scholarly journals Angle-Tuned Coils: Enabling Building Blocks for High Performance and Multisite TMS Systems

2021 ◽  
Author(s):  
Hedyeh Bagherzadeh ◽  
QINGLEI MENG ◽  
Zhi-De Deng ◽  
Hanbing Lu ◽  
Elliott Hong ◽  
...  
Keyword(s):  
Electric Field ◽  
Composite Structures ◽  
High Performance ◽  
Near Field ◽  
Building Blocks ◽  
Brain Regions ◽  
Brain Functions ◽  
Surface Areas ◽  
Head Surface

Objective: A novel angle-tuned ring coil is proposed for improving the depth-spread performance of Transcranial Magnetic Stimulation (TMS) coils and serve as the building blocks for high-performance composite coils and multisite TMS systems. Approach: Improving depth-spread performance by reducing field divergence through creating a more elliptical emitted field distribution from the coil. To accomplish that, instead of enriching the Fourier components along the planarized (x-y) directions, which requires different arrays to occupy large brain surface areas, we worked along the radial (z) direction by using tilted coil angles and stacking coil numbers to reduce the divergence of the emitted near field without occupying large head surface areas. The emitted electric field distributions were theoretically simulated in spherical and real human head models to analyze the depth-spread performance of proposed coils and compare with existing figure-8 coils. The results were then experimentally validated with field probes and in-vivo animal tests. Main Results: The proposed "angle-tuning" concept improves the depth-spread performance of individual coils with a significantly smaller footprint than existing and proposed coils. For composite structures, using the proposed coils as basic building blocks simplifies the design and manufacturing process and helps accomplish a leading depth-spread performance. In addition, the footprint of the proposed system is intrinsically small, making them suitable for multisite stimulations of inter and intra-hemispheric brain regions with an improved spread and less electric field divergence. Significance: Few brain functions are operated by isolated single brain regions but rather by coordinated networks involving multiple brain regions. Simultaneous or sequential multisite stimulations may provide tools for mechanistic studies of brain functions and the treatment of neuropsychiatric disorders. The proposed AT coil goes beyond the traditional depth-spread tradeoff rule of TMS coils, which provides the possibility of building new composite structures and new multisite TMS tools.

scholarly journals A Modeling Study Suggesting a Possible Pharmacological Target to Mitigate the Effects of Ethanol on Reward-Related Dopaminergic Signaling

2008 ◽  
Vol 99 (5) ◽  
pp. 2703-2707 ◽  
Author(s):  
Michele Migliore ◽  
Claudio Cannia ◽  
Carmen C. Canavier
Keyword(s):  
Dopaminergic Neurons ◽  
Temporal Structure ◽  
Ionic Current ◽  
Brain Regions ◽  
Point Of View ◽  
Dopamine Level ◽  
Addictive Behaviors ◽  
Brain Functions

Midbrain dopaminergic neurons are involved in several critical brain functions controlling goal-directed behaviors, reinforcing/reward processes, and motivation. Their dysfunctions alter dopamine release and contribute to a vast range of neural disorders, from Parkinson's disease to schizophrenia and addictive behaviors. These neurons have thus been a natural target of pharmacological treatments trying to ameliorate the consequences of several neuropathologies. From this point of view, a clear experimental link has been recently established between the increase in the pacemaker frequency of dopaminergic neurons in vitro after acute ethanol application and a particular ionic current ( Ih). The functional consequences in vivo, however, are not clear and they are very difficult to explore experimentally. Here we use a realistic computational model of dopaminergic neurons in vivo to suggest that ethanol, through its effects on Ih, modifies the temporal structure of the spiking activity. The model predicts that the dopamine level may increase much more during bursting than during pacemaking activity, especially in those brain regions with a slow dopamine clearance rate. The results suggest that a selective pharmacological remedy could thus be devised against the rewarding effects of ethanol that are postulated to mediate alcohol abuse and addiction, targeting the specific HCN genes expressed in dopaminergic neurons.

scholarly journals Carbon Nanoelectrodes for the Electrochemical Detection of Neurotransmitters

2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Alexander G. Zestos
Keyword(s):  
Electrode Materials ◽  
Brain Regions ◽  
Fused Silica ◽  
Carbon Fiber Microelectrode ◽  
Disease States ◽  
Surface Areas ◽  
Fused Silica Capillaries ◽  
Living Organisms ◽  
Carbon Based

Carbon-based electrodes have been developed for the detection of neurotransmitters over the past 30 years using voltammetry and amperometry. The traditional electrode for neurotransmitter detection is the carbon fiber microelectrode (CFME). The carbon-based electrode is suitable for in vivo neurotransmitter detection due to the fact that it is biocompatible and relatively small in surface area. The advent of nanoscale electrodes is in high demand due to smaller surface areas required to target specific brain regions that are also minimally invasive and cause relatively low tissue damage when implanted into living organisms. Carbon nanotubes (CNTs), carbon nanofibers, carbon nanospikes, and carbon nanopetals among others have all been utilized for this purpose. Novel electrode materials have also required novel insulations such as glass, epoxy, and polyimide coated fused silica capillaries for their construction and usage. Recent research developments have yielded a wide array of carbon nanoelectrodes with superior properties and performances in comparison to traditional electrode materials. These electrodes have thoroughly enhanced neurotransmitter detection allowing for the sensing of biological compounds at lower limits of detection, fast temporal resolution, and without surface fouling. This will allow for greater understanding of several neurological disease states based on the detection of neurotransmitters.

Hyperlocomotion during Recovery from Isoflurane Anesthesia Is Associated with Increased Dopamine Turnover in the Nucleus Accumbens and Striatum in Mice

1997 ◽  
Vol 86 (2) ◽  
pp. 464-475 ◽  
Author(s):  
Masahiro Irifune ◽  
Tomoaki Sato ◽  
Takashige Nishikawa ◽  
Takashi Masuyama ◽  
Masahiro Nomoto ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Nucleus Accumbens ◽  
High Performance ◽  
Gas Flow ◽  
Brain Regions ◽  
Dopamine Neurons ◽  
Dopamine Turnover

Background It was recently reported that isoflurane increases dopamine release in the striatum in rats both in vivo and in vitro, and that isoflurane inhibits uptake of dopamine in the rat brain synaptosomes. However, the functional role of these effects of isoflurane on dopamine neurons is uncertain. Dopaminergic mechanisms within the nucleus accumbens and striatum play an important role in the control of locomotor activity, and a change in dopamine turnover depends essentially on a change in impulse flow in the dopamine neurons. In this study, the effects of isoflurane on locomotor activity and on dopamine turnover were investigated in discrete brain regions in mice. Methods Mice were placed in individual airtight clear plastic chambers and spontaneously breathed isoflurane in 25% oxygen and 75% nitrogen (fresh gas flow, 4 l/min). Locomotor activity was measured with an Animex activity meter. Animals were decapitated after treatments with or without isoflurane, and the concentrations of monoamines and their metabolites in different brain areas were measured by high-performance liquid chromatography. Results During the 10 min after the cessation of the 20-min exposure to isoflurane, there was a significant increase in locomotor activity in animals breathing 1.5% isoflurane but not 0.7% isoflurane. This increase in locomotor activity produced by 1.5% isoflurane was abolished by a low dose of haloperidol (0.1 mg/kg), a dopamine receptor antagonist. Regional brain monoamine assays revealed that 1.5% isoflurane significantly increased the 3,4-dihydroxyphenylacetic acid:dopamine ratio (one indicator of transmitter turnover) in the nucleus accumbens and striatum, but a concentration of 0.7% did not. This significant increase in dopamine turnover in these regions continued during 20 min after the cessation of the administration of 1.5% isoflurane. Conclusions These results suggest that isoflurane-induced hyperlocomotion during emergence may be associated with increased dopamine turnover in the nucleus accumbens and striatum.

scholarly journals MicroRNA-dependent control of neuroplasticity in affective disorders

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Helena Caria Martins ◽  
Gerhard Schratt
Keyword(s):  
Affective Disorders ◽  
Gene Networks ◽  
Molecular Mechanisms ◽  
Brain Regions ◽  
Functional Studies ◽  
Brain Functions ◽  
Small Regulatory Rnas ◽  
Therapeutic Tools ◽  
Mood And Cognition

AbstractAffective disorders are a group of neuropsychiatric disorders characterized by severe mood dysregulations accompanied by sleep, eating, cognitive, and attention disturbances, as well as recurring thoughts of suicide. Clinical studies consistently show that affective disorders are associated with reduced size of brain regions critical for mood and cognition, neuronal atrophy, and synaptic loss in these regions. However, the molecular mechanisms that mediate these changes and thereby increase the susceptibility to develop affective disorders remain poorly understood. MicroRNAs (miRNAs or miRs) are small regulatory RNAs that repress gene expression by binding to the 3ʹUTR of mRNAs. They have the ability to bind to hundreds of target mRNAs and to regulate entire gene networks and cellular pathways implicated in brain function and plasticity, many of them conserved in humans and other animals. In rodents, miRNAs regulate synaptic plasticity by controlling the morphology of dendrites and spines and the expression of neurotransmitter receptors. Furthermore, dysregulated miRNA expression is frequently observed in patients suffering from affective disorders. Together, multiple lines of evidence suggest a link between miRNA dysfunction and affective disorder pathology, providing a rationale to consider miRNAs as therapeutic tools or molecular biomarkers. This review aims to highlight the most recent and functionally relevant studies that contributed to a better understanding of miRNA function in the development and pathogenesis of affective disorders. We focused on in vivo functional studies, which demonstrate that miRNAs control higher brain functions, including mood and cognition, in rodents, and that their dysregulation causes disease-related behaviors.

Neurochemical differences in two rat strains exposed to social isolation rearing

2012 ◽  
Vol 24 (5) ◽  
pp. 286-295 ◽  
Author(s):  
Luigia Trabace ◽  
Margherita Zotti ◽  
Marilena Colaianna ◽  
Maria G. Morgese ◽  
Stefania Schiavone ◽  
...  
Keyword(s):  
High Performance ◽  
Tissue Concentration ◽  
Brain Area ◽  
Brain Regions ◽  
Post Mortem ◽  
Isolation Rearing ◽  
Post Mortem Brain ◽  
Rat Strain ◽  
Neurochemical Changes

Objective: Isolation rearing of rats provides a non-pharmacological method of inducing behavioural changes in rodents that resemble schizophrenia or depression. Nevertheless, results are variable within different strains. We focused on neurochemical changes in several in vivo and post-mortem brain regions of Wistar (W) and Lister Hooded (LH) rats following post-weaning social separation.Methods: Experiments were conducted after 6–8 weeks of isolation. For post-mortem studies, prefrontal cortex (PFC), nucleus accumbens (NAC), hippocampus (Hipp) and striatum (St) were collected by tissue dissection. In vivo experiments were conducted by microdialysis in the PFC. Analyses of dopamine (DA), serotonin (5-HT) levels and relative turnover were performed by using high-performance liquid chromatography.Results: We found significant strain-related differences in biogenic amine content. LH rats were characterised by markedly raised DA, along with its turnover reduction, in all the post-mortem brain regions examined as well as in microdialysis samples, while in W rats 5-HT tissue concentration was lower in PFC and St and higher in NAC and Hipp. Cortical extracellular 5-HT concentrations were increased in group housed and decreased in isolated W animals. Moreover, isolation increased DA concentrations in the PFC of LH rats, and decreased 5-HT in W rats in NAC and Hipp. Lately, 5-HT turnover was also affected by both strain and isolation conditions.Conclusions: This study suggests that W and LH rats have markedly different neurochemical profiles in response to isolation, resulting in altered monoamine levels that vary according to brain area and rat strain. These findings highlight the importance of selecting an appropriate rat strain when considering isolation rearing to model symptoms of schizophrenia and/or depression.

scholarly journals A High-Resolution In Vivo Atlas of the Human Brain’s Benzodiazepine Binding Site of GABAA Receptors

2020 ◽  
Author(s):  
Martin Nørgaard ◽  
Vincent Beliveau ◽  
Melanie Ganz ◽  
Claus Svarer ◽  
Lars H Pinborg ◽  
...  
Keyword(s):  
High Resolution ◽  
Human Brain ◽  
Mrna Expression ◽  
Brain Regions ◽  
Mrna Levels ◽  
Gamma Aminobutyric Acid ◽  
Healthy Human ◽  
Brain Functions ◽  
The Brain

ABSTRACTGamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human brain and plays a key role in several brain functions and neuropsychiatric disorders such as anxiety, epilepsy, and depression. The binding of benzodiazepines to the benzodiazepine receptor sites (BZR) located on GABAA receptors (GABAARs) potentiates the inhibitory effect of GABA leading to the anxiolytic, anticonvulsant and sedative effects used for treatment of those disorders. However, the function of GABAARs and the expression of BZR protein is determined by the GABAAR subunit stoichiometry (19 genes coding for individual subunits), and it remains to be established how the pentamer composition varies between brain regions and individuals.Here, we present a quantitative high-resolution in vivo atlas of the human brain BZRs, generated on the basis of [11C]flumazenil Positron Emission Tomography (PET) data. Next, based on autoradiography data, we transform the PET-generated atlas from binding values into BZR protein density. Finally, we examine the brain regional association with mRNA expression for the 19 subunits in the GABAAR, including an estimation of the minimally required expression of mRNA levels for each subunit to translate into BZR protein.This represents the first publicly available quantitative high-resolution in vivo atlas of the spatial distribution of BZR densities in the healthy human brain. The atlas provides a unique neuroscientific tool as well as novel insights into the association between mRNA expression for individual subunits in the GABAAR and the BZR density at each location in the brain.

scholarly journals Long-range interhemispheric projection neurons show biased response properties and fine-scale local subnetworks in mouse visual cortex

2019 ◽  
Author(s):  
Kenta M. Hagihara ◽  
Ayako W. Ishikawa ◽  
Yumiko Yoshimura ◽  
Yoshiaki Tagawa ◽  
Kenichi Ohki
Keyword(s):  
Long Range ◽  
Brain Regions ◽  
Projection Neurons ◽  
Fine Scale ◽  
Local Connectivity ◽  
Cortical Projection ◽  
Response Properties ◽  
Brain Functions ◽  
Mouse Visual Cortex

SummaryIntegration of information processed separately in distributed brain regions is essential for brain functions. This integration is enabled by long-range projection neurons, and further, concerted interactions between long-range projections and local microcircuits are crucial. It is not well known, however, how this interaction is implemented in cortical circuits. Here, to decipher this logic, using callosal projection neurons (CPNs) as a model of long-range projections, we found that CPNs exhibited distinct response properties and fine-scale local connectivity patterns. In vivo 2-photon calcium imaging revealed that CPNs showed a higher ipsilateral eye (with respect to their somata) preference, and that CPN pairs showed stronger signal/noise correlation than random pairs. Slice recordings showed CPNs were preferentially connected to CPNs, demonstrating the existence of projection target-dependent fine-scale subnetworks. Collectively, our results suggest that long-range projection target predicts response properties and local connectivity of cortical projection neurons.

Ultrasonic Assembly of Biologically Inspired Anisotropic Short Fibre Reinforced Composites

2014 ◽  
Author(s):  
Richard S. Trask
Keyword(s):  
Self Assembly ◽  
Composite Structures ◽  
High Performance ◽  
Mechanical Performance ◽  
Low Cost ◽  
Building Blocks ◽  
Functionally Graded ◽  
Fibre Reinforcement ◽  
Fibre Direction ◽  
Volume Percentage

In nature, both material and structure are formed according to the principles of biologically controlled self-assembly, a process defined as the spontaneous and reversible ordering of small molecular building blocks under the influence of non-covalent, static interactions. The orientation and distribution of reinforcing entities in engineering composites is key to enabling structural efficiency, yet the architecture remains simplistic when compared to the distinctive and unique hierarchies found in Nature. These biological ‘composite’ materials achieve such configurations by accurately controlling the orientation of anisotropic nano- and micro-sized ‘building blocks’, thereby reinforcing the material in specific directions to carry the multidirectional external loads at different length scales. Capturing the design principles underlying the exquisite architecture of such biological materials will overcome many of the mechanical limitations of current engineering composites. The scientific vision for this study is the development of a novel and highly ordered complex architecture fibrous material for additive layer manufacturing. Using novel chemistry and controlled field-effect assembly, functionally graded, stiffness modulated architectures, analogous to those found in nature, are synthesised to realise enhanced mechanical performance, multi-dimensional composite structures. To achieve this, both hierarchical discontinuous fibres (glass fibres with ZnO nanrods) and a new type of ultrasonic device has been developed. The two studies reported here have been successfully employed to manufacture and mechanically characterise the fibres and aligned discontinuous fibres. A 43 % improvement in strength was observed for samples tested parallel to the direction of the fibre reinforcement over those strained normal to the fibre direction, despite the relatively low volume percentage of the reinforcement phase. This technique shows great potential for the low cost instantaneous alignment of structural reinforcement to generate the light-weight high performance structures required for the future.

scholarly journals Development of a neural interface for high-definition, long-term recording in rodents and nonhuman primates

2020 ◽  
Vol 12 (538) ◽  
pp. eaay4682 ◽  
Author(s):  
Chia-Han Chiang ◽  
Sang Min Won ◽  
Amy L. Orsborn ◽  
Ki Jun Yu ◽  
Michael Trumpis ◽  
...  
Keyword(s):  
High Performance ◽  
Nonhuman Primates ◽  
Electrode Array ◽  
Brain Regions ◽  
Electrode Arrays ◽  
High Definition ◽  
Neural Recordings ◽  
Essential Components ◽  
Large Brain

Long-lasting, high-resolution neural interfaces that are ultrathin and flexible are essential for precise brain mapping and high-performance neuroprosthetic systems. Scaling to sample thousands of sites across large brain regions requires integrating powered electronics to multiplex many electrodes to a few external wires. However, existing multiplexed electrode arrays rely on encapsulation strategies that have limited implant lifetimes. Here, we developed a flexible, multiplexed electrode array, called “Neural Matrix,” that provides stable in vivo neural recordings in rodents and nonhuman primates. Neural Matrix lasts over a year and samples a centimeter-scale brain region using over a thousand channels. The long-lasting encapsulation (projected to last at least 6 years), scalable device design, and iterative in vivo optimization described here are essential components to overcoming current hurdles facing next-generation neural technologies.

Hair cell changes after cationic stimulation of corti's organ

1989 ◽  
Vol 47 ◽  
pp. 798-799
Author(s):  
Cesar D. Fermin ◽  
Hans-Peter Zenner
Keyword(s):  
Organ Of Corti ◽  
Cross Sectional ◽  
Surface Areas ◽  
High K ◽  
Anatomical Arrangement ◽  
Cell Cytosol ◽  
High Concentrations ◽  
K Concentration ◽  
Cell Changes

Contraction of outer and inner hair cells (OHC&IHC) in the Organ of Corti (OC) of the inner ear is necessary for sound transduction. Getting at HC in vivo preparations is difficult. Thus, isolated HCs have been used to study OHC properties. Even though viability has been shown in isolated (iOHC) preparations by good responses to current and cationic stimulation, the contribution of adjoining cells can not be explained with iOHC preparations. This study was undertaken to examine changes in the OHC after expossure of the OHC to high concentrations of potassium (K) and sodium (Na), by carefully immersing the OC in either artifical endolymph or perilymph. After K and Na exposure, OCs were fixed with 3% glutaraldehyde, post-fixed in osmium, separated into base, middle and apex and embedded in Araldite™. One μm thick sections were prepared for analysis with the light and E.M. Cross sectional areas were measured with Bioquant™ software.Potassium and sodium both cause isolated guinea pig OHC to contract. In vivo high K concentration may cause uncontrolled and sustained contractions that could contribute to Meniere's disease. The behavior of OHC in the vivo setting might be very different from that of iOHC. We show here changes of the cell cytosol and cisterns caused by K and Na to OHC in situs. The table below shows results from cross sectional area measurements of OHC from OC that were exposed to either K or Na. As one would expect, from the anatomical arrangement of the OC, OHC#l that are supported by rigid tissue would probably be displaced (move) less than those OHC located away from the pillar. Surprisingly, cells in the middle turn of the cochlea changed their surface areas more than those at either end of the cochlea. Moreover, changes in surface area do not seem to differ between K and Na treated OCs.

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