Neuroarchitecture of the central complex in the brain of the honeybee: Neuronal cell types

The brain is assembled during development by both innate and experience-dependent mechanisms1-7, but the relative contribution of these factors is poorly understood. Axons of retinal ganglion cells (RGCs) connect the eye to the brain, forming a bottleneck for the transmission of visual information to central visual areas. RGCs secrete molecules from their axons that control proliferation, differentiation and migration of downstream components7-9. Spontaneously generated waves of retinal activity, but also intense visual stimulation, can entrain responses of RGCs10 and central neurons11-16. Here we asked how the cellular composition of central targets is altered in a vertebrate brain that is depleted of retinal input throughout development. For this, we first established a molecular catalog17 and gene expression atlas18 of neuronal subpopulations in the retinorecipient areas of larval zebrafish. We then searched for changes in lakritz (atoh7-) mutants, in which RGCs do not form19. Although individual forebrain-expressed genes are dysregulated in lakritz mutants, the complete set of 77 putative neuronal cell types in thalamus, pretectum and tectum are present. While neurogenesis and differentiation trajectories are overall unaltered, a greater proportion of cells remain in an uncommitted progenitor stage in the mutant. Optogenetic stimulation of a pretectal area20,21 evokes a visual behavior in blind mutants indistinguishable from wildtype. Our analysis shows that, in this vertebrate visual system, neurons are produced more slowly, but specified and wired up in a proper configuration in the absence of any retinal signals.

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Neuronal apoptosis: signal and cell diversity

Colombia Medica ◽

10.25100/cm.v40i1.634 ◽

1969 ◽

Vol 40 (1) ◽

pp. 124-133

Author(s):

Lina Vanessa Becerra ◽

Hernán José Pimienta

Keyword(s):

Cell Death ◽

Programmed Cell Death ◽

Neuronal Response ◽

Neuronal Cell ◽

Cell Types ◽

Point Of View ◽

Trophic Factors ◽

Cell Diversity ◽

Apoptotic Pathways ◽

The Brain

Programmed cell death occurs as a physiological process during development. In the brain and spinal cord this event determines the number and location of the different cell types. In adulthood, programmed cell death or apoptosis is more restricted but it may play a major role in different acute and chronic pathological entities. However, in contrast to other tissues where apoptosis has been widely documented from a morphological point of view, in the central nervous system complete anatomical evidence of apoptosis is scanty. In spite of this there is consensus about the activation of different signal systems associated to programmed cell death. In the present article we attempt to summarize the main apoptotic pathways so far identified in nervous tissue. Considering that apoptotic pathways are multiple, the neuronal cell types are highly diverse and specialized and that neuronal response to injury and survival depends upon tissue context, (i.e., preservation of connectivity, glial integrity and cell matrix, blood supply and trophic factors availability) what is relevant for the apoptotic process in a sector of the brain may not be important in another.

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6B4 proteoglycan/phosphacan is a repulsive substratum but promotes morphological differentiation of cortical neurons

Development ◽

10.1242/dev.122.2.647 ◽

1996 ◽

Vol 122 (2) ◽

pp. 647-658

Author(s):

N. Maeda ◽

M. Noda

Keyword(s):

Cell Adhesion ◽

Neurite Outgrowth ◽

Cortical Neurons ◽

Tyrosine Phosphatase ◽

Neuronal Cell ◽

Morphological Differentiation ◽

Cell Types ◽

Thalamic Neurons ◽

Neurite Extension ◽

The Brain

6B4 proteoglycan/phosphacan is one of the major phosphate-buffered saline-soluble chondroitin sulfate proteoglycans of the brain. Recently, this molecule has been demonstrated to be an extracellular variant of the proteoglycan-type protein tyrosine phosphatase, PTPzeta (RPTPbeta). The influence of the 6B4 proteoglycan, adsorbed onto the substratum, on cell adhesion and neurite outgrowth was studied using dissociated neurons from the cerebral cortex and thalamus. 6B4 proteoglycan adsorbed onto plastic tissue culture dishes did not support neuronal cell adhesion, but rather exerted repulsive effects on cortical and thalamic neurons. When neurons were densely seeded on patterned substrata consisting of a grid-like structure of alternating poly-L-lysine and 6B4 proteoglycan-coated poly-L-lysine domains, they were concentrated on the poly-L-lysine domains. However, 6B4 proteoglycan did not retard the differentiation of neurons but rather promoted neurite outgrowth and development of the dendrites of cortical neurons, when neurons were sparsely seeded on poly-L-lysine-conditioned coverslips continuously coated with 6B4 proteoglycan. This effect of 6B4 proteoglycan on the neurite extension of cortical neurons was apparent even on coverslips co-coated with fibronectin or tenascin. By contrast, the neurite extension of thalamic neurons was not modified by 6B4 proteoglycan. Chondroitinase ABC or keratanase digestion of 6B4 proteoglycan did not affect its neurite outgrowth promoting activity, but a polyclonal antibody against 6B4 proteoglycan completely suppressed this activity, suggesting that a protein moiety is responsible for the activity. 6B4 proteoglycan transiently promoted tyrosine phosphorylation of an 85x10(3) Mr protein in the cortical neurons, which correlated with the induction of neurite outgrowth. These results suggest that 6B4 proteoglycan/phosphacan modulates morphogenesis and differentiation of neurons dependent on its spatiotemporal distribution and the cell types in the brain.

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Form and Function in Cells of the Brain

The Neuron ◽

10.1093/med/9780199773893.003.0002 ◽

2015 ◽

pp. 23-38

Author(s):

Irwin B. Levitan ◽

Leonard K. Kaczmarek

Keyword(s):

Axonal Transport ◽

Molecular Motors ◽

Critical Role ◽

Neuronal Cell ◽

Cell Types ◽

Neuronal Cell Body ◽

Long Distance ◽

Form And Function ◽

And Function ◽

The Brain

This chapter examines unique mechanisms that the neuron has evolved to establish and maintain the form required for its specialized signaling functions. Unlike some other organs, the brain contains a variety of cell types including several classes of glial cells, which play a critical role in the formation of the myelin sheath around axons and may be involved in immune responses, synaptic transmission, and long-distance calcium signaling in the brain. Neurons share many features in common with other cells (including glia), but they are distinguished by their highly asymmetrical shapes. The neuronal cytoskeleton is essential for establishing this cell shape during development and for maintaining it in adulthood. The process of axonal transport moves vesicles and other organelles to regions remote from the neuronal cell body. Proteins such as kinesin and dynein, called molecular motors, make use of the energy released by hydrolysis of ATP to drive axonal transport.

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Reconstruction of 1,000 projection neurons reveals new cell types and organization of long-range connectivity in the mouse brain

10.1101/537233 ◽

2019 ◽

Cited By ~ 4

Author(s):

Johan Winnubst ◽

Erhan Bas ◽

Tiago A. Ferreira ◽

Zhuhao Wu ◽

Michael N. Economo ◽

...

Keyword(s):

Long Range ◽

Mouse Brain ◽

Neuronal Cell ◽

Cell Types ◽

Neuronal Morphology ◽

Projection Neurons ◽

Axonal Arbor ◽

Flow Of Information ◽

Organizational Principles ◽

The Brain

SummaryNeuronal cell types are the nodes of neural circuits that determine the flow of information within the brain. Neuronal morphology, especially the shape of the axonal arbor, provides an essential descriptor of cell type and reveals how individual neurons route their output across the brain. Despite the importance of morphology, few projection neurons in the mouse brain have been reconstructed in their entirety. Here we present a robust and efficient platform for imaging and reconstructing complete neuronal morphologies, including axonal arbors that span substantial portions of the brain. We used this platform to reconstruct more than 1,000 projection neurons in the motor cortex, thalamus, subiculum, and hypothalamus. Together, the reconstructed neurons comprise more than 75 meters of axonal length and are available in a searchable online database. Axonal shapes revealed previously unknown subtypes of projection neurons and suggest organizational principles of long-range connectivity.

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