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Synapse (New York, N.Y.) Jul 2014
Topics: Action Potentials; Animals; Cocaine; Male; Neurons; Olfactory Tubercle; Rats; Rats, Long-Evans; Self Administration
PubMed: 24700541
DOI: 10.1002/syn.21744 -
Molecular and Cellular Neurosciences Jul 2019The olfactory tubercle (OT) is located in the ventral-medial region of the brain where it receives primary input from olfactory bulb (OB) projection neurons and...
The olfactory tubercle (OT) is located in the ventral-medial region of the brain where it receives primary input from olfactory bulb (OB) projection neurons and processes olfactory behaviors related to motivation, hedonics of smell and sexual encounters. The OT is part of the dopamine reward system that shares characteristics with the striatum. Together with the nucleus accumbens, the OT has been referred to as the "ventral striatum". However, despite its functional importance little is known about the embryonic development of the OT and the phenotypic properties of the OT cells. Here, using thymidine analogs, we establish that mouse OT neurogenesis occurs predominantly between E11-E15 in a lateral-to-medial gradient. Then, using a piggyBac multicolor technique we characterized the migratory route of OT neuroblasts from their embryonic point of origin. Following neurogenesis in the ventral lateral ganglionic eminence (vLGE), neuroblasts destined for the OT followed a dorsal-ventral pathway we named "ventral migratory course" (VMC). Upon reaching the nascent OT, neurons established a prototypical laminar distribution that was determined, in part, by the progenitor cell of origin. A phenotypic analysis of OT neuroblasts using a single-color piggyBac technique, showed that OT shared the molecular specification of striatal neurons. In addition to primary afferent input from the OB, the OT also receives a robust dopaminergic input from ventral tegmentum (Ikemoto, 2007). We used tyrosine hydroxylase (TH) expression as a proxy for dopaminergic innervation and showed that TH onset occurs at E13 and progressively increased until postnatal stages following an 'inside-out' pattern. Postnatally, we established the myelination in the OT occurring between P7 and P14, as shown with CNPase staining, and we characterized the cellular phenotypes populating the OT by immunohistochemistry. Collectively, this work provides the first detailed analysis of the developmental and maturation processes occurring in mouse OT, and demonstrates the striatal nature of the OT as part of the ventral striatum (vST).
Topics: Animals; Dopaminergic Neurons; Female; Male; Mice; Myelin Sheath; Neurogenesis; Olfactory Tubercle
PubMed: 31200100
DOI: 10.1016/j.mcn.2019.06.002 -
Neuroscience Research May 2023The olfactory centres are the evolutionary oldest and most conservative area of the telencephalon. Olfactory deficiencies are involved in a large spectrum of neurologic... (Review)
Review
The olfactory centres are the evolutionary oldest and most conservative area of the telencephalon. Olfactory deficiencies are involved in a large spectrum of neurologic disorders and neurodegenerative diseases. The growing interest in human olfaction has been also been driven by COVID-19-induced transitional anosmia. Nevertheless, recent data on the human olfactory centres concerning normal histology and morphogenesis are rare. Published data in the field are mainly restricted to classic studies with non-uniform nomenclature and varied definitions of certain olfactory areas. While the olfactory system in model animals (rats, mice, and more rarely non-human primates) has been extensively investigated, the developmental timetable of olfactory centres in both human prenatal and postnatal ontogeny are poorly understood and unsystemised, which complicates the process of analysing human material, including medical researches. The main purpose of this review is to provide and discuss relevant morphological data on the normal ontogeny of the human olfactory centres, with a focus on the timetable of maturation and developmental cytoarchitecture, and with special reference to the definitions and terminology of certain olfactory areas.
Topics: Pregnancy; Female; Humans; Rats; Animals; Mice; Smell; COVID-19; Primates; Olfactory Bulb; Olfactory Pathways
PubMed: 36521642
DOI: 10.1016/j.neures.2022.12.005 -
The Journal of Neuroscience : the... Mar 2015Sensory information acquires meaning to adaptively guide behaviors. Despite odors mediating a number of vital behaviors, the components of the olfactory system...
Sensory information acquires meaning to adaptively guide behaviors. Despite odors mediating a number of vital behaviors, the components of the olfactory system responsible for assigning meaning to odors remain unclear. The olfactory tubercle (OT), a ventral striatum structure that receives monosynaptic input from the olfactory bulb, is uniquely positioned to transform odor information into behaviorally relevant neural codes. No information is available, however, on the coding of odors among OT neurons in behaving animals. In recordings from mice engaged in an odor discrimination task, we report that the firing rate of OT neurons robustly and flexibly encodes the valence of conditioned odors over identity, with rewarded odors evoking greater firing rates. This coding of rewarded odors occurs before behavioral decisions and represents subsequent behavioral responses. We predict that the OT is an essential region whereby odor valence is encoded in the mammalian brain to guide goal-directed behaviors.
Topics: Animals; Discrimination Learning; Male; Mice; Mice, Inbred C57BL; Odorants; Olfactory Tubercle; Smell; Ventral Striatum
PubMed: 25788670
DOI: 10.1523/JNEUROSCI.4750-14.2015 -
The Journal of Neuroscience : the... Feb 2010Historical and psychophysical literature has demonstrated a perceptual interplay between olfactory and auditory stimuli-the neural mechanisms of which are not...
Historical and psychophysical literature has demonstrated a perceptual interplay between olfactory and auditory stimuli-the neural mechanisms of which are not understood. Here, we report novel findings revealing that the early olfactory code is subjected to auditory cross-modal influences. In vivo extracellular recordings from the olfactory tubercle, a trilaminar structure within the basal forebrain, of anesthetized mice revealed that olfactory tubercle single units selectively respond to odors-with 65% of units showing significant odor-evoked activity. Remarkably, 19% of olfactory tubercle single units also showed robust responses to an auditory tone. Furthermore, 29% of single units tested displayed supraadditive or suppressive responses to the simultaneous presentation of odor and tone, suggesting cross-modal modulation. In contrast, olfactory bulb units did not show significant responses to tone presentation nor modulation of odor-evoked activity by tone-suggesting a lack of olfactory-auditory convergence upstream from the olfactory tubercle. Thus, the tubercle presents itself as a source for direct multimodal convergence within an early stage of odor processing and may serve as a seat for psychophysical interactions between smells and sounds.
Topics: Acoustic Stimulation; Action Potentials; Animals; Association; Auditory Pathways; Auditory Perception; Auditory Threshold; Electrophysiology; Hearing; Male; Mice; Odorants; Olfactory Pathways; Olfactory Perception; Psychophysics; Sensory Receptor Cells; Smell; Structure-Activity Relationship
PubMed: 20181598
DOI: 10.1523/JNEUROSCI.6003-09.2010 -
Brain Research Reviews Nov 2007Anatomical and functional refinements of the meso-limbic dopamine system of the rat are discussed. Present experiments suggest that dopaminergic neurons localized in the... (Review)
Review
Anatomical and functional refinements of the meso-limbic dopamine system of the rat are discussed. Present experiments suggest that dopaminergic neurons localized in the posteromedial ventral tegmental area (VTA) and central linear nucleus raphe selectively project to the ventromedial striatum (medial olfactory tubercle and medial nucleus accumbens shell), whereas the anteromedial VTA has few if any projections to the ventral striatum, and the lateral VTA largely projects to the ventrolateral striatum (accumbens core, lateral shell and lateral tubercle). These findings complement the recent behavioral findings that cocaine and amphetamine are more rewarding when administered into the ventromedial striatum than into the ventrolateral striatum. Drugs such as nicotine and opiates are more rewarding when administered into the posterior VTA or the central linear nucleus than into the anterior VTA. A review of the literature suggests that (1) the midbrain has corresponding zones for the accumbens core and medial shell; (2) the striatal portion of the olfactory tubercle is a ventral extension of the nucleus accumbens shell; and (3) a model of two dopamine projection systems from the ventral midbrain to the ventral striatum is useful for understanding reward function. The medial projection system is important in the regulation of arousal characterized by affect and drive and plays a different role in goal-directed learning than the lateral projection system, as described in the variation-selection hypothesis of striatal functional organization.
Topics: Animals; Brain Mapping; Central Nervous System Stimulants; Cocaine; Dopamine; Dopamine Uptake Inhibitors; Efferent Pathways; Fluorescent Dyes; Immunohistochemistry; Male; Models, Neurological; Nucleus Accumbens; Olfactory Pathways; Psychotropic Drugs; Rats; Rats, Wistar; Reward; Tyrosine 3-Monooxygenase; Ventral Tegmental Area
PubMed: 17574681
DOI: 10.1016/j.brainresrev.2007.05.004 -
Neurochemical Research Jun 2021Activation of dopamine (DA) neurons is essential for the transition from sleep to wakefulness and maintenance of awakening, and sufficient to accelerate the emergence...
Activation of dopamine (DA) neurons is essential for the transition from sleep to wakefulness and maintenance of awakening, and sufficient to accelerate the emergence from general anesthesia in animals. Dopamine receptors (DR) are involve in arousal mediation. In the present study, we showed that the olfactory tubercle (OT) was active during emergence from isoflurane anesthesia, local injection of dopamine D1 receptor (D1R) agonist chloro-APB (1 mg/mL) and D2 receptor (D2R) agonist quinpirole (1 mg/mL) into OT enhanced behavioural and cortical arousal from isoflurane anesthesia, while D1R antagonist SCH-23390 (1 mg/mL) and D2R antagonist raclopride (2.5 mg/mL) prolonged recovery time. Optogenetic activation of DAergic terminals in OT also promoted behavioural and cortical arousal from isoflurane anesthesia. However, neither D1R/D2R agonists nor D1R/D2R antagonists microinjection had influences on the induction of isoflurane anesthesia. Optogenetic stimulation on DAergic terminals in OT also had no impact on the anesthesia induction. Our results indicated that DA signals in OT accelerated emergence from isoflurane anesthesia. Furthermore, the induction of general anesthesia, different from the emergence process, was not mediated by the OT DAergic pathways.
Topics: Anesthetics, Inhalation; Animals; Arousal; Benzazepines; Dopamine Agonists; Dopamine D2 Receptor Antagonists; Isoflurane; Male; Mice, Inbred C57BL; Olfactory Tubercle; Quinpirole; Raclopride; Receptors, Dopamine D1; Receptors, Dopamine D2; Mice
PubMed: 33710536
DOI: 10.1007/s11064-021-03291-4 -
Journal of Neurochemistry Apr 2022The olfactory tubercle (OT), an important component of the ventral striatum and limbic system, is involved in multi-sensory integration of reward-related information in...
The olfactory tubercle (OT), an important component of the ventral striatum and limbic system, is involved in multi-sensory integration of reward-related information in the brain. However, its functional roles are often overshadowed by the neighboring nucleus accumbens. Increasing evidence has highlighted that dense dopamine (DA) innervation of the OT from the ventral tegmental area (VTA) is implicated in encoding reward, natural reinforcers, and motivated behaviors. Recent studies have further suggested that OT subregions may have distinct roles in these processes due to their heterogeneous DA transmission. Currently, very little is known about regulation (release and clearance) of extracellular DA across OT subregions due to its limited anatomical accessibility and proximity to other DA-rich brain regions, making it difficult to isolate VTA-DA signaling in the OT with conventional methods. Herein, we characterized heterogeneous VTA-DA regulation in the medial (m) and lateral (l) OT in "wild-type," urethane-anesthetized rats by integrating in vivo fast-scan cyclic voltammetry with cell-type specific optogenetics to stimulate VTA-DA neurons. Channelrhodopsin-2 was selectively expressed in the VTA-DA neurons of wild-type rats and optical stimulating parameters were optimized to determine VTA-DA transmission across the OT. Our anatomical, neurochemical, and pharmacological results show that VTA-DA regulation in the mOT is less dependent on DA transporters and has greater DA transmission than the lOT. These findings establish the OT as a unique, compartmentalized structure and will aid in future behavioral characterization of the roles of VTA-DA signaling in the OT subregions in reward, drug addiction, and encoding behavioral outputs necessary for survival.
Topics: Animals; Dopamine; Nucleus Accumbens; Olfactory Tubercle; Optogenetics; Rats; Ventral Tegmental Area
PubMed: 35061915
DOI: 10.1111/jnc.15577 -
FEBS Open Bio May 2020Odor adaptation allows the olfactory system to regulate sensitivity to different stimulus intensities, which is essential for preventing saturation of the...
Odor adaptation allows the olfactory system to regulate sensitivity to different stimulus intensities, which is essential for preventing saturation of the cell-transducing machinery and maintaining high sensitivity to persistent and repetitive odor stimuli. Although many studies have investigated the structure and mechanisms of the mammalian olfactory system that responds to chemical sensation, few studies have considered differences in neuronal activation that depend on the manner in which the olfactory system is exposed to odorants, or examined activity patterns of olfactory-related regions in the brain under different odor exposure conditions. To address these questions, we designed three different odor exposure conditions that mimicked diverse odor environments and analyzed c-Fos-expressing cells (c-Fos+ cells) in the odor columns of the olfactory bulb (OB). We then measured differences in the proportions of c-Fos-expressing cell types depending on the odor exposure condition. Surprisingly, under the specific odor condition in which the olfactory system was repeatedly exposed to the odorant for 1 min at 5-min intervals, one of the lateral odor columns and the ipsilateral hemisphere of the olfactory tubercle had more c-Fos+ cells than the other three odor columns and the contralateral hemisphere of the olfactory tubercle. However, this interhemispheric asymmetry of c-Fos expression was not observed in the anterior piriform cortex. To confirm whether the anterior olfactory nucleus pars externa (AONpE), which connects the left and right OB, contributes to this asymmetry, AONpE-lesioned mice were analyzed under the specific odor exposure condition. Asymmetric c-Fos expression was not observed in the OB or the olfactory tubercle. These data indicate that the c-Fos expression patterns of the olfactory-related regions in the brain are influenced by the odor exposure condition and that asymmetric c-Fos expression in these regions was observed under a specific odor exposure condition due to synaptic linkage via the AONpE.
Topics: Animals; Brain; Female; Gene Expression; Gene Expression Regulation; Male; Mice; Mice, Inbred C57BL; Neurons; Odorants; Olfactory Bulb; Olfactory Cortex; Olfactory Pathways; Olfactory Perception; Olfactory Tubercle; Proto-Oncogene Proteins c-fos; Smell
PubMed: 32237058
DOI: 10.1002/2211-5463.12851 -
Frontiers in Neural Circuits 2022The olfactory tubercle (OT) is a striatal region that receives olfactory inputs. mRNAs of prodynorphin (Pdyn) and preproenkephalin (Penk), precursors of dynorphins and...
The olfactory tubercle (OT) is a striatal region that receives olfactory inputs. mRNAs of prodynorphin (Pdyn) and preproenkephalin (Penk), precursors of dynorphins and enkephalins, respectively, are strongly expressed in the striatum. Both produce opioid peptides with various physiological effects such as pain relief and euphoria. Recent studies have revealed that OT has anatomical and cytoarchitectonic domains that play different roles in odor-induced motivated behavior. Neuronal subtypes of the OT can be distinguished by their expression of the dopamine receptors D1 (Drd1) and D2 (Drd2). Here, we addressed whether and which type of opioid peptide precursors the D1- and D2-expressing neurons in the OT express. We used multiple fluorescence hybridization for mRNAs of the opioid precursors and dopamine receptors to characterize mouse OT neurons. Pdyn was mainly expressed by Drd1-expressing cells in the dense cell layer (DCL) of the OT, whereas Penk was expressed primarily by Drd2-expressing cells in the DCL. We also confirmed the presence of a larger population of Pdyn-Penk-Drd1 co-expressing cells in the DCL of the anteromedial OT compared with the anterolateral OT. These observations will help understand whether and how dynorphins and enkephalins in the OT are involved in diverse odor-induced motivated behaviors.
Topics: Animals; Corpus Striatum; Dynorphins; Enkephalins; In Situ Hybridization, Fluorescence; Mice; Neurons; Olfactory Tubercle; Protein Precursors; RNA, Messenger; Receptors, Dopamine D1
PubMed: 35937204
DOI: 10.3389/fncir.2022.908964