1
|
Lizbinski KM, Dacks AM. Intrinsic and Extrinsic Neuromodulation of Olfactory Processing. Front Cell Neurosci 2018; 11:424. [PMID: 29375314 PMCID: PMC5767172 DOI: 10.3389/fncel.2017.00424] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 12/18/2017] [Indexed: 12/03/2022] Open
Abstract
Neuromodulation is a ubiquitous feature of neural systems, allowing flexible, context specific control over network dynamics. Neuromodulation was first described in invertebrate motor systems and early work established a basic dichotomy for neuromodulation as having either an intrinsic origin (i.e., neurons that participate in network coding) or an extrinsic origin (i.e., neurons from independent networks). In this conceptual dichotomy, intrinsic sources of neuromodulation provide a “memory” by adjusting network dynamics based upon previous and ongoing activation of the network itself, while extrinsic neuromodulators provide the context of ongoing activity of other neural networks. Although this dichotomy has been thoroughly considered in motor systems, it has received far less attention in sensory systems. In this review, we discuss intrinsic and extrinsic modulation in the context of olfactory processing in invertebrate and vertebrate model systems. We begin by discussing presynaptic modulation of olfactory sensory neurons by local interneurons (LNs) as a mechanism for gain control based on ongoing network activation. We then discuss the cell-class specific effects of serotonergic centrifugal neurons on olfactory processing. Finally, we briefly discuss the integration of intrinsic and extrinsic neuromodulation (metamodulation) as an effective mechanism for exerting global control over olfactory network dynamics. The heterogeneous nature of neuromodulation is a recurring theme throughout this review as the effects of both intrinsic and extrinsic modulation are generally non-uniform.
Collapse
Affiliation(s)
- Kristyn M Lizbinski
- Department of Biology, West Virginia University, Morgantown, WV, United States
| | - Andrew M Dacks
- Department of Biology, West Virginia University, Morgantown, WV, United States
| |
Collapse
|
2
|
Uytingco CR, Puche AC, Munger SD. Interglomerular Connectivity within the Canonical and GC-D/Necklace Olfactory Subsystems. PLoS One 2016; 11:e0165343. [PMID: 27902696 PMCID: PMC5130179 DOI: 10.1371/journal.pone.0165343] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/10/2016] [Indexed: 01/25/2023] Open
Abstract
The mammalian main olfactory system contains several subsystems that differ not only in the receptors they express and the glomerular targets they innervate within the main olfactory bulb (MOB), but also in the strategies they use to process odor information. The canonical main olfactory system employs a combinatorial coding strategy that represents odorant identity as a pattern of glomerular activity. By contrast, the "GC-D/necklace" olfactory subsystem—formed by olfactory sensory neurons expressing the receptor guanylyl cyclase GC-D and their target necklace glomeruli (NGs) encircling the caudal MOB—is critical for the detection of a small number of semiochemicals that promote the acquisition of food preferences. The formation of these socially-transmitted food preferences requires the animal to integrate information about two types of olfactory stimuli: these specialized social chemosignals and the food odors themselves. However, the neural mechanisms with which the GC-D/necklace subsystem processes this information are unclear. We used stimulus-induced increases in intrinsic fluorescence signals to map functional circuitry associated with NGs and canonical glomeruli (CGs) in the MOB. As expected, CG-associated activity spread laterally through both the glomerular and external plexiform layers associated with activated glomeruli. Activation of CGs or NGs resulted in activity spread between the two types of glomeruli; there was no evidence of preferential connectivity between individual necklace glomeruli. These results support previous anatomical findings that suggest the canonical and GC-D/necklace subsystems are functionally connected and may integrate general odor and semiochemical information in the MOB.
Collapse
Affiliation(s)
- Cedric R. Uytingco
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Adam C. Puche
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Steven D. Munger
- Center for Smell and Taste, University of Florida, Gainesville, Florida, United States of America
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States of America
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| |
Collapse
|
3
|
Gao S, Guo X, Liu T, Liu J, Chen W, Xia Q, Chen Y, Tang Y. Serotonin modulates outward potassium currents in mouse olfactory receptor neurons. Physiol Res 2013; 62:455-62. [PMID: 23590600 DOI: 10.33549/physiolres.932413] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Monoaminergic neurotransmitter 5-hydroxytryptamine (5-HT), also known as serotonin, plays important roles in modulating the function of the olfactory system. However, thus far, the knowledge about 5-HT and its receptors in olfactory receptor neurons (ORNs) and their physiological role have not been fully characterized. In the present study, reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed the presence of 5-HT(1A) and 5-HT(1B) receptor subtypes in mouse olfactory epithelium at the mRNA level. With subtype selective antibodies and standard immunohistochemical techniques, both receptor subtypes were found to be positively labeled. To further elucidate the molecular mechanisms of 5-HT act on the peripheral olfactory transduction, the whole-cell patch clamp techniques were used on freshly isolated ORNs. We found that 5-HT decreased the magnitude of outward K(+) current in a dose-dependent manner and these inhibitory effects were markedly attenuated by the 5-HT(1A) receptor blocker WAY-100635 and the 5-HT(1B) receptor antagonist GR55562. These data suggested that 5-HT may play a role in the modulation of peripheral olfactory signals by regulating outward potassium currents, both 5-HT(1A) and 5-HT(1B) receptors were involved in this regulation.
Collapse
Affiliation(s)
- S Gao
- Department of Otorhinolaryngology and Translational Neuroscience Center, West China Hospital of Sichuan University, Chengdu, China
| | | | | | | | | | | | | | | |
Collapse
|
4
|
Abstract
Although it has been known for decades that the mammalian olfactory bulb receives a substantial number of centrifugal inputs from other regions of the brain, relatively few data have been available on the function of the centrifugal olfactory system. Knowing the role of the centrifugal projection and how it works is of critical importance to fully understanding olfaction. The centrifugal fibers can be classified into two groups, a group that release neuromodulators, such as noradrenaline, serotonin, or acetylcholine, and a group originating in the olfactory cortex. Accumulating evidence suggests that centrifugal neuromodulatory inputs are associated with acquisition of odor memory. Because the distribution of the terminals on these fibers is diffuse and widespread, the neuromodulatory inputs must affect diverse subsets of bulbar neurons at the same time. In contrast, knowledge of the role of centrifugal fibers from the olfactory cortical areas is limited. Judging from recent morphological evidence, these fibers may modify the activity of neurons located in sparse and discrete loci in the olfactory bulb. Given the modular organization of the olfactory bulb, centrifugal fibers from the olfactory cortex may help coordinate the activities of restricted subsets of neurons belonging to distinct functional modules in an odor-specific manner. Because the olfactory cortex receives inputs from limbic and neocortical areas in addition to inputs from the bulb, the centrifugal inputs from the cortex can modulate odor processing in the bulb in response to non-olfactory as well as olfactory cues.
Collapse
Affiliation(s)
- Shinji Matsutani
- Department of Functional Morphology, Kitasato University School of Nursing, Kanagawa, Japan.
| | | |
Collapse
|
5
|
Koh US, Hwang IK, Lee JC, Lee HY, Seong NS, Chung HG, Kim JH, Lee HJ, Choi GP, Kang TC, Won MH. Histochemical study on neurodegeneration in the olfactory bulb after transient forebrain ischaemia in the Mongolian gerbil. Anat Histol Embryol 2004; 33:208-11. [PMID: 15239811 DOI: 10.1111/j.1439-0264.2004.00538.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the present study, we investigated the ischaemia-related neurodegeneration in the main and accessory olfactory bulb (AOB) after 5 min transient forebrain ischaemia in the Mongolian gerbil using the acid fuchsin staining method. Between 5 and 15 days after ischaemia, acid fuchsin positive cells markedly increased in the external plexiform layer (EPL), mitral cell layer (ML) and glomerular layer (GL) of the main olfactory bulb (MOB), and in the mixed cell layer (MCL) and GL of the AOB. By 30 days after ischaemia reperfusion, acid fuchsin positive neurons were shrunken and showed low acidophilia in somata. Many necrotic vacuoles were found in the EPL and GL of the MOB 30 days after ischaemia. At this time, necrotic vacuoles were very few in the AOB. Therefore, our results suggest that the GL and EPL of the MOB are vulnerable to ischaemic damage at a later time after ischaemic insult, and that the AOB is more resistant to ischaemic damage as compared with the MOB.
Collapse
Affiliation(s)
- U S Koh
- Department of Anatomy, College of Medicine, Hallym University, Chunchon 200-702, South Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Hwang IK, Lee JC, Park SK, An SJ, Lee HY, Lee YB, Sohn HS, Lee IS, Kang TC, Won MH. Age-related change of somatostatin-immunoreactive neurones in the main olfactory bulb of the rat. Anat Histol Embryol 2004; 33:59-63. [PMID: 15027965 DOI: 10.1046/j.1439-0264.2003.00515.x] [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: 11/20/2022]
Abstract
Somatostatin is found in the olfactory system, including the main olfactory bulb (MOB), and is thought to be one of the neuroactive substances for olfaction. However, somatostatin immunoreactivity in the olfactory system has not been determined during ageing. Hence, we examined the age-related changes of somatostatin-immunoreactive (IR) neurones in the rat MOB over a period of 2 years, at the following various ageing stages: post-natal month 1 (PM 1), PM 3, PM 6, PM 12 and PM 24. In PM 1 group, a few somatostatin-IR neurones were detected in the granule cell layer (GCL), and had slender or oval somata and short processes. At PM 3, somatostatin-IR neurones were observed in the glomerular, external plexiform and GCL. The size of somatostatin-IR somata was larger than that at PM 1. In PM 6 group, the number and size of somatostatin-IR neurones increased, and their processes became longer while running in various directions. At PM 12, somatostatin-IR neurones increased in number, and their processes became markedly longer than those at PM 6. At this stage, somatostatin-IR neurones had multipolar somata, and were the largest in size. In PM 24 group, somatostatin-IR neurones were most numerous. However, the processes of somatostatin-IR neurones were shorter than those at PM 12. This study suggests that the increased number of somatostatin-IR neurones in the MOB of aged rats may play a role to compensate for any decrease of olfactory function.
Collapse
Affiliation(s)
- I K Hwang
- Department of Anatomy, College of Medicine, Hallym University, Chunchon 200-702, South Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Hwang IK, Kang TC, Lee JC, Park SK, An SJ, Lee IS, Lee YB, Sohn HS, Kang JH, Choi SY, Won MH. Chronological alterations of calbindin D-28k immunoreactivity in the gerbil main olfactory bulb after ischemic insult. Brain Res 2003; 971:250-4. [PMID: 12706242 DOI: 10.1016/s0006-8993(03)02480-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We investigated spatial and temporal alterations of calbindin D-28k (CB) immunoreactivity in the gerbil main olfactory bulb after transient ischemia-reperfusion. In sham-operated animals, CB-immunoreactive (IR) neurons were found in the periglomerular layer, external plexiform layer and granule cell layer. At 1-4 days after ischemic insult, the number of CB-IR neurons significantly increased. This result suggests that the increased CB may buffer the intracellular calcium at an early time point after the ischemic insult. In contrast, 10-30 days after the ischemic insult, the number of CB-IR neurons significantly decreased as compared to sham-operated animals. This result suggests that a malfunction in olfactory process may have occurred in the olfactory bulb at a later time point after the ischemic insult.
Collapse
Affiliation(s)
- In Koo Hwang
- Department of Anatomy, College of Medicine, Hallym University, Chunchon 200-702, South Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Won MH, Kang TC, Lee JC, Choi KY, Park SK, Jeong YG, Jo SM. Age-related change of neuropeptide Y-immunoreactive neurons in the rat main olfactory bulb. Neurosci Lett 2000; 289:119-22. [PMID: 10904134 DOI: 10.1016/s0304-3940(00)01282-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The change of neuropeptide Y (NPY)-immunoreactive (IR) neurons in the rat main olfactory bulb as a result of aging was investigated at several aging stages over a two-year period; postnatal 1-24 months (P 1-P 24). From P 1 to P 12, the number of NPY-IR neurons and fibers increased with highest number in P 12, and the type of NPY-IR neurons had changed from bipolar neurons with short processes to bipolar/multipolar neurons with long processes. At P 24 the population of NPY-IR neurons and fibers had significantly decreased. Furthermore, the morphology of NPY-IR neurons showed a tendency to decrease in size and processes. It is suggested that the decrease of the number and size of NPY-IR neurons and fibers may underlie the age-related changes in the olfactory processes.
Collapse
Affiliation(s)
- M H Won
- Department of Anatomy, College of Medicine, Hallym University, 200-702, Chunchon, South Korea.
| | | | | | | | | | | | | |
Collapse
|
9
|
Zielinski BS, Moretti N, Hua HN, Zaidi AU, Bisaillon AD. Serotonergic nerve fibers in the primary olfactory pathway of the larval sea lamprey,Petromyzon marinus. J Comp Neurol 2000. [DOI: 10.1002/(sici)1096-9861(20000508)420:3<324::aid-cne4>3.0.co;2-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|