GABAergic synapses in the antennal lobe and mushroom body of the locust olfactory system

1996 ◽  
Vol 372 (4) ◽  
pp. 487-514 ◽  
Author(s):  
Beulah Leitch ◽  
Gilles Laurent
Keyword(s):  
Olfactory System ◽  
Mushroom Body ◽  
Antennal Lobe ◽  
Gabaergic Synapses

scholarly journals Information flow, cell types and stereotypy in a full olfactory connectome

2020 ◽  
Author(s):  
Philipp Schlegel ◽  
Alexander Shakeel Bates ◽  
Tomke Stürner ◽  
Sridhar R. Jagannathan ◽  
Nikolas Drummond ◽  
...  
Keyword(s):  
Information Flow ◽  
Olfactory System ◽  
Mushroom Body ◽  
Antennal Lobe ◽  
Large Scale ◽  
Cell Types ◽  
Neuronal Morphology ◽  
Striking Similarity ◽  
Data Set ◽  
Lateral Horn

AbstractThe hemibrain connectome (Scheffer et al., 2020) provides large scale connectivity and morphology information for the majority of the central brain of Drosophila melanogaster. Using this data set, we provide a complete description of the most complex olfactory system studied at synaptic resolution to date, covering all first, second and third-order neurons of the olfactory system associated with the antennal lobe and lateral horn (mushroom body neurons are described in a parallel paper, (Li et al., 2020)). We develop a generally applicable strategy to extract information flow and layered organisation from synaptic resolution connectome graphs, mapping olfactory input to descending interneurons. This identifies a range of motifs including highly lateralised circuits in the antennal lobe and patterns of convergence downstream of the mushroom body and lateral horn. We also leverage a second data set (FAFB, (Zheng et al., 2018)) to provide a first quantitative assessment of inter- versus intra-individual stereotypy. Complete reconstruction of select developmental lineages in two brains (three brain hemispheres) reveals striking similarity in neuronal morphology across brains for >170 cell types. Within and across brains, connectivity correlates with morphology. Notably, neurons of the same morphological type show similar connection variability within one brain as across brains; this property should enable a rigorous quantitative approach to cell typing.

scholarly journals Structural and Functional Plasticity in the Regenerating Olfactory System of the Migratory Locust

2020 ◽  
Vol 11 ◽  
Author(s):  
Gerd Bicker ◽  
Michael Stern
Keyword(s):  
Olfactory Receptor ◽  
Olfactory System ◽  
Mushroom Body ◽  
Antennal Lobe ◽  
Second Order ◽  
Neural Regeneration ◽  
Current Evidence ◽  
Olfactory Pathway ◽  
Nerve Crush ◽  
Migratory Locust

Regeneration after injury is accompanied by transient and lasting changes in the neuroarchitecture of the nervous system and, thus, a form of structural plasticity. In this review, we introduce the olfactory pathway of a particular insect as a convenient model to visualize neural regeneration at an anatomical level and study functional recovery at an electrophysiological level. The olfactory pathway of the locust (Locusta migratoria) is characterized by a multiglomerular innervation of the antennal lobe by olfactory receptor neurons. These olfactory afferents were axotomized by crushing the base of the antenna. The resulting degeneration and regeneration in the antennal lobe could be quantified by size measurements, dye labeling, and immunofluorescence staining of cell surface proteins implicated in axonal guidance during development. Within 3 days post lesion, the antennal lobe volume was reduced by 30% and from then onward regained size back to normal by 2 weeks post injury. The majority of regenerating olfactory receptor axons reinnervated the glomeruli of the antennal lobe. A few regenerating axons project erroneously into the mushroom body on a pathway that is normally chosen by second-order projection neurons. Based on intracellular responses of antennal lobe output neurons to odor stimulation, regenerated fibers establish functional synapses again. Following complete absence after nerve crush, responses to odor stimuli return to control level within 10–14 days. On average, regeneration of afferents, and re-established synaptic connections appear faster in younger fifth instar nymphs than in adults. The initial degeneration of olfactory receptor axons has a trans-synaptic effect on a second order brain center, leading to a transient size reduction of the mushroom body calyx. Odor-evoked oscillating field potentials, absent after nerve crush, were restored in the calyx, indicative of regenerative processes in the network architecture. We conclude that axonal regeneration in the locust olfactory system appears to be possible, precise, and fast, opening an avenue for future mechanistic studies. As a perspective of biomedical importance, the current evidence for nitric oxide/cGMP signaling as positive regulator of axon regeneration in connectives of the ventral nerve cord is considered in light of particular regeneration studies in vertebrate central nervous systems.

scholarly journals Characterization of the olfactory system in Apis dorsata, an Asian honey bee

2018 ◽  
Author(s):  
Sandhya Mogily ◽  
Meenakshi VijayKumar ◽  
Sunil Kumar Sethy ◽  
Joby Joseph
Keyword(s):  
Apis Mellifera ◽  
Learning And Memory ◽  
Honey Bee ◽  
Olfactory System ◽  
Mushroom Body ◽  
Antennal Lobe ◽  
Equivalent Model ◽  
Memory Retention ◽  
Apis Dorsata ◽  
Lateral Protocerebrum

AbstractThe European honeybee, Apis mellifera is the most common insect model system for studying learning and memory. We establish that the olfactory system of Apis dorsata, an Asian species of honeybee as an equivalent model to Apis mellifera to study physiology underlying learning and memory. We created an Atlas of the antennal lobe and counted the number of glomeruli in the antennal lobe of Apis dorsata to be around 165 which is similar to the number in the other honey bee species Apis mellifera and Apis florea. Apis dorsata was found to have five antenno-cerebral tracts namely mACT, lACT and 3 mlACTS which appear identical to Apis mellifera. Intracellular recording showed that the antennal lobe interneurons exhibit temporally patterned odor-cell specific responses. The neuritis of Kenyon cells with cell bodies located in a neighborhood in calyx retain their relative neighborhoods in the peduncle and alpha lobe forming a columnar organization in the mushroom body. Alpha lobe and the calyx of the mushroom body were innervated by extrinsic neurons with cell bodies in the lateral protocerebrum. A set of GABA positive cells in the lateral protocerebrum send their neurites towards alpha-lobe. Apis dorsata was amenable to olfactory conditioning and showed good learning and memory retention at 24 hours. They were amenable to massed and spaced conditioning and could distinguish trained odor from an untrained novel odor.

scholarly journals Avoidance response to CO2 in the lateral horn

2018 ◽  
Author(s):  
Nélia Varela ◽  
Miguel Gaspar ◽  
Sophie Dias ◽  
Maria Luísa Vasconcelos
Keyword(s):  
Calcium Imaging ◽  
Mushroom Body ◽  
Antennal Lobe ◽  
Functional Role ◽  
Direct Evidence ◽  
Physiological Responses ◽  
Lateral Horn ◽  
The One ◽  
The Brain

ABSTRACTIn flies, the olfactory information is carried from the first relay in the brain, the antennal lobe, to the mushroom body (MB) and the lateral horn (LH). Olfactory associations are formed in the MB. The LH was ascribed a role in innate responses based on the stereotyped connectivity with the antennal lobe, stereotyped physiological responses to odors and MB silencing experiments. Direct evidence for the functional role of the LH is still missing. Here we investigate the behavioral role of the LH neurons directly, using the CO2 response as a paradigm. Our results show the involvement of the LH in innate responses. Specifically, we demonstrate that activity in two sets of neurons is required for the full behavioral response to CO2. Using calcium imaging we observe that the two sets of neurons respond to CO2 in different manners. Using independent manipulation and recording of the two sets of neurons we find that the one that projects to the SIP also outputs to the local neurons within the LH. The design of simultaneous output at the LH and the SIP, an output of the MB, allows for coordination between innate and learned responses.

Olfactory Microcircuits in Drosophila Melanogaster

2017 ◽  
pp. 361-368
Author(s):  
Jürgen Rybak ◽  
Bill S. Hansson
Keyword(s):  
Drosophila Melanogaster ◽  
Sensory Neurons ◽  
Mushroom Body ◽  
Antennal Lobe ◽  
Odorant Receptor ◽  
Second Order ◽  
Projection Neurons ◽  
Order Processing ◽  
Vinegar Fly ◽  
Maxillary Palps

In the vinegar fly (Drosophila melanogaster), the neuronal pathway that processes olfactory information is organized into multiple layers: a peripheral set of olfactory sensory neurons (OSNs); the primary olfactory center, or antennal lobe (AL); and two second-order neuropils, the mushroom body (MB) and lateral horn (LH). Odorants are detected by the dendrites of OSNs housed in sensilla on the maxillary palps and antennae. The OSN axons converge onto spherical synaptic neuropil within the AL termed glomeruli. OSNs that express the same odorant receptor project to the same glomerulus in a one-to-one fashion, forming discrete olfactory pathways. In the AL, a network of local interneurons (LNs) and projection neurons (PNs) contribute to the first-order processing within the glomeruli. Two types of PNs constitute the principal, parallel output pathways made by PN axons that end in the second-order neuropils of the MB and LH: uniglomerular PNs (uPNs) and multiglomerular PNs (mPNs).

Targeting expression to projection neurons that innervate specific mushroom body calyx and antennal lobe glomeruli in larval Drosophila

2010 ◽  
Vol 10 (7-8) ◽  
pp. 328-337 ◽  
Author(s):  
Liria M. Masuda-Nakagawa ◽  
Takeshi Awasaki ◽  
Kei Ito ◽  
Cahir J. O’Kane
Keyword(s):  
Mushroom Body ◽  
Antennal Lobe ◽  
Projection Neurons ◽  
Mushroom Body Calyx

scholarly journals Distributed representation of social odors indicates parallel processing in the antennal lobe of ants

2011 ◽  
Vol 106 (5) ◽  
pp. 2437-2449 ◽  
Author(s):  
Andreas Simon Brandstaetter ◽  
Christoph Johannes Kleineidam
Keyword(s):  
Parallel Processing ◽  
Olfactory System ◽  
Antennal Lobe ◽  
Activity Patterns ◽  
Insect Brain ◽  
Camponotus Floridanus ◽  
Colony Odor ◽  
Spatial Activity ◽  
Neuronal Representation ◽  
Social Odors

In colonies of eusocial Hymenoptera cooperation is organized through social odors, and particularly ants rely on a sophisticated odor communication system. Neuronal information about odors is represented in spatial activity patterns in the primary olfactory neuropile of the insect brain, the antennal lobe (AL), which is analog to the vertebrate olfactory bulb. The olfactory system is characterized by neuroanatomical compartmentalization, yet the functional significance of this organization is unclear. Using two-photon calcium imaging, we investigated the neuronal representation of multicomponent colony odors, which the ants assess to discriminate friends (nestmates) from foes (nonnestmates). In the carpenter ant Camponotus floridanus, colony odors elicited spatial activity patterns distributed across different AL compartments. Activity patterns in response to nestmate and nonnestmate colony odors were overlapping. This was expected since both consist of the same components at differing ratios. Colony odors change over time and the nervous system has to constantly adjust for this (template reformation). Measured activity patterns were variable, and variability was higher in response to repeated nestmate than to repeated nonnestmate colony odor stimulation. Variable activity patterns may indicate neuronal plasticity within the olfactory system, which is necessary for template reformation. Our results indicate that information about colony odors is processed in parallel in different neuroanatomical compartments, using the computational power of the whole AL network. Parallel processing might be advantageous, allowing reliable discrimination of highly complex social odors.

scholarly journals Sparsening and Temporal Sharpening of Olfactory Representations in the Honeybee Mushroom Bodies

2005 ◽  
Vol 94 (5) ◽  
pp. 3303-3313 ◽  
Author(s):  
Paul Szyszka ◽  
Mathias Ditzen ◽  
Alexander Galkin ◽  
C. Giovanni Galizia ◽  
Randolf Menzel
Keyword(s):  
Mushroom Body ◽  
Antennal Lobe ◽  
Activity Patterns ◽  
Projection Neuron ◽  
Insect Brain ◽  
Projection Neurons ◽  
Similar Response ◽  
Kenyon Cell ◽  
Cell Responses ◽  
Kenyon Cells

We explored the transformations accompanying the transmission of odor information from the first-order processing area, the antennal lobe, to the mushroom body, a higher-order integration center in the insect brain. Using Ca2+ imaging, we recorded activity in the dendrites of the projection neurons that connect the antennal lobe with the mushroom body. Next, we recorded the presynaptic terminals of these projection neurons. Finally, we characterized their postsynaptic partners, the intrinsic neurons of the mushroom body, the clawed Kenyon cells. We found fundamental differences in odor coding between the antennal lobe and the mushroom body. Odors evoked combinatorial activity patterns at all three processing stages, but the spatial patterns became progressively sparser along this path. Projection neuron dendrites and boutons showed similar response profiles, but the boutons were more narrowly tuned to odors. The transmission from projection neuron boutons to Kenyon cells was accompanied by a further sparsening of the population code. Activated Kenyon cells were highly odor specific. Furthermore, the onset of Kenyon cell responses to projection neurons occurred within the first 200 ms and complex temporal patterns were transformed into brief phasic responses. Thus two types of transformations occurred within the MB: sparsening of a combinatorial code, mediated by pre- and postsynaptic processing within the mushroom body microcircuits, and temporal sharpening of postsynaptic Kenyon cell responses, probably involving a broader loop of inhibitory recurrent neurons.

scholarly journals Long-term enhancement of synaptic transmission between antennal lobe and mushroom body in culturedDrosophilabrain

2012 ◽  
Vol 591 (1) ◽  
pp. 287-302 ◽  
Author(s):  
Kohei Ueno ◽  
Shintaro Naganos ◽  
Yukinori Hirano ◽  
Junjiro Horiuchi ◽  
Minoru Saitoe
Keyword(s):  
Synaptic Transmission ◽  
Mushroom Body ◽  
Antennal Lobe

scholarly journals Circuit and cellular mechanisms facilitate the transformation from dense to sparse coding in the insect olfactory system

2017 ◽  
Author(s):  
Rinaldo Betkiewicz ◽  
Benjamin Lindner ◽  
Martin P. Nawrot
Keyword(s):  
Lateral Inhibition ◽  
Olfactory System ◽  
Mushroom Body ◽  
Stimulus Onset ◽  
Cellular Level ◽  
Neural Mechanisms ◽  
Testable Hypothesis ◽  
Cellular Mechanisms ◽  
Spatio Temporal ◽  
Spiking Model

AbstractTransformations between sensory representations are shaped by neural mechanisms at the cellular and the circuit level. In the insect olfactory system encoding of odor information undergoes a transition from a dense spatio-temporal population code in the antennal lobe to a sparse code in the mushroom body. However, the exact mechanisms shaping odor representations and their role in sensory processing are incompletely identified. Here, we investigate the transformation from dense to sparse odor representations in a spiking model of the insect olfactory system, focusing on two ubiquitous neural mechanisms: spike-frequency adaptation at the cellular level and lateral inhibition at the circuit level. We find that cellular adaptation is essential for sparse representations in time (temporal sparseness), while lateral inhibition regulates sparseness in the neuronal space (population sparseness). The interplay of both mechanisms shapes dynamical odor representations, which are optimized for discrimination of odors during stimulus onset and offset. In addition, we find that odor identity is stored on a prolonged time scale in the adaptation levels but not in the spiking activity of the principal cells of the mushroom body, providing a testable hypothesis for the location of the so-called odor trace.

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