-
ENeuro Sep 2015Attraction to opposite-sex pheromones during rodent courtship involves a pathway that includes inputs to the medial amygdala (Me) from the main and accessory olfactory...
Attraction to opposite-sex pheromones during rodent courtship involves a pathway that includes inputs to the medial amygdala (Me) from the main and accessory olfactory bulbs, and projections from the Me to nuclei in the medial hypothalamus that control reproduction. However, the consideration of circuitry that attributes hedonic properties to opposite-sex odors has been lacking. The medial olfactory tubercle (mOT) has been implicated in the reinforcing effects of natural stimuli and drugs of abuse. We performed a tract-tracing study wherein estrous female mice that had received injections of the retrograde tracer, cholera toxin B, into the mOT were exposed to volatile odors from soiled bedding. Both the anterior Me and ventral tegmental area sent direct projections to the mOT, of which a significant subset was selectively activated (expressed Fos protein) by testes-intact male (but not female) volatile odors from soiled bedding. Next, the inhibitory DREADD (designer receptors exclusively activated by designer drugs) receptor hM4Di was bilaterally expressed in the mOT of female mice. Urinary preferences were then assessed after intraperitoneal injection of either saline or clozapine-N-oxide (CNO), which binds to the hM4Di receptor to hyperpolarize infected neurons. After receiving CNO, estrous females lost their preference for male over female urinary odors, whereas the ability to discriminate these odors remained intact. Male odor preference returned after vehicle treatment in counterbalanced tests. There were no deficits in locomotor activity or preference for food odors when subject mice received CNO injections prior to testing. The mOT appears to be a critical segment in the pheromone-reward pathway of female mice.
PubMed: 26478911
DOI: 10.1523/ENEURO.0078-15.2015 -
Psychopharmacology Jun 2008Behavioral and anatomical data suggest that the ventral striatum, consisting of the nucleus accumbens and olfactory tubercle, is functionally heterogeneous. Cocaine and...
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.
OBJECTIVES
We sought to determine whether rats self-administer the popular recreational drug (+/-)-3,4-methylenedioxymethamphetamine (MDMA) into ventrostriatal subregions and whether the medial olfactory tubercle and medial accumbens shell mediate MDMA's positive reinforcing effects more effectively than their lateral counterparts.
RESULTS
Rats receiving 30 mM MDMA into the medial olfactory tubercle, medial accumbens shell, or accumbens core, but not the lateral tubercle or lateral shell, showed higher self-administration rates than rats receiving vehicle. The medial shell supported more vigorous self-administration of MDMA at higher concentrations than the core or medial olfactory tubercle. In addition, intra-medial shell MDMA self-administration was disrupted by co-administration of the D1 or D2 receptor antagonists SCH 23390 (1-3 mM) or raclopride (3-10 mM).
CONCLUSIONS
Our data suggest that the ventral striatum is functionally heterogeneous. The medial accumbens shell appears to be more important than other ventrostriatal subregions in mediating the positive reinforcing effects of MDMA via both D1- and D2-type receptors. Together with previous data, our data also suggest that unidentified actions of MDMA interfere with the positive reinforcing effects of dopamine in the medial olfactory tubercle.
Topics: Animals; Behavior, Animal; Dopamine; Hallucinogens; Male; Motor Activity; N-Methyl-3,4-methylenedioxyamphetamine; Neostriatum; Nucleus Accumbens; Olfactory Bulb; Rats; Rats, Wistar; Receptors, Dopamine D1; Receptors, Dopamine D2; Reward; Self Administration
PubMed: 18389222
DOI: 10.1007/s00213-008-1131-x -
Experimental Brain Research 1986In this study immunohistochemistry is used to investigate the distribution of opioid peptides, substance P (SP), neuropeptide Y (NPY) and acetylcholine (ChAT) in the...
In this study immunohistochemistry is used to investigate the distribution of opioid peptides, substance P (SP), neuropeptide Y (NPY) and acetylcholine (ChAT) in the olfactory tubercle (OT) of the cat. On the basis of our histochemical findings we divide the OT into two parts: the cortical part and the cap regions, the latter containing the granule cell islands. The cortical part shows an intensely ir-punctate staining pattern (opioid and SP), similar to that observed in the striatum, to which it is connected via plexus bridges. The pyramidal neurons representing the main cell type of the cortical part are ir-negative. NPY-ir neurons invade the OT via the plexus bridges from the striatum and are restricted to the cortical part. A different staining pattern exists in the cap regions: dwarf and small pyramidal-like cells display opioid- and SP-like immunoreactivity and therefore are clearly separated from the cortical part. The intensely stained axonal plexus of the cap-region neurons occupies the hilus regions dorsal to the granule islands. In addition, dendrites of large pallidal neurons densely enmeshed in opioid- and SP-ir fibers (woolly fibers) enter the OT from the dorsally located ventral pallidum, pass through the hilus, traverse the granule islands and reach the dwarf cell layer, where the ir-axons apparently terminate. The granule islands do not receive ir-terminals and the granule cells are ir-negative, except some SP-positive granules in the medial islands. Within the hilus regions some large neurons are ChAT-positive, but the majority is ir-negative. The hilus neurons are regarded as the main target of the cap region efferent system. The findings of this study parallel and confirm our morphological observations (Meyer and Wahle 1986).
Topics: Acetylcholine; Animals; Axons; Cats; Dendrites; Endorphins; Female; Immunoenzyme Techniques; Male; Nerve Tissue Proteins; Neurons; Neuropeptide Y; Olfactory Bulb; Staining and Labeling; Substance P
PubMed: 2424779
DOI: 10.1007/BF00236031 -
Experimental Brain Research 1986On the basis of morphology and arrangement of cell types, the olfactory tubercle (OT) of the cat is divided into two main components: a cortical part and the cap/hilus...
On the basis of morphology and arrangement of cell types, the olfactory tubercle (OT) of the cat is divided into two main components: a cortical part and the cap/hilus regions in which cortical characteristics are not recognizable. The cortical part undergoes a gradual transformation from a more cortex-like structure in the lateral half of the OT - possibly related to the presence of olfactory fibers - to a more striatum-like organization in the medial half. Cell bridges extend between the polymorph layer of the cortical part and the striatum and especially the n. accumbens. The cap regions form 8 or 9 superficial grooves running in a rostro-caudal direction. They contain dwarf and small pyramidal-like neurons and lie immediately ventral to the granule islands of Calleja. Dwarf and small pyramidal-like neurons give rise to an ascending axonal plexus which may contact large neurons in the hilus regions dorsal to the Calleja islands and in part also neurons of the ventral pallidum, the dendrites of which enter the lateral hilus zones. The proportion of dwarf cells to granule cells in the cap regions gradually reverses from lateral, where dwarf cells dominate, to medial, where the caps contain almost exclusively granule cells. No interconnections are observed between the two components of the OT.
Topics: Animals; Axons; Cats; Cell Communication; Dendrites; Functional Laterality; Neurons; Olfactory Bulb; Silver; Staining and Labeling
PubMed: 2424778
DOI: 10.1007/BF00236030 -
The European Journal of Neuroscience Jan 2012Biologically relevant odours were used to stimulate olfactory tubercle neurons in anaesthetized male rats. Among 120 recorded neurons, 118 showed spontaneous activity...
Biologically relevant odours were used to stimulate olfactory tubercle neurons in anaesthetized male rats. Among 120 recorded neurons, 118 showed spontaneous activity (mean firing rate, 15.0 ± 1.4 spikes/s). Ninety-eight neurons were exposed to at least one of the four following odour sources: an empty vial, or a vial containing food pellets (familiar odour), a sample of oestrous rat faeces (conspecific sexual odour), or a sample of male fox faeces (predator odour). The proportion of neurons responding with a change in activity was significantly linked to the odour applied. Repetition of the stimulation with the same odour elicited the same activity change. Between 50 and 70% of neuronal activity changes were not accompanied by respiration changes. Fifty-six neurons were exposed successively to all four odours, and 38 of them showed an activity change in response to at least one. The response of a neuron to an odour was not affected by its response to the previous one, and no neuron responded in the same manner to all odours. Conversely, no odour elicited a unique response in this population of neurons. However, the proportions of excited, inhibited and insensitive neurons depended significantly on the odour applied, suggesting that the recruitment of olfactory tubercle neurons is directly dependent on the biological significance of the odour.
Topics: Action Potentials; Animals; Electrophysiology; Male; Neurons; Odorants; Olfactory Pathways; Rats; Stimulation, Chemical
PubMed: 22118424
DOI: 10.1111/j.1460-9568.2011.07940.x -
The Journal of Neuroscience : the... May 2005When projection analyses placed the nucleus accumbens and olfactory tubercle in the striatal system, functional links between these sites began to emerge. The accumbens... (Comparative Study)
Comparative Study
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?
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.
Topics: Animals; Behavior, Animal; Central Nervous System Stimulants; Corpus Striatum; Dextroamphetamine; Discrimination, Psychological; Dose-Response Relationship, Drug; Functional Laterality; Male; Nucleus Accumbens; Rats; Rats, Wistar; Reinforcement, Psychology; Self Administration
PubMed: 15901788
DOI: 10.1523/JNEUROSCI.0892-05.2005 -
BMC Neuroscience Nov 2007Vertebrates sense chemical stimuli through the olfactory receptor neurons whose axons project to the main olfactory bulb. The main projections of the olfactory bulb are...
BACKGROUND
Vertebrates sense chemical stimuli through the olfactory receptor neurons whose axons project to the main olfactory bulb. The main projections of the olfactory bulb are directed to the olfactory cortex and olfactory amygdala (the anterior and posterolateral cortical amygdalae). The posterolateral cortical amygdaloid nucleus mainly projects to other amygdaloid nuclei; other seemingly minor outputs are directed to the ventral striatum, in particular to the olfactory tubercle and the islands of Calleja.
RESULTS
Although the olfactory projections have been previously described in the literature, injection of dextran-amines into the rat main olfactory bulb was performed with the aim of delimiting the olfactory tubercle and posterolateral cortical amygdaloid nucleus in our own material. Injection of dextran-amines into the posterolateral cortical amygdaloid nucleus of rats resulted in anterograde labeling in the ventral striatum, in particular in the core of the nucleus accumbens, and in the medial olfactory tubercle including some islands of Calleja and the cell bridges across the ventral pallidum. Injections of Fluoro-Gold into the ventral striatum were performed to allow retrograde confirmation of these projections.
CONCLUSION
The present results extend previous descriptions of the posterolateral cortical amygdaloid nucleus efferent projections, which are mainly directed to the core of the nucleus accumbens and the medial olfactory tubercle. Our data indicate that the projection to the core of the nucleus accumbens arises from layer III; the projection to the olfactory tubercle arises from layer II and is much more robust than previously thought. This latter projection is directed to the medial olfactory tubercle including the corresponding islands of Calleja, an area recently described as critical node for the neural circuit of addiction to some stimulant drugs of abuse.
Topics: Amygdala; Animals; Corpus Striatum; Female; Male; Neurons; Olfactory Pathways; Rats; Rats, Sprague-Dawley
PubMed: 18047654
DOI: 10.1186/1471-2202-8-103 -
Journal of Neurophysiology Nov 2007Olfactory information is processed by a diverse group of interconnected forebrain regions. Most efforts to define the cellular mechanisms involved in processing...
Olfactory information is processed by a diverse group of interconnected forebrain regions. Most efforts to define the cellular mechanisms involved in processing olfactory information have been focused on understanding the function of the olfactory bulb, the primary second-order olfactory region, and its principal target, the piriform cortex. However, the olfactory bulb also projects to other targets, including the rarely studied olfactory tubercle, a ventral brain region recently implicated in regulating cocaine-related reward behavior. We used whole cell patch-clamp recordings from rat tubercle slices to define the intrinsic properties of neurons in the dense and multiform cell layers. We find three common firing modes of tubercle neurons: regular-spiking, intermittent-discharging, and bursting. Regular-spiking neurons are typically spiny-dense-cell-layer cells with pyramidal-shaped, dendritic arborizations. Intermittently discharging and bursting neurons comprise the majority of the deeper multiform layer and share a common morphology: multipolar, sparsely spiny cells. Rather than generating all-or-none stereotyped discharges, as observed in many brain areas, bursting cells in the tubercle generate depolarizing plateau potentials that trigger graded but time-limited discharges. We find two distinct subclasses of bursting cells that respond similarly to step stimuli but differ in the role transmembrane Ca currents play in their intrinsic behavior. Calcium currents amplify depolarizing inputs and enhance excitability in regenerative bursting cells, whereas the primary action of Ca in nonregenerative bursting tubercle neurons appears to be to decrease excitability by triggering Ca-activated K currents. Nonregenerative bursting cells exhibit a prolonged refractory period after even short discharges suggesting that they may function to detect transient events.
Topics: Action Potentials; Anesthetics, Local; Animals; Animals, Newborn; Biotin; Calcium; Dose-Response Relationship, Radiation; Electric Stimulation; In Vitro Techniques; Neurons; Olfactory Pathways; Rats; Rats, Sprague-Dawley; Tetrodotoxin; Time Factors
PubMed: 17855583
DOI: 10.1152/jn.00807.2007 -
Journal of Morphology May 1981The neural organization of the olfactory system in the desert iguana, Dipsosaurus dorsalis, has been investigated by using the Fink-Heimer technique to trace the...
The neural organization of the olfactory system in the desert iguana, Dipsosaurus dorsalis, has been investigated by using the Fink-Heimer technique to trace the efferents of the main and accessory olfactory bulbs, and Golgi preparations to determine the spatial relations between olfactory afferents and neurons in the primary olfactory centers. The accessory olfactory bulb projects to the ipsilateral nucleus sphericus via the accessory olfactory tract. The main olfactory bulb projects to the ipsilateral telen-cephalon via four tracts. The medial olfactory tract projects to the rostral continuation of medial cortex and to the septum. The intermediate olfactory tract projects to the olfactory tubercle and retrobulbar formation. The lateral olfactory tract projects to the rostral part of lateral cortex. The intermediate and lateral olfactory tracts also merge caudally to form the stria medullaris, which crosses the midline in the habenular commissure and distributes fibers to the contralateral hemisphere via two tracts. The lateral corticohabenular tract terminates in the contralateral lateral cortex. The anterior olfactohabenular tract terminates in the contralateral olfactory tubercle, retrobulbar formation and septum. The relation of olfactory afferents to neurons in the medial cortex, lateral cortex, nucleus sphericus, and septum corresponds to a pattern of organization that is typical of many olfactorecipient structures. Such structures are trilaminar, with neurons whose somata are situated in the intermediate layer (layer 2) sending spine-laden dendrites into an outer, molecular layer (layer 1). Olfactory afferents intersect the distal segments of these dendrites. By contrast, other olfactorecipient structures in Dipsoaurus deviate from the familiar pattern. Olfactory afferents intersect somata lying in layer 2 of the retrobulbar formation. Olfactory afferents include some fibers which course perpendicularly to the surface of the olfactory tubercle and extend deep to layer 2.
PubMed: 30139194
DOI: 10.1002/jmor.1051680208 -
Electroencephalography and Clinical... Jun 1979The centrifugal control exerted by different arousal states on the rat olfactory bulb was investigated. The olfactory tubercle was unilaterally coagulated with either 1...
The centrifugal control exerted by different arousal states on the rat olfactory bulb was investigated. The olfactory tubercle was unilaterally coagulated with either 1 mA or 3 mA current. The vigilance state parameters and multiunit mitral cell activity were recorded in freely moving rats, stimulated either by their usual food odor or by isoamyl acetate, in a hungry or a satiated state. In each animal, a unilateral lesion affected resting activity and the relative proportion of positive (excitatory) and negative (inhibitory) responses in the same way in both olfactory bulbs; these effects were proportional to the extent of the lesion. In wakefulness, a nutritional modulation of the bulb responses for food odor existed in spite of a slight decrease in the general arousal level. In slow wave sleep (SWS), when compared to a control group, the rats with lesions showed an increase of neocortical desynchronization induced by olfactory stimulation, and a large decrease of mitral cell excitability. Inhibition of the olfactory input, which normally develops during SWS, could involve mainly mesencephalic neurons reaching the olfactory tubercle and the bulb via the ventral part of the medial forebrain bundle.
Topics: Acetates; Animals; Arousal; Food; Hunger; Male; Odorants; Olfactory Bulb; Pentanols; Rats; Satiation
PubMed: 87311
DOI: 10.1016/0013-4694(79)90104-4