The mushroom bodies ofDrosophila melanogaster: An immunocytological and golgi study of Kenyon cell organization in the calyces and lobes

2003 ◽  
Vol 62 (2) ◽  
pp. 151-169 ◽  
Author(s):  
Nicholas J. Strausfeld ◽  
Irina Sinakevitch ◽  
Ilya Vilinsky
Keyword(s):  
Mushroom Bodies ◽  
Kenyon Cell ◽  
Golgi Study ◽  
Cell 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.

A Resorcinol-Formaldehyde Resin as an Embedding Material for Electron Microscopy of Membranes

1969 ◽  
Vol 27 ◽  
pp. 328-329 ◽  
Author(s):  
J. G. Robertson ◽  
D. F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Osmium Tetroxide ◽  
Neutral Lipids ◽  
Lipid Extraction ◽  
Water Soluble ◽  
Formaldehyde Resin ◽  
Electron Microscope Autoradiography ◽  
Resorcinol Formaldehyde ◽  
Major Disadvantage ◽  
Cell Organization

The extraction of lipids from tissues during fixation and embedding for electron microscopy is widely recognized as a source of possible artifact, especially at the membrane level of cell organization. Lipid extraction is also a major disadvantage in electron microscope autoradiography of radioactive lipids, as in studies of the uptake of radioactive fatty acids by intestinal slices. Retention of lipids by fixation with osmium tetroxide is generally limited to glycolipids, phospholipids and highly unsaturated neutral lipids. Saturated neutral lipids and sterols tend to be easily extracted by organic dehydrating reagents prior to embedding. Retention of the more saturated lipids in embedded tissue might be achieved by developing new cross-linking reagents, by the use of highly water soluble embedding materials or by working at very low temperatures.

Three-dimensional image analysis and visualization in confocal light microscopy

1993 ◽  
Vol 51 ◽  
pp. 158-159
Author(s):  
J. K. Samarabandu ◽  
R. Acharya ◽  
D. R. Pareddy ◽  
P. C. Cheng
Keyword(s):  
Depth Perception ◽  
Computer Graphic ◽  
Three Dimensional ◽  
Cellular Organization ◽  
Data Set ◽  
Computational Burden ◽  
Interactive Operation ◽  
Cell Organization ◽  
Confocal Images ◽  
3D Digitization

In the study of cell organization in a maize meristem, direct viewing of confocal optical sections in 3D (by means of 3D projection of the volumetric data set, Figure 1) becomes very difficult and confusing because of the large number of nucleus involved. Numerical description of the cellular organization (e.g. position, size and orientation of each structure) and computer graphic presentation are some of the solutions to effectively study the structure of such a complex system. An attempt at data-reduction by means of manually contouring cell nucleus in 3D was reported (Summers et al., 1990). Apart from being labour intensive, this 3D digitization technique suffers from the inaccuracies of manual 3D tracing related to the depth perception of the operator. However, it does demonstrate that reducing stack of confocal images to a 3D graphic representation helps to visualize and analyze complex tissues (Figure 2). This procedure also significantly reduce computational burden in an interactive operation.

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