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Aversive learning-induced plasticity throughout the adult mammalian olfactory system: insights across development. J Bioenerg Biomembr 2018; 51:15-27. [PMID: 30171506 DOI: 10.1007/s10863-018-9770-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/27/2018] [Indexed: 10/28/2022]
Abstract
Experiences, such as sensory learning, are known to induce plasticity in mammalian sensory systems. In recent years aversive olfactory learning-induced plasticity has been identified at all stages of the adult olfactory pathway; however, the underlying mechanisms have yet to be identified. Much of the work regarding mechanisms of olfactory associative learning comes from neonates, a time point before which the brain or olfactory system is fully developed. In addition, pups and adults often express different behavioral outcomes when subjected to the same olfactory aversive conditioning paradigm, making it difficult to directly attribute pup mechanisms of plasticity to adults. Despite the differences, there is evidence of similarities between pups and adults in terms of learning-induced changes in the olfactory system, suggesting at least some conserved mechanisms. Identifying these conserved mechanisms of plasticity would dramatically increase our understanding of how the brain is able to alter encoding and consolidation of salient olfactory information even at the earliest stages following aversive learning. The focus of this review is to systematically examine literature regarding olfactory associative learning across developmental stages and search for similarities in order to build testable hypotheses that will inform future studies of aversive learning-induced sensory plasticity in adults.
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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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Abstract
The nature of memory is a central issue in neuroscience. How does our representation of the world change with learning and experience? Here we use the transcription of Arc mRNA, which permits probing the neural representations of temporally separated events, to address this in a well characterized odor learning model. Rat pups readily associate odor with maternal care. In pups, the lateralized olfactory networks are independent, permitting separate training and within-subject control. We use multiday training to create an enduring memory of peppermint odor. Training stabilized rewarded, but not nonrewarded, odor representations in both mitral cells and associated granule cells of the olfactory bulb and in the pyramidal cells of the anterior piriform cortex. An enlarged core of stable, likely highly active neurons represent rewarded odor at both stages of the olfactory network. Odor representations in anterior piriform cortex were sparser than typical in adult rat and did not enlarge with learning. This sparser representation of odor is congruent with the maturation of lateral olfactory tract input in rat pups. Cortical representations elsewhere have been shown to be highly variable in electrophysiological experiments, suggesting brains operate normally using dynamic and network-modulated representations. The olfactory cortical representations here are consistent with the generalized associative model of sparse variable cortical representation, as normal responses to repeated odors were highly variable (∼70% of the cells change as indexed by Arc). Learning and memory modified rewarded odor ensembles to increase stability in a core representational component.
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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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Cellular registration without behavioral recall of olfactory sensory input under general anesthesia. Anesthesiology 2014; 120:890-905. [PMID: 24694846 DOI: 10.1097/aln.0000000000000137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Previous studies suggest that sensory information is "received" but not "perceived" under general anesthesia. Whether and to what extent the brain continues to process sensory inputs in a drug-induced unconscious state remain unclear. METHODS One hundred seven rats were randomly assigned to 12 different anesthesia and odor exposure paradigms. The immunoreactivities of the immediate early gene products c-Fos and Egr1 as neural activity markers were combined with behavioral tests to assess the integrity and relationship of cellular and behavioral responsiveness to olfactory stimuli under a surgical plane of ketamine-xylazine general anesthesia. RESULTS The olfactory sensory processing centers could distinguish the presence or absence of experimental odorants even when animals were fully anesthetized. In the anesthetized state, the c-Fos immunoreactivity in the higher olfactory cortices revealed a difference between novel and familiar odorants similar to that seen in the awake state, suggesting that the anesthetized brain functions beyond simply receiving external stimulation. Reexposing animals to odorants previously experienced only under anesthesia resulted in c-Fos immunoreactivity, which was similar to that elicited by familiar odorants, indicating that previous registration had occurred in the anesthetized brain. Despite the "cellular memory," however, odor discrimination and forced-choice odor-recognition tests showed absence of behavioral recall of the registered sensations, except for a longer latency in odor recognition tests. CONCLUSIONS Histologically distinguishable registration of sensory processing continues to occur at the cellular level under ketamine-xylazine general anesthesia despite the absence of behavioral recognition, consistent with the notion that general anesthesia causes disintegration of information processing without completely blocking cellular communications.
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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, Shionoya K, Sander K, Sullivan RM. Ontogeny of odor-LiCl vs. odor-shock learning: similar behaviors but divergent ages of functional amygdala emergence. Learn Mem 2009; 16:114-21. [PMID: 19181617 DOI: 10.1101/lm.977909] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Both odor-preference and odor-aversion learning occur in perinatal pups before the maturation of brain structures that support this learning in adults. To characterize the development of odor learning, we compared three learning paradigms: (1) odor-LiCl (0.3M; 1% body weight, ip) and (2) odor-1.2-mA shock (hindlimb, 1 sec)--both of which consistently produce odor-aversion learning throughout life and (3) odor-0.5-mA shock, which produces an odor preference in early life but an odor avoidance as pups mature. Pups were trained at postnatal day (PN) 7-8, 12-13, or 23-24, using odor-LiCl and two odor-shock conditioning paradigms of odor-0.5-mA shock and odor-1.2-mA shock. Here we show that in the youngest pups (PN7-8), odor-preference learning was associated with activity in the anterior piriform (olfactory) cortex, while odor-aversion learning was associated with activity in the posterior piriform cortex. At PN12-13, when all conditioning paradigms produced an odor aversion, the odor-0.5-mA shock, odor-1.2-mA shock, and odor-LiCl all continued producing learning-associated changes in the posterior piriform cortex. However, only odor-0.5-mA shock induced learning-associated changes within the basolateral amygdala. At weaning (PN23-24), all learning paradigms produced learning-associated changes in the posterior piriform cortex and basolateral amygdala complex. These results suggest at least two basic principles of the development of the neurobiology of learning: (1) Learning that appears similar throughout development can be supported by neural systems showing very robust developmental changes, and (2) the emergence of amygdala function depends on the learning protocol and reinforcement condition being assessed.
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Affiliation(s)
- Charlis Raineki
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, Child and Adolescent Psychiatry, Child Study Center, New York University Langone Medical Center, Orangeburg, New York 10962, USA
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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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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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Roth TL, Moriceau S, Sullivan RM. Opioid modulation of Fos protein expression and olfactory circuitry plays a pivotal role in what neonates remember. Learn Mem 2006; 13:590-8. [PMID: 17015856 PMCID: PMC1783613 DOI: 10.1101/lm.301206] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Accepted: 07/18/2006] [Indexed: 01/02/2023]
Abstract
Paradoxically, fear conditioning (odor-0.5 mA shock) yields a learned odor preference in the neonate, presumably due to a unique learning and memory circuit that does not include apparent amygdala participation. Post-training opioid antagonism with naltrexone (NTX) blocks consolidation of this odor preference and instead yields memory of a learned odor aversion. Here we characterize the neural circuitry underlying this switch during memory consolidation. Experiment 1 assessed post-training opioid modulation of Fos protein expression within olfactory circuitry (olfactory bulb, piriform cortex, amygdala). Odor-shock conditioning with no post-training treatment (odor preference) induced significant changes in Fos protein expression in the granule cell layer of the olfactory bulb and anterior piriform cortex. Post-training opioid receptor antagonism (odor aversion) prevented the learning-induced changes in the anterior piriform cortex and also induced significant changes in Fos protein expression in the central nucleus of the amygdala. Experiment 2 assessed intra-amygdala opioid modulation of neonate memory consolidation. Post-training infusion of NTX within the amygdala permitted consolidation of an odor aversion, while vehicle-infused pups continued to demonstrate an odor preference. Overall, results demonstrate that opioids modulate memory consolidation in the neonate via modulating Fos protein expression in olfactory circuitry. Furthermore, these results suggest that opioids are instrumental in suppressing neonate fear behavior via modulating the amygdala.
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Affiliation(s)
- Tania L Roth
- Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
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Magavi SSP, Mitchell BD, Szentirmai O, Carter BS, Macklis JD. Adult-born and preexisting olfactory granule neurons undergo distinct experience-dependent modifications of their olfactory responses in vivo. J Neurosci 2005; 25:10729-39. [PMID: 16291946 PMCID: PMC6725839 DOI: 10.1523/jneurosci.2250-05.2005] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 09/28/2005] [Accepted: 09/28/2005] [Indexed: 11/21/2022] Open
Abstract
Neurogenesis continues throughout adulthood in the mammalian olfactory bulb and hippocampal dentate gyrus, suggesting the hypothesis that recently generated, adult-born neurons contribute to neural plasticity and learning. To explore this hypothesis, we examined whether olfactory experience modifies the responses of adult-born neurons to odorants, using immediate early genes (IEGs) to assay the response of olfactory granule neurons. We find that, shortly after they differentiate and synaptically integrate, the population of adult-born olfactory granule neurons has a greater population IEG response to novel odors than mature, preexisting neurons. Familiarizing mice with test odors increases the response of the recently incorporated adult-born neuron population to the test odors, and this increased responsiveness is long lasting, demonstrating that the response of the adult-born neuron population is altered by experience. In contrast, familiarizing mice with test odors decreases the IEG response of developmentally generated neurons, suggesting that recently generated adult-born neurons play a distinct role in olfactory processing. The increased IEG response is stimulus specific; familiarizing mice with a set of different, "distractor" odors does not increase the adult-born neuron population response to the test odors. Odor familiarization does not influence the survival of adult-born neurons, indicating that the changes in the population response of adult-born neurons are not attributable to increased survival of odor-stimulated neurons. These results demonstrate that recently generated adult-born olfactory granule neurons and older, preexisting granule neurons undergo contrasting experience-dependent modifications in vivo and support the hypothesis that adult-born neurons are involved in olfactory learning.
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Affiliation(s)
- Sanjay S P Magavi
- Massachusetts General Hospital-Harvard Medical School Center for Nervous System Repair, Department of Neurosurgery, Boston, Massachusetts 02114, USA
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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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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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Beech RD, Cleary MA, Treloar HB, Eisch AJ, Harrist AV, Zhong W, Greer CA, Duman RS, Picciotto MR. Nestin promoter/enhancer directs transgene expression to precursors of adult generated periglomerular neurons. J Comp Neurol 2004; 475:128-41. [PMID: 15176089 DOI: 10.1002/cne.20179] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The subventricular zone (SVZ) is a major neurogenic region in the adult brain. Cells from the SVZ give rise to two populations of olfactory bulb interneurons: the granule cells and periglomerular (PG) cells. Currently, little is known about the signaling pathways that direct these newly generated neurons to become either granule or PG neurons. In the present study, we used the nestin promoter and enhancer to direct expression of the tetracycline transactivator (tTA). We generated two independent strains of nestin-tTA transgenic animals and crossed founder mice from both lines to mice containing a tetracycline-regulated transgene (mCREB) whose expression served as a marker for the activity of the nestin-tTA transgene. mCREB expression occurred in a subset of proliferating cells in the SVZ and rostral migratory stream in both lines. Surprisingly, in both lines of nestin-tTA mice transgene expression in the olfactory bulb was limited to PG neurons and was absent from granule cells, suggesting that this nestin promoter construct differentiates between the two interneuronal populations. Transgene expression occurred in several subtypes of PG neurons, including those expressing calretinin, calbindin, GAD67, and tyrosine hydroxylase. These results suggest that a unique subset of SVZ precursor cells gives rise to PG, and not granule cells. The ability to express different transgenes within this subpopulation of neuronal precursors provides a powerful system to define the signals regulating the differentiation and survival of adult-generated neurons in the olfactory bulb.
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Affiliation(s)
- Robert D Beech
- Department of Psychiatry, Yale University School of Medicine, 34 Park Street, 3rd Floor, New Haven, CT 06508, USA.
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Abstract
Olfactory perceptual learning is a relatively long-term, learned increase in perceptual acuity, and has been described in both humans and animals. Data from recent electrophysiological studies have indicated that olfactory perceptual learning may be correlated with changes in odorant receptive fields of neurons in the olfactory bulb and piriform cortex. These changes include enhanced representation of the molecular features of familiar odors by mitral cells in the olfactory bulb, and synthetic coding of multiple coincident odorant features into odor objects by cortical neurons. In this paper, data are reviewed that show the critical role of acetylcholine (Ach) in olfactory system function and plasticity, and cholinergic modulation of olfactory perceptual learning at both the behavioral and cortical level.
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Affiliation(s)
- Donald A Wilson
- 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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Shah A, Oxley G, Lovic V, Fleming AS. Effects of preweaning exposure to novel maternal odors on maternal responsiveness and selectivity in adulthood. Dev Psychobiol 2002; 41:187-96. [PMID: 12325133 DOI: 10.1002/dev.10064] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We examined the effects of odor exposure in the nest on the offspring's subsequent adult responsivity to pups scented with the same odor or a different odor. It was hypothesized that animals receiving exposure to the odor in the nest would be more maternally responsive to pups scented with the (same) exposed odor than to unscented (water-scented) pups. In the first part of the study (Part A), Sprague-Dawley female rat pups (days 1-18 of age) either received exposure to an artificial lemon odor or to the natural (water) odor in the nest. In the second part of the study (Part B), rat pups were exposed daily to lemon or neutral odorants in an incubator at a distance from the mother and the nest. On day 21, animals received odor preference tests for lemon versus neutral pine bedding. On day 60, animals were mated and their pups were removed at 15-min intervals at the time of parturition. Animals were then tested for maternal behavior to foster pups on day 1 or 7 after parturition. Foster pups were scented either with the lemon odor or with water (unscented). Early exposure to lemon in the nest context enhanced animals' attraction to the lemon odor in juvenile tests. In adult maternal tests, exposure to odor on the mother and in the nest had two effects. It increased the latency for animals to express maternal behavior; however, once mothers expressed maternal behavior, they spent more time licking and crouching over pups scented with the same odorant to which they had been exposed earlier on their own mothers. Simple exposure to the lemon odorant out of context of the nest had no effect on adult maternal latencies or behavior.
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Affiliation(s)
- Akeel Shah
- Department of Psychology, University of Toronto, Mississauga, Ontario, L5L 1C6 Canada
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Inaki K, Takahashi YK, Nagayama S, Mori K. Molecular-feature domains with posterodorsal-anteroventral polarity in the symmetrical sensory maps of the mouse olfactory bulb: mapping of odourant-induced Zif268 expression. Eur J Neurosci 2002; 15:1563-74. [PMID: 12059964 DOI: 10.1046/j.1460-9568.2002.01991.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Individual glomeruli in the mammalian olfactory bulb presumably represent a single type of odourant receptor. Thus, the glomerular sheet provides odourant receptor maps at the surface of the olfactory bulb. To understand the basic spatial organization of the olfactory sensory maps, we first compared the spatial distribution of odourant-induced responses measured by the optical imaging of intrinsic signals with that detected immunohistochemically by expressions of Zif268, one of the immediate early gene products in juxtaglomerular cells. In the dorsal surface of the bulb, we detected a clear correlation in the spatial pattern between these responses. In addition, the molecular-feature domains and their polarities (spatial shifts of responses with an increase in carbon chain length) that were defined by the optical imaging method could be also detected by the Zif268 mapping method. We then mapped the Zif268 signals over the entire olfactory bulb using a homologous series of fatty acids and aliphatic alcohols as stimulus odourants. We superimposed the Zif268 signals onto the standard unrolled map with the help of cell adhesion molecule compartments. Each odourant typically elicited two pairs of clusters of dense Zif268 signals. The results showed that molecular-feature domains and their polarities were arranged symmetrically at stereotypical positions in a mirror-image fashion between the lateral and the medial sensory maps. The polarity of each domain was roughly in parallel with the posterodorsal-anteroventral axis that was defined by the cell adhesion molecule compartments. These results suggest that the molecular-feature domain with its fixed polarity is one of the basic structural units in the spatial organization of the odourant receptor maps in the olfactory bulb.
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Affiliation(s)
- Koichiro Inaki
- Department of Physiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Japan.
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Chapter VIII c-Fos in learning: beyond the mapping of neuronal activity. HANDBOOK OF CHEMICAL NEUROANATOMY 2002. [DOI: 10.1016/s0924-8196(02)80019-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Chaudhuri A, Zangenehpour S. Chapter V Molecular activity maps of sensory function. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s0924-8196(02)80016-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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Abstract
Functional imaging methods permit analysis of neuronal systems in which activity is broadly distributed in time and space. In the olfactory system the dimensions that describe odorant stimuli in "odorant space" are still poorly defined. One way of trying to characterize the attributes of this space is to examine the ways in which its dimensions are encoded by the neurons and circuits making up the system and to compare these responses with physical-chemical attributes of the stimuli and with the output behavior of the animal. For documenting distributed events as they occur, imaging methods are among the few tools available. We are still in the early stages of this analysis; however, a number of recent studies have contributed new information to our understanding of the odorant coding problem. This paper describes imaging results in the context of other data that have contributed to our understanding of how odors are encoded by the peripheral olfactory pathway.
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Affiliation(s)
- J S Kauer
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, Massachusetts 02111, USA.
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22
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Spatial Coding in the Olfactory System. Dev Psychobiol 2001. [DOI: 10.1007/978-1-4615-1209-7_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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23
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Faas AE, Spontón ED, Moya PR, Molina JC. Differential responsiveness to alcohol odor in human neonates: effects of maternal consumption during gestation. Alcohol 2000; 22:7-17. [PMID: 11109023 DOI: 10.1016/s0741-8329(00)00103-8] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Previous human and animal studies have shown that specific memories arise during prenatal life as a function of fetal processing of chemosensory stimuli present in the amniotic fluid. Furthermore, the animal literature indicates that fetal exposure to alcohol modifies subsequent neonatal and infantile responsiveness toward the sensory attributes of the drug. The main goal of the present study was to analyze whether differential maternal alcohol consumption during pregnancy affects neonatal reactivity to ethanol odor. To achieve this goal, an initial experiment examined how healthy human neonates respond to olfactory stimuli. In this first experiment, newborns (postpartum age: 24-48 h) were evaluated in terms of motor responsiveness elicited by repetitive stimulation with either alcohol or lemon odors. Infants exhibited a marked increase in duration of overall body and head and facial activity when the odorants were first presented. In four successive trials, behavioral responsiveness progressively declined until reaching baseline values. The introduction of a novel odorant served to dishabituate the motor responses under analysis. In the second experiment newborn's reactivity to the mentioned odorants was evaluated as a function of maternal self-reported patterns of consumption of alcohol during gestation. Mothers were classified as frequent or infrequent drinkers. Babies born to frequent drinkers exhibited heightened reactivity toward ethanol odor when compared to newborns delivered by infrequent drinkers. No differences emerged when comparing the responses of both groups of infants elicited by a non-ethanol stimulus such as lemon. The results coupled with prior human and animal research suggest the possibility of intrauterine experience with alcohol odor that yields a sensory memory likely to be retrieved immediately after birth.
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Affiliation(s)
- A E Faas
- Servicio de Neonatología, Hospital Universitario de Maternidad y Neonatología, Universidad Nacional de Córdoba, 5000, Córdoba, Argentina
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24
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Allingham K, Brennan PA, Distel H, Hudson R. Expression of c-fos in the main olfactory bulb of neonatal rabbits in response to garlic as a novel and conditioned odour. Behav Brain Res 1999; 104:157-67. [PMID: 11125735 DOI: 10.1016/s0166-4328(99)00061-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Expression of c-Fos was examined in the olfactory bulbs of 3-day-old rabbits after they had been presented with the odour of garlic as a novel stimulus, as a learned odour, or during conditioning, and this expression compared with baseline levels in non-stimulated controls. Exposure to garlic odour resulted in substantial and widespread increases in c-Fos expression in the olfactory bulbs of all animals. However, although conditioned pups showed a specific behavioural response to the learned garlic odour, neither the amount nor pattern of c-Fos expression differed compared to pups exposed to garlic as a novel odour. The odour-induced expression of c-Fos was not well localised, although there was a significant increase in the number of granule cells expressing c-Fos in the ventrolateral region of the bulb. These results support previous reports that the response to odours in the olfactory bulb of new-born animals is not as spatially distinct as that in adults. Nevertheless, the immature olfactory system of these young animals is clearly capable of very specific odour learning.
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Affiliation(s)
- K Allingham
- Institut für Medizinische Psychologie, University of Munich, München, Germany.
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25
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Paban V, Alescio-Lautier B, Devigne C, Soumireu-Mourat B. Fos protein expression induced by intracerebroventricular injection of vasopressin in unconditioned and conditioned mice. Brain Res 1999; 825:115-31. [PMID: 10216179 DOI: 10.1016/s0006-8993(99)01232-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Arginine8-vasopressin (AVP) has been shown to improve memory consolidation in various mnemonic tasks. Our previous studies have pointed out the involvement of the hippocampus in memory consolidation and retrieval processes during discriminative learning by mice. The present study attempts to determine what other brain areas besides the hippocampus might be involved in the enhancing effect of intracerebroventricularly (i.c.v.) injected AVP on memory consolidation in a visual discrimination task using a polyclonal antibody that acts against Fos and Fos-like proteins. For behavioral testing, AVP was i.c.v. injected at the behaviorally active dose of 2 ng after the last learning session and improvement in consolidation processes was assessed in a retention session. Changes in Fos and Fos-like protein expression were determined in non-conditioned and conditioned mice. In non-conditioned mice, AVP i. c.v. injected at a dose of 2 ng evoked a time-dependent increase in Fos and Fos-like protein expression in the dentate gyrus (DG), CA1 and CA3 hippocampal fields, lateral septum (LS), bed nucleus of the stria terminalis, and basolateral and central amygdaloid nuclei, with a peak 120 min after the injection in most of the these brain areas. In contrast, in conditioned mice, an increase in the level of Fos expression, assessed 120 min after the end of learning and the injection of AVP, was detected only in the DG, ventral CA3 hippocampal field, and LS. Thus, the pattern observed after post-training injection of AVP was not the same as that evoked by AVP alone, since among the limbic structures activated following AVP alone, only the DG, the CA3 hippocampal field, and the LS seem to be involved in the enhancing effect of AVP on memory consolidation in discriminative learning.
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Affiliation(s)
- V Paban
- Lab. de Neurobiologie des Comportements, UMR 6562 CNRS, Université de Provence, IBHOP, Traverse Charles Susini, 13388 Marseille Cedex 13, France
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26
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Brown HE, Garcia MM, Harlan RE. A two focal plane method for digital quantification of nuclear immunoreactivity in large brain areas using NIH-image software. BRAIN RESEARCH. BRAIN RESEARCH PROTOCOLS 1998; 2:264-72. [PMID: 9630665 DOI: 10.1016/s1385-299x(98)00003-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In principle, digital acquisition of cell-count data from serially-sectioned immunocytochemical material is a straightforward enterprise. First, a serial brain section is magnified by use of a microscope interfaced to a computer. Then, using appropriate hardware and software, a digital image is captured, and cellular profiles of interest are segmented from background objects according to mean grayscale intensity and pixel area. Ideally, the cells of interest would be uniformly distinguishable from other objects or areas of the image, with respect to grayscale intensity and size. However, due to non-uniformity in background staining of neuropil, immunocytochemical material often departs markedly from this ideal situation. As a consequence, determining grayscale intensity and cell size cutoff values which separate cells of interest from background becomes laborious and arbitrary. This problem can be diminished by increasing the magnification of the digitized image, which increases the figure-ground resolution of the image. However, high-magnification images make tissue navigation difficult and require that multiple images be captured. This paper describes a two focal plane procedure for obtaining cell counts from nuclear-stained immunocytochemistry material. This procedure allows the capturing and cell counting of relatively low-magnification images with high digital figure-ground resolution.
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Affiliation(s)
- H E Brown
- Department of Anatomy and Neuroscience, Training Program, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
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27
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Baba K, Ikeda M, Houtani T, Nakagawa H, Ueyama T, Sato K, Sakuma S, Yamashita T, Tsukahara Y, Sugimoto T. Odor exposure reveals non-uniform expression profiles of c-Jun protein in rat olfactory bulb neurons. Brain Res 1997; 774:142-8. [PMID: 9452202 DOI: 10.1016/s0006-8993(97)81697-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In the main olfactory bulb, neurons are arranged strategically in distinct layers among which translaminar synaptic transmission can be made from the superficial, sensory to the deep, output layers that account for the processing of olfactory information. To search for stimulus-transcription coupling thought to be operated differentially in several cell types, c-Jun expression was examined immunohistochemically in rat olfactory bulb following 30-min odor stimulation with acetic acid and 1-butanol. c-Jun was rapidly induced in neuronal cell nuclei belonging to periglomerular, tufted, mitral and granule cells. The disappearance of c-Jun, however, differed between each cell type. In the glomerular layer, the glomeruli composed of c-Jun-expressing periglomerular cells were seen. Different odors led to labeling of different sets of glomeruli. The labeled periglomerular cells disappeared within 2 h. In all the deeper layers, however, a rather homogeneous label was noted for the tufted, mitral and granule cells present throughout the olfactory bulb, regardless of the difference in odor. In tufted and mitral cells, the c-Jun expression persisted for 4 days after odor stimulation. In the granule cell layer, numerous granule cells increased c-Jun immunoreactivity which lasted for 1 day following odor application. In control rats which were given clean air, the basal amount of c-Jun expression was seen confined to scattered granule cells. The results suggest that c-Jun is expressed in a variety of odorant-stimulated bulb neurons with a time course being dependent on cell type.
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Affiliation(s)
- K Baba
- Department of Anatomy, Kansai Medical University, Moriguchi, Osaka, Japan
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28
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McCollum JF, Woo CC, Leon M. Granule and mitral cell densities are unchanged following early olfactory preference training. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1997; 99:118-20. [PMID: 9088573 DOI: 10.1016/s0165-3806(96)00201-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Early olfactory preference training causes both an increased number of juxtaglomerular cells and an increased number of such cells expressing Fos protein. In contrast, there are fewer cells expressing Fos protein in the granule cell layer after training. Here, we report no change in the number or size of granule and mitral cells as a consequence of these early olfactory experiences.
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Affiliation(s)
- J F McCollum
- Department of Psychobiology, University of California, Irvine 92697-4550, USA
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