scholarly journals Fine structure of mushroom bodies and the brain in Sthenelais boa (Phyllodocida, Annelida)

Zoomorphology ◽  
2021 ◽  
Author(s):  
Patrick Beckers ◽  
Carla Pein ◽  
Thomas Bartolomaeus
Keyword(s):  
Mushroom Body ◽  
Convergent Evolution ◽  
Small Diameter ◽  
Synaptic Activity ◽  
Mushroom Bodies ◽  
Glia Cells ◽  
Close Relationship ◽  
Body Design ◽  
Morphological Differences ◽  
The Brain

AbstractMushroom bodies are known from annelids and arthropods and were formerly assumed to argue for a close relationship of these two taxa. Since molecular phylogenies univocally show that both taxa belong to two different clades in the bilaterian tree, similarity must either result from convergent evolution or from transformation of an ancestral mushroom body. Any morphological differences in the ultrastructure and composition of mushroom bodies could thus indicate convergent evolution that results from similar functional constraints. We here study the ultrastructure of the mushroom bodies, the glomerular neuropil, glia-cells and the general anatomy of the nervous system in Sthenelais boa. The neuropil of the mushroom bodies is composed of densely packed, small diameter neurites that lack individual or clusterwise glia enwrapping. Neurites of other regions of the brain are much more prominent, are enwrapped by glia-cell processes and thus can be discriminated from the neuropil of the mushroom bodies. The same applies to the respective neuronal somata. The glomerular neuropil of insects and annelids is a region of higher synaptic activity that result in a spheroid appearance of these structures. However, while these structures are sharply delimited from the surrounding neuropil of the brain by glia enwrapping in insects, this is not the case in Sthenelais boa. Although superficially similar, there are anatomical differences in the arrangement of glia-cells in the mushroom bodies and the glomerular neuropil between insects and annelids. Hence, we suppose that the observed differences rather evolved convergently to solve similar functional constrains than by transforming an ancestral mushroom body design.

scholarly journals Drosophila mef2 is essential for normal mushroom body and wing development

2018 ◽  
Author(s):  
Jill R. Crittenden ◽  
Efthimios M. C. Skoulakis ◽  
Elliott. S. Goldstein ◽  
Ronald L. Davis
Keyword(s):  
Nuclear Localization ◽  
Mushroom Body ◽  
Normal Development ◽  
Cell Types ◽  
Mushroom Bodies ◽  
Wing Development ◽  
Myocyte Enhancer Factor 2 ◽  
Multiple Cell ◽  
The Brain ◽  
Enhancer Factor

ABSTRACTMEF2 (myocyte enhancer factor 2) transcription factors are found in the brain and muscle of insects and vertebrates and are essential for the differentiation of multiple cell types. We show that in the fruitfly Drosophila, MEF2 is essential for normal development of wing veins, and for mushroom body formation in the brain. In embryos mutant for D-mef2, there was a striking reduction in the number of mushroom body neurons and their axon bundles were not detectable. D-MEF2 expression coincided with the formation of embryonic mushroom bodies and, in larvae, expression onset was confirmed to be in post-mitotic neurons. With a D-mef2 point mutation that disrupts nuclear localization, we find that D-MEF2 is restricted to a subset of Kenyon cells that project to the α/β, and γ axonal lobes of the mushroom bodies, but not to those forming the α’/β’ lobes. Our findings that ancestral mef2 is specifically important in dopamine-receptive neurons has broad implications for its function in mammalian neurocircuits.

scholarly journals Brain composition in Heliconius butterflies, post-eclosion growth and experience dependent neuropil plasticity

2015 ◽  
Author(s):  
Stephen H Montgomery ◽  
Richard M Merrill ◽  
Swidbert R Ott
Keyword(s):  
Behavioral Ecology ◽  
Neural Development ◽  
Mushroom Body ◽  
Brain Regions ◽  
Mushroom Bodies ◽  
Heliconius Butterflies ◽  
Sensory Adaptations ◽  
Differential Expansion ◽  
The Brain

Behavioral and sensory adaptations are often based in the differential expansion of brain components. These volumetric differences represent changes in investment, processing capacity and/or connectivity, and can be used to investigate functional and evolutionary relationships between different brain regions, and between brain composition and behavioral ecology. Here, we describe the brain composition of two species of Heliconius butterflies, a long-standing study system for investigating ecological adaptation and speciation. We confirm a previous report of striking mushroom body expansion, and explore patterns of post-eclosion growth and experience-dependent plasticity in neural development. This analysis uncovers age- and experience-dependent post-emergence mushroom body growth comparable to that in foraging hymenoptera, but also identifies plasticity in several other neuropil. An interspecific analysis indicates that Heliconius display remarkable levels of investment in mushroom bodies for a lepidopteran, and indeed rank highly compared to other insects. Our analyses lay the foundation for future comparative and experimental analyses that will establish Heliconius as a useful case study in evolutionary neurobiology.

scholarly journals An insect-like mushroom body in a crustacean brain

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Gabriella Hannah Wolff ◽  
Hanne Halkinrud Thoen ◽  
Justin Marshall ◽  
Marcel E Sayre ◽  
Nicholas James Strausfeld
Keyword(s):  
Spatial Memory ◽  
Learning And Memory ◽  
Sensory Integration ◽  
Mushroom Body ◽  
Convergent Evolution ◽  
Visual Recognition ◽  
Common Ancestor ◽  
Mushroom Bodies ◽  
Morphological Criteria

Mushroom bodies are the iconic learning and memory centers of insects. No previously described crustacean possesses a mushroom body as defined by strict morphological criteria although crustacean centers called hemiellipsoid bodies, which serve functions in sensory integration, have been viewed as evolutionarily convergent with mushroom bodies. Here, using key identifiers to characterize neural arrangements, we demonstrate insect-like mushroom bodies in stomatopod crustaceans (mantis shrimps). More than any other crustacean taxon, mantis shrimps display sophisticated behaviors relating to predation, spatial memory, and visual recognition comparable to those of insects. However, neuroanatomy-based cladistics suggesting close phylogenetic proximity of insects and stomatopod crustaceans conflicts with genomic evidence showing hexapods closely related to simple crustaceans called remipedes. We discuss whether corresponding anatomical phenotypes described here reflect the cerebral morphology of a common ancestor of Pancrustacea or an extraordinary example of convergent evolution.

Age-dependent and task-related morphological changes in the brain and the mushroom bodies of the ant Camponotus floridanus

1996 ◽  
Vol 199 (9) ◽  
pp. 2011-2019
Author(s):  
W Gronenberg ◽  
S Heeren ◽  
B Hölldobler
Keyword(s):  
Mushroom Body ◽  
Brain Volume ◽  
Morphological Changes ◽  
Brain Morphology ◽  
Mushroom Bodies ◽  
Additional Increase ◽  
Camponotus Floridanus ◽  
Behavioural Activity ◽  
Age Dependent ◽  
The Brain

Based on a brief description of the general brain morphology of Camponotus floridanus, development of the brain is examined in ants of different ages (pupa to 10 months). During this period, brain volume increases by approximately 20 % while the antennal lobes and the mushroom body neuropile show a more substantial growth, almost doubling their volume. In addition to the age-dependent changes, the volume of the mushroom body neuropile also increases as a consequence of behavioural activity associated with brood care and foraging. Foraging activity may lead to a more than 50 % additional increase in mushroom body neuropile volume. It is unlikely that the growth of mushroom body neuropile results from cell proliferation because no neurogenesis could be observed in adult ant brains.

scholarly journals Early Development of Mushroom Bodies in the Brain of the Honeybee Apis mellifera as Revealed by BrdU Incorporation and Ablation Experiments

1998 ◽  
Vol 5 (1) ◽  
pp. 90-101 ◽  
Author(s):  
Dagmar Malun
Keyword(s):  
Stem Cells ◽  
Larval Stage ◽  
Mushroom Body ◽  
Brdu Incorporation ◽  
Homogeneous Distribution ◽  
Mushroom Bodies ◽  
Kenyon Cell ◽  
Cell Clusters ◽  
Stage 1 ◽  
The Brain

In the honeybee the mushroom bodies are prominent neuropil structures arranged as pairs in the dorsal protocerebrum of the brain. Each mushroom body is composed of a medial and a lateral subunit. To understand their development, the proliferation pattern of mushroom body intrinsic cells, the Kenyon cells, were examined during larval and pupal stages using the bromodeoxyuridine (BrdU) technique and chemical ablation with hydroxyurea.By larval stage 1, ∼40 neuroblasts are located in the periphery of the protocerebrum. Many of these stem cells divide asymmetrically to produce a chain of ganglion mother cells. Kenyon cell precursors underly a different proliferation pattern. With the beginning of larval stage 3, they are arranged in two large distinct cell clusters in each side of the brain. BrdU incorporation into newly synthesized DNA and its immunohistochemical detection show high mitotic activity in these cell clusters that lasts until mid-pupal stages. The uniform diameter of cells, the homogeneous distribution of BrdU-labeled nuclei, and the presence of equally dividing cells in these clusters indicate symmetrical cell divisions of Kenyon cell precursors.Hydroxyurea applied to stage 1 larvae caused the selective ablation of mushroom bodies. Within these animals a variety of defects were observed. In the majority of brains exhibiting mushroom body defects, either one mushroom body subunit on one or on both sides, or three or four subunits (e.g., complete mushroom body ablation) were missing. In contrast, partial ablation of mushroom body subunits resulting in small Kenyon cell clusters and peduncles was observed very rarely. These findings indicate that hydroxyurea applied during larval stage 1 selectively deletes Kenyon stem cells. The results also show that each mushroom body subunit originates from a very small number of stem cells and develops independently of its neighboring subunit.

scholarly journals Reward signaling in a recurrent circuit of dopaminergic neurons and Kenyon cells

2018 ◽  
Author(s):  
Radostina Lyutova ◽  
Maximilian Pfeuffer ◽  
Dennis Segebarth ◽  
Jens Habenstein ◽  
Mareike Selcho ◽  
...  
Keyword(s):  
Learning And Memory ◽  
Dopaminergic Neurons ◽  
Mushroom Body ◽  
Olfactory Learning ◽  
Mushroom Bodies ◽  
Neuronal Circuitry ◽  
Sustained Activity ◽  
Kenyon Cells ◽  
Reward Information ◽  
The Brain

1.AbstractDopaminergic neurons in the brain of theDrosophilalarva play a key role in mediating reward information to the mushroom bodies during appetitive olfactory learning and memory. Using optogenetic activation of Kenyon cells we provide evidence that a functional recurrent signaling loop exists between Kenyon cells and dopaminergic neurons of the primary protocerebral anterior (pPAM) cluster. An optogenetic activation of Kenyon cells paired with an odor is sufficient to induce appetitive memory, while a simultaneous impairment of the dopaminergic pPAM neurons abolishes memory expression. Thus, dopaminergic pPAM neurons mediate reward information to the Kenyon cells, but in turn receive feedback from Kenyon cells. We further show that the activation of recurrent signaling routes within mushroom body circuitry increases the persistence of an odor-sugar memory. Our results suggest that sustained activity in a neuronal circuitry is a conserved mechanism in insects and vertebrates to consolidate memories.

scholarly journals Olfactory Learning in Drosophila

Physiology ◽  
2010 ◽  
Vol 25 (6) ◽  
pp. 338-346 ◽  
Author(s):  
Germain U. Busto ◽  
Isaac Cervantes-Sandoval ◽  
Ronald L. Davis
Keyword(s):  
Dopaminergic Neurons ◽  
Mushroom Body ◽  
Sensory Information ◽  
Brain Regions ◽  
Olfactory Learning ◽  
Mushroom Bodies ◽  
Neural Pathways ◽  
Olfactory Information ◽  
Appetitive Stimuli ◽  
The Brain

Studies of olfactory learning in Drosophila have provided key insights into the brain mechanisms underlying learning and memory. One type of olfactory learning, olfactory classical conditioning, consists of learning the contingency between an odor with an aversive or appetitive stimulus. This conditioning requires the activity of molecules that can integrate the two types of sensory information, the odorant as the conditioned stimulus and the aversive or appetitive stimulus as the unconditioned stimulus, in brain regions where the neural pathways for the two stimuli intersect. Compelling data indicate that a particular form of adenylyl cyclase functions as a molecular integrator of the sensory information in the mushroom body neurons. The neuronal pathway carrying the olfactory information from the antennal lobes to the mushroom body is well described. Accumulating data now show that some dopaminergic neurons provide information about aversive stimuli and octopaminergic neurons about appetitive stimuli to the mushroom body neurons. Inhibitory inputs from the GABAergic system appear to gate olfactory information to the mushroom bodies and thus control the ability to learn about odors. Emerging data obtained by functional imaging procedures indicate that distinct memory traces form in different brain regions and correlate with different phases of memory. The results from these and other experiments also indicate that cross talk between mushroom bodies and several other brain regions is critical for memory formation.

Differences in the brain stem terminations of large- and small-diameter vestibular primary afferents

1995 ◽  
Vol 74 (3) ◽  
pp. 1362-1366 ◽  
Author(s):  
J. A. Huwe ◽  
E. H. Peterson
Keyword(s):  
Brain Stem ◽  
Large Diameter ◽  
Small Diameter ◽  
Movement Control ◽  
Three Dimensions ◽  
Significant Shift ◽  
Axon Diameter ◽  
Vestibular Complex ◽  
The Brain ◽  
Adjacent Brain

1. We visualized the central axons of 32 vestibular afferents from the posterior canal by extracellular application of horseradish peroxidase, reconstructed them in three dimensions, and quantified their morphology. Here we compare the descending limbs of central axons that differ in parent axon diameter. 2. The brain stem distribution of descending limb terminals (collaterals and associated varicosities) varies systematically with parent axon diameter. Large-diameter afferents concentrate their terminals in rostral regions of the medial/descending nuclei. As axon diameter decreases, there is a significant shift of terminal concentration toward the caudal vestibular complex and adjacent brain stem. 3. Rostral and caudal regions of the medial/descending nuclei have different labyrinthine, cerebellar, intrinsic, commissural, and spinal connections; they are believed to play different roles in head movement control. Our data help clarify the functions of large- and small-diameter afferents by showing that they contribute differentially to rostral and caudal vestibular complex.

scholarly journals Bystander Attenuation of Neuronal and Astrocyte Intercellular Communication by Murine Cytomegalovirus Infection of Glia

2007 ◽  
Vol 81 (13) ◽  
pp. 7286-7292 ◽  
Author(s):  
Winson S. C. Ho ◽  
Anthony N. van den Pol
Keyword(s):  
Intercellular Communication ◽  
Neuronal Development ◽  
Primary Cultures ◽  
Synaptic Activity ◽  
Murine Cytomegalovirus ◽  
Intercellular Signaling ◽  
Mcmv Infection ◽  
High Potassium ◽  
Infected Cells ◽  
The Brain

ABSTRACT Astrocytes are the first cells infected by murine cytomegalovirus (MCMV) in primary cultures of brain. These cells play key roles in intercellular signaling and neuronal development, and they modulate synaptic activity within the nervous system. Using ratiometric fura-2 digital calcium imaging of >8,000 neurons and glia, we found that MCMV-infected astrocytes showed an increase in intracellular basal calcium levels and an enhanced response to neuroactive substances, including glutamate and ATP, and to high potassium levels. Cultured neurons with no sign of MCMV infection showed attenuated synaptic signaling after infection of the underlying astrocyte substrate, and intercellular communication between astrocytes with no sign of infection was reduced by the presence of infected glia. These bystander effects would tend to cause further deterioration of cellular communication in the brain in addition to the problems caused by the loss of directly infected cells.

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