-evoked activity has yet to be determined. Therefore, we examined the effect of odorant exposure and early postnatal deprivation on ERK activity. We found that odor stimulation induced ERK phosphorylation, that activation of the ERK pathway was decreased with early postnatal deprivation, and that ERK phosphorylation was subsequently increased by restoring stimulation. Further, locations of ERK activation in bulbar neurons after exposure to single odorants corresponded to odor-evoked activity patterns found with other measures of activity in the bulb. Finally, due to the cytoplasmic location of pERK, activated dendrites belonging to the primary excitatory output neurons of the bulb were observed following a single odor exposure. The results indicate that the MAPK/ERK pathway is activated by odorant stimulation and may play an important role in developmental sensory plasticity in the olfactory bulb.
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Affiliation(s)
- Jennifer M Mirich
- Department of Psychology, University of Virginia, Charlottesville, Virginia 22904, USA
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41
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Bozza T, McGann JP, Mombaerts P, Wachowiak M. In vivo imaging of neuronal activity by targeted expression of a genetically encoded probe in the mouse. Neuron 2004; 42:9-21. [PMID: 15066261 DOI: 10.1016/s0896-6273(04)00144-8] [Citation(s) in RCA: 262] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 01/23/2004] [Accepted: 02/25/2004] [Indexed: 11/21/2022]
Abstract
Genetically encoded probes show great promise in permitting functional imaging of specified neuronal populations in the intact nervous system, yet their in vivo application has been limited. Here, we have targeted expression of synapto-pHluorin, a pH-sensitive protein that reports synaptic vesicle fusion, to olfactory sensory neurons in mouse. Synapto-pHluorin selectively labeled presynaptic terminals of sensory neurons in glomeruli of the olfactory bulb. Odorant stimulation evoked large-amplitude fluorescence increases that were localized to individual glomeruli in vivo, correlated with presynaptic calcium influx, graded with stimulus intensity, and stable over a period of days. Spatial patterns of odorant-activated glomeruli were distributed and did not change systematically with increasing carbon chain length, in contrast to the finely organized chemotopy that has been reported using other imaging methods. Targeted expression of synapto-pHluorin in mouse will permit the analysis of previously inaccessible neuronal populations and chronic imaging from genetically identified neurons in vivo.
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Affiliation(s)
- Thomas Bozza
- The Rockefeller University, New York, NY 10021, USA
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42
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Abstract
Infant rats exhibit sensitive-period odor learning characterized by olfactory bulb neural changes and odor preference acquisitions critical for survival. This sensitive period is coincident with low endogenous corticosterone (CORT) levels and stress hyporesponsivity. The authors hypothesized that low corticosterone levels modulate sensitive-period learning. They assessed the effects of manipulating CORT levels by increasing and removing CORT during (Postnatal Day 8) and after (Postnatal Day 12) the sensitive period. Results show that (a) exogenous CORT prematurely ends sensitive-period odor-shock-induced preferences; (b) adrenalectomy developmentally extends the sensitive period as indicated by odor-shock-induced odor-preference learning in older pups, whereas CORT replacement can reinstate fear learning; and (c) CORT manipulation modulates olfactory bulb correlates of sensitive-period odor learning in a manner consistent with behavior.
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Moriceau S, Sullivan RM. Unique neural circuitry for neonatal olfactory learning. J Neurosci 2004; 24:1182-9. [PMID: 14762136 PMCID: PMC1868533 DOI: 10.1523/jneurosci.4578-03.2004] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2003] [Revised: 11/21/2003] [Accepted: 11/25/2003] [Indexed: 01/02/2023] Open
Abstract
Imprinting ensures that the infant forms the caregiver attachment necessary for altricial species survival. In our mammalian model of imprinting, neonatal rats rapidly learn the odor-based maternal attachment. This rapid learning requires reward-evoked locus ceruleus (LC) release of copious amounts of norepinephrine (NE) into the olfactory bulb. This imprinting ends at postnatal day 10 (P10) and is associated with a dramatic reduction in reward-evoked LC NE release. Here we assess whether the functional emergence of LC alpha2 inhibitory autoreceptors and the downregulation of LC alpha1 excitatory autoreceptors underlie the dramatic reduction in NE release associated with termination of the sensitive period. Postsensitive period pups (P12) were implanted with either LC or olfactory bulb cannulas, classically conditioned with intracranial drug infusions (P14), and tested for an odor preference (P15). During conditioning, a novel odor was paired with either olfactory bulb infusion of abeta-receptor agonist (isoproterenol) to assess the target effects of NE or direct LC cholinergic stimulation combined with alpha2 antagonists and alpha1 agonists in a mixture to reinstate neonatal levels of LC autoreceptor activity to assess the source of NE. Pups learned an odor preference when the odor was paired with either olfactory bulb isoproterenol infusion or reinstatement of neonatal LC receptor activity. These results suggest that LC autoreceptor functional changes rather than olfactory bulb changes underlie sensitive period termination.
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Affiliation(s)
- Stephanie Moriceau
- Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
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Neurobehavioral Development of Infant Learning and Memory: Implications for Infant Attachment. ADVANCES IN THE STUDY OF BEHAVIOR 2004. [DOI: 10.1016/s0065-3454(04)34003-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Abstract
The perception of odorant molecules provides the essential information that allows animals to explore their surrounding. We describe here how the external world of scents may sculpt the activity of the first central relay of the olfactory system, i.e., the olfactory bulb. This structure is one of the few brain areas to continuously replace one of its neuronal populations: the local GABAergic interneurons. How the newly generated neurons integrate into a pre-existing neural network and how basic olfactory functions are maintained when a large percentage of neurons are subjected to continuous renewal, are important questions that have recently received new insights. Furthermore, we shall see how the adult neurogenesis is specifically subjected to experience-dependent modulation. In particular, we shall describe the sensitivity of the bulbar neurogenesis to the activity level of sensory inputs from the olfactory epithelium and, in turn, how this neurogenesis may adjust the neural network functioning to optimize odor information processing. Finally, we shall discuss the behavioral consequences of the bulbar neurogenesis and how it may be appropriate for the sense of smell. By maintaining a constitutive turnover of bulbar interneurons subjected to modulation by environmental cues, we propose that adult ongoing neurogenesis in the olfactory bulb is associated with improved olfactory memory. These recent findings not only provide new fuel for the molecular and cellular bases of sensory perception but should also shed light onto cellular bases of learning and memory.
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Affiliation(s)
- Pierre-Marie Lledo
- Laboratory of Perception and Memory, Centre National de la Recherche Scientifique, Unité de Recherche Associée 2182, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris, France.
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Early odor preference learning in the rat: bidirectional effects of cAMP response element-binding protein (CREB) and mutant CREB support a causal role for phosphorylated CREB. J Neurosci 2003. [PMID: 12805315 DOI: 10.1523/jneurosci.23-11-04760.2003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Early odor preference learning in rats is associated with increases of phosphorylated CREB (pCREB) in mitral cells of the olfactory bulb. In the present study, herpes simplex virus expressing CREB (HSV-CREB) and dominant-negative mutant CREB (HSV-mCREB) have been injected into the bulb to assess a causal role for CREB and pCREB in this model. Odor paired with stroking or with the beta-adrenoceptor agonist isoproterenol produces odor approach 24 hr later. Isoproterenol-induced learning exhibits an inverted U curve dose-dependent learning relationship with both low and high doses failing to produce learning. pCREB increases have only been seen at the learning effective dose. In the present study, injection of an HSV vector expressing mutant CREB into the olfactory bulb prevented learning induced by stroking. Control HSV expressing LacZ was without effect. Expression of mutant CREB shifted the dose-learning curve for isoproterenol to the right such that a higher dose was required to induce learning. Expression of CREB shifted the dose-learning curve for isoproterenol to the left, with a lower dose now producing learning. As expected from this shift, CREB overexpression interfered with learning induced by stroking. When learning occurred, with either CREB or mutant CREB, pCREB was observed to be elevated relative to the nonlearning LacZ control groups. Unexpectedly, with odor plus stroking in the nonlearning CREB group, the level of pCREB was also higher than with odor plus stroking in LacZ controls that did learn. The data demonstrate a causal role for CREB and pCREB in early mammalian odor preference learning, reinforcing CREB as a "universal" memory molecule. They support evidence that CREB overexpression can be deleterious and suggest the hypothesis of an optimal pCREB window for learning.
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Leon M, Johnson BA. Olfactory coding in the mammalian olfactory bulb. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2003; 42:23-32. [PMID: 12668289 DOI: 10.1016/s0165-0173(03)00142-5] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
There have been a number of recent approaches to the study of olfactory coding, each of which has its advantages and disadvantages. In the present review, we discuss our own work on this topic, which has involved mapping uptake of [14C]2-deoxyglucose across the entire glomerular layer of the rat main olfactory bulb in response to systematically selected pure odorant molecules. Our strategy to understand the olfactory code has involved four approaches. In the first, we determined whether the system encodes odorants in their entirety, or whether it encodes odorants by representing combinations of molecular features that add together to comprise a neural picture of each odorant. Multiple odorant features appeared to be coded by multiple receptors. Our second strategy examined the ways that such features are represented. We stimulated rats with odorants that differed greatly in their molecular structure to be able to identify a set of odorant feature response domains. Our third approach asked how odorants with very small differences in molecular structure are coded, and we found systematic differences in the representation of such features within response domains. Finally, we were able to predict odor perception from the neural representations of odorants that differed in only a single aspect of their structure. Using these strategies, we have been able to learn some of the rules by which the olfactory code operates. These rules have allowed us to predict where previously unmapped molecules would be represented and how differences in molecular representations affect olfactory perceptions.
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Affiliation(s)
- Michael Leon
- Department of Neurobiology and Behavior, University of California, Room 2205 MH, Irvine, CA 92697-4550, USA.
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Ferrari CC, Johnson BA, Leon M, Pixley SK. Spatiotemporal distribution of the insulin-like growth factor receptor in the rat olfactory bulb. Neurochem Res 2003; 28:29-43. [PMID: 12587661 DOI: 10.1023/a:1021639926941] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Insulin-like growth factor I (IGF-I) and its receptor (IGF-IR) are involved in growth of neurons. In the rat olfactory epithelium, we previously showed IGF-IR immunostaining in subsets of olfactory receptor neurons. We now report that IGF-IR staining was heaviest in the olfactory nerve layer of the rat olfactory bulb at embryonic days 18, and 19 and postnatal day 1, with labeling of protoglomeruli. In the adult, only a few glomeruli were IGF-IR-positive, some of which were unusually small and strongly labeled. Some IGF-IR-positive fibers penetrated deeper into the external plexiform layer, even in adults. In developing tissues, IGF-IR staining co-localized with that for olfactory marker protein and growth associated protein GAP-43, but to a lesser extent with synaptophysin. In the adult, IGF-IR-positive fibers were compartmentalized within glomeruli. IGF-I may play a role in glomerular synaptogenesis and/or plasticity, possibly contributing to development of coding patterns for odor detection or identification.
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Affiliation(s)
- Carina C Ferrari
- Department of Cell Biology, Neurobiology and Anatomy, University Cincinnati College of Medicine, Cincinnati, Ohio 45267-0521, USA
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49
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Affiliation(s)
- Regina M Sullivan
- Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
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50
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Yuan Q, Harley CW, McLean JH, Knöpfel T. Optical imaging of odor preference memory in the rat olfactory bulb. J Neurophysiol 2002; 87:3156-9. [PMID: 12037216 DOI: 10.1152/jn.00917.2001] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Early olfactory preference learning in rat pups occurs when novel odors are paired with reinforcing tactile stimulation that activate the noradrenergic locus coeruleus. Pairing of odor and a noradrenergic agonist in the olfactory bulb is both necessary and sufficient for odor preference learning. This suggests the memory change occurs in the olfactory bulb. Previous electrophysiological experiments demonstrated that odor preference training induces an increase in the field excitatory postsynaptic potential to olfactory nerve input and an alteration, after training, in glomerular [14C]2- deoxyglucose uptake and in single-unit responses of principal cells. We investigate here whether, 24 h after olfactory preference training, there is an alteration in intrinsic optical signals at the glomerular level. Six-day-old rat pups were trained, as previously, for a peppermint odor preference. Trained pups and control littermates were subjected to imaging of odor-induced intrinsic optical signals 1 day after the training session. Trained pups exhibited significantly larger responses to the peppermint compared with untrained littermates previously exposed to the same odor. The response of trained pups to a control odor (amyl acetate) was, however, not significantly different from that of untrained littermates. These observations demonstrate that odor preference memory can be read-out by optical imaging techniques.
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Affiliation(s)
- Qi Yuan
- Laboratory for Neuronal Circuit Dynamics, Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN), Saitama 351-0198, Japan
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