Axon terminals with unusual vesicles in the brain of the polychaete, Ophryotrocha puerilis

1982 ◽  
Vol 226 (1) ◽  
Author(s):  
ClaudiaB. Grothe
Keyword(s):  
Axon Terminals ◽  
The Brain

scholarly journals Widespread inhibition, antagonism, and synergy in mouse olfactory sensory neurons in vivo

2019 ◽  
Author(s):  
Shigenori Inagaki ◽  
Ryo Iwata ◽  
Masakazu Iwamoto ◽  
Takeshi Imai
Keyword(s):  
Sensory Neurons ◽  
Calcium Imaging ◽  
Odorant Receptor ◽  
Sensory Information ◽  
Olfactory Sensory Neurons ◽  
Axon Terminals ◽  
Two Photon ◽  
Odor Mixtures ◽  
The Brain

SUMMARYSensory information is selectively or non-selectively inhibited and enhanced in the brain, but it remains unclear whether this occurs commonly at the peripheral stage. Here, we performed two-photon calcium imaging of mouse olfactory sensory neurons (OSNs) in vivo and found that odors produce not only excitatory but also inhibitory responses at their axon terminals. The inhibitory responses remained in mutant mice, in which all possible sources of presynaptic lateral inhibition were eliminated. Direct imaging of the olfactory epithelium revealed widespread inhibitory responses at OSN somata. The inhibition was in part due to inverse agonism toward the odorant receptor. We also found that responses to odor mixtures are often suppressed or enhanced in OSNs: Antagonism was dominant at higher odor concentrations, whereas synergy was more prominent at lower odor concentrations. Thus, odor responses are extensively tuned by inhibition, antagonism, and synergy, at the early peripheral stage, contributing to robust odor representations.

scholarly journals Functional dichotomy in spinal- vs prefrontal-projecting locus coeruleus modules splits descending noradrenergic analgesia from ascending aversion and anxiety in rats

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Stefan Hirschberg ◽  
Yong Li ◽  
Andrew Randall ◽  
Eric J Kremer ◽  
Anthony E Pickering
Keyword(s):  
Locus Coeruleus ◽  
Viral Vectors ◽  
Spontaneous Pain ◽  
Pain Model ◽  
Axon Terminals ◽  
Neuronal Populations ◽  
Functional Organisation ◽  
Neuropathic Pain Model ◽  
Brain And Spinal Cord ◽  
The Brain

The locus coeruleus (LC) projects throughout the brain and spinal cord and is the major source of central noradrenaline. It remains unclear whether the LC acts functionally as a single global effector or as discrete modules. Specifically, while spinal-projections from LC neurons can exert analgesic actions, it is not known whether they can act independently of ascending LC projections. Using viral vectors taken up at axon terminals, we expressed chemogenetic actuators selectively in LC neurons with spinal (LC:SC) or prefrontal cortex (LC:PFC) projections. Activation of the LC:SC module produced robust, lateralised anti-nociception while activation of LC:PFC produced aversion. In a neuropathic pain model, LC:SC activation reduced hind-limb sensitisation and induced conditioned place preference. By contrast, activation of LC:PFC exacerbated spontaneous pain, produced aversion and increased anxiety-like behaviour. This independent, contrasting modulation of pain-related behaviours mediated by distinct noradrenergic neuronal populations provides evidence for a modular functional organisation of the LC.

Protein products of the bacterial reporter gene are found within axon terminals in the brain of transgenic mice

1994 ◽  
Vol 168 (1-2) ◽  
pp. 76-80 ◽  
Author(s):  
Ryohachi Arai ◽  
Nobuyuki Karasawa ◽  
Shigeyuki Deura ◽  
Kazuto Kobayashi ◽  
Toshiharu Nagatsu ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Reporter Gene ◽  
Axon Terminals ◽  
The Brain

719 Transgene product is found within axon terminals in the brain of transgenic mice

1993 ◽  
Vol 18 ◽  
pp. S85
Author(s):  
Ryohachi Arai ◽  
Keiki Yamada ◽  
Tetsuya Fujii ◽  
Kazuto Kobayashi ◽  
Toshiharu Nagatsu ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Axon Terminals ◽  
The Brain

scholarly journals Serial synapse formation through filopodial competition for synaptic seeding factors

2018 ◽  
Author(s):  
M. Neset Özel ◽  
Abhishek Kulkarni ◽  
Amr Hasan ◽  
Josephine Brummer ◽  
Marian Moldenhauer ◽  
...  
Keyword(s):  
Synapse Formation ◽  
Growth Cones ◽  
Data Driven ◽  
Axon Pathfinding ◽  
Analysis Method ◽  
Formation Model ◽  
Axon Terminals ◽  
Winner Takes All ◽  
The Brain ◽  
Time Point

SummaryFollowing axon pathfinding, growth cones transition from stochastic filopodial exploration to the formation of a limited number of synapses. How the interplay of filopodia and synapse assembly ensures robust connectivity in the brain has remained a challenging problem. Here, we developed a new 4D analysis method for filopodial dynamics and a data-driven computational model of synapse formation for R7 photoreceptor axons in developing Drosophila brains. Our live data support a ‘serial synapse formation’ model, where at any time point only a single ‘synaptogenic’ filopodium suppresses the synaptic competence of other filopodia through competition for synaptic seeding factors. Loss of the synaptic seeding factors Syd-1 and Liprin-α leads to a loss of this suppression, filopodial destabilization and reduced synapse formation, which is sufficient to cause the destabilization of entire axon terminals. Our model provides a filopodial ‘winner-takes-all’ mechanism that ensures the formation of an appropriate number of synapses.

scholarly journals Appetite controlled by a cholecystokinin nucleus of the solitary tract to hypothalamus neurocircuit

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Giuseppe D'Agostino ◽  
David J Lyons ◽  
Claudia Cristiano ◽  
Luke K Burke ◽  
Joseph C Madara ◽  
...  
Keyword(s):  
Body Weight ◽  
Paraventricular Nucleus ◽  
Anterograde Tracing ◽  
Solitary Tract ◽  
Close Apposition ◽  
Axon Terminals ◽  
Melanocortin 4 Receptor ◽  
Positive Valence ◽  
The Brain ◽  
Chemical Mediators

The nucleus of the solitary tract (NTS) is a key gateway for meal-related signals entering the brain from the periphery. However, the chemical mediators crucial to this process have not been fully elucidated. We reveal that a subset of NTS neurons containing cholecystokinin (CCKNTS) is responsive to nutritional state and that their activation reduces appetite and body weight in mice. Cell-specific anterograde tracing revealed that CCKNTS neurons provide a distinctive innervation of the paraventricular nucleus of the hypothalamus (PVH), with fibers and varicosities in close apposition to a subset of melanocortin-4 receptor (MC4RPVH) cells, which are also responsive to CCK. Optogenetic activation of CCKNTS axon terminals within the PVH reveal the satiating function of CCKNTS neurons to be mediated by a CCKNTS→PVH pathway that also encodes positive valence. These data identify the functional significance of CCKNTS neurons and reveal a sufficient and discrete NTS to hypothalamus circuit controlling appetite.

scholarly journals Multisensory expectations shape olfactory input to the brain

2018 ◽  
Author(s):  
Lindsey A. Czarnecki ◽  
Andrew H. Moberly ◽  
Cynthia D. Fast ◽  
Daniel J. Turkel ◽  
John P. McGann
Keyword(s):  
Neurotransmitter Release ◽  
Sensory Input ◽  
Gaba Release ◽  
External World ◽  
Mammalian Brain ◽  
Axon Terminals ◽  
Sensory Modalities ◽  
Olfactory Input ◽  
The Brain ◽  
Interneuron Activity

SummaryThe mammalian brain interprets sensory input based on prior multisensory knowledge of the external world, but it is unknown how this knowledge influences neural processing in individual sensory modalities. We found that GABAergic periglomerular interneuron populations in the olfactory bulb endogenously respond not only to odors but also to visual, auditory, and somatosensory stimuli in waking (but not anesthetized) mice. When these stimuli predict future odors, they evoke enhanced interneuron activity during the time odor normally occurs. When expectations are violated by omitting an expected “warning tone” before an odor, odor presentation evokes a burst of interneuron activity. The resulting GABA release presynaptically suppresses neurotransmitter release from the axon terminals of olfactory sensory neurons, the cells that transduce odor in the nasal epithelium and communicate this information to the brain. Expectations, even those evoked by cues in other sensory modalities, can thus affect the very first neurons in the olfactory system.

scholarly journals Dopaminergic neurons establish a distinctive axonal arbor with a majority of non-synaptic terminals

2020 ◽  
Author(s):  
Charles Ducrot ◽  
Marie-Josée Bourque ◽  
Constantin V. L. Delmas ◽  
Anne-Sophie Racine ◽  
Dainelys Guadarrama Bello ◽  
...  
Keyword(s):  
Dopaminergic Neurons ◽  
Synapse Formation ◽  
Critical Role ◽  
Gabaergic Neurons ◽  
Dopamine Neurons ◽  
Target Cells ◽  
Axon Terminals ◽  
Synaptic Terminals ◽  
Axonal Arbor ◽  
The Brain

ABSTRACTChemical neurotransmission in the brain typically occurs through synapses, which are structurally and functionally defined as sites of close apposition between an axon terminal and a postsynaptic domain. Ultrastructural examinations of axon terminals established by monoamine neurons in the brain often failed to identify a similar tight pre- and postsynaptic coupling, giving rise to the concept of “diffuse” or “volume” transmission. Whether this results from intrinsic properties of such modulatory neurons remains undefined. Using an efficient co-culture model, we find that dopaminergic neurons establish an axonal arbor that is distinctive compared to glutamatergic or GABAergic neurons in both size and propensity of terminals to avoid direct contact with target neurons. Furthermore, while most dopaminergic varicosities express key proteins involved in exocytosis such as synaptotagmin 1, only ~20% of these are synaptic. The active zone protein bassoon was found to be enriched in a subset of dopaminergic terminals that are in proximity to a target cell. Irrespective of their structure, a majority of dopaminergic terminals were found to be active. Finally, we found that the presynaptic protein Nrxn-1αSS4- and the postsynaptic protein NL-1AB, two major components involved in excitatory synapse formation, play a critical role in the formation of synapses by dopamine neurons. Taken together, our findings support the idea that dopamine neurons in the brain are endowed with a distinctive developmental program that leads them to adopt a fundamentally different mode of connectivity, compared to glutamatergic and GABAergic neurons involved in fast point-to-point signaling.SIGNIFICANCE STATEMENTMidbrain dopamine (DA) neurons regulate circuits controlling movement, motivation, and learning. The axonal connectivity of DA neurons is intriguing due to its hyperdense nature, with a particularly large number of release sites, most of which not adopting a classical synaptic structure. In this study, we provide new evidence highlighting the unique ability of DA neurons to establish a large and heterogeneous axonal arbor with terminals that, in striking contrast with glutamate and GABA neurons, actively avoid contact with the target cells. The majority of synaptic and non-synaptic terminals express proteins for exocytosis and are active. Finally, our finding suggests that, NL-1A+B and Nrxn-1αSS4-, play a critical role in the formation of synapses by DA neurons.

scholarly journals Distribution and localization of phosphatidylinositol 5-phosphate, 4-kinase alpha and beta in the brain

2020 ◽  
Author(s):  
Evan K. Noch ◽  
Isaiah Yim ◽  
Teresa A. Milner ◽  
Lewis C. Cantley
Keyword(s):  
Second Messengers ◽  
Immunohistochemical Analysis ◽  
Synaptic Function ◽  
Synaptic Membrane ◽  
Human Brain Tissue ◽  
Neuronal Marker ◽  
Axon Terminals ◽  
The Brain

AbstractPhosphatidylinositol-4,5-bisphosphate (PI-4,5-P2) is critical for synaptic vesicle docking and fusion and generation of the second messengers, diacylglycerol and inositol-1,4,5-trisphosphate. PI-4,5-P2 can be generated by two families of kinases: type 1 phosphatidylinositol-4-phosphate 5-kinases, encoded by PIP5K1A, PIP5K1B and PIP5K1C, and type 2 phosphatidylinositol-5-phosphate 4-kinases, encoded by PIP4K2A, PIP4K2B, and PIP4K2C. While the roles of the type 1 enzymes in brain function have been extensively studied, the roles of the type 2 enzymes are poorly understood. Using selective antibodies validated by genetic deletion of pip4k2a or pip4k2b in mouse brain, we characterized the location of the enzymes, PI5P4Kα and PI5P4Kß, encoded by these genes. In mice, we demonstrate that PI5P4Kα is expressed in adulthood, whereas PI5P4Kß is expressed early in development. PI5P4Kα localizes to white matter tracts, especially the corpus callosum, and at a low level in neurons, while PI5P4Kß is expressed in neuronal populations, especially hippocampus and cortex. Dual labeling studies demonstrate that PI5P4Kα co-localizes with the oligodendrocyte marker, Olig2, whereas PI5P4Kß co-localizes with the neuronal marker, NeuN. Immunohistochemical subcellular distribution studies demonstrate that PI5P4Kα and PI5P4Kß are expressed in the early endosome system. Ultrastructural analysis demonstrates that both kinases are contained in axon terminals and dendritic spines adjacent to the synaptic membrane, which support a potential role in synaptic transmission. Immunohistochemical analysis of macaque and human brain tissue demonstrate a conserved pattern for PI5P4Kα and PI5P4Kß. These results highlight the diverse cell-autonomous expression of PI5P4Kα and PI5P4Kß and support further exploration into their role in synaptic function in the brain.

scholarly journals A Basal Ganglia Circuit Sufficient To Guide Birdsong Learning

2017 ◽  
Author(s):  
Lei Xiao ◽  
Gaurav Chattree ◽  
Francisco Garcia Oscos ◽  
Mou Cao ◽  
Matthew J. Wanat ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Basal Ganglia ◽  
Negative Reinforcement ◽  
Vocal Learning ◽  
Optical Excitation ◽  
Performance Outcomes ◽  
Axon Terminals ◽  
Area X ◽  
Candidate Performance ◽  
The Brain

SUMMARYLearning complex vocal behaviors, like speech and birdsong, is thought to rely on continued performance evaluation. Whether candidate performance evaluation circuits in the brain are sufficient to guide vocal learning is not known. Here, we test the sufficiency of VTA projections to the vocal basal ganglia (Area X) in singing zebra finches, a songbird species that learns to produce a complex and stereotyped multi-syllabic courtship song during development. We optogenetically manipulate VTA axon terminals in singing birds contingent on how the pitch of individual song syllables are naturally performed. We find that optical excitation and inhibition of VTA terminals have opponent effects on future performances of targeted song syllables and are each sufficient to reliably guide learned changes in song, consistent with positive and negative reinforcement of performance outcomes. These findings define a central role for reinforcement mechanisms in learning vocalizations and provide the first demonstration of minimal circuit elements for learning vocal behaviors.

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