Development of laminar organization in the mushroom bodies of the cockroach: Kenyon cell proliferation, outgrowth, and maturation

2001 ◽  
Vol 439 (3) ◽  
pp. 331-351 ◽  
Author(s):  
Sarah M. Farris ◽  
Nicholas J. Strausfeld
Keyword(s):  
Cell Proliferation ◽  
Mushroom Bodies ◽  
Kenyon Cell ◽  
Laminar Organization

scholarly journals Flexible neural connectivity under constraints on total connection strength

2019 ◽  
Author(s):  
Gabriel Koch Ocker ◽  
Michael A. Buice
Keyword(s):  
Neural Circuits ◽  
Neural Circuit ◽  
Synaptic Weight ◽  
Null Model ◽  
Mushroom Bodies ◽  
Random Structure ◽  
Connection Strength ◽  
Kenyon Cell ◽  
Physiological Constraints ◽  
Bayesian Model Comparison

AbstractNeural computation is determined by neuron dynamics and circuit connectivity. Uncertain and dynamic environments may require neural hardware to adapt to different computational tasks, each requiring different connectivity configurations. At the same time, connectivity is subject to a variety of constraints, placing limits on the possible computations a given neural circuit can perform. Here we examine the hypothesis that the organization of neural circuitry favors computational flexibility: that it makes many computational solutions available, given physiological constraints. From this hypothesis, we develop models of the degree distributions of connectivity based on constraints on a neuron’s total synaptic weight. To test these models, we examine reconstructions of the mushroom bodies from the first instar larva and the adult Drosophila melanogaster. We perform a Bayesian model comparison for two constraint models and a random wiring null model. Overall, we find that flexibility under a homeostatically fixed total synaptic weight describes Kenyon cell connectivity better than other models, suggesting a principle shaping the apparently random structure of Kenyon cell wiring. Furthermore, we find evidence that larval Kenyon cells are more flexible earlier in development, suggesting a mechanism whereby neural circuits begin as flexible systems that develop into specialized computational circuits.Author summaryHigh-throughput electron microscopic anatomical experiments have begun to yield detailed maps of neural circuit connectivity. Uncovering the principles that govern these circuit structures is a major challenge for systems neuroscience. Healthy neural circuits must be able to perform computational tasks while satisfying physiological constraints. Those constraints can restrict a neuron’s possible connectivity, and thus potentially restrict its computation. Here we examine simple models of constraints on total synaptic weights, and calculate the number of circuit configurations they allow: their computational flexibility. We propose probabilistic models of connectivity that weight the number of synaptic partners according to computational flexibility under a constraint and test them using recent wiring diagrams from a learning center, the mushroom body, in the fly brain. We compare constraints that fix or bound a neuron’s total connection strength to a simple random wiring null model. Of these models, the fixed total connection strength matched the overall connectivity best in mushroom bodies from both larval and adult flies. We also provide evidence suggesting that neural circuits are more flexible in early stages of development and lose this flexibility as they grow towards specialized function.

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 Mushroom Bodies Suppress Locomotor Activity in Drosophila melanogaster

1998 ◽  
Vol 5 (1) ◽  
pp. 179-191 ◽  
Author(s):  
Jean-René Martin ◽  
Roman Ernst ◽  
Martin Heisenberg
Keyword(s):  
Locomotor Activity ◽  
Mushroom Body ◽  
Mushroom Bodies ◽  
Kenyon Cell ◽  
Noninvasive Methods ◽  
Rest Periods ◽  
Walking Activity ◽  
Targeted Expression ◽  
The Time Domain

Locomotor activity of single, freely walking flies in small tubes is analyzed in the time domain of several hours. To assess the influence of the mushroom bodies on walking activity, three independent noninvasive methods interfering with mushroom body function are applied: chemical ablation of the mushroom body precursor cells; a mutant affecting Kenyon cell differentiation (mushroom body miniature1); and the targeted expression of the catalytic subunit of tetanus toxin in subsets of Kenyon cells. All groups of flies with mushroom body defects show an elevated level of total walking activity. This increase is attributable to the slower and less complete attenuation of activity during the experiment. Walking activity in normal and mushroom body-deficient flies is clustered in active phases (bouts) and rest periods (pauses). Neither the initiation nor the internal structure, but solely the termination of bouts seems to be affected by the mushroom body defects. How this finding relates to the well-documented role of the mushroom bodies in olfactory learning and memory remains to be understood.

Fibroblasts During Hypertrophic Scar Formation and Resolution

1973 ◽  
Vol 31 ◽  
pp. 428-429
Author(s):  
C. W. Kischer
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Proliferation ◽  
Fine Structure ◽  
Metabolic Activity ◽  
Hypertrophic Scar ◽  
Normal Skin ◽  
Ground Substance ◽  
Hypertrophic Scars ◽  
Scanning Electron

The morphology of the fibroblasts changes markedly as the healing period from burn wounds progresses, through development of the hypertrophic scar, to resolution of the scar by a self-limiting process of maturation or therapeutic resolution. In addition, hypertrophic scars contain an increased cell proliferation largely made up of fibroblasts. This tremendous population of fibroblasts seems congruous with the abundance of collagen and ground substance. The fine structure of these cells should reflect some aspects of the metabolic activity necessary for production of the scar, and might presage the stage of maturation.A comparison of the fine structure of the fibroblasts from normal skin, different scar types, and granulation tissue has been made by transmission (TEM) and scanning electron microscopy (SEM).

The Effect of Androgen Depletion and Replacement on the Epithelium of the Seminal Vesicle of the Aging Rat

1975 ◽  
Vol 33 ◽  
pp. 590-591
Author(s):  
Venita F. Allison
Keyword(s):  
Cell Proliferation ◽  
Seminal Vesicle ◽  
Male Rats ◽  
Target Cells ◽  
Cell Regeneration ◽  
Secretory Function ◽  
Electron Microscopic ◽  
Aging Rat ◽  
Microscopic Studies ◽  
Androgen Depletion

In 1930, Moore, Hughes and Gallager reported that after castration seminal vesicle epithelial cell atrophy occurred and that cell regeneration could be achieved with daily injections of testis extract. Electron microscopic studies have confirmed those observations and have shown that testosterone injections restore the epithelium of the seminal vesicle in adult castrated male rats. Studies concerned with the metabolism of androgens point out that dihydrotestosterone stimulates cell proliferation and that other metabolites of testosterone probably influence secretory function in certain target cells.Although the influence of androgens on adult seminal vesicle epithelial cytology is well documented, little is known of the effect of androgen depletion and replacement on those cells in aging animals. The present study is concerned with the effect of castration and testosterone injection on the epithelium of the seminal vesicle of aging rats.

Acetaminophen: Macula densa hypersecretory activity by induced hepatotoxicity

1987 ◽  
Vol 45 ◽  
pp. 934-935
Author(s):  
S.S. Poolsawat ◽  
C.A. Huerta ◽  
S.TY. Lae ◽  
G.A. Miranda
Keyword(s):  
Cell Proliferation ◽  
Liver Function ◽  
Chronic Inflammation ◽  
Foam Cell ◽  
Term Effect ◽  
Short Term ◽  
Drug Induced ◽  
Experimental Induction ◽  
Tissue Alterations ◽  
Toxic Responses

Introduction. Experimental induction of altered histology by chemical toxins is of particular importance if its outcome resembles histopathological phenomena. Hepatotoxic drugs and chemicals are agents that can be converted by the liver into various metabolites which consequently evoke toxic responses. Very often, these drugs are intentionally administered to resolve an illness unrelated to liver function. Because of hepatic detoxification, the resulting metabolites are suggested to be integrated into the macromolecular processes of liver function and cause an array of cellular and tissue alterations, such as increased cytoplasmic lysis, centrilobular and localized necroses, chronic inflammation and “foam cell” proliferation of the hepatic sinusoids (1-4).Most experimentally drug-induced toxicity studies have concentrated primarily on the hepatic response, frequently overlooking other physiological phenomena which are directly related to liver function. Categorically, many studies have been short-term effect investigations which seldom have followed up the complications to other tissues and organs when the liver has failed to function normally.

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