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Zhang Y, Sun L, Liu E, Wang A, Yan J. The olfactory stimulation slows down the substance clearance in the extracellular space of the hippocampus in rat brain. Biochem Biophys Res Commun 2019; 515:429-435. [PMID: 31155295 DOI: 10.1016/j.bbrc.2019.05.159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 05/26/2019] [Indexed: 12/25/2022]
Abstract
Accelerating the clearance of toxin in the brain extracellular space (ECS) has grown a promising strategy for treating some central nervous system diseases. As oldest sensory system, we know little about the influence of olfaction on the brain, but preclinical studies such as treatment of neurological diseases through it are in the ascendant. This makes it important to clarify the effects of olfaction on brain ECS and interstitial fluid (ISF) drainage. In this study, the effect of olfactory stimulation (eugenol, EUG) on ISF flow in hippocampus and its association with aquaporin 4 (Aqp4) had been investigated. The results show that eugenol can significantly increase the activity of hippocampal neurons, but reduce the clearance and diffusion rates of Gd-DTPA and A-594 in hippocampus. Similarly, eugenol inhalation slows down the rate of Gd-DTPA in CSF entering the hippocampus and its clearance. And knockout of Aqp4 gene aggravated these processes. In vitro results showed that after Aqp4 gene silencing, astrocytes grew slowly, with significantly decreased cells number, less nuclei, atrophied bodies and shorter processes. These results concluded that olfactory stimulation can change the ECS structure of the hippocampus, slow down the ISF drainage, and improve the function of neurons, while Aqp4 plays important roles.
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Affiliation(s)
- Yixuan Zhang
- Department of Anatomy and Histology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - Linlin Sun
- Department of Anatomy and Histology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - E Liu
- Department of Anatomy and Histology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - Aibo Wang
- Department of Radiology, Peking University Third Hospital, Beijing, 100191, China; Beijing Key Lab of Magnetic Resonance Imaging Technology, Beijing, 100191, China
| | - Junhao Yan
- Department of Anatomy and Histology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China; Beijing Key Lab of Magnetic Resonance Imaging Technology, Beijing, 100191, China.
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2
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Nativio P, Zoratto F, Romano E, Lacivita E, Leopoldo M, Pascale E, Passarelli F, Laviola G, Adriani W. Stimulation of 5-HT7 receptor during adolescence determines its persistent upregulation in adult rat forebrain areas. Synapse 2015; 69:533-42. [PMID: 26364910 DOI: 10.1002/syn.21846] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 07/15/2015] [Accepted: 07/30/2015] [Indexed: 12/21/2022]
Abstract
Brain serotonin 7 (5-HT7) receptors play an important functional role in learning and memory, in regulation of mood and motivation, and for circadian rhythms. Recently, we have studied the modulatory effects of a developmental exposure (under subchronic regimen) in rats with LP-211, a brain-penetrant and selective 5-HT7 receptor agonist. We aimed at further deciphering long-term sequelae into adulthood. LP-211 (0.250 mg/kg i.p., once/day) was administered for 5 days during the adolescent phase (postnatal days 43-45 to 47-49). When adult (postnatal days >70), forebrain areas were obtained for ex vivo immunohistochemistry, whose results prompted us to reconsider the brain connectivity maps presented in our previous study (Canese et al., Psycho-Pharmacol 2015;232:75-89.) Significant elevation in levels of 5-HT7 receptors were evidenced due to adolescent LP-211 exposure, in dorsal striatum (which also shows an increase of dopaminergic D2 auto-receptors) and-unexpectedly-in piriform cortex, with no changes in ventral striatum. We observed that functional connectivity from a seed on the right hippocampus was more extended than reported, also including the piriform cortex. As a whole, the cortical loop rearranged by adolescent LP-211 exposure consisted in a hippocampus receiving connections from piriform cortex and dorsal striatum, the latter both directly and through functional control over the 'extended amygdala'. Such results represent a starting point to explore neurophysiology of 5-HT7 receptors. Further investigation is warranted to develop therapies for sleep disorders, for impaired emotional and motivational regulation, for attentive and executive deficit. The 5-HT7 agonist LP-211 (0.250 mg/kg i.p., once/day) was administered for 5 days during adolescence (postnatal days 43-45 to 47-49) in rats. When adult (postnatal days >70), a significant elevation in levels of 5-HT7 receptors were evidenced in dorsal striatum and-unexpectedly-in piriform cortex.
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Affiliation(s)
- Paola Nativio
- Departments of Molecular Medicine and of Medical Surgical Sciences and Biotechnology, "Sapienza" University of Rome, Rome, Italy
| | - Francesca Zoratto
- Department of Cell Biology and Neurosciences, Istituto Superiore Di Sanità, Rome, Italy
| | - Emilia Romano
- Department of Cell Biology and Neurosciences, Istituto Superiore Di Sanità, Rome, Italy
| | - Enza Lacivita
- Department of Pharmacy, Università Degli Studi "a. Moro", Bari, Italy
| | - Marcello Leopoldo
- Department of Pharmacy, Università Degli Studi "a. Moro", Bari, Italy
| | - Esterina Pascale
- Departments of Molecular Medicine and of Medical Surgical Sciences and Biotechnology, "Sapienza" University of Rome, Rome, Italy
| | - Francesca Passarelli
- Departments of Molecular Medicine and of Medical Surgical Sciences and Biotechnology, "Sapienza" University of Rome, Rome, Italy
| | - Giovanni Laviola
- Department of Cell Biology and Neurosciences, Istituto Superiore Di Sanità, Rome, Italy
| | - Walter Adriani
- Department of Cell Biology and Neurosciences, Istituto Superiore Di Sanità, Rome, Italy
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Wang D, Zhao J, Gao Z, Chen N, Wen B, Lu W, Lei Z, Chen C, Liu Y, Feng J, Wang JH. Neurons in the barrel cortex turn into processing whisker and odor signals: a cellular mechanism for the storage and retrieval of associative signals. Front Cell Neurosci 2015; 9:320. [PMID: 26347609 PMCID: PMC4543922 DOI: 10.3389/fncel.2015.00320] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/03/2015] [Indexed: 12/28/2022] Open
Abstract
Associative learning and memory are essential to logical thinking and cognition. How the neurons are recruited as associative memory cells to encode multiple input signals for their associated storage and distinguishable retrieval remains unclear. We studied this issue in the barrel cortex by in vivo two-photon calcium imaging, electrophysiology, and neural tracing in our mouse model that the simultaneous whisker and olfaction stimulations led to odorant-induced whisker motion. After this cross-modal reflex arose, the barrel and piriform cortices connected. More than 40% of barrel cortical neurons became to encode odor signal alongside whisker signal. Some of these neurons expressed distinct activity patterns in response to acquired odor signal and innate whisker signal, and others encoded similar pattern in response to these signals. In the meantime, certain barrel cortical astrocytes encoded odorant and whisker signals. After associative learning, the neurons and astrocytes in the sensory cortices are able to store the newly learnt signal (cross-modal memory) besides the innate signal (native-modal memory). Such associative memory cells distinguish the differences of these signals by programming different codes and signify the historical associations of these signals by similar codes in information retrievals.
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Affiliation(s)
- Dangui Wang
- State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China
| | - Jun Zhao
- State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China ; Department of Biology, University of Chinese Academy of Sciences Beijing, China
| | - Zilong Gao
- State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China ; Department of Biology, University of Chinese Academy of Sciences Beijing, China
| | - Na Chen
- State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China
| | - Bo Wen
- State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China
| | - Wei Lu
- Department of Pharmacology and Collaborative Innovation, Center for Neurodegenerative Disorders in Shandong, Qingdao University, Medical College Dengzhou, China
| | - Zhuofan Lei
- Department of Pharmacology and Collaborative Innovation, Center for Neurodegenerative Disorders in Shandong, Qingdao University, Medical College Dengzhou, China
| | - Changfeng Chen
- Department of Physiology, Bengbu Medical College Bengbu, China
| | - Yahui Liu
- Department of Physiology, Bengbu Medical College Bengbu, China
| | - Jing Feng
- State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China
| | - Jin-Hui Wang
- State Key Lab of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences Beijing, China ; Department of Biology, University of Chinese Academy of Sciences Beijing, China ; Department of Physiology, Bengbu Medical College Bengbu, China
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4
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Environmental enrichment rescues memory in mice deficient for the polysialytransferase ST8SiaIV. Brain Struct Funct 2015; 221:1591-605. [DOI: 10.1007/s00429-015-0991-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 01/09/2015] [Indexed: 02/06/2023]
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5
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Manrique C, Migliorati M, Gilbert V, Brezun JM, Chaillan FA, Truchet B, Khrestchatisky M, Guiraudie-Capraz G, Roman FS. Dynamic expression of the polysialyltransferase in adult rat hippocampus performing an olfactory associative task. Hippocampus 2014; 24:979-89. [DOI: 10.1002/hipo.22284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 04/07/2014] [Accepted: 04/09/2014] [Indexed: 01/16/2023]
Affiliation(s)
| | | | - Valérie Gilbert
- Aix Marseille Université, CNRS; FR 3512 13331 Marseille France
| | | | | | - Bruno Truchet
- Aix Marseille Université, CNRS; UMR 7291 13331 Marseille France
| | | | | | - François S. Roman
- Aix Marseille Université, CNRS, NICN; UMR 7259 13344 Marseille France
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Álvarez-Salvado E, Pallarés V, Moreno A, Canals S. Functional MRI of long-term potentiation: imaging network plasticity. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130152. [PMID: 24298154 PMCID: PMC3843884 DOI: 10.1098/rstb.2013.0152] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Neurons are able to express long-lasting and activity-dependent modulations of their synapses. This plastic property supports memory and conveys an extraordinary adaptive value, because it allows an individual to learn from, and respond to, changes in the environment. Molecular and physiological changes at the cellular level as well as network interactions are required in order to encode a pattern of synaptic activity into a long-term memory. While the cellular mechanisms linking synaptic plasticity to memory have been intensively studied, those regulating network interactions have received less attention. Combining high-resolution fMRI and in vivo electrophysiology in rats, we have previously reported a functional remodelling of long-range hippocampal networks induced by long-term potentiation (LTP) of synaptic plasticity in the perforant pathway. Here, we present new results demonstrating an increased bilateral coupling in the hippocampus specifically supported by the mossy cell commissural/associational pathway in response to LTP. This fMRI-measured increase in bilateral connectivity is accompanied by potentiation of the corresponding polysynaptically evoked commissural potential in the contralateral dentate gyrus and depression of the inactive convergent commissural pathway to the ipsilateral dentate. We review these and previous findings in the broader context of memory consolidation.
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Affiliation(s)
| | | | | | - Santiago Canals
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, Sant Joan d'Alacant 03550, Spain
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7
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Breton-Provencher V, Saghatelyan A. Newborn neurons in the adult olfactory bulb: Unique properties for specific odor behavior. Behav Brain Res 2012; 227:480-9. [DOI: 10.1016/j.bbr.2011.08.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 07/31/2011] [Accepted: 08/01/2011] [Indexed: 01/02/2023]
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8
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Neuroprotective efficacy of Nardostachys jatamansi and crocetin in conjunction with selenium in cognitive impairment. Neurol Sci 2011; 33:1011-20. [DOI: 10.1007/s10072-011-0880-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2011] [Accepted: 12/03/2011] [Indexed: 11/27/2022]
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Abstract
Adult neurogenesis has captivated neuroscientists for decades, with hopes that understanding the programs underlying this phenomenon may provide unique insight toward avenues for brain repair. Interestingly, however, despite intense molecular and cellular investigation, the evolutionary roles and biological functions for ongoing neurogenesis have remained elusive. Here I review recent work published in the Journal of Neuroscience that reveals a functional role for continued neurogenesis toward forming short-term olfactory memories.
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Affiliation(s)
- Benjamin R Arenkiel
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
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10
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Interneurons produced in adulthood are required for the normal functioning of the olfactory bulb network and for the execution of selected olfactory behaviors. J Neurosci 2009; 29:15245-57. [PMID: 19955377 DOI: 10.1523/jneurosci.3606-09.2009] [Citation(s) in RCA: 196] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Olfactory bulb (OB) interneurons are continuously renewed throughout an animal's lifespan. Despite extensive investigation of this phenomenon, little is known about bulbar circuitry functioning and olfactory performances under conditions of ablated arrival of new neurons into the adult OB. To address this issue we performed morphological, electrophysiological, and behavioral analysis in mice with suppressed bulbar neurogenesis. Infusion of the antimitotic drug AraC to the lateral ventricle via 28 d osmotic minipumps abolished the arrival of newly born neurons into the adult OB without affecting the total number of granule cells. The number, dendritic arborization, and spine density of interneurons generated in adulthood, before pump installation, were also not affected by AraC treatment. As a result of ablated neurogenesis, mitral cells--the principal output neurons in the OB--receive fewer inhibitory synapses, display reduced frequency of spontaneous IPSCs, experience smaller dendrodendritic inhibition, and exhibit decreased synchronized activity. Consequently, short-term olfactory memory was drastically reduced in AraC-treated mice. In contrast, olfactory performances of AraC-treated animals were undistinguishable from those of control mice in other odor-associated tests, such as spontaneous odor discrimination and long-term odor-associative memory tasks. Altogether, our data highlight the importance of adult neurogenesis for the proper functioning of the OB network and imply that new bulbar interneurons are involved in some, but not all, odor-associated tasks.
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11
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Linked activity of neurons in the sensorimotor cortex of the rabbit in the state of a defensive dominant and "animal hypnosis". NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2009; 39:395-402. [PMID: 19340584 DOI: 10.1007/s11055-009-9135-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Accepted: 11/12/2007] [Indexed: 10/20/2022]
Abstract
A cryptic focus of excitation (a dominant focus) was created in the brains of rabbits by threshold stimulation of the left limb with a current at a frequency of 0.5 Hz. After creation of a focus, there were equal probabilities of detecting pairs of neurons whose linked activity was dominated by a 2-sec rhythm in the sensorimotor cortex of both the right and left hemispheres (29.3% and 32.4%, respectively). When animals were placed in "animal hypnosis," the total proportion of neuron pairs whose activity was dominated by the rhythm created by establishment of the dominant decreased significantly only in the right hemisphere (21%). After exiting the state of animal hypnosis, the proportion of neurons in the cortex of the right hemisphere whose activity was dominated by the 2-sec rhythm increased significantly if the neurons in the pair were close-lying but decreased significantly if the neurons in the pair were mutually distant. No such changes after hypnotization were seen in the cortex of the left hemisphere. In both the right and left hemispheres, dominance of the 2-sec rhythm in the activity of pairs of neurons was seen significantly more frequently when cross-correlation histograms were constructed by analyzing cells in relation to the spike activity of neurons generating spikes of the lowest (right hemisphere) or lowest and intermediate (left hemisphere) amplitude on neurograms of multineuron activity.
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12
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de la Rosa-Prieto C, Ubeda-Banon I, Mohedano-Moriano A, Pro-Sistiaga P, Saiz-Sanchez D, Insausti R, Martinez-Marcos A. Subicular and CA1 hippocampal projections to the accessory olfactory bulb. Hippocampus 2009; 19:124-9. [PMID: 18777562 DOI: 10.1002/hipo.20495] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The hippocampal formation is anatomically and functionally related to the olfactory structures especially in rodents. The entorhinal cortex (EC) receives afferent projections from the main olfactory bulb; this constitutes an olfactory pathway to the hippocampus. In addition to the olfactory system, most mammals possess an accessory olfactory (or vomeronasal) system. The relationships between the hippocampal formation and the vomeronasal system are virtually unexplored. Recently, a centrifugal projection from CA1 to the accessory olfactory bulb has been identified using anterograde tracers. In the study reported herein, experiments using anterograde tracers confirm this projection, and injections of retrograde tracers show the distribution and morphology of a population of CA1 and ventral subicular neurons projecting to the accessory olfactory bulb of rats. These results extend previous descriptions of hippocampal projections to the accessory olfactory bulb by including the ventral subiculum and characterizing the morphology, neurochemistry (double labeling with somatostatin), and distribution of such neurons. These data suggest feedback hippocampal control of chemosensory stimuli in the accessory olfactory bulb. Whether this projection processes spatial information on conspecifics or is involved in learning and memory processes associated with chemical stimuli remains to be elucidated.
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Affiliation(s)
- C de la Rosa-Prieto
- Laboratorio de Neuroanatomía Humana, Departamento de Ciencias Médicas, Facultad de Medicina, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Albacete, Spain
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13
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Chaillan F, Rivera S, Marchetti E, Jourquin J, Werb Z, Soloway P, Khrestchatisky M, Roman F. Involvement of tissue inhibition of metalloproteinases-1 in learning and memory in mice. Behav Brain Res 2006; 173:191-8. [PMID: 16860884 PMCID: PMC2659720 DOI: 10.1016/j.bbr.2006.06.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 06/17/2006] [Accepted: 06/19/2006] [Indexed: 11/19/2022]
Abstract
Tissue inhibitor of metalloproteinases (TIMP-1) is one of the four-member family (TIMPs-1-4) of multifunctional proteins that inhibit matrix metalloproteinases (MMPs). Its expression in the hippocampus is neuronal-activity-dependent and dramatically induced by stimuli leading to long-term potentiation (LTP), suggesting that TIMP-1 is a candidate plasticity protein potentially involved in learning and memory processes. We tested this hypothesis in a hippocampus-dependent task using the new olfactory tubing maze, with mice carrying a null mutation for TIMP-1 (TIMP-1 KO) and mice overexpressing TIMP-1 (TIMP-1 (tg)). The TIMP-1 KO mice were significantly impaired in making correct odor-reward associations when compared with their respective wild type (WT) littermates, while TIMP-1 overexpressing mice performed better than their WT controls. Both genetically modified mice learned the paradigm and the timing of the task, like their respective WTs, and no olfactory dysfunctioning was observed. These data suggest that TIMP-1 is involved in learning and memory processes related to the hippocampus, and support the hypothesis that the MMP/TIMP ratio, and hence MMP activity, modulates neuronal plasticity in normal learning and memory processes, while altered proteolytic activity could impair cognitive functions.
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Affiliation(s)
- F.A. Chaillan
- Lab. Neurobiologie des Processus Mnésiques, UMR 6149 CNRS, Université de Provence, Centre St Charles, 3, Place Victor Hugo, 13331 Marseille Cedex 03, France
| | - S. Rivera
- Lab. Neurobiologie des Interactions Cellulaires et Neurophysiopathologie (NICN), UMR 6184 CNRS, Université de la Méditerranée, Faculté de Médecine de Marseille, IFR Jean Roche, 51, Boulevard Pierre Dramard, 13916 Marseille Cedex 20, France
| | - E. Marchetti
- Lab. Neurobiologie des Processus Mnésiques, UMR 6149 CNRS, Université de Provence, Centre St Charles, 3, Place Victor Hugo, 13331 Marseille Cedex 03, France
| | - J. Jourquin
- Lab. Neurobiologie des Interactions Cellulaires et Neurophysiopathologie (NICN), UMR 6184 CNRS, Université de la Méditerranée, Faculté de Médecine de Marseille, IFR Jean Roche, 51, Boulevard Pierre Dramard, 13916 Marseille Cedex 20, France
| | - Z. Werb
- Division of Nutritional Sciences, Cornell University, Savage Hall, Ithaca, NY 14853, USA
| | - P.D. Soloway
- Lab. Neurobiologie des Interactions Cellulaires et Neurophysiopathologie (NICN), UMR 6184 CNRS, Université de la Méditerranée, Faculté de Médecine de Marseille, IFR Jean Roche, 51, Boulevard Pierre Dramard, 13916 Marseille Cedex 20, France
| | - M. Khrestchatisky
- Lab. Neurobiologie des Interactions Cellulaires et Neurophysiopathologie (NICN), UMR 6184 CNRS, Université de la Méditerranée, Faculté de Médecine de Marseille, IFR Jean Roche, 51, Boulevard Pierre Dramard, 13916 Marseille Cedex 20, France
| | - F.S. Roman
- Lab. Neurobiologie des Processus Mnésiques, UMR 6149 CNRS, Université de Provence, Centre St Charles, 3, Place Victor Hugo, 13331 Marseille Cedex 03, France
- Corresponding author. Tel.: +33 4 88 57 68 05; fax: +33 4 88 68 57 04. E-mail address: (F.S. Roman)
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Martin C, Gervais R, Messaoudi B, Ravel N. Learning-induced oscillatory activities correlated to odour recognition: a network activity. Eur J Neurosci 2006; 23:1801-10. [PMID: 16623837 DOI: 10.1111/j.1460-9568.2006.04711.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In trained behaving rats, the expression of a prominent beta oscillatory activity in the olfactory system was previously identified as a correlate of odour recognition. The aim of the present study was to assess the putative role of a functional coupling between the olfactory bulb (OB) and higher structures in this activity. We performed a unilateral inactivation of the medial part of the olfactory peduncle by lidocaine infusion. Inactivation deprived the OB from most of its centrifugal afferences, including feedback connections from the piriform cortex (PC) while sparing the ascending fibres from the OB to higher cortical structures. This treatment reduced the amplitude of odour-induced oscillatory beta responses both in OB and PC. In parallel, gamma activity classically observed in these two structures during spontaneous activity displayed a strong enhancement. Results suggest that odour-induced oscillatory response could be the emergent feature of an olfactory functional network set up through learning.
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Affiliation(s)
- Claire Martin
- Institut des Sciences Cognitives, UMR 5015 CNRS-Université Lyon I, IFR19, Institut Fédératif des Neurosciences de Lyon, Bron, 69675 France
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15
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Affiliation(s)
- Alan Gelperin
- Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104, USA.
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16
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Kourrich S, Manrique C, Salin P, Mourre C. Transient hippocampal down-regulation of Kv1.1 subunit mRNA during associative learning in rats. Learn Mem 2006; 12:511-9. [PMID: 16204203 PMCID: PMC1240063 DOI: 10.1101/lm.86305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Voltage-gated potassium channels (Kv) are critically involved in learning and memory processes. It is not known, however, whether the expression of the Kv1.1 subunit, constituting Kv1 channels, can be specifically regulated in brain areas important for learning and memory processing. Radioactive in situ hybridization was used to evaluate the content of Kv1.1 alpha-subunit mRNA in the olfactory bulb, ventral, and dorsal hippocampus at different stages of an odor-discrimination associative task in rats. Naive, conditioned, and pseudoconditioned animals were sacrificed at different times either prior to a two-odor significance learning or after odor discrimination was established. Important decreases of Kv1.1 mRNA levels were transiently observed in the ventral hippocampus before successful learning when compared with the pseudoconditioned group. Moreover, temporal group analysis showed significant labeling alterations in the hippocampus of conditioned and pseudoconditioned groups throughout the training. Finally, Kv1.1 mRNA levels in the hippocampus were positively correlated with odor-reward association learning in rats that were beginning to discriminate between odors. These findings indicate that the Kv1.1 subunit is transiently down-regulated in the early stages of learning and suggest that Kv1 channel expression regulation is critical for the modification of neuronal substrates underlying new information acquisition.
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Affiliation(s)
- Saïd Kourrich
- Laboratoire de Neurobiologie des Processus Mnésiques, UMR 6149 CNRS-Université de Provence, Marseille, France
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