scholarly journals Circuits and Synapses: Hypothesis, Observation, Controversy and Serendipity – An Opinion Piece

2021 ◽  
Vol 15 ◽  
Author(s):  
Alex M. Thomson
Keyword(s):  
Nervous System ◽  
Experimental Design ◽  
Experimental Approach ◽  
Neural Circuits ◽  
Neuronal Circuits ◽  
Opinion Piece ◽  
Important Progress

More than a century of dedicated research has resulted in what we now know, and what we think we know, about synapses and neural circuits. This piece asks to what extent some of the major advances – both theoretical and practical – have resulted from carefully considered theory, or experimental design: endeavors that aim to address a question, or to refute an existing hypothesis. It also, however, addresses the important part that serendipity and chance have played. There are cases where hypothesis driven research has resulted in important progress. There are also examples where a hypothesis, a model, or even an experimental approach – particularly one that seems to provide welcome simplification – has become so popular that it becomes dogma and stifles advance in other directions. The nervous system rejoices in complexity, which should neither be ignored, nor run from. The emergence of testable “rules” that can simplify our understanding of neuronal circuits has required the collection of large amounts of data that were difficult to obtain. And although those collecting these data have been criticized for not advancing hypotheses while they were “collecting butterflies,” the beauty of the butterflies always enticed us toward further exploration.

scholarly journals Neural Changes Underlying Rapid Fly Song Evolution

2017 ◽  
Author(s):  
Yun Ding ◽  
Joshua L. Lillvis ◽  
Jessica Cande ◽  
Gordon J. Berman ◽  
Benjamin J. Arthur ◽  
...  
Keyword(s):  
Nervous System ◽  
Drosophila Melanogaster ◽  
Experimental Approach ◽  
Neural Circuits ◽  
Neural Circuitry ◽  
Courtship Song ◽  
Neural Basis ◽  
Electrophysiological Properties ◽  
Song Types ◽  
Behavioural Diversity

AbstractThe neural basis for behavioural evolution is poorly understood. Functional comparisons of homologous neurons may reveal how neural circuitry contributes to behavioural evolution, but homologous neurons cannot be identified and manipulated in most taxa. Here, we compare the function of homologous courtship song neurons by exporting neurogenetic reagents that label identified neurons in Drosophila melanogaster to D. yakuba. We found a conserved role for a cluster of brain neurons that establish a persistent courtship state. In contrast, a descending neuron with conserved electrophysiological properties drives different song types in each species. Our results suggest that song evolved, in part, due to changes in the neural circuitry downstream of this descending neuron. This experimental approach can be generalized to other neural circuits and therefore provides an experimental framework for studying how the nervous system has evolved to generate behavioural diversity.

scholarly journals Neurons interact with the microbiome: an evolutionary-informed perspective

Neuroforum ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Christoph Giez ◽  
Alexander Klimovich ◽  
Thomas C. G. Bosch
Keyword(s):  
Nervous System ◽  
Neural Circuits ◽  
Current Knowledge ◽  
System Development ◽  
Nervous System Development ◽  
Comprehensive Understanding ◽  
Strategic Model ◽  
Microbe Interactions ◽  
Host Microbe Interactions ◽  
And Function

Abstract Animals have evolved within the framework of microbes and are constantly exposed to diverse microbiota. Microbes colonize most, if not all, animal epithelia and influence the activity of many organs, including the nervous system. Therefore, any consideration on nervous system development and function in the absence of the recognition of microbes will be incomplete. Here, we review the current knowledge on the nervous systems of Hydra and its role in the host–microbiome communication. We show that recent advances in molecular and imaging methods are allowing a comprehensive understanding of the capacity of such a seemingly simple nervous system in the context of the metaorganism. We propose that the development, function and evolution of neural circuits must be considered in the context of host–microbe interactions and present Hydra as a strategic model system with great basic and translational relevance for neuroscience.

Transfer of Habituation Shows an Interaction Between Neuronal Circuits of the Gill Withdrawal Reflex in Aplysia Californica

1982 ◽  
Vol 96 (1) ◽  
pp. 107-124
Author(s):  
JEFF GOLDBERG ◽  
KEN LUKOWIAK
Keyword(s):  
Tactile Stimulation ◽  
Neural Circuits ◽  
Repetitive Stimulation ◽  
Integrated System ◽  
Neuronal Circuits ◽  
Withdrawal Reflex ◽  
Motor Neurones ◽  
Excitatory Responses ◽  
Lines Of Evidence ◽  
Stimulation Of

The gill withdrawal reflex (GWR) and its subsequent habituation can be evoked by tactile stimulation of the siphon or gill when the CNS is either intact or removed. It has been suggested that the neural circuits that mediate the GWR evoked at these two loci are parallel and independent. We provide three lines of evidence which show that these circuits interact and, therefore, comprise a single integrated system. Firtly, siphon and gill stimulation evoked similar excitatory responses in the central gill motor neurones. Secondly, the GWR habituated by repetitive stimulation at one locus was dishabituated by stimulation of the other locus. Thirdly, transfer of habituation occurred. Although the transfer was seen neurally at the level of central gill motor neurones, transfer of habituation also occurred after the CNS was removed. Therefore, the neuronal circuits mediating the reflexes evoked at the siphon and gill interact within both the CNS and PNS. The PNS is largely responsible for mediating this gill behaviour that is based on such interactions, while the CNS provides suppressive and facilitatory plasticity to these responses to enable Aplysia to better adapt to a changing environment.

scholarly journals Serotonin 2A (5-HT2A) receptor affects cell–matrix adhesion and the formation and maintenance of stress fibers in HEK293 cells

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Joe Anand Kumar John Jayakumar ◽  
Mitradas. M. Panicker ◽  
Basudha Basu
Keyword(s):  
Nervous System ◽  
Neural Circuits ◽  
Stress Fibers ◽  
Hek293 Cells ◽  
Matrix Adhesion ◽  
Cell Matrix ◽  
Cell Matrix Adhesion ◽  
G Protein Coupled ◽  
Serotonin 2A ◽  
Stimulation Of

Abstract5-HT2A, a G-protein coupled receptor, is widely expressed in the human body, including in the gastrointestinal tract, platelets and the nervous system. It mediates various functions, for e.g. learning, memory, mood regulation, platelet aggregation and vasoconstriction, but its involvement in cell-adhesion remains largely unknown. Here we report a novel role for 5-HT2A in cell–matrix adhesion.In HEK293 cells, which are loosely adherent, expression and stimulation of human or rat 5-HT2A receptor by agonists such as serotonin or 2,5-dimethoxy-4-iodoamphetamine (DOI) led to a significant increase in adhesion, while inhibition of 5-HT2A by antipsychotics, such as risperidone, olanzapine or chlorpromazine prevented it. 5-HT2A activation gave rise to stress fibers in these cells and was also required for their maintenance. Mechanistically, the 5-HT2A-mediated adhesion was mediated by downstream PKC and Rho signaling. Since 5-HT2A is associated with many disorders such as dementia, depression and schizophrenia, its role in cell–matrix adhesion could have implications for neural circuits.

scholarly journals Odorant Receptors Signaling Instructs the Development and Plasticity of the Glomerular Map

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Pablo Valle-Leija
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Olfactory System ◽  
Neural Circuits ◽  
Odorant Receptors ◽  
Great Opportunity ◽  
Essential Information ◽  
Olfactory Information ◽  
The Central Nervous System ◽  
And Function

The olfactory system provides a great opportunity to explore the mechanisms that underlie the formation and function of neural circuits because of the simplicity of its structure. Olfactory sensory neurons (OSNs) located in the peripheral olfactory epithelium (OE) take part in the initial formation and function of glomeruli in the olfactory bulb (OB) inside the central nervous system. Glomeruli are key in the process of transduction of olfactory information, as they constitute a map in the OB that sorts the different types of odorant inputs. This odorant categorization allows proper olfactory perception, and it is achieved through the anatomical organization and function of the different glomerular circuits. Once formed, glomeruli keep the capacity to undergo diverse plasticity processes, which is unique among the different neural circuits of the central nervous system. In this context, through the expression and function of the odorant receptors (ORs), OSNs perform two of the most important roles in the olfactory system: transducing odorant information to the nervous system and initiating the development of the glomerular map to organize olfactory information. This review addresses essential information that has emerged in recent years about the molecular basis of these processes.

In and Out of the Central Nervous System

2016 ◽  
Author(s):  
Michael J. Aminoff
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Experimental Approach ◽  
Cranial Nerves ◽  
Motor Functions ◽  
System P ◽  
The Central Nervous System ◽  
Experimental Findings ◽  
The Brain

In 1811, Bell had printed privately a monograph titled Idea of a New Anatomy of the Brain. In it, Bell correctly showed that the anterior but not the posterior roots had motor functions. François Magendie subsequently showed that the anterior roots were motor, and the posterior roots were sensory. This led to a dispute about priority during which Bell republished some of his early work with textual alterations to support his claims. Bell was involved in a similar dispute with Herbert Mayo concerning the separate functions of the fifth (sensory) and seventh (motor) cranial nerves, and Mayo today is a forgotten man. In both instances, Bell deserves credit for the concepts and initial experimental approach, and Magendie and Mayo deserve credit for obtaining and correctly interpreting the definitive experimental findings.

scholarly journals Regenerative Potential of Carbon Monoxide in Adult Neural Circuits of the Central Nervous System

2020 ◽  
Vol 21 (7) ◽  
pp. 2273
Author(s):  
Eunyoung Jung ◽  
Seong-Ho Koh ◽  
Myeongjong Yoo ◽  
Yoon Kyung Choi
Keyword(s):  
Central Nervous System ◽  
Carbon Monoxide ◽  
Nervous System ◽  
Neurotrophic Factors ◽  
Neural Circuits ◽  
Cns Injury ◽  
Cns Regeneration ◽  
The Central Nervous System ◽  
Endogenous Neural Stem Cells

Regeneration of adult neural circuits after an injury is limited in the central nervous system (CNS). Heme oxygenase (HO) is an enzyme that produces HO metabolites, such as carbon monoxide (CO), biliverdin and iron by heme degradation. CO may act as a biological signal transduction effector in CNS regeneration by stimulating neuronal intrinsic and extrinsic mechanisms as well as mitochondrial biogenesis. CO may give directions by which the injured neurovascular system switches into regeneration mode by stimulating endogenous neural stem cells and endothelial cells to produce neurons and vessels capable of replacing injured neurons and vessels in the CNS. The present review discusses the regenerative potential of CO in acute and chronic neuroinflammatory diseases of the CNS, such as stroke, traumatic brain injury, multiple sclerosis and Alzheimer’s disease and the role of signaling pathways and neurotrophic factors. CO-mediated facilitation of cellular communications may boost regeneration, consequently forming functional adult neural circuits in CNS injury.

Neuroimmune signaling in regulation of intestinal ion transport

1994 ◽  
Vol 266 (2) ◽  
pp. G167-G178 ◽  
Author(s):  
H. J. Cooke
Keyword(s):  
Nervous System ◽  
Immune System ◽  
Epithelial Cells ◽  
Enteric Nervous System ◽  
Inflammatory Mediators ◽  
Neural Circuits ◽  
Selective Excitation ◽  
Response Threshold ◽  
Complex Interactions ◽  
Intestinal Ion Transport

Complex interactions between the enteric nervous system, the immune system, and the epithelium govern the transport rates of salt and water across the intestinal lining. Luminal antigens or bacterial products are detected by the immune system, which triggers a cascade of events associated with the release of inflammatory mediators. These mediators, by lowering the response threshold for transmission in some neural circuits, augment ongoing neural reflexes that promote secretion. Associated with these effects is a dampening of responses in other neural circuits innervating the mucosal effectors. Selective excitation and inhibition of the neural reflex circuitry coupled with direct actions of inflammatory mediators on epithelial cells result in stereotypical motility and secretory patterns that are characterized by strong muscular contractions, copious secretion, and diarrhea.

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