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Journal of Neurophysiology Mar 2009The olfactory tubercle (OT) is a cortical component of the olfactory system involved in reward mechanisms of drug abuse. This region covers an extensive part of the...
The olfactory tubercle (OT) is a cortical component of the olfactory system involved in reward mechanisms of drug abuse. This region covers an extensive part of the rostral ventral cerebrum and is relatively poorly studied. The intrinsic network interactions evoked by olfactory input are analyzed in the OT of the in vitro isolated guinea pig brain by means of field potential analysis and optical imaging of voltage-sensitive signals. Stimulation of the lateral olfactory tract induces a monosynaptic response that progressively decreases in amplitude from lateral to medial. The monosynaptic input induces a disynaptic response that is proportionally larger in the medial portion of the OT. Direct stimulation of the piriform cortex and subsequent lesion of this pathway showed the existence of an associative disynaptic projection from the anterior part of the piriform cortex to the lateral part of the OT that integrates with the component mediated by the local intra-OT collaterals. Optical and electrophysiological recordings of the signals evoked by stimulation of the olfactory tract during arterial perfusion with the voltage-sensitive dye di-2-ANEPEQ confirmed the pattern of distribution of the mono and disynaptic responses in the OT. Finally, current source density analysis of laminar profiles recorded with 16-channel silicon probes confirmed that the monosynaptic and disynaptic potentials localize in the most superficial and the deep portions of the plexiform layer I, as suggested by previous reports. This study sets the standard for further analysis of the modulation of network properties in this largely unexplored brain region.
Topics: Action Potentials; Animals; Brain; Brain Mapping; Electric Stimulation; Guinea Pigs; Image Processing, Computer-Assisted; In Vitro Techniques; Olfactory Pathways; Reaction Time
PubMed: 18922946
DOI: 10.1152/jn.90792.2008 -
The Journal of Neuroscience : the... Nov 2019Sensory cortices process stimuli in manners essential for perception. Very little is known regarding interactions between olfactory cortices. The piriform "primary"...
Sensory cortices process stimuli in manners essential for perception. Very little is known regarding interactions between olfactory cortices. The piriform "primary" olfactory cortex, especially its anterior division (aPCX), extends dense association fibers into the ventral striatum's olfactory tubercle (OT), yet whether this corticostriatal pathway is capable of shaping OT activity, including odor-evoked activity, is unknown. Further unresolved is the synaptic circuitry and the spatial localization of OT-innervating PCX neurons. Here we build upon standing literature to provide some answers to these questions through studies in mice of both sexes. First, we recorded the activity of OT neurons in awake mice while optically stimulating principal neurons in the aPCX and/or their association fibers in the OT while the mice were delivered odors. This uncovered evidence that PCX input indeed influences OT unit activity. We then used patch-clamp recordings and viral tracing to determine the connectivity of aPCX neurons upon OT neurons expressing dopamine receptor types D1 or D2, two prominent cell populations in the OT. These investigations uncovered that both populations of neurons receive monosynaptic inputs from aPCX glutamatergic neurons. Interestingly, this input originates largely from the ventrocaudal aPCX. These results shed light on some of the basic physiological properties of this pathway and the cell-types involved and provide a foundation for future studies to identify, among other things, whether this pathway has implications for perception. Sensory cortices interact to process stimuli in manners considered essential for perception. Very little is known regarding interactions between olfactory cortices. The present study sheds light on some of the basic physiological properties of a particular intercortical pathway in the olfactory system and provides a foundation for future studies to identify, among other things, whether this pathway has implications for perception.
Topics: Animals; Female; Glutamic Acid; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Odorants; Olfactory Receptor Neurons; Olfactory Tubercle; Piriform Cortex; Receptors, Dopamine D1; Receptors, Dopamine D2; Smell
PubMed: 31628176
DOI: 10.1523/JNEUROSCI.1444-19.2019 -
Journal of Neurology, Neurosurgery, and... Oct 1984
Topics: Aged; Alzheimer Disease; Choline O-Acetyltransferase; Down Syndrome; Female; Humans; Huntington Disease; Male; Middle Aged; Olfactory Bulb
PubMed: 6239011
DOI: 10.1136/jnnp.47.10.1138-a -
Brain, Behavior and Evolution 197713 of 17 cats which received unilateral olfactory tubercle lesions exhibited contralateral sensory inattention and ipsilateral circling and hyperresponsiveness. The...
13 of 17 cats which received unilateral olfactory tubercle lesions exhibited contralateral sensory inattention and ipsilateral circling and hyperresponsiveness. The possible neural substrates involved in these asymmetries are discussed, including ascending amine systems and ascending and descending connections with the orbital cortex.
Topics: Animals; Behavior, Animal; Cats; Electric Stimulation; Electrodes, Implanted; Female; Frontal Lobe; Olfactory Bulb; Time Factors
PubMed: 871899
DOI: 10.1159/000125664 -
Brain Research Mar 1983Behavioral recovery and cortical reinnervation after early olfactory tract section were assessed in the infant golden hamster (Mesocricetus auratus). Hamster pups show...
Behavioral recovery and cortical reinnervation after early olfactory tract section were assessed in the infant golden hamster (Mesocricetus auratus). Hamster pups show strong thermotaxis at birth which declines abruptly after postnatal day (P) 8 in normal pups. Unilateral olfactory bulbectomy on P5 causes persistent thermotaxis through the second postnatal week. In this study, the bulb's output pathway, the lateral olfactory tract, was unilaterally severed on P5 and pup thermotaxis was tested through P15. Complete tract section, like bulbectomy, prolonged thermal responding beyond P8. In contrast to bulbectomy, however, some tract-sectioned pups showed recovery before P15 while others continued to show persistent thermotaxis throughout testing. The olfactory bulb projection was examined 10 days after tract section in order to determine whether recovery and persistent thermotaxis were associated with different patterns of cortical innervation. Eleven pups with complete transections showed recovery during the second week. In 10 of these pups, olfactory bulb fibers had penetrated the damaged region after surgery to reinnervate the olfactory tubercle. Three of these pups also exhibited some reinnervation of piriform cortex. The lesions of pups showing persistent thermotaxis were more severe, extending bilaterally or into deep cortical layers, and olfactory fibers had failed to reinnervate caudal terminal fields. All pups with olfactory tract sections showed extensive sprouting rostral to the cut, regardless of their behavioral profile. In no case had postlesion growth innervated the entorhinal or amygdaloid areas. Inhibition of thermotaxis was associated with reinnervation of the olfactory tubercle rather than more rostral, lateral or caudal olfactory cortex. We conclude that regrowth of olfactory tract fibers caudal to early transection is rapid and has functional consequences for early behavioral development.
Topics: Animals; Animals, Newborn; Body Temperature Regulation; Brain Mapping; Central Nervous System; Cricetinae; Dominance, Cerebral; Mesocricetus; Nerve Regeneration; Neuronal Plasticity; Olfactory Bulb; Olfactory Pathways; Orientation; Smell; Synaptic Transmission
PubMed: 6299477
DOI: 10.1016/0165-3806(83)90078-0 -
Frontiers in Neural Circuits 2017The medial part of the olfactory tubercle (OT) is a brain structure located at the interface of the reward and olfactory system. It is closely related to...
The medial part of the olfactory tubercle (OT) is a brain structure located at the interface of the reward and olfactory system. It is closely related to pheromone-rewards, natural reinforcement, addiction and many other behaviors. However, the structure of the anatomic circuitry of the medial part of the OT is still unclear. In the present study, the medial part of the OT was found to be highly connected with a wide range of brain areas with the help of the pseudorabies virus tracing tool. In order to further investigate the detailed connections for specific neurons, another tracing tool - rabies virus was utilized for D1R-cre and D2R-cre mice. The D1R and D2R neurons in the medial part of the OT were both preferentially innervated by the olfactory areas, especially the piriform cortex, and both had similar direct input patterns. With the help of the adeno-associated virus labeling, it was found that the two subpopulations of neurons primarily innervate with the reward related brain regions, with slightly less axons projecting to the olfactory areas. Thus, the whole-brain input and output circuitry structures for specific types of neurons in the medial part of the OT were systematically investigated, and the results revealed many unique connecting features. This work could provide new insights for further study into the physiological functions of the medial part of the OT.
Topics: Animals; Male; Mice, Inbred C57BL; Mice, Transgenic; Microscopy, Confocal; Neuroanatomical Tract-Tracing Techniques; Neurons; Olfactory Pathways; Olfactory Tubercle; Receptors, Dopamine D1; Receptors, Dopamine D2
PubMed: 28804450
DOI: 10.3389/fncir.2017.00052 -
Otolaryngology--head and Neck Surgery :... Feb 1987The projection between the ventral tegmental area (VTA) and the olfactory tubercle (OT) was examined electrophysiologically in the rat. Stimulation of the olfactory bulb...
The projection between the ventral tegmental area (VTA) and the olfactory tubercle (OT) was examined electrophysiologically in the rat. Stimulation of the olfactory bulb (OB) determined if the OT neurons were olfactory-related. Ipsilateral VTA stimulation produced a change in neuronal activity in 77% of the neurons tested, with 41% being inhibited, 24% excited, and 12% had mixed response. Contralateral VTA stimulation produced changes in only 38%. Intravenous administration of haloperidol was used in examination of the role of dopamine in this neural connection. The results suggest that the VTA-induced inhibitory response on OT neurons is mediated by dopamine, whereas excitatory responses are not. The VTA inhibitory influence projects primarily to olfactory-related neurons, since 60% of olfactory-related OT neurons were inhibited--as compared to 34% of non-olfactory-related neurons. This study documents electrophysiologically the VTA-OT connection and suggests that the dopaminergic input may modulate olfactory information projected to the OT from the OB. It also supports the concept that the OT acts as an integration center in central olfactory processing.
Topics: Animals; Dopamine; Electric Stimulation; Electrophysiology; Haloperidol; Neurons; Olfactory Bulb; Rats; Rats, Inbred Strains; Tegmentum Mesencephali
PubMed: 3120089
DOI: 10.1177/019459988709600207 -
Experimental Neurology Jul 2019Traumatic brain injury (TBI) affects at least 3 M people annually. In humans, repetitive mild TBI (rmTBI) can lead to increased impulsivity and may be associated with...
Repetitive closed-head impact model of engineered rotational acceleration (CHIMERA) injury in rats increases impulsivity, decreases dopaminergic innervation in the olfactory tubercle and generates white matter inflammation, tau phosphorylation and degeneration.
Traumatic brain injury (TBI) affects at least 3 M people annually. In humans, repetitive mild TBI (rmTBI) can lead to increased impulsivity and may be associated with chronic traumatic encephalopathy. To better understand the relationship between repetitive TBI (rTBI), impulsivity and neuropathology, we used CHIMERA (Closed-Head Injury Model of Engineered Rotational Acceleration) to deliver five TBIs to rats, which were continuously assessed for trait impulsivity using the delay discounting task and for neuropathology at endpoint. Compared to sham controls, rats with rTBI displayed progressive impairment in impulsive choice. Histological analyses revealed reduced dopaminergic innervation from the ventral tegmental area to the olfactory tubercle, consistent with altered impulsivity neurocircuitry. Consistent with diffuse axonal injury generated by CHIMERA, white matter inflammation, tau immunoreactivity and degeneration were observed in the optic tract and corpus callosum. Finally, pronounced grey matter microgliosis was observed in the olfactory tubercle. Our results provide insight into the mechanisms by which rTBI leads to post-traumatic psychiatric-like symptoms in a novel rat TBI platform.
Topics: Animals; Axons; Choice Behavior; Corpus Callosum; Disease Models, Animal; Dopaminergic Neurons; Gliosis; Head Injuries, Closed; Inflammation; Male; Neurodegenerative Diseases; Olfactory Tubercle; Phosphorylation; Rats; Rats, Long-Evans; Reward; Tauopathies; White Matter; tau Proteins
PubMed: 30822421
DOI: 10.1016/j.expneurol.2019.02.012 -
Cells, Tissues, Organs 2002The mammalian primary olfactory system consists of a set of different telencephalic structures, including paleo-, archi-, periarchi- and mesocortical components. We...
The mammalian primary olfactory system consists of a set of different telencephalic structures, including paleo-, archi-, periarchi- and mesocortical components. We present the first characterisation of the normal and connectional anatomy of the primary olfactory cortex of the common marmoset, a microsmatic simian species increasingly used in primate research. The centrifugal and centripetal bulbar projections were determined by injections of the anterograde and retrograde tracer wheat germ agglutinin-conjugated horseradish peroxidase and fluorescent dyes into the ipsilateral main olfactory bulb. The efferent projections of the marmoset bulb are organised entirely ipsilaterally and are established via a rudimentary medial olfactory tract and the dominant lateral olfactory tract. Target areas are the anterior olfactory nucleus, the entire prepiriform cortex, ventral tenia tecta, periamygdaloid cortex and the rostral part of the entorhinal cortex. The bulbar axons predominantly terminate in the outer part of layer I. The anterior olfactory nucleus receives a weak additional input within layer II and III, which is not found in macrosmatic rodents. Further anterograde labelling was found in the endopiriform nucleus deep under the prepiriform cortex and within an anterolateral strip of the olfactory tubercle. However, control injections into the olfactory tubercle suggest that the marmoset olfactory tubercle receives a bisynaptic olfactory input only. Retrograde labelling after bulb injections revealed that, except for the olfactory tubercle, all primary olfactory cortices contributed to an ipsilateral bulbopetal feedback projection. Like in rodents, the only bulbopetal projection organised bilaterally in the marmoset is maintained by the anterior olfactory nucleus. With few exceptions, the projections of the marmoset olfactory brain are organised similarly to that of the macaque monkey or those of macrosmatic species.
Topics: Animals; Axons; Brain Mapping; Callithrix; Entorhinal Cortex; Female; Functional Laterality; Male; Olfactory Bulb; Olfactory Pathways; Smell; Synaptic Transmission; Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
PubMed: 12364829
DOI: 10.1159/000064386 -
The Journal of Comparative Neurology Jan 1993The retinal projection to the basal telencephalon was studied in eight species of primates from the suborders Strepsirhini and Haplorhini, including one anthropoid...
The retinal projection to the basal telencephalon was studied in eight species of primates from the suborders Strepsirhini and Haplorhini, including one anthropoid primate, the gibbon. Animals received an intraocular injection of tritiated amino acids and the distribution of retinal fibers and terminals was demonstrated by autoradiographic techniques in horizontal and coronal sections. In all species a discrete group of labeled retinal fibers is observed to branch off from the dorsolateral aspect of the optic tract at the level of the suprachiasmatic nucleus. These fibers, destined to the basal telencephalon, are topographically distinct from the retinal fibers which innervate the suprachiasmatic nucleus and medial hypothalamic regions. The fibers of the retinotelencephalic tract course dorsally above the supraoptic nucleus through the lateral hypothalamic area and then proceed further rostrally and laterally below the diagonal band of Broca towards the olfactory tubercle. Within the olfactory tubercle, terminal distribution of label is observed in the mediocaudal region along the granular cell layer II. In the macaque this cellular layer shows a characteristic thickening in the region of retinal terminals which is evident in both coronal and horizontal section. In some species this labeled region is seen within the superficial bulge of the tubercle on the ventral aspect of basal telencephalon. In all primates the retinal projection to olfactory tubercle is bilateral. In prosimians label is predominantly contralateral to the injected eye, in New World monkeys label is equally distributed on both sides of the brain and in Old World monkeys label is mainly found ipsilaterally. Retinal fibers were also seen in the periamygdaloid region but never extended as far as piriform cortex. These results, in addition to previous studies in other mammalian orders, confirm that the basal telencephalon, and in particular the olfactory tubercle, constitutes a region of visual and olfactory convergence. This sensory integration may be related to photic and chemosensory modulation of reproductive physiology and behavior.
Topics: Animals; Autoradiography; Macaca; Nerve Endings; Nerve Fibers; Neural Pathways; Olfactory Bulb; Primates; Retina; Telencephalon; Visual Pathways
PubMed: 8425942
DOI: 10.1002/cne.903270204