1
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Benkhatar H, Loubieres C, Kada AR, De Malherbe M, Meunier N. Midline olfactory implantation: a cadaveric study of endoscopic transseptal transcribriform approach. Rhinology 2022; 60:145-147. [PMID: 35167628 DOI: 10.4193/rhin21.376] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- H Benkhatar
- Centre Hospitalier de Versailles, Service d'ORL et chirurgie cervico-faciale, Le Chesnay-Rocquencourt, France.,Ecole de Chirurgie du Fer à Moulin, Paris, France
| | - C Loubieres
- Centre Hospitalier de Versailles, Service d'ORL et chirurgie cervico-faciale, Le Chesnay-Rocquencourt, France.,Ecole de Chirurgie du Fer à Moulin, Paris, France
| | - A R Kada
- Centre Hospitalier de Versailles, Service d'ORL et chirurgie cervico-faciale, Le Chesnay-Rocquencourt, France.,Ecole de Chirurgie du Fer à Moulin, Paris, France
| | - M De Malherbe
- Centre Hospitalier de Versailles, Service de Radiologie, Le Chesnay-Rocquencourt, France
| | - N Meunier
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
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2
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Strauch C, Hoang TH, Angenstein F, Manahan-Vaughan D. Olfactory Information Storage Engages Subcortical and Cortical Brain Regions That Support Valence Determination. Cereb Cortex 2021; 32:689-708. [PMID: 34379749 PMCID: PMC8841565 DOI: 10.1093/cercor/bhab226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/15/2021] [Accepted: 06/15/2021] [Indexed: 01/08/2023] Open
Abstract
The olfactory bulb (OB) delivers sensory information to the piriform cortex (PC) and other components of the olfactory system. OB-PC synapses have been reported to express short-lasting forms of synaptic plasticity, whereas long-term potentiation (LTP) of the anterior PC (aPC) occurs predominantly by activating inputs from the prefrontal cortex. This suggests that brain regions outside the olfactory system may contribute to olfactory information processing and storage. Here, we compared functional magnetic resonance imaging BOLD responses triggered during 20 or 100 Hz stimulation of the OB. We detected BOLD signal increases in the anterior olfactory nucleus (AON), PC and entorhinal cortex, nucleus accumbens, dorsal striatum, ventral diagonal band of Broca, prelimbic–infralimbic cortex (PrL-IL), dorsal medial prefrontal cortex, and basolateral amygdala. Significantly stronger BOLD responses occurred in the PrL-IL, PC, and AON during 100 Hz compared with 20 Hz OB stimulation. LTP in the aPC was concomitantly induced by 100 Hz stimulation. Furthermore, 100 Hz stimulation triggered significant nuclear immediate early gene expression in aPC, AON, and PrL-IL. The involvement of the PrL-IL in this process is consistent with its putative involvement in modulating behavioral responses to odor experience. Furthermore, these results indicate that OB-mediated information storage by the aPC is embedded in a connectome that supports valence evaluation.
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Affiliation(s)
- Christina Strauch
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, 44780 Bochum, Germany
| | - Thu-Huong Hoang
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, 44780 Bochum, Germany
| | - Frank Angenstein
- Functional Neuroimaging Group, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), 39118 Magdeburg, Germany.,Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany.,Medical Faculty, Otto-von Guericke University, 39118 Magdeburg, Germany
| | - Denise Manahan-Vaughan
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, 44780 Bochum, Germany
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3
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Mizoguchi N, Muramoto K, Kobayashi M. Olfactory signals from the main olfactory bulb converge with taste information from the chorda tympani nerve in the agranular insular cortex of rats. Pflugers Arch 2020; 472:721-732. [PMID: 32458087 DOI: 10.1007/s00424-020-02399-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 04/09/2020] [Accepted: 05/07/2020] [Indexed: 10/24/2022]
Abstract
Gustation and olfaction are integrated into flavor, which contribute to detection and identification of foods. We focused on the insular cortex (IC), as a possible center of flavor integration, because the IC has been reported to receive olfactory in addition to gustatory inputs. In the present report, we tested the hypothesis that these two chemosensory signals are integrated in the IC. We examined the spatiotemporal dynamics of cortical responses induced by stimulating the chorda tympani nerve (CT) and the main olfactory bulb (mOB) in male Sprague-Dawley rats by in vivo optical imaging with a voltage-sensitive dye (VSD). CT stimulation elicited responses in the rostral part of the dysgranular IC (DI), while responses to mOB stimulation were observed in the agranular IC (AI) as well as in the piriform cortex (PC). To characterize the temporal specificity of these responses, we performed combined mOB and CT stimulation with three different timings: simultaneous stimulation and the stimulation of the mOB 150 ms before or after CT stimulation. Simultaneous stimulation increased the signal amplitude in AI additively. These results indicate that the AI and DI contribute to the convergence of gustatory and olfactory information. Of them the DI predominantly processes the taste information, whereas the AI is more sensitive to the olfactory signal.
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Affiliation(s)
- Naoko Mizoguchi
- Division of Physiology, Department of Human Development and Fostering, Meikai University School of Dentistry, 1-1 Keyaki-dai, Sakado, Saitama, 350-0283, Japan. .,Department of Pharmacology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-8310, Japan. .,Division of Pharmacology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, 1-1 Keyaki-dai, Sakado, Saitama, 350-0283, Japan.
| | - Kazuyo Muramoto
- Division of Physiology, Department of Human Development and Fostering, Meikai University School of Dentistry, 1-1 Keyaki-dai, Sakado, Saitama, 350-0283, Japan
| | - Masayuki Kobayashi
- Department of Pharmacology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.,Division of Oral and Craniomaxillofacial Research, Dental Research Center, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.,Molecular Imaging Research Center, RIKEN, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, 60-047, Japan
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4
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Adair D, Truong D, Esmaeilpour Z, Gebodh N, Borges H, Ho L, Bremner JD, Badran BW, Napadow V, Clark VP, Bikson M. Electrical stimulation of cranial nerves in cognition and disease. Brain Stimul 2020; 13:717-750. [PMID: 32289703 PMCID: PMC7196013 DOI: 10.1016/j.brs.2020.02.019] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 02/13/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023] Open
Abstract
The cranial nerves are the pathways through which environmental information (sensation) is directly communicated to the brain, leading to perception, and giving rise to higher cognition. Because cranial nerves determine and modulate brain function, invasive and non-invasive cranial nerve electrical stimulation methods have applications in the clinical, behavioral, and cognitive domains. Among other neuromodulation approaches such as peripheral, transcranial and deep brain stimulation, cranial nerve stimulation is unique in allowing axon pathway-specific engagement of brain circuits, including thalamo-cortical networks. In this review we amalgamate relevant knowledge of 1) cranial nerve anatomy and biophysics; 2) evidence of the modulatory effects of cranial nerves on cognition; 3) clinical and behavioral outcomes of cranial nerve stimulation; and 4) biomarkers of nerve target engagement including physiology, electroencephalography, neuroimaging, and behavioral metrics. Existing non-invasive stimulation methods cannot feasibly activate the axons of only individual cranial nerves. Even with invasive stimulation methods, selective targeting of one nerve fiber type requires nuance since each nerve is composed of functionally distinct axon-types that differentially branch and can anastomose onto other nerves. None-the-less, precisely controlling stimulation parameters can aid in affecting distinct sets of axons, thus supporting specific actions on cognition and behavior. To this end, a rubric for reproducible dose-response stimulation parameters is defined here. Given that afferent cranial nerve axons project directly to the brain, targeting structures (e.g. thalamus, cortex) that are critical nodes in higher order brain networks, potent effects on cognition are plausible. We propose an intervention design framework based on driving cranial nerve pathways in targeted brain circuits, which are in turn linked to specific higher cognitive processes. State-of-the-art current flow models that are used to explain and design cranial-nerve-activating stimulation technology require multi-scale detail that includes: gross anatomy; skull foramina and superficial tissue layers; and precise nerve morphology. Detailed simulations also predict that some non-invasive electrical or magnetic stimulation approaches that do not intend to modulate cranial nerves per se, such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), may also modulate activity of specific cranial nerves. Much prior cranial nerve stimulation work was conceptually limited to the production of sensory perception, with individual titration of intensity based on the level of perception and tolerability. However, disregarding sensory emulation allows consideration of temporal stimulation patterns (axon recruitment) that modulate the tone of cortical networks independent of sensory cortices, without necessarily titrating perception. For example, leveraging the role of the thalamus as a gatekeeper for information to the cerebral cortex, preventing or enhancing the passage of specific information depending on the behavioral state. We show that properly parameterized computational models at multiple scales are needed to rationally optimize neuromodulation that target sets of cranial nerves, determining which and how specific brain circuitries are modulated, which can in turn influence cognition in a designed manner.
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Affiliation(s)
- Devin Adair
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Dennis Truong
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Zeinab Esmaeilpour
- Department of Biomedical Engineering, City College of New York, New York, NY, USA.
| | - Nigel Gebodh
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Helen Borges
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Libby Ho
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - J Douglas Bremner
- Department of Psychiatry & Behavioral Sciences and Radiology, Emory University School of Medicine, Atlanta, GA, USA; Atlanta VA Medical Center, Decatur, GA, USA
| | - Bashar W Badran
- Department of Psychiatry & Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Vitaly Napadow
- Martinos Center for Biomedical Imaging, Department of Radiology, MGH, Harvard medical school, Boston, MA, USA
| | - Vincent P Clark
- Psychology Clinical Neuroscience Center, Dept. Psychology, MSC03-2220, University of New Mexico, Albuquerque, NM, 87131, USA; Department of Psychology, University of New Mexico, Albuquerque, NM, 87131, USA; The Mind Research Network of the Lovelace Biomedical Research Institute, 1101 Yale Blvd. NE, Albuquerque, NM, 87106, USA
| | - Marom Bikson
- Department of Biomedical Engineering, City College of New York, New York, NY, USA.
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Holbrook EH, Coelho DH. Cranial Nerve Stimulation for Olfaction (Cranial Nerve 1). Otolaryngol Clin North Am 2019; 53:73-85. [PMID: 31685237 DOI: 10.1016/j.otc.2019.09.014] [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] [Indexed: 12/18/2022]
Abstract
Like sensory maps in other systems, the sense of smell has an organizational structure based on converging projections of olfactory receptor neurons containing unique odorant receptors onto the olfactory bulb in synaptic aggregations termed glomeruli. This organizational structure provides the potential for electrical stimulation and restoration of smell. Prior animal and human studies support the feasibility of an olfactory stimulation device, encouraging ongoing work in development of olfactory implants.
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Affiliation(s)
- Eric H Holbrook
- Department of Otolaryngology Head & Neck Surgery, Massachusetts Eye & Ear, Harvard Medical School, 243 Charles Street, Boston, MA 02114, USA.
| | - Daniel H Coelho
- Department of Otolaryngology-Head & Neck Surgery, Virginia Commonwealth University School of Medicine, PO Box 980146, Richmond, VA 23298-0146, USA
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Holbrook EH, Puram SV, See RB, Tripp AG, Nair DG. Induction of smell through transethmoid electrical stimulation of the olfactory bulb. Int Forum Allergy Rhinol 2018; 9:158-164. [PMID: 30480384 DOI: 10.1002/alr.22237] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/07/2018] [Accepted: 10/12/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND Anosmia has an estimated prevalence of 5% of the general population. Outside of inflammatory causes, therapeutic options are limited despite research advances. Bypassing peripheral neuronal damage through central stimulation is a potential therapeutic option that has shown success in other sensory systems, most notably with hearing. We performed a pilot study to determine the feasibility of inducing smell through artificial electrical stimulation of the olfactory bulbs in humans. METHODS Subjects with a history of sinus surgery, including total ethmoidectomy, with intact ability to smell were enrolled. The ability to smell was confirmed with a 40-item smell identification test. Awake subjects underwent nasal endoscopy and either a monopolar or bipolar electrode was positioned at 3 areas along the lateral lamella of the cribriform plate within the ethmoid sinus cavity. A graded stimulation current of 1-20 mA at 3.17 Hz was administered while cortical evoked potential (CEP) recordings were collected. Subjective responses of perceived smell along with reports of discomfort were recorded. Subjects with artificially induced smell underwent repeat stimulation after medically induced anosmia. RESULTS Five subjects (age, 43-72 years) were enrolled. Three subjects reported smell perception smell with electrical stimulation. This was reproducible after inducing anosmia, but CEP recordings could not provide objective support. All subjects tolerated the study with minimal discomfort. CONCLUSION This is the first report of induced smell through transethmoid electrical stimulation of the olfactory bulb. These results provide a proof of concept for efforts in development of an olfactory implant system.
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Affiliation(s)
- Eric H Holbrook
- Department of Otolaryngology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA
| | - Sidharth V Puram
- Department of Otolaryngology and Department of Genetics, Washington University School of Medicine, St Louis, MO
| | - Reiner B See
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Aaron G Tripp
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Dinesh G Nair
- Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
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7
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Peripheral Gene Therapeutic Rescue of an Olfactory Ciliopathy Restores Sensory Input, Axonal Pathfinding, and Odor-Guided Behavior. J Neurosci 2018; 38:7462-7475. [PMID: 30061191 DOI: 10.1523/jneurosci.0084-18.2018] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 07/09/2018] [Accepted: 07/11/2018] [Indexed: 01/08/2023] Open
Abstract
Cilia of olfactory sensory neurons (OSNs) are the primary site of odor binding; hence, their loss results in anosmia, a clinical manifestation of pleiotropic ciliopathies for which there are no curative therapies. We used OSN-specific Ift88 knock-out mice (Ift88osnKO) of both sexes to examine the mechanisms of ciliopathy-induced olfactory dysfunction and the potential for gene replacement to rescue odorant detection, restore olfactory circuitry, and restore odor-guided behaviors. Loss of OSN cilia in Ift88osnKO mice resulted in substantially reduced odor detection and odor-driven synaptic activity in the olfactory bulb (OB). Defects in OSN axon targeting to the OB were also observed in parallel with aberrant odor-guided behavior. Intranasal gene delivery of wild-type IFT88 to Ift88osnKO mice rescued OSN ciliation and peripheral olfactory function. Importantly, this recovery of sensory input in a limited number of mature OSNs was sufficient to restore axonal targeting in the OB of juvenile mice, and with delayed onset in adult mice. In addition, restoration of sensory input re-established course odor-guided behaviors. These findings highlight the spare capacity of the olfactory epithelium and the plasticity of primary synaptic input into the central olfactory system. The restoration of peripheral and central neuronal function supports the potential for treatment of ciliopathy-related anosmia using gene therapy.SIGNIFICANCE STATEMENT Ciliopathies, for which there are no curative therapies, are genetic disorders that alter cilia morphology and/or function in numerous tissue types, including the olfactory system, leading to sensory dysfunction. We show that in vivo intranasal gene delivery restores peripheral olfactory function in a ciliopathy mouse model, including axonal targeting in the juvenile and adult olfactory bulb. Gene therapy also demonstrated restoration of olfactory perception by rescuing odor-guided behaviors. Understanding the therapeutic window and viability for gene therapy to restore odor detection and perception may facilitate translation of therapies to ciliopathy patients with olfactory dysfunctions.
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8
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Coelho DH, Socolovsky LD, Costanzo RM. Activation of the rat olfactory bulb by direct ventral stimulation after nerve transection. Int Forum Allergy Rhinol 2018; 8:922-927. [PMID: 29719130 DOI: 10.1002/alr.22133] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 03/27/2018] [Indexed: 11/07/2022]
Abstract
BACKGROUND The aim of this study was to demonstrate how direct electrical stimulation can activate the olfactory bulb after denervation of the olfactory nerve input. METHODS Sprague-Dawley rats (n = 5) were anesthetized and olfactory bulbs exposed. Olfactory nerves were transected by passing a Teflon blade between the cribriform plate and ventral surface of the bulb. A cochlear implant electrode array was used to stimulate 6 different positions along the ventral surface of the olfactory bulb. Biphasic constant-current pulses were used (50-1000 μA, 50-1000 μs) to stimulate the bulb, and a 16-electrode paddle array was used to record localized negative field potential responses at the dorsal surface of the bulb. RESULTS Localized negative field potentials were reliably obtained using biphasic, 500-μA, 200-μs pulses. A shift in stimulating position by 1 mm resulted in a significant change in the dorsal field potential. CONCLUSION Direct stimulation of the deafferented olfactory bulb was effective in generating localized field potential responses. These findings support the potential use of direct electrical stimulation for the treatment of anosmia.
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Affiliation(s)
- Daniel H Coelho
- Department of Otolaryngology-Head and Neck Surgery, Virginia Commonwealth University School of Medicine, Richmond
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Leandro D Socolovsky
- Department of Otolaryngology-Head and Neck Surgery, Virginia Commonwealth University School of Medicine, Richmond
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Richard M Costanzo
- Department of Otolaryngology-Head and Neck Surgery, Virginia Commonwealth University School of Medicine, Richmond
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA
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9
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Coelho DH, Costanzo RM. Spatial Mapping in the Rat Olfactory Bulb by Odor and Direct Electrical Stimulation. Otolaryngol Head Neck Surg 2016; 155:526-32. [PMID: 27165674 DOI: 10.1177/0194599816646358] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 04/05/2016] [Indexed: 11/17/2022]
Abstract
OBJECTIVES To directly measure the spatial mapping in the olfactory bulb by odor presentation and by direct electrical stimulation. STUDY DESIGN Experimental (animal). SETTING University research laboratory. SUBJECTS AND METHODS Odor (n = 8) and electrical stimulation (n = 4) of the olfactory bulb in rats were used to demonstrate the spatial mapping of neural responses in the olfactory bulb. Both multiunit responses to odor stimulation and evoked potential responses to localized electrical stimulation were measured in different regions of the olfactory bulb. RESULTS Responses that were recorded simultaneously from an array of 32 electrodes positioned at different locations within the olfactory bulb were mapped. Results show different spatial patterns of neural activity for different odors (odor maps). Direct stimulation of the olfactory bulb with electrical current pulses from electrodes positioned at different locations was also effective in generating spatial patterns of neural activity. CONCLUSION These data suggest that by programming an array of stimulating electrodes, it should be possible to selectively activate different regions of the olfactory bulb, generating unique patterns of neural activity as seen in normal smell.
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Affiliation(s)
- Daniel H Coelho
- Department of Physiology and Biophysics, Department of Otolaryngology-Head and Neck Surgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Richard M Costanzo
- Department of Physiology and Biophysics, Department of Otolaryngology-Head and Neck Surgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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10
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Rebello MR, McTavish TS, Willhite DC, Short SM, Shepherd GM, Verhagen JV. Perception of odors linked to precise timing in the olfactory system. PLoS Biol 2014; 12:e1002021. [PMID: 25514030 PMCID: PMC4267717 DOI: 10.1371/journal.pbio.1002021] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 10/30/2014] [Indexed: 11/19/2022] Open
Abstract
The temporal dynamics of glomeruli activity can be behaviorally discerned by mice down to 13 milliseconds. While the timing of neuronal activity in the olfactory bulb (OB) relative to sniffing has been the object of many studies, the behavioral relevance of timing information generated by patterned activation within the bulbar response has not been explored. Here we show, using sniff-triggered, dynamic, 2-D, optogenetic stimulation of mitral/tufted cells, that virtual odors that differ by as little as 13 ms are distinguishable by mice. Further, mice are capable of discriminating a virtual odor movie based on an optically imaged OB odor response versus the same virtual odor devoid of temporal dynamics—independently of the sniff-phase. Together with studies showing the behavioral relevance of graded glomerular responses and the response timing relative to odor sampling, these results imply that the mammalian olfactory system is capable of very high transient information transmission rates. Olfactory receptor neurons respond to odors in the olfactory epithelium located in the nasal cavity in mammals. Each olfactory receptor neuron expresses only one olfactory receptor, out of several hundred encoded in the mammalian genome. Olfactory receptor neurons expressing the same olfactory receptor are scattered throughout the olfactory epithelium; however, their axons converge in one of thousands of glomeruli in the olfactory bulb. The glomeruli are the first neural relay station in the olfactory system, where olfactory receptor neurons transmit olfactory information to mitral cells. It is well established that different odors evoke different spatial patterns across the glomeruli. It is believed that the more similar the patterns, the more similar the evoked odor perceptions. Glomeruli also are activated in odor-specific sequences in time. These dynamics could increase the amount of information about odors by immense amounts. We used transgenic mice, whose mitral cells were made responsive to light, and asked how well they could discriminate the temporal dynamics of simple spatial patterns of light presented to the olfactory bulb after each sniff. Mice could detect the presence of temporal dynamics down to 13 ms, which provides ample resolution for them to be able to detect the dynamics in response to actual odors. Mice could also discern whether virtual odors, based on actual olfactory bulb activity, were dynamic or static and did so without reference to exact sniff-time. We conclude that both the spatial glomerular activity patterns and the temporal dynamics thereof are used in the mammalian olfactory system to encode odors.
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Affiliation(s)
- Michelle R. Rebello
- The John B. Pierce Laboratory, New Haven, Connecticut, United States of America
- Yale School of Medicine, Dept. Neurobiology, New Haven, Connecticut, United States of America
| | - Thomas S. McTavish
- Yale School of Medicine, Dept. Neurobiology, New Haven, Connecticut, United States of America
| | - David C. Willhite
- The John B. Pierce Laboratory, New Haven, Connecticut, United States of America
- Yale School of Medicine, Dept. Neurobiology, New Haven, Connecticut, United States of America
| | - Shaina M. Short
- The John B. Pierce Laboratory, New Haven, Connecticut, United States of America
- Yale School of Medicine, Dept. Neurobiology, New Haven, Connecticut, United States of America
| | - Gordon M. Shepherd
- Yale School of Medicine, Dept. Neurobiology, New Haven, Connecticut, United States of America
| | - Justus V. Verhagen
- The John B. Pierce Laboratory, New Haven, Connecticut, United States of America
- Yale School of Medicine, Dept. Neurobiology, New Haven, Connecticut, United States of America
- * E-mail:
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11
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Abstract
Odor perception is hypothesized to be an experience-dependent process involving the encoding of odor objects by distributed olfactory cortical ensembles. Olfactory cortical neurons coactivated by a specific pattern of odorant evoked input become linked through association fiber synaptic plasticity, creating a template of the familiar odor. In this way, experience and memory play an important role in odor perception and discrimination. In other systems, memory consolidation occurs partially via slow-wave sleep (SWS)-dependent replay of activity patterns originally evoked during waking. SWS is ideal for replay given hyporesponsive sensory systems, and thus reduced interference. Here, using artificial patterns of olfactory bulb stimulation in a fear conditioning procedure in the rat, we tested the effects of imposed post-training replay during SWS and waking on strength and precision of pattern memory. The results show that imposed replay during post-training SWS enhanced the subsequent strength of memory, whereas the identical replay during waking induced extinction. The magnitude of this enhancement was dependent on the timing of imposed replay relative to cortical sharp-waves. Imposed SWS replay of stimuli, which differed from the conditioned stimulus, did not affect conditioned stimulus memory strength but induced generalization of the fear memory to novel artificial patterns. Finally, post-training disruption of piriform cortex intracortical association fiber synapses, hypothesized to be critical for experience-dependent odor coding, also impaired subsequent memory precision but not strength. These results suggest that SWS replay in the olfactory cortex enhances memory consolidation, and that memory precision is dependent on the fidelity of that replay.
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12
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Fitzgerald BJ, Richardson K, Wesson DW. Olfactory tubercle stimulation alters odor preference behavior and recruits forebrain reward and motivational centers. Front Behav Neurosci 2014; 8:81. [PMID: 24672445 PMCID: PMC3954079 DOI: 10.3389/fnbeh.2014.00081] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 02/24/2014] [Indexed: 11/17/2022] Open
Abstract
Rodents show robust behavioral responses to odors, including strong preferences or aversions for certain odors. The neural mechanisms underlying the effects of odors on these behaviors in animals are not well understood. Here, we provide an initial proof-of-concept study into the role of the olfactory tubercle (OT), a structure with known anatomical connectivity with both brain reward and olfactory structures, in regulating odor-motivated behaviors. We implanted c57bl/6 male mice with an ipsilateral bipolar electrode into the OT to administer electric current and thereby yield gross activation of the OT. We confirmed that electrical stimulation of the OT was rewarding, with mice frequently self-administering stimulation on a fixed ratio schedule. In a separate experiment, mice were presented with either fox urine or peanut odors in a three-chamber preference test. In absence of OT stimulation, significant preference for the peanut odor chamber was observed which was abolished in the presence of OT stimulation. Perhaps providing a foundation for this modulation in behavior, we found that OT stimulation significantly increased the number of c-Fos positive neurons in not only the OT, but also in forebrain structures essential to motivated behaviors, including the nucleus accumbens and lateral septum. The present results support the notion that the OT is integral to the display of motivated behavior and possesses the capacity to modulate odor hedonics either by directly altering odor processing or perhaps by indirect actions on brain reward and motivation structures.
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Affiliation(s)
- Brynn J Fitzgerald
- Department of Neurosciences, Case Western Reserve University Cleveland, OH, USA
| | - Kara Richardson
- Department of Neurosciences, Case Western Reserve University Cleveland, OH, USA
| | - Daniel W Wesson
- Department of Neurosciences, Case Western Reserve University Cleveland, OH, USA ; Department of Biology, Case Western Reserve University Cleveland, OH, USA
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13
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Synchronization Across Sensory Cortical Areas by Electrical Microstimulation is Sufficient for Behavioral Discrimination. Cereb Cortex 2012; 23:2976-86. [DOI: 10.1093/cercor/bhs288] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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14
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Falasconi M, Gutierrez-Galvez A, Leon M, Johnson BA, Marco S. Cluster analysis of rat olfactory bulb responses to diverse odorants. Chem Senses 2012; 37:639-53. [PMID: 22459165 DOI: 10.1093/chemse/bjs045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In an effort to deepen our understanding of mammalian olfactory coding, we have used an objective method to analyze a large set of odorant-evoked activity maps collected systematically across the rat olfactory bulb to determine whether such an approach could identify specific glomerular regions that are activated by related odorants. To that end, we combined fuzzy c-means clustering methods with a novel validity approach based on cluster stability to evaluate the significance of the fuzzy partitions on a data set of glomerular layer responses to a large diverse group of odorants. Our results confirm the existence of glomerular response clusters to similar odorants. They further indicate a partial hierarchical chemotopic organization wherein larger glomerular regions can be subdivided into smaller areas that are rather specific in their responses to particular functional groups of odorants. These clusters bear many similarities to, as well as some differences from, response domains previously proposed for the glomerular layer of the bulb. These data also provide additional support for the concept of an identity code in the mammalian olfactory system.
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Affiliation(s)
- Matteo Falasconi
- Department of Chemistry and Physics, University of Brescia and CNR-IDASC, Via Valotti 9, 25133 Brescia, Italy
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Leon M, Johnson BA. Is there a space-time continuum in olfaction? Cell Mol Life Sci 2009; 66:2135-50. [PMID: 19294334 PMCID: PMC2705728 DOI: 10.1007/s00018-009-0011-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 02/18/2009] [Accepted: 02/23/2009] [Indexed: 11/22/2022]
Abstract
The coding of olfactory stimuli across a wide range of organisms may rely on fundamentally similar mechanisms in which a complement of specific odorant receptors on olfactory sensory neurons respond differentially to airborne chemicals to initiate the process by which specific odors are perceived. The question that we address in this review is the role of specific neurons in mediating this sensory system--an identity code--relative to the role that temporally specific responses across many neurons play in producing an olfactory perception--a temporal code. While information coded in specific neurons may be converted into a temporal code, it is also possible that temporal codes exist in the absence of response specificity for any particular neuron or subset of neurons. We review the data supporting these ideas, and we discuss the research perspectives that could help to reveal the mechanisms by which odorants become perceptions.
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Affiliation(s)
- Michael Leon
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA 92697-4550, USA.
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16
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Di Lorenzo PM, Leshchinskiy S, Moroney DN, Ozdoba JM. Making time count: functional evidence for temporal coding of taste sensation. Behav Neurosci 2009; 123:14-25. [PMID: 19170426 DOI: 10.1037/a0014176] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although the temporal characteristics of neural responses have been proposed as a mechanism for sensory neural coding, there has been little evidence thus far that this type of information is actually used by the nervous system. Here the authors show that patterned electrical pulses trains that mimic the response to the taste of quinine can produce a bitterlike sensation when delivered to the nucleus tractus solitarius of behaving rats. Following conditioned aversion training using either "quinine simulation" patterns of electrical stimulation or natural quinine (0.1 mM) as a conditioned stimulus, rats specifically generalized the aversion to 2 bitter tastants: quinine and urea. Randomization of the quinine simulation patterns resulted in generalization patterns that resembled those to a perithreshold concentration (0.01 mM) of quinine. These data provide strong evidence that the temporal pattern of brainstem activity may convey information about taste quality and underscore the functional significance of temporal coding.
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17
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Abstract
Systematic mapping studies involving 365 odorant chemicals have shown that glomerular responses in the rat olfactory bulb are organized spatially in patterns that are related to the chemistry of the odorant stimuli. This organization involves the spatial clustering of principal responses to numerous odorants that share key aspects of chemistry such as functional groups, hydrocarbon structural elements, and/or overall molecular properties related to water solubility. In several of the clusters, responses shift progressively in position according to odorant carbon chain length. These response domains appear to be constructed from orderly projections of sensory neurons in the olfactory epithelium and may also involve chromatography across the nasal mucosa. The spatial clustering of glomerular responses may serve to "tune" the principal responses of bulbar projection neurons by way of inhibitory interneuronal networks, allowing the projection neurons to respond to a narrower range of stimuli than their associated sensory neurons. When glomerular activity patterns are viewed relative to the overall level of glomerular activation, the patterns accurately predict the perception of odor quality, thereby supporting the notion that spatial patterns of activity are the key factors underlying that aspect of the olfactory code. A critical analysis suggests that alternative coding mechanisms for odor quality, such as those based on temporal patterns of responses, enjoy little experimental support.
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Affiliation(s)
- Brett A Johnson
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-4550, USA.
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18
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Gheusi G, Bluthé RM, Goodall G, Dantzer R. Social and individual recognition in rodents: Methodological aspects and neurobiological bases. Behav Processes 2002; 33:59-87. [PMID: 24925240 DOI: 10.1016/0376-6357(94)90060-4] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/1994] [Indexed: 11/26/2022]
Abstract
What animals know about each other, and how they construct and use knowledge of their social world involves at least an ability to recognise different social categories. Although much evidence has accumulated that animals are able to identify and classify other individuals into different categories, few studies have definitively demonstrated true individual recognition, i.e. discrimination between individuals on the basis of their idiosyncratic characteristics. Furthermore, the neural structures and pathways involved in social and, a fortiori, individual recognition have as yet been poorly investigated. This paper discusses various methods and measures currently used to assess different forms of social categorisations in animals, with special reference to rodents. Recent progress concerning the neurobiological bases involved in social recognition is also discussed. Finally, integrative perspectives for studying individual recognition in the context of social cognition is underlined in relation to different approaches investigating rodents' ability to use learned olfactory information.
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Affiliation(s)
- G Gheusi
- Neurobiologie Intégrative, Inserm Unité 394, 1 rue Camille Saint-Saëns, 33077 Bordeaux, France
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19
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Mouly AM, Gervais R. Polysynaptic potentiation at different levels of rat olfactory pathways following learning. Learn Mem 2002; 9:66-75. [PMID: 11992017 PMCID: PMC155934 DOI: 10.1101/lm.45602] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
This study was aimed at investigating the consequences of learning on late polysynaptic components of evoked field potential signals recorded in parallel at different levels of the olfactory pathways. For this, evoked field potentials induced by electrical stimulation of the olfactory bulb were recorded simultaneously in the anterior piriform cortex, the posterior piriform cortex, the lateral entorhinal cortex, and the dentate gyrus. The different parameters of late components were measured in each site before and after completion of associative learning in anesthetized rats. In the learning task, rats were trained to associate electrical stimulation of one olfactory bulb electrode with the delivery of sucrose (positive reward) and stimulation of a second olfactory bulb electrode with the delivery of quinine (negative reward). In this way, stimulation of the same olfactory bulb electrodes used for inducing field potentials served as a discriminative cue in the learning paradigm. The data confirmed previous observation that learning was associated with a lowering in late-component-1 intensity of induction in the posterior piriform cortex. The use of simultaneous recording allowed us to further specify the consequences of learning on late-component distribution in the studied network. Indeed the data showed that whereas before learning, late component 1 was rather uniformly distributed among the recorded sites; following learning, its expression was facilitated preferentially in the posterior piriform cortex and lateral entorhinal cortex. Furthermore, learning was accompanied by the emergence of a new late component (late component 2), which occurred simultaneously in the four recording sites. The possible involvement of potentiation of polysynaptic components in recognition and/or consolidation processes will be discussed.
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Affiliation(s)
- Anne Marie Mouly
- Institut des Sciences Cognitives, Centre National de la Recherche Scientifique Unité Mixte de Recherche (UMR) 5015, 69675 Bron Cédex, France.
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Mouly AM, Fort A, Ben-Boutayab N, Gervais R. Olfactory learning induces differential long-lasting changes in rat central olfactory pathways. Neuroscience 2001; 102:11-21. [PMID: 11226666 DOI: 10.1016/s0306-4522(00)00476-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In the present work, we investigated lasting changes induced by olfactory learning at different levels of the olfactory pathways. For this, evoked field potentials induced by electrical stimulation of the olfactory bulb were recorded simultaneously in the anterior piriform cortex, the posterior piriform cortex, the lateral entorhinal cortex and the dentate gyrus. The amplitude of the evoked field potential's main component was measured in each site before, immediately after, and 20 days after completion of associative learning. Evoked field potential recordings were carried out under two experimental conditions in the same animals: awake and anesthetized. In the learning task, rats were trained to associate electrical stimulation of one olfactory bulb electrode with the delivery of sucrose (positive reward), and stimulation of a second olfactory bulb electrode with the delivery of quinine (negative reward). In this way, stimulation of the same olfactory bulb electrodes used for inducing field potentials served as a discriminative cue in the learning paradigm. The data showed that positively reinforced learning resulted in a lasting increase in evoked field potential amplitude restricted to posterior piriform cortex and lateral entorhinal cortex. In contrast, negatively reinforced learning was mainly accompanied by a decrease in evoked field potential amplitude in the dentate gyrus. Moreover, the expression of these learning-related changes occurred to be modulated by the animals arousal state. Indeed, the comparison between anesthetized versus awake animals showed that although globally similar, the changes were expressed earlier with respect to learning, under anesthesia than in the awake state. From these data we suggest that associative olfactory learning involves different neural circuits depending on the acquired value of the stimulus. Furthermore, they show the existence of a functional dissociation between anterior and posterior piriform cortex in mnesic processes, and stress the importance of the animal's arousal state on the expression of learning-induced plasticity.
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Affiliation(s)
- A M Mouly
- Institut des Sciences Cognitives, CNRS UMR 5015, 67 Boulevard Pinel, 69675 Bron Cédex, France.
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21
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Roman FS, Truchet B, Marchetti E, Chaillan FA, Soumireu-Mourat B. Correlations between electrophysiological observations of synaptic plasticity modifications and behavioral performance in mammals. Prog Neurobiol 1999; 58:61-87. [PMID: 10321797 DOI: 10.1016/s0301-0082(98)00076-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Within the past century it has been well established that most mature neurons lose their ability to divide. Since then, it has been assumed that behavioral performance leads to synaptic changes in the brain. The existence of these potential changes has been demonstrated in numerous experiments, and different mechanisms contributing to synaptic plasticity have been discovered. Many structures involved in different types of learning have now been identified. This article reviews the different methods used with mammals to detect electrophysiological modifications in synaptic plasticity following behavior. Evidence of long-term potentiation and long-term depression has been found in the hippocampus and cerebellum, respectively, and empirical data has been used to correlate these mechanisms with specific learning performance. Similar observations were made recently in the septum and amygdala. These phenomena seem to be involved in maintaining the performance in the cortical areas of the brain. Ongoing attempts to find the relationship between behavioral performance and modifications in synaptic efficacy allow to speculate upon the dynamics of cellular mechanisms that contribute to the ability of mammals to modify wide neuronal networks in the brain during their life.
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Affiliation(s)
- F S Roman
- Laboratoire de Neurobiologie des Comportements, UMR 6562 CNRS, Université de Provence, IBHOP Traverse Charles Susini, Marseille, France
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22
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Ambrogi Lorenzini CG, Baldi E, Bucherelli C, Sacchetti B, Tassoni G. Neural topography and chronology of memory consolidation: a review of functional inactivation findings. Neurobiol Learn Mem 1999; 71:1-18. [PMID: 9889069 DOI: 10.1006/nlme.1998.3865] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Findings on the role of subcortical and cortical structures in mnemonic processes, obtained by means of the reversible functional inactivation technique, are reviewed. The main advantage of this method (subcortical or cortical administration of local anesthetics or tetrodotoxin) is that it provides information not only on "where" but also "when" and for "how long" these processes take place, thus adding to the topographical dimension the chronological one. The review covers several types of memory (e.g., passive avoidance and spatial memory) studies examining the neural substrates of memory consolidation on the basis of the functional inactivation of the nucleus of the solitary tract, parabrachial nuclei, substantia nigra, hippocampus (dorsal and ventral), nucleus basalis magnocellularis, amygdala, medial septal area, striatum, olfactory bulb, and neocortex. The data are discussed in relation to earlier research and with respect to the anatomical and functional connectivity of the examined centers.
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Affiliation(s)
- C G Ambrogi Lorenzini
- Dipartimento di Scienze Fisiologiche, Università degli Studi di Firenze, Viale G. B. Morgagni 63, Florence, I-50134, Italy
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23
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Mouly AM, Litaudon P, Chabaud P, Ravel N, Gervais R. Spatiotemporal distribution of a late synchronized activity in olfactory pathways following stimulation of the olfactory bulb in rats. Eur J Neurosci 1998; 10:1128-35. [PMID: 9753181 DOI: 10.1046/j.1460-9568.1998.00126.x] [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: 11/20/2022]
Abstract
The evoked potential recorded in the rat piriform cortex in response to electrical stimulation of the olfactory bulb is composed of an early component occasionally followed by a late component (60-70 ms). We previously showed that the late component occurrence was enhanced following an olfactory learning. In the present study carried out in naive rats, we investigated the precise conditions of induction of this late component, and its spatiotemporal distribution along the olfactory pathways. In the anaesthetized rat, a stimulating electrode was implanted in the olfactory bulb. Four recording electrodes were positioned, respectively, in the olfactory bulb, the anterior and posterior parts of the piriform cortex, and the entorhinal cortex. Simultaneous recording of signals evoked in the four sampled structures in response to stimulation of the olfactory bulb revealed that the late component was detected in anterior and posterior piriform cortex as well as in entorhinal cortex, but not in the olfactory bulb. The late component occurred reliably for a narrow range of low intensities of stimulation delivered at frequencies not exceeding 1 Hz. Comparison of late component amplitude and latency across the different recorded sites showed that this component appeared first and with the greatest amplitude in the posterior piriform cortex. In addition to showing a functional dissociation between anterior and posterior parts of the piriform cortex, these data suggest that the posterior piriform cortex could be the locus of generation of this late high amplitude synchronized activity, which would then propagate to the neighbouring regions.
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Affiliation(s)
- A M Mouly
- Institut des Sciences Cognitives, CNRS UPR 9075, UCB Lyon I, France.
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Litaudon P, Mouly AM, Sullivan R, Gervais R, Cattarelli M. Learning-induced changes in rat piriform cortex activity mapped using multisite recording with voltage sensitive dye. Eur J Neurosci 1997; 9:1593-602. [PMID: 9283814 DOI: 10.1111/j.1460-9568.1997.tb01517.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The piriform cortex (PCx) has a potential role in storage and recall of olfactory information. This study is a first extensive investigation of the spatiotemporal distribution of activity in the PCx induced by learned sensory inputs following conditioning. In a conditioned group, rats chronically implanted with four electrodes in the olfactory bulb were trained to associate the electrical stimulation of a given bulbar electrode with a positive reinforcement, while stimulation of a different electrode predicted a negative reinforcement. In a familiarized group, rats received the same protocol of daily electrical stimulation with no associated reinforcement. At the end of the conditioning or familiarization episode, activity evoked in the PCx was optically mapped using a 144 photodiode array. In the anaesthetized rats, PCx maps were recorded in response to stimulation of each of the four bulbar electrodes using either high (0.5-1 mA) or low (0.1 mA) test current intensities. Low intensity stimulation revealed that conditioning selectively enhanced the probability of occurrence of a signal composed of a single late (56-73 ms) component which occurred almost simultaneously on a large PCx area. In the conditioned group, high intensity stimulation through either of the four electrodes revealed a potentiation of the early (17-30 ms) disynaptic component of the PCx response in the most posterior part of the PCx as well as a homogeneous increase of the late (39-52 ms) component spread over the PCx areas. These data suggest that learning induces synaptic changes at different nodes of the PCx circuitry.
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Abstract
The piriform cortex (PCx) is a phylogenetically old brain structure which presents characteristics of a content-addressable memory. Taking into account its particular anatomo-functional organization, we hypothesized that this cortex could behave rather as an assembly of different functional units than as a functionally homogeneous structure. This hypothesis was tested by using both anatomical and functional approaches. Immunohistological and tracing experiments demonstrated that both the connections of the PCx with the higher nervous centres, and its monoaminergic and cholinergic modulatory afferents exhibited a heterogeneous distribution. Then, optical monitoring of its neuronal activity with a voltage-sensitive dye pointed out that the PCx is a functionally heterogeneous structure. Electrical stimulations of the olfactory bulb showed that the inhibitory processes which control the cortical responsiveness were not identical in all the PCx area. Two different functional areas at least could be distinguished: in the ventromedial PCx, the afferent activity is privileged since the level of inhibition of disynaptic activation remained large during repetitive stimuli. Contrarily, in the posterior PCx, the disynaptic activity remained unchanged in response to successive stimulations and the responses of neighbouring sites were statistically more synchronized than in its anterior part. Moreover, a late depolarization wave was significantly larger in the posterior PCx. These data are in good agreement with the results provided by computational models of the PCx. In the future, theoretical and experimental investigations of this cortex will be useful for understanding olfactory information processing and as a model of brain functioning at the neocortical level as well.
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Affiliation(s)
- P Litaudon
- Laboratoire de Neurosciences et Systèmes Sensoriels, CNRS, Université Claude Bernard Lyon I, Villeurbanne, France
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Mouly AM, Gervais R, Holley A. Evidence for the Involvement of Rat Olfactory Bulb in Processes Supporting Long-Term Olfactory Memory. Eur J Neurosci 1990; 2:978-984. [PMID: 12106085 DOI: 10.1111/j.1460-9568.1990.tb00010.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Current advances in the neurobiology of learning and memory suggest the existence of experience-induced plasticity in sensorial pathways conveying relevant information to higher integrative brain structures. For instance, olfactory learning is known to induce long-lasting modifications of neural activity at the level of the first relay structure of the olfactory system, the olfactory bulb. The observed forms of plasticity depend on the action exerted during learning by ascending neuromodulatory systems, such as the noradrenergic (NA) system originating from the locus ceruleus. This study was aimed at investigating the importance of olfactory bulb plasticity in learning and retention of an olfactory task. In a daily training schedule animals had to learn to use multi-site electrical stimulation patterns of the olfactory bulb as discriminative cues for choosing between a palatable and a nonpalatable solution. We first examined the effects of a continuous intrabulbar infusion of propranolol (a beta-NA receptor antagonist) carried out during the learning period. We found that this treatment neither impaired the retention of a previously learned task nor the learning of a new task. However, the animals presented a severe deficit in long-term retention (>5 days) of the task learned under perfusion. Unexpectedly, this effect cannot be ascribed to a selective blockade of beta-NA receptors since infusion of the drug vehicle (saline-ascorbate) produced exactly the same deficit while a saline solution remained without effect. A final experiment showed that the selective deficit in long-term retention was not observed when the infusion of the saline-ascorbate solution started on the day following completion of learning. Taken together, these results suggest that ascorbate-sensitive neural processes occurring within the olfactory bulb during learning are of functional importance for long-term storage of olfactory information.
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Affiliation(s)
- A. M. Mouly
- Laboratoire de Physiologie Neurosensorielle, UA CNRS 180, Université Claude Bernard, 69622 Villeurbanne, France
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Abstract
The study of memory is a great challenge, perhaps the greatest in biological sciences. Memory involves changes in a tiny fraction of an extremely large pool of elements, a conclusion that makes the task of finding those changes using current technologies formidable. What can be done about this roadblock to neurological investigations of learning? One response that has become particularly productive in recent years is to study learning or learning-like phenomena in relatively simple "model" systems. The idea is to extract basic principles from these models in which molecular and anatomical details can be studied and then to use these in analyzing learning in higher regions of the brain. In this article we discuss current progress and emerging concepts derived from the simple system approach using animal models.
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Monod B, Mouly AM, Vigouroux M, Holley A. An investigation of some temporal aspects of olfactory coding with the model of multi-site electrical stimulation of the olfactory bulb in the rat. Behav Brain Res 1989; 33:51-63. [PMID: 2544198 DOI: 10.1016/s0166-4328(89)80018-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Electrical stimulation of the olfactory bulb was used to investigate some temporal aspects of olfactory coding, with reference to respiration. Food-deprived rats implanted with permanent electrodes were trained to use bulbar multi-site stimulation patterns as discriminative stimuli for predicting the nature of an incoming reinforcement. Electrical pulse trains (100 Hz) were periodically delivered in phase with precisely defined moments of the respiratory cycle (during inspiration or expiration). Temporal aspects of olfactory coding were first considered through the measurement of the minimum duration of a stimulus necessary to identify this stimulus. The results showed that a bulbar stimulation lasting for 30 ms (3 pulses), and delivered during inspiration, was clearly identified by the rats. Stimulus identification induced a discriminative respiratory response which could manifest itself as early as the first cycle concomitant with the beginning of stimulation. It was then shown that a bulbar electrical stimulation pattern was identified with the same latency whether it occurred during expiration or during inspiration. Moreover, the perceptive events induced in those two conditions of stimulation were not different enough to be discriminated by the animals. The findings are discussed within the framework of olfactory information processing.
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Affiliation(s)
- B Monod
- Laboratoire de Physiologie Neuro-sensorielle associé au CNRS, Université Claude-Bernard, Villeurbanne, France
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Simulation and Analysis of a Simple Cortical Network. PSYCHOLOGY OF LEARNING AND MOTIVATION 1989. [DOI: 10.1016/s0079-7421(08)60112-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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30
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Abstract
The connections between the lateral olfactory tract (LOT) and layer I of the piriform cortex were used to test the idea that certain forms of learning involve potentiation of cortical synapses. Rats were trained on a series of two-odor discriminations over a period of several days after which patterned electrical stimulation (short, high frequency bursts with 5-6 bursts per second) of the LOT was used as a discriminative cue. The animals reacted to the stimulation as though it were an odor and quickly learned to respond appropriately and to distinguish between 'positive' and 'negative' electrodes. Comparisons of the monosynaptic responses in the piriform cortex evoked by single pulse stimulation of the LOT before and after learning revealed that the population synaptic responses were substantially potentiated by the training. This effect was present in an unchanged form 24 h later. Responses elicited by control stimulating electrodes were slightly or not at all affected by training to stimulation with another electrode. Synaptic potentiation was not found in a small group of rats that did not learn to respond to patterned stimulation and was also absent when the stimulation was applied to naive rats. These results provide evidence that rapid learning of a specific cue potentiates cortical synapses in a defined terminal field.
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Affiliation(s)
- F Roman
- Center for the Neurobiology of Learning and Memory, University of California, Irvine 92717
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31
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Mouly AM, Holley A. Perceptive properties of the multi-site electrical microstimulation of the olfactory bulb in the rat. Behav Brain Res 1986; 21:1-12. [PMID: 3741592 DOI: 10.1016/0166-4328(86)90054-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Electrical microstimulation of the olfactory bulb in different locations has been shown to provide water-deprived rats with discriminative cues for selecting a palatable solution without tasting it in a two-choice test. Some perceptive properties of bulbar electrical stimulation were investigated. It was shown that the perceptive effect evoked by stimulating a given site could be recognized when this site was stimulated together with several others. The animals' perception of multi-site stimulation patterns seems therefore to be analytical rather than synthetic. Discrimination of stimulation patterns did not require presentation of concurrent patterns inside a short time interval. Identification of a multi-site pattern was possible when this pattern was presented alone in a test session. Individual characteristics of bulbar microstimulation appear to be perceived absolutely rather than differentially. A good retention of the discrimination learning of specific stimulation patterns was observed. Animals could identify stimulation patterns after complete interruption of the training for 17 days. The results are discussed with reference to the properties of the natural stimulation of the olfactory system.
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