The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Daniel W Wesson - One of the best experts on this subject based on the ideXlab platform.
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neurochemical organization of the ventral striatum s Olfactory Tubercle
Journal of Neurochemistry, 2020Co-Authors: Hillary L Cansler, Katherine N Wright, Lucas A Stetzik, Daniel W WessonAbstract:The ventral striatum is a collection of brain structures, including the nucleus accumbens, ventral pallidum and the Olfactory Tubercle (OT). While much attention has been devoted to the nucleus accumbens, a comprehensive understanding of the ventral striatum and its contributions to neurological diseases requires an appreciation for the complex neurochemical makeup of the ventral striatum's other components. This review summarizes the rich neurochemical composition of the OT, including the neurotransmitters, neuromodulators and hormones present. We also address the receptors and transporters involved in each system as well as their putative functional roles. Finally, we end with briefly reviewing select literature regarding neurochemical changes in the OT in the context of neurological disorders, specifically neurodegenerative disorders. By overviewing the vast literature on the neurochemical composition of the OT, this review will serve to aid future research into the neurobiology of the ventral striatum.
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illustrated review of the ventral striatum s Olfactory Tubercle
Chemical Senses, 2016Co-Authors: Angeline Xiong, Daniel W WessonAbstract:Modern neuroscience often relies upon artistic renderings to illustrate key aspects of anatomy. These renderings can be in 2 or even 3 dimensions. Three-dimensional renderings are especially helpful in conceptualizing highly complex aspects of neuroanatomy which otherwise are not visually apparent in 2 dimensions or even intact biological samples themselves. Here, we provide 3 dimensional renderings of the gross- and cellular-anatomy of the rodent Olfactory Tubercle. Based upon standing literature and detailed investigations into rat brain specimens, we created biologically inspired illustrations of the Olfactory Tubercle in 3 dimensions as well as its connectivity with Olfactory bulb projection neurons, the piriform cortex association fiber system, and ventral pallidum medium spiny neurons. Together, we intend for these illustrations to serve as a resource to the neuroscience community in conceptualizing and discussing this highly complex and interconnected brain system with established roles in sensory processing and motivated behaviors.
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The Neural Representation of Goal-Directed Actions and Outcomes in the Ventral Striatum's Olfactory Tubercle
The Journal of Neuroscience, 2016Co-Authors: Marie A. Gadziola, Daniel W WessonAbstract:The ventral striatum is critical for evaluating reward information and the initiation of goal-directed behaviors. The many cellular, afferent, and efferent similarities between the ventral striatum9s nucleus accumbens and Olfactory Tubercle (OT) suggests the distributed involvement of neurons within the ventral striatopallidal complex in motivated behaviors. Although the nucleus accumbens has an established role in representing goal-directed actions and their outcomes, it is not known whether this function is localized within the nucleus accumbens or distributed also within the OT. Answering such a fundamental question will expand our understanding of the neural mechanisms underlying motivated behaviors. Here we address whether the OT encodes natural reinforcers and serves as a substrate for motivational information processing. In recordings from mice engaged in a novel water-motivated instrumental task, we report that OT neurons modulate their firing rate during initiation and progression of the instrumental licking behavior, with some activity being internally generated and preceding the first lick. We further found that as motivational drive decreases throughout a session, the activity of OT neurons is enhanced earlier relative to the behavioral action. Additionally, OT neurons discriminate the types and magnitudes of fluid reinforcers. Together, these data suggest that the processing of reward information and the orchestration of goal-directed behaviors is a global principle of the ventral striatum and have important implications for understanding the neural systems subserving addiction and mood disorders. SIGNIFICANCE STATEMENT Goal-directed behaviors are widespread among animals and underlie complex behaviors ranging from food intake, social behavior, and even pathological conditions, such as gambling and drug addiction. The ventral striatum is a neural system critical for evaluating reward information and the initiation of goal-directed behaviors. Here we show that neurons in the Olfactory Tubercle subregion of the ventral striatum robustly encode the onset and progression of motivated behaviors, and discriminate the type and magnitude of a reward. Our findings are novel in showing that Olfactory Tubercle neurons participate in such coding schemes and are in accordance with the principle that ventral striatum substructures may cooperate to guide motivated behaviors.
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the Olfactory Tubercle encodes odor valence in behaving mice
The Journal of Neuroscience, 2015Co-Authors: Marie A. Gadziola, Kate A Tylicki, Diana Christian, Daniel W WessonAbstract: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.
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odor and state dependent Olfactory Tubercle local field potential dynamics in awake rats
Journal of Neurophysiology, 2014Co-Authors: Kaitlin S Carlson, Maggie R Dillione, Daniel W WessonAbstract:The Olfactory Tubercle (OT), a trilaminar structure located in the basal forebrain of mammals, is thought to play an important role in olfaction. While evidence has accumulated regarding the contributions of the OT to odor information processing, studies exploring the role of the OT in olfaction in awake animals remain unavailable. In the present study, we begin to address this void through multiday recordings of local field potential (LFP) activity within the OT of awake, freely exploring Long-Evans rats. We observed spontaneous OT LFP activity consisting of theta- (2-12 Hz), beta- (15-35 Hz) and gamma- (40-80 Hz) band activity, characteristic of previous reports of LFPs in other principle Olfactory structures. Beta- and gamma-band powers were enhanced upon odor presentation. Simultaneous recordings of OT and upstream Olfactory bulb (OB) LFPs revealed odor-evoked LFP power at statistically similar levels in both structures. Strong spectral coherence was observed between the OT and OB during both spontaneous and odor-evoked states. Furthermore, the OB theta rhythm more strongly cohered with the respiratory rhythm, and respiratory-coupled theta cycles in the OT occurred following theta cycles in the OB. Finally, we found that the animal's internal state modulated LFP activity in the OT. Together, these data provide initial insights into the network activity of the OT in the awake rat, including spontaneous rhythmicity, odor-evoked modulation, connectivity with upstream sensory input, and state-dependent modulation.
Satoshi Ikemoto - One of the best experts on this subject based on the ideXlab platform.
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intracranial self administration of mdma into the ventral striatum of the rat differential roles of the nucleus accumbens shell core and Olfactory Tubercle
Psychopharmacology, 2008Co-Authors: Rick Shin, Mei Qin, Zhonghua Liu, Satoshi IkemotoAbstract:Rationale Behavioral and anatomical data suggest that the ventral striatum, consisting of the nucleus accumbens and Olfactory Tubercle, is functionally heterogeneous. Cocaine and d-amphetamine appear to be more rewarding when administered into the medial Olfactory Tubercle or medial accumbens shell than into their lateral counterparts, including the accumbens core.
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Dopamine reward circuitry: Two projection systems from the ventral midbrain to the nucleus accumbens-Olfactory Tubercle complex
Brain Research Reviews, 2007Co-Authors: Satoshi IkemotoAbstract: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.
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the functional divide for primary reinforcement of d amphetamine lies between the medial and lateral ventral striatum is the division of the accumbens core shell and Olfactory Tubercle valid
The Journal of Neuroscience, 2005Co-Authors: Satoshi Ikemoto, Mei Qin, Zhonghua LiuAbstract:When projection analyses placed the nucleus accumbens and Olfactory Tubercle in the striatal system, functional links between these sites began to emerge. The accumbens has been implicated in the rewarding effects of psychomotor stimulants, whereas recent work suggests that the medial accumbens shell and medial Olfactory Tubercle mediate the rewarding effects of cocaine. Interestingly, anatomical evidence suggests that medial portions of the shell and Tubercle receive afferents from common zones in a number of regions. Here, we report results suggesting that the current division of the ventral striatum into the accumbens core and shell and the Olfactory Tubercle does not reflect the functional organization for amphetamine reward. Rats quickly learned to self-administer D-amphetamine into the medial shell or medial Tubercle, whereas they failed to learn to do so into the accumbens core, ventral shell, or lateral Tubercle. Our results suggest that primary reinforcement of amphetamine is mediated via the medial portion of the ventral striatum. Thus, the medial shell and medial Tubercle are more functionally related than the medial and ventral shell or the medial and lateral Tubercle. The current core-shell-Tubercle scheme should be reconsidered in light of recent anatomical data and these functional findings.
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a five minute but not a fifteen minute conditioning trial duration induces conditioned place preference for cocaine administration into the Olfactory Tubercle
Synapse, 2005Co-Authors: Satoshi Ikemoto, Kathleen M DonahueAbstract:The establishment of conditioned place preference (CPP) with intracranial injections requires specific injection sites, drug doses, and conditioning trial durations. We examined the role of conditioning trial duration in CPP with cocaine injections into the medial Olfactory Tubercle. Only those rats that had spent 5 min in the compartments showed CPP for cocaine, while rats that had been removed immediately or spent 15 min following cocaine injections did not show CPP. Effective conditioning trial durations for CPP induced by intracranial cocaine injections are apparently much shorter than those typically used for intracranial injections of other drugs of abuse.
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involvement of the Olfactory Tubercle in cocaine reward intracranial self administration studies
The Journal of Neuroscience, 2003Co-Authors: Satoshi IkemotoAbstract:Cocaine has multiple actions and multiple sites of action in the brain. Evidence from pharmacological studies indicates that it is the ability of cocaine to block dopamine uptake and elevate extracellular dopamine concentrations, and thus increase dopaminergic receptor activation, that makes cocaine rewarding. Lesion studies have implicated the nucleus accumbens (the dorsal portion of the "ventral striatum") as the probable site of the rewarding action of the drug. However, the drug is only marginally self-administered into this site. We now report that cocaine (60 or 200 mm in 75 nl/infusion) is readily self-administered into the Olfactory Tubercle, the most ventral portion of the ventral striatum. Cocaine (200 mm) was self-administered marginally into the accumbens shell but not into the core, dorsal striatum, or ventral pallidum. In addition, cocaine injections (200 mm in 300 nl) into the Tubercle but not the shell or ventral pallidum induced conditioned place preference. Rewarding effects of cocaine in the Tubercle were blocked by coadministration of dopamine D1 or D2 antagonists (1 mm SCH 23390 or 3 mm raclopride) and were not mimicked by injections of the local anesthetic procaine (800 mm). In conclusion, the Tubercle plays a critical role in mediating rewarding action of cocaine.
Kanji Yoshimoto - One of the best experts on this subject based on the ideXlab platform.
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Chronic treatment with melatonin attenuates serotonergic degeneration in the striatum and Olfactory Tubercle of zitter mutant rats.
Neuroscience letters, 2008Co-Authors: Shiuchi Ueda, Shin Ichi Sakakibara, Taro Kadowaki, Takuya Naitoh, Koichi Hirata, Kanji YoshimotoAbstract:The effects of chronic treatment with the antioxidant hormone melatonin on degeneration of serotonergic fibers were studied in the striatum and Olfactory Tubercle of the zitter rat, which shows a loss-of-function mutation of the glycosylated transmembrane protein attractin. In these animals, serotonergic fibers in the striatum and Olfactory Tubercle undergo spontaneous and progressive degeneration as a result of abnormal metabolism of reactive oxygen species. Homozygous zitter (zi/zi) rats were provided ad libitum access to drinking water containing melatonin for 9 months (M) after weaning. High-performance liquid chromatography analysis revealed that melatonin treatment significantly increased serotonin in the caudate-putamen, (CPU), nucleus accumbens (NA) and Olfactory Tubercle (OT). Immunohistochemical staining for serotonin was consistent with the neurochemical data and further demonstrated substantially increased numbers of serotonergic nerve terminals in these areas. Aberrant serotonergic fibers characterized by swollen varicosities (>1 microm in diameter) were observed in the CPU and NA of 10 M zi/zi rats. The number of these fibers decreased after melatonin treatment ended. Furthermore, hyperinnervation of serotonergic fibers was observed in the OT of melatonin-treated zi/zi rats. These results suggest that melatonin protects serotonergic fibers and terminals in zitter rats and/or promotes their neuroplasticity.
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age related dopamine deficiency in the mesostriatal dopamine system of zitter mutant rats regional fiber vulnerability in the striatum and the Olfactory Tubercle
Neuroscience, 1999Co-Authors: Shuichi Ueda, Masuo Aikawa, Atsuko Ishizuyaoka, Sadao Yamaoka, Noriyuki Koibuchi, Kanji YoshimotoAbstract:Oxidant stress has been implicated in the pathogenesis of Parkinson's disease. To test the oxidant stress hypothesis of dopaminergic degeneration, age-related changes in the mesostriatal dopamine neuron system were compared between zitter mutant rats which have abnormal metabolism of oxygen species in the brain and Sprague-Dawley rat as a control using the neurochemistry and immunohistochemistry. Dopamine content in the caudate-putamen, nucleus accumbens and Olfactory Tubercle of zitter rats decreased significantly with age, and was lower than that found in corresponding age-matched controls. In the zitter rats, the reduction of dopamine was more prominent in the caudate-putamen than in the nucleus accumbens and Olfactory Tubercle. A characteristic decline of tyrosine hydroxylase-immunoreactive fibers in the caudate-putamen of the zitter rat was also observed. In the dorsolateral caudate-putamen, reduction of tyrosine hydroxylase-immunoreactive fibers was observed in the matrix-like area, whereas in the ventromedial caudate-putamen the reduction occurred in the patch-like areas. Degeneration of tyrosine hydroxylase-immunoreactive fibers which was characterized by swollen varicosities and clustered fibers was observed in the caudate-putamen and nucleus accumbens and preceded loss of normal tyrosine hydroxylase-immunoreactive fibers in the caudate-putamen. Thus, the depletion of dopamine in the terminal areas is related to axonal degeneration. However, there was no degenerative tyrosine hydroxylase-immunoreactive fibers in the Olfactory Tubercle at any examined age, but reductions of tyrosine hydroxylase-immunoreactive fibers and dopamine contents were noted in the Olfactory Tubercle after four months-of-age. Since the zitter rats have an abnormal oxygen metabolism, the degeneration of tyrosine hydroxylase-immunoreactive fibers could result from an accumulation of superoxide species. The present results provide support for the oxidant stress hypothesis of dopaminergic neuronal degeneration and further indicate the region-specific vulnerability of the nigrostriatal dopamine system.
Masahiro Yamaguchi - One of the best experts on this subject based on the ideXlab platform.
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functional development of Olfactory Tubercle domains during weaning period in mice
Scientific Reports, 2018Co-Authors: Wataru Murofushi, Koshi Murata, Kensaku Mori, Masahiro YamaguchiAbstract:Mammals shift their feeding habits from mother's milk to environmental foods postnatally. While this weaning process accompanies the acquisition of attractive behaviour toward environmental foods, the underlying neural mechanism for the acquisition is poorly understood. We previously found that adult mouse Olfactory Tubercle (OT), which belongs to the Olfactory cortex and ventral striatum, has functional domains that represent odour-induced motivated behaviours, and that c-fos induction occurs mainly in the anteromedial domain of OT following learned odour-induced food seeking behaviour. To address the question whether the anteromedial OT domain is involved in the postnatal acquisition of food seeking behaviour, we examined OT development during weaning of mice. Whereas at postnatal day 15 (P15), all mice were attracted to lactating mothers, P21 mice were more attracted to familiar food pellets. Mapping of c-fos induction during food seeking and eating behaviours showed that while c-fos activation was observed across wide OT domains at P15, the preferential activation of c-fos in the anteromedial domain occurred at P21 and later ages. These results indicate that preferential c-fos activation in the anteromedial OT domain occurred concomitantly with the acquisition of attractive behaviour toward food, which suggests the importance of this domain in the weaning process.
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functional sub circuits of the Olfactory system viewed from the Olfactory bulb and the Olfactory Tubercle
Frontiers in Neuroanatomy, 2017Co-Authors: Masahiro YamaguchiAbstract:Understanding of the Olfactory neural circuits has progressed beyond analysis of how odor information from the external environment is processed in the brain. While spatially-organized sub-circuits were found to exist up to the Olfactory bulb (OB), the arrangement in the Olfactory cortex (OC), especially in its representative piriform cortex (PC), appears diffuse and dispersed. An emerging view is that the activity of OC neurons may not simply encode odor identity but rather encode plastic odor information such as odor value. Although many studies support this notion, odor value can be either positive or negative, and the existence of sub-circuits corresponding to individual value types is not well explored. To address this question, I introduce here two Olfactory areas other than the PC, OB and Olfactory Tubercle (OT) whose analysis may facilitate understanding of functional sub-circuits related to different odor values. Peripheral and centrifugal inputs to the OB are considered to relate to odor identity and odor value, respectively, and centrifugal inputs to the OB potentially represent different odor values during different behavioral periods. The OT has spatially-segregated functional domains related to distinct motivated and hedonic behaviors. Thus, the OT provides a good starting point from which functional sub-circuits across various Olfactory regions can be traced. Further analysis across wide areas of the Olfactory system will likely reveal the functional sub-circuits that link odor identity with distinct odor values and direct distinct odor-induced motivated and hedonic behaviors.
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Mapping of Learned Odor-Induced Motivated Behaviors in the Mouse Olfactory Tubercle
Journal of Neuroscience, 2015Co-Authors: Koshi Murata, Michiko Kanno, Nao Ieki, Kensaku Mori, Masahiro YamaguchiAbstract:An odor induces food-seeking behaviors when humans and animals learned to associate the odor with food, whereas the same odor elicits aversive behaviors following odor-danger association learning. It is poorly understood how central Olfactory circuits transform the learned odor cue information into appropriate motivated behaviors. The Olfactory Tubercle (OT) is an intriguing area of the Olfactory cortex in that it contains medium spiny neurons as principal neurons and constitutes a part of the ventral striatum. The OT is therefore a candidate area for participation in odor-induced motivated behaviors. Here we mapped c-Fos activation of medium spiny neurons in different domains of the mouse OT following exposure to learned odor cues. Mice were trained to associate odor cues to a sugar reward or foot shock punishment to induce odor-guided approach behaviors or aversive behaviors. Regardless of odorant types, the anteromedial domain of the OT was activated by learned odor cues that induced approach behaviors, whereas the lateral domain was activated by learned odor cues that induced aversive behaviors. In each domain, a larger number of dopamine receptor D1 type neurons were activated than D2 type neurons. These results indicate that specific domains of the OT represent odor-induced distinct motivated behaviors rather than odor stimuli, and raise the possibility that neuronal type-specific activation in individual domains of the OT plays crucial roles in mediating the appropriate learned odor-induced motivated behaviors. Significance statement: Although animals learn to associate odor cues with various motivated behaviors, the underlying circuit mechanisms are poorly understood. The Olfactory Tubercle (OT), a subarea of the Olfactory cortex, also constitutes the ventral striatum. Here, we trained mice to associate odors with either reward or punishment and mapped odor-induced c-Fos activation in the OT. Regardless of odorant types, the anteromedial domain was activated by approach behavior-inducing odors, whereas the lateral domain was activated by aversive behavior-inducing odors. In each domain, dopamine receptor D1 neurons were preferentially activated over D2 neurons. The results indicate that specific OT domains represent odor-induced distinct motivated behaviors rather than odor types, and suggest the importance of neuronal type-specific activation in individual domains in mediating appropriate behaviors.
Kensaku Mori - One of the best experts on this subject based on the ideXlab platform.
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functional development of Olfactory Tubercle domains during weaning period in mice
Scientific Reports, 2018Co-Authors: Wataru Murofushi, Koshi Murata, Kensaku Mori, Masahiro YamaguchiAbstract:Mammals shift their feeding habits from mother's milk to environmental foods postnatally. While this weaning process accompanies the acquisition of attractive behaviour toward environmental foods, the underlying neural mechanism for the acquisition is poorly understood. We previously found that adult mouse Olfactory Tubercle (OT), which belongs to the Olfactory cortex and ventral striatum, has functional domains that represent odour-induced motivated behaviours, and that c-fos induction occurs mainly in the anteromedial domain of OT following learned odour-induced food seeking behaviour. To address the question whether the anteromedial OT domain is involved in the postnatal acquisition of food seeking behaviour, we examined OT development during weaning of mice. Whereas at postnatal day 15 (P15), all mice were attracted to lactating mothers, P21 mice were more attracted to familiar food pellets. Mapping of c-fos induction during food seeking and eating behaviours showed that while c-fos activation was observed across wide OT domains at P15, the preferential activation of c-fos in the anteromedial domain occurred at P21 and later ages. These results indicate that preferential c-fos activation in the anteromedial OT domain occurred concomitantly with the acquisition of attractive behaviour toward food, which suggests the importance of this domain in the weaning process.
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Mapping of Learned Odor-Induced Motivated Behaviors in the Mouse Olfactory Tubercle
Journal of Neuroscience, 2015Co-Authors: Koshi Murata, Michiko Kanno, Nao Ieki, Kensaku Mori, Masahiro YamaguchiAbstract:An odor induces food-seeking behaviors when humans and animals learned to associate the odor with food, whereas the same odor elicits aversive behaviors following odor-danger association learning. It is poorly understood how central Olfactory circuits transform the learned odor cue information into appropriate motivated behaviors. The Olfactory Tubercle (OT) is an intriguing area of the Olfactory cortex in that it contains medium spiny neurons as principal neurons and constitutes a part of the ventral striatum. The OT is therefore a candidate area for participation in odor-induced motivated behaviors. Here we mapped c-Fos activation of medium spiny neurons in different domains of the mouse OT following exposure to learned odor cues. Mice were trained to associate odor cues to a sugar reward or foot shock punishment to induce odor-guided approach behaviors or aversive behaviors. Regardless of odorant types, the anteromedial domain of the OT was activated by learned odor cues that induced approach behaviors, whereas the lateral domain was activated by learned odor cues that induced aversive behaviors. In each domain, a larger number of dopamine receptor D1 type neurons were activated than D2 type neurons. These results indicate that specific domains of the OT represent odor-induced distinct motivated behaviors rather than odor stimuli, and raise the possibility that neuronal type-specific activation in individual domains of the OT plays crucial roles in mediating the appropriate learned odor-induced motivated behaviors. Significance statement: Although animals learn to associate odor cues with various motivated behaviors, the underlying circuit mechanisms are poorly understood. The Olfactory Tubercle (OT), a subarea of the Olfactory cortex, also constitutes the ventral striatum. Here, we trained mice to associate odors with either reward or punishment and mapped odor-induced c-Fos activation in the OT. Regardless of odorant types, the anteromedial domain was activated by approach behavior-inducing odors, whereas the lateral domain was activated by aversive behavior-inducing odors. In each domain, dopamine receptor D1 neurons were preferentially activated over D2 neurons. The results indicate that specific OT domains represent odor-induced distinct motivated behaviors rather than odor types, and suggest the importance of neuronal type-specific activation in individual domains in mediating appropriate behaviors.
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sharp wave associated synchronized inputs from the piriform cortex activate Olfactory Tubercle neurons during slow wave sleep
Journal of Neurophysiology, 2014Co-Authors: Kimiya Narikiyo, Hiroyuki Manabe, Kensaku MoriAbstract:During slow-wave sleep, anterior piriform cortex neurons show highly synchronized discharges that accompany Olfactory cortex sharp waves (OC-SPWs). The OC-SPW-related synchronized activity of anterior piriform cortex neurons travel down to the Olfactory bulb and is thought to be involved in the reorganization of bulbar neuronal circuitry. However, influences of the OC-SPW-related activity on other regions of the central Olfactory system are still unknown. Olfactory Tubercle is an area of OC and part of ventral striatum that plays a key role in reward-directed motivational behaviors. In this study, we show that in freely behaving rats, Olfactory Tubercle receives OC-SPW-associated synchronized inputs during slow-wave sleep. Local field potentials in the Olfactory Tubercle showed SPW-like activities that were in synchrony with OC-SPWs. Single-unit recordings showed that a subpopulation of Olfactory Tubercle neurons discharged in synchrony with OC-SPWs. Furthermore, correlation analysis of spike activity of anterior piriform cortex and Olfactory Tubercle neurons revealed that the discharges of anterior piriform cortex neurons tended to precede those of Olfactory Tubercle neurons. Current source density analysis in urethane-anesthetized rats indicated that the current sink of the OC-SPW-associated input was located in layer III of the Olfactory Tubercle. These results indicate that OC-SPW-associated synchronized discharges of piriform cortex neurons travel to the deep layer of the Olfactory Tubercle and drive discharges of Olfactory Tubercle neurons. The entrainment of Olfactory Tubercle neurons in the OC-SPWs suggests that OC-SPWs coordinate reorganization of neuronal circuitry across wide areas of the central Olfactory system including Olfactory Tubercle during slow-wave sleep.
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piriform cortex and Olfactory Tubercle
2014Co-Authors: Kensaku MoriAbstract:This chapter describes perspectives on the possible functional logic of neuronal circuits in the central Olfactory system. The central Olfactory system has multiplex pathways and loops that connect the Olfactory bulb, Olfactory cortex, neocortex, thalamus, ventral striatum, amygdala, hippocampus, and hypothalamus. Among the complex circuits, this chapter focuses on the possible functional differentiation of “Olfactory bulb axon–Ib association axon (afferent) circuits” and “deep association axon (recurrent and top-down) circuits” in the piriform cortex. It is hypothesized that the activity of the former circuits is induced mainly by Olfactory sensory inputs during the on-line inhalation phase of the sniff cycle, whereas activity of the latter circuits may occur mainly during the off-line exhalation phase. This chapter also discusses the possible function of motivation modules in the neuronal circuits of the Olfactory Tubercle.
