Passive Dendritic Trees

1998 ◽  
Author(s):  
Christof Koch
Keyword(s):  
Nervous System ◽  
Morphological Structure ◽  
Pyramidal Cells ◽  
Quantitative Relationship ◽  
Cell Types ◽  
Dendritic Morphology ◽  
Granule Cell Layer ◽  
Dendritic Trees ◽  
A Cell ◽  
The Brain

The previous chapter dealt with the solution of the cable equation in response to current pulses and steps within a single unbranched cable. However, real nerve cells possess highly branched and extended dendritic trees with quite distinct morphologies. Figure 3.1 illustrates the fantastic variety of dendritic trees found throughout the animal kingdom, ranging from neurons in the locust to human brain cells and cells from many different parts of the nervous system. Some of these cells are spatially compact, such as retinal amacrine cells, which are barely one-fifth of a millimeter across, while some cells have immense dendritic trees, such as α motoneurones in the spinal cord extending across several millimeters. Yet, in all cases, neurons are very tightly packed: in vertebrates, peak density appears to be reached in the granule cell layer of the human cerebellum with around 5 million cells per cubic millimeter (Braitenberg and Atwood, 1958) while the packing density of the cells filling the 0.25 mm3 nervous system of the housefly Musca domestica is around 1.2 million cells per cubic millimeter (Strausfeld, 1976). The dendritic arbor of some cell types encompasses a spherical volume, such as for thalamic relay cells, while other cells, such as the cerebellar Purkinje cell, fill a thin slablike volume with a width less than one-tenth of their extent. Different cell types do not appear at random in the brain but are unique to specific parts of the brain. By far the majority of excitatory cells in the cortex are the pyramidal cells. Yet even within this class, considerable diversity exists. But why this diversity of shapes? To what extent do these quite distinct dendritic architectures reflect differences in their roles in information processing and computation? What influence does the dendritic morphology have on the electrical properties of the cell, or, in other words, what is the relationship between the morphological structure of a cell and its electrical function? One of the few cases where a quantitative relationship between form and some aspect of neuronal function has been established is the retinal neurons.

scholarly journals Beyond the GFAP-Astrocyte Protein Markers in the Brain

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1361
Author(s):  
Agnieszka M. Jurga ◽  
Martyna Paleczna ◽  
Justyna Kadluczka ◽  
Katarzyna Z. Kuter
Keyword(s):  
Nervous System ◽  
Experimental Studies ◽  
Structural Diversity ◽  
Cell Types ◽  
Cellular Interactions ◽  
Quick Response ◽  
Protein Markers ◽  
Marker Proteins ◽  
Functional Efficiency ◽  
The Brain

The idea of central nervous system as one-man band favoring neurons is long gone. Now we all are aware that neurons and neuroglia are team players and constant communication between those various cell types is essential to maintain functional efficiency and a quick response to danger. Here, we summarize and discuss known and new markers of astroglial multiple functions, their natural heterogeneity, cellular interactions, aging and disease-induced dysfunctions. This review is focused on newly reported facts regarding astrocytes, which are beyond the old stereotypes. We present an up-to-date list of marker proteins used to identify a broad spectrum of astroglial phenotypes related to the various physiological and pathological nervous system conditions. The aim of this review is to help choose markers that are well-tailored for specific needs of further experimental studies, precisely recognizing differential glial phenotypes, or for diagnostic purposes. We hope it will help to categorize the functional and structural diversity of the astroglial population and ease a clear readout of future experimental results.

Spalt modifies EGFR-mediated induction of chordotonal precursors in the embryonic PNS of Drosophila promoting the development of oenocytes

Development ◽  
2001 ◽  
Vol 128 (5) ◽  
pp. 711-722 ◽  
Author(s):  
T.E. Rusten ◽  
R. Cantera ◽  
J. Urban ◽  
G. Technau ◽  
F.C. Kafatos ◽  
...  
Keyword(s):  
Nervous System ◽  
Cell Fate ◽  
System Development ◽  
Cell Types ◽  
Nervous System Development ◽  
Dual Function ◽  
Evolutionarily Conserved ◽  
A Cell ◽  
And Migration

Genes of the spalt family encode nuclear zinc finger proteins. In Drosophila melanogaster, they are necessary for the establishment of head/trunk identity, correct tracheal migration and patterning of the wing imaginal disc. Spalt proteins display a predominant pattern of expression in the nervous system, not only in Drosophila but also in species of fish, mouse, frog and human, suggesting an evolutionarily conserved role for these proteins in nervous system development. Here we show that Spalt works as a cell fate switch between two EGFR-induced cell types, the oenocytes and the precursors of the pentascolopodial organ in the embryonic peripheral nervous system. We show that removal of spalt increases the number of scolopodia, as a result of extra secondary recruitment of precursor cells at the expense of the oenocytes. In addition, the absence of spalt causes defects in the normal migration of the pentascolopodial organ. The dual function of spalt in the development of this organ, recruitment of precursors and migration, is reminiscent of its role in tracheal formation and of the role of a spalt homologue, sem-4, in the Caenorhabditis elegans nervous system.

Synaptic Interactions in a Passive Dendritic Tree

1998 ◽  
Author(s):  
Christof Koch
Keyword(s):  
Nervous System ◽  
Dendritic Tree ◽  
Extreme Case ◽  
Pyramidal Cells ◽  
Inhibitory Synapses ◽  
Dendritic Trees ◽  
Central Processing ◽  
Voltage Dependent ◽  
Dendritic Spikes ◽  
Spatial Positioning

Nerve cells are the targets of many thousands of excitatory and inhibitory synapses. An extreme case are the Purkinje cells in the primate cerebellum, which receive between one and two hundred thousand synapses onto dendritic spines from an equal number of parallel fibers (Braitenberg and Atwood, 1958; Llinas and Walton, 1998). In fact, this structure has a crystalline-like quality to it, with each parallel fiber making exactly one synapse onto a spine of a Purkinje cell. For neocortical pyramidal cells, the total number of afferent synapses is about an order of magnitude lower (Larkman, 1991). These numbers need to be compared against the connectivity in the central processing unit (CPU) of modern computers, where the gate of a typical transistor usually receives input from one, two, or three other transistors or connects to one, two, or three other transistor gates. The large number of synapses converging onto a single cell provide the nervous system with a rich substratum for implementing a very large class of linear and nonlinear neuronal operations. As we discussed in the introductory chapter, it is only these latter ones, such as multiplication or a threshold operation, which are responsible for “computing” in the nontrivial sense of information processing. It therefore becomes crucial to study the nature of the interaction among two or more synaptic inputs located in the dendritic tree. Here, we restrict ourselves to passive dendritic trees, that is, to dendrites that do not contain voltage-dependent membrane conductances. While such an assumption seemed reasonable 20 or even 10 years ago, we now know that the dendritic trees of many, if not most, cells contain significant nonlinearities, including the ability to generate fast or slow all-or-none electrical events, so-called dendritic spikes. Indeed, truly passive dendrites may be the exception rather than the rule in the nervous In Sec. 1.5, we studied this interaction for the membrane patch model. With the addition of the dendritic tree, the nervous system has many more degrees of freedom to make use of, and the strength of the interaction depends on the relative spatial positioning, as we will see now. That this can be put to good use by the nervous system is shown by the following experimental observation and simple model.

scholarly journals Electrophysiological Diversity of Layer 5 Pyramidal Cells in the Prefrontal Cortex of the Rhesus Monkey: In Vitro Slice Studies

2007 ◽  
Vol 98 (5) ◽  
pp. 2622-2632 ◽  
Author(s):  
Yu-Ming Chang ◽  
Jennifer I. Luebke
Keyword(s):  
Prefrontal Cortex ◽  
Rhesus Monkey ◽  
Spike Train ◽  
Pyramidal Cells ◽  
Cell Types ◽  
Dendritic Morphology ◽  
Firing Patterns ◽  
Electrophysiological Properties ◽  
Whole Cell Patch Clamp

Whole cell patch-clamp recordings were employed to characterize the electrophysiological properties of layer 5 pyramidal cells in slices of the prefrontal cortex (Area 46) of the rhesus monkey. Four electrophysiologically distinct cell types were discriminated based on distinctive repetitive action potential (AP) firing patterns and single AP characteristics: regular-spiking slowly adapting type-1 cells (RS1; 62%), regular-spiking slowly adapting type-2 cells (RS2; 18%), regular-spiking fast-adapting cells (FA; 15%), and intrinsically bursting cells (IB; 5%). These cells did not differ with regard to their location in layer 5 nor in their dendritic morphology. In RS1 cells, AP threshold and amplitude did not change significantly during a 2-s spike train, whereas in RS2 and FA cells, AP threshold increased significantly and AP amplitude decreased significantly during the train. In FA cells, complete adaptation of AP firing was observed within 600 ms. IB cells displayed an all-or-none burst of three to six APs, followed by RS1-type firing behavior. RS1 cells could be further subdivided into three subtypes. Low-threshold spiking (LTS) RS1 cells exhibited an initial doublet riding on a depolarizing potential at the onset of a spike train and a prominent depolarizing afterpotential (DAP); intermediate RS1 cells (IM) exhibited a DAP, but no initial doublet, and non-LTS RS1 cells exhibited neither a DAP nor an initial doublet. RS2 and FA cells did not exhibit a DAP or initial doublets. The distinctive firing patterns of these diverse layer 5 pyramidal cells may reflect different roles played by these cells in the mediation of subcortical neuronal activity by the dorsolateral PFC.

scholarly journals Neuronal expression of STM2 mRNA in human brain is reduced in Alzheimer's disease.

1996 ◽  
Vol 44 (11) ◽  
pp. 1215-1222 ◽  
Author(s):  
P J McMillan ◽  
J B Leverenz ◽  
P Poorkaj ◽  
G D Schellenberg ◽  
D M Dorsa
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Human Brain ◽  
Basal Forebrain ◽  
Cell Types ◽  
Hybridization Histochemistry ◽  
In Situ Hybridization Histochemistry ◽  
A Cell ◽  
The Brain

Mutations in the STM2 gene cause familial Alzheimer's disease (AD) in Volga Germans. To understand the function of this protein and how mutations lead to AD, it is important to determine which cell types in the brain express this gene. In situ hybridization histochemistry indicates that STM2 expression in the human brain is widespread and is primarily neuronal. In addition, STM2 mRNA is expressed in a cell line with neuronal origins. Quantification of the level of expression of the STM2 message in the basal forebrain, frontal cortex, and hippocampus reveals a significant decrease in AD-affected subjects compared to normal age-matched controls. These data suggest that downregulation of neuronal STM2 gene expression may be involved in the progression of AD.

scholarly journals On the role of the extracellular space on the holistic behavior of the brain

2015 ◽  
Vol 26 (5) ◽  
pp. 489-506 ◽  
Author(s):  
Manuela Marcoli ◽  
Luigi F. Agnati ◽  
Francesco Benedetti ◽  
Susanna Genedani ◽  
Diego Guidolin ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Extracellular Matrix ◽  
Nervous System ◽  
Cellular Networks ◽  
Intercellular Communication ◽  
Extracellular Space ◽  
Cell Types ◽  
Molecular Network ◽  
The Central Nervous System ◽  
The Brain

AbstractMultiple players are involved in the brain integrative action besides the classical neuronal and astrocyte networks. In the past, the concept of complex cellular networks has been introduced to indicate that all the cell types in the brain can play roles in its integrative action. Intercellular communication in the complex cellular networks depends not only on well-delimited communication channels (wiring transmission) but also on diffusion of signals in physically poorly delimited extracellular space pathways (volume transmission). Thus, the extracellular space and the extracellular matrix are the main players in the intercellular communication modes in the brain. Hence, the extracellular matrix is an ‘intelligent glue’ that fills the brain and, together with the extracellular space, contributes to the building-up of the complex cellular networks. In addition, the extracellular matrix is part of what has been defined as the global molecular network enmeshing the entire central nervous system, and plays important roles in synaptic contact homeostasis and plasticity. From these premises, a concept is introduced that the global molecular network, by enmeshing the central nervous system, contributes to the brain holistic behavior. Furthermore, it is suggested that plastic ‘brain compartments’ can be detected in the central nervous system based on the astrocyte three-dimensional tiling of the brain volume and on the existence of local differences in cell types and extracellular space fluid and extracellular matrix composition. The relevance of the present view for neuropsychiatry is discussed. A glossary box with terms and definitions is provided.

scholarly journals Cerebral Apolipoprotein D Exits the Brain and Accumulates in Peripheral Tissues

2021 ◽  
Vol 22 (8) ◽  
pp. 4118
Author(s):  
Frederik Desmarais ◽  
Vincent Hervé ◽  
Karl F. Bergeron ◽  
Gaétan Ravaut ◽  
Morgane Perrotte ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Cell Types ◽  
Strongly Correlated ◽  
Peripheral Tissues ◽  
Additional Cell ◽  
The Central Nervous System ◽  
Apolipoprotein D ◽  
Pass Through ◽  
The Brain

Apolipoprotein D (ApoD) is a secreted lipocalin associated with neuroprotection and lipid metabolism. In rodent, the bulk of its expression occurs in the central nervous system. Despite this, ApoD has profound effects in peripheral tissues, indicating that neural ApoD may reach peripheral organs. We endeavor to determine if cerebral ApoD can reach the circulation and accumulate in peripheral tissues. Three hours was necessary for over 40% of all the radiolabeled human ApoD (hApoD), injected bilaterally, to exit the central nervous system (CNS). Once in circulation, hApoD accumulates mostly in the kidneys/urine, liver, and muscles. Accumulation specificity of hApoD in these tissues was strongly correlated with the expression of lowly glycosylated basigin (BSG, CD147). hApoD was observed to pass through bEnd.3 blood brain barrier endothelial cells monolayers. However, cyclophilin A did not impact hApoD internalization rates in bEnd.3, indicating that ApoD exit from the brain is either independent of BSG or relies on additional cell types. Overall, our data showed that ApoD can quickly and efficiently exit the CNS and reach the liver and kidneys/urine, organs linked to the recycling and excretion of lipids and toxins. This indicated that cerebral overexpression during neurodegenerative episodes may serve to evacuate neurotoxic ApoD ligands from the CNS.

scholarly journals Plectin in the Central Nervous System and a Putative Role in Brain Astrocytes

Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2353
Author(s):  
Maja Potokar ◽  
Jernej Jorgačevski
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Current Knowledge ◽  
Cell Types ◽  
Cellular Proteins ◽  
Bidirectional Communication ◽  
The Central Nervous System ◽  
Brain And Spinal Cord ◽  
The Brain

Plectin, a high-molecular-mass cytolinker, is abundantly expressed in the central nervous system (CNS). Currently, a limited amount of data about plectin in the CNS prevents us from seeing the complete picture of how plectin affects the functioning of the CNS as a whole. Yet, by analogy to its role in other tissues, it is anticipated that, in the CNS, plectin also functions as the key cytoskeleton interlinking molecule. Thus, it is likely involved in signalling processes, thereby affecting numerous fundamental functions in the brain and spinal cord. Versatile direct and indirect interactions of plectin with cytoskeletal filaments and enzymes in the cells of the CNS in normal physiological and in pathologic conditions remain to be fully addressed. Several pathologies of the CNS related to plectin have been discovered in patients with plectinopathies. However, in view of plectin as an integrator of a cohesive mesh of cellular proteins, it is important that the role of plectin is also considered in other CNS pathologies. This review summarizes the current knowledge of plectin in the CNS, focusing on plectin isoforms that have been detected in the CNS, along with its expression profile and distribution alongside diverse cytoskeleton filaments in CNS cell types. Considering that the bidirectional communication between neurons and glial cells, especially astrocytes, is crucial for proper functioning of the CNS, we place particular emphasis on the known roles of plectin in neurons, and we propose possible roles of plectin in astrocytes.

scholarly journals Deciphering how specialized interneuron-specific cell types contribute to circuit function

2020 ◽  
Author(s):  
Alexandre Guet-McCreight ◽  
Frances K Skinner
Keyword(s):  
Computational Models ◽  
Brain Area ◽  
Pyramidal Cells ◽  
Cell Types ◽  
Specific Cell ◽  
Cell Type ◽  
Inhibitory Cell ◽  
Cell Firing ◽  
The Brain

AbstractThe wide diversity of inhibitory cells across the brain makes them fit to contribute to network dynamics in specialized fashions. However, the contributions of a particular inhibitory cell type in a behaving animal is challenging to decipher as one needs to both record cellular activities and identify the cell type being recorded. Thus, using computational modeling to explore cell-specific contributions so as to predict and hypothesize functional contributions is desirable. Here we examine potential contributions of interneuron-specific 3 (I-S3) cells - a type of inhibitory interneuron found in CA1 hippocampus that only targets other inhibitory interneurons - during simulated theta rhythms. We use previously developed multi-compartment models of oriens lacunosum-moleculare (OLM) cells, the main target of I-S3 cells, and explore how I-S3 cell inputs during in vitro and in vivo scenarios contribute to theta. We find that I-S3 cells suppress OLM cell spiking, rather than engender its spiking via post-inhibitory rebound mechanisms. To elicit recruitment similar to experiment, the inclusion of disinhibited pyramidal cell inputs is necessary, suggesting that I-S3 cell firing can broaden the window for disinhibiting pyramidal cells. Using in vivo virtual networks, we show that I-S3 cells can contribute to a sharpening of OLM cell recruitment at theta frequencies. Further, a shifting of the timing of I-S3 cell spiking due to external modulation can shift the timing of the OLM cell firing and thus disinhibitory windows. We thus propose a specialized contribution of I-S3 cells to create temporally precise coordination of modulation pathways.Significance StatementHow information is processed across different brain structures is an important question that relates to the different functions that the brain performs. In this work we use computational models that focus on a particular inhibitory cell type that only inhibits other inhibitory cell types – the I-S3 cell in the hippocampus. We show that this cell type is able to broaden the window for disinhibition of excitatory cells. We further illustrate that this broadening presents itself as a mechanism for input pathway switching and modulation over the timing of inhibitory cell spiking. Overall, this work contributes to our knowledge of how coordination between sensory and memory consolidation information is attained in a brain area that is involved in memory formation.

Computation of motion direction in the vertebrate retina

e-Neuroforum ◽  
2012 ◽  
Vol 18 (3) ◽  
Author(s):  
T. Euler ◽  
S.E. Hausselt
Keyword(s):  
Large Scale ◽  
Petri Dish ◽  
Cell Types ◽  
Direction Selectivity ◽  
Dendritic Morphology ◽  
Image Motion ◽  
Target Area ◽  
Motion Direction ◽  
Preferred Direction ◽  
The Brain

AbstractHow direction of image motion is detected as early as at the level of the vertebrate eye has been intensively studied in retina research. Although the first direction-selective (DS) ret­inal ganglion cells were already described in the 1960s and have since then been in the fo­cus of many studies, scientists are still puz­zled by the intricacy of the neuronal circuits and computational mechanisms underlying retinal direction selectivity. The fact that the retina can be easily isolated and studied in a Petri dish-by presenting light stimuli while recording from the various cell types in the retinal circuits-in combination with the ex­tensive anatomical, molecular and physiolog­ical knowledge about this part of the brain presents a unique opportunity for studying this intriguing visual circuit in detail. This ar­ticle provides a brief overview of the histo­ry of research on retinal direction selectivi­ty, but then focuses on the past decade and the progress achieved, in particular driven by methodological advances in optical record­ing techniques, molecular genetics approach­es and large-scale ultrastructural reconstruc­tions. As it turns out, retinal direction selec­tivity is a complex, multi-tiered computation, involving dendrite-intrinsic mechanisms as well as several types of network interactions on the basis of highly selective, likely genet­ically predetermined synaptic connectivi­ty. Moreover, DS ganglion cell types appear to be more diverse than previously thought, differing not only in their preferred direction and response polarity, but also in physiology, DS mechanism, dendritic morphology and, importantly, the target area of their projec­tions in the brain.

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