Neural modulation of the human visual cortex

Neuroplasticity is a phenomenon that refers to the brain’s ability to reorganize, strengthen, and form neural connections, a process that becomes increasingly more difficult with age. Gamma amino-butyric acid (GABA), the primary inhibitory neurotransmitter in the brain, is thought to gate neuroplasticity, with increasing concentrations related to the closure of the critical period of development. As a result, the modulation of neuroplasticity and GABA concentration may have implications in the recovery and rehabilitation of neural functions. This research addresses neuroplasticity in the visual cortex by applying rapid visual stimulation and non-invasive brain stimulation using both physiological and psychophysical outcome measures. One fundamental mechanism of neuroplasticity is known as long-term potentiation (LTP), a synaptic strengthening mechanism characterized by changes in cortical physiology and underlies the processes of learning and memory formation. While LTP can be induced in animal models of the brain through invasive electrical stimulation, recent studies have demonstrated LTP-like effects induced by rapid visual stimulation. Another technique that modulates neuroplasticity is non-invasive brain stimulation. Anodal transcranial direct current stimulation (a-tDCS) has been reported to decrease GABA concentration in the motor cortex, while a form of magnetic stimulation, continuous theta-burst stimulation (cTBS) has the opposite effect. Cortical GABA concentration is measured directly using magnetic resonance spectroscopy (MRS) an imaging technique that quantifies neural metabolites within a small region of interest. Binocular rivalry—a phenomenon wherein perception alternates stochastically when two different images are shown to each eye—has been directly and indirectly associated with visual cortex GABA concentration, which poses the question of whether binocular rivalry dynamics can be used as an indirect measure of GABA concentration. First, we tested the hypothesis that rapid monocular visual stimulation would increase the dominance of the stimulated eye during a binocular rivalry task. Unexpectedly, we found that rapid monocular visual stimulation strengthens the non-stimulated eye, a result which was not explained by adaptation, suggesting that the shift in dominance towards the non-stimulated eye may result from a homeostatic gain control mechanism. Secondly, we investigated the effects of two opposing forms of non-invasive brain stimulation, a-tDCS and cTBS, on binocular rivalry dynamics. We hypothesized that a reduction of GABA using a-tDCS would result in an increase in binocular rivalry alternation rates, while cTBS would have the opposite effect. Although binocular rivalry alternation rates did not change with either stimulation method, duration of mixed perception increased significantly following cTBS. An increase in the inhibitory neurotransmitter GABA may translate to a reduction in neural noise, a complement to the phenomenon of stochastic resonance where increased neural noise may increase the detection of weak signals. Finally, we investigated the effects of a-tDCS on visual cortex GABA and glutamate concentration. Although many studies report a reduction in motor cortex GABA concentration following a-tDCS, our results showed that visual cortex GABA concentration remained the same. Unexpectedly, we found a trend for an increase in glutamate following active a-tDCS, supporting the possibility that a-tDCS effects the visual cortex and motor cortex differently. It is evident that there are many complex mechanisms that gate plasticity, and that modulating neuroplasticity is not as simple as we may have thought. Understanding these mechanisms, however, and the effects of modulatory techniques such as rapid visual stimulation and non-invasive brain stimulation on visual cortex plasticity, will provide a foundation for improving the recovery and rehabilitation potential of neurodevelopmental disorders and brain damage

Understanding the Mechanisms Underlying Brain Plasticity in Adult Humans

Purpose: The human brain changes signi cantly with age. The plasticity of the visual cortex is thought to decrease into adulthood while childrens' brains are highly plastic. This change in plasticity is thought to be due, in part, to an inhibitory neurotransmitter known as gamma-aminobutyric acid (GABA). Recent research has established a general increase in GABA levels from childhood into adulthood, thought to be associated, in part, with the decrease in plasticity. It is unclear, however, whether GABA levels a ect the changes in plasticity that occur from young adulthood into older age. In older age, a further decrease in GABA levels has been suggested. The purpose of this thesis is threefold: (1) To implement a strategy for inducing long-term potentiation (LTP), (2) to understand the associations between psychophysical and physiological measures of neuroplasticity within the primary visual cortex, (3) to assess the e ect of age on both measures We hypothesize that as plasticity continues to decline into older age, GABA levels will continue to increase. Methods: Binocular rivalry alternation rates (ARs) were used as a behavioural measure of cortical GABA levels. A dichoptic presentation using red/green glasses was displayed on an Asus 3D Vision Ready monitor. Young (18-40 years) and older (60-80 years) participants wearing red/green glasses indicated whether they perceived the red grating, green grating, or a mix of the two{referred to as piecemeal{using 3 keys. Visually-evoked potentials (VEPs) were then used as a measure of the change in plasticity following a rapid onset/o set checkerboard stimulus thought to induce LTP within the primary visual cortex. VEPs before and after the inducing stimulus were recorded and compared. Results: ARs were signi cantly slower in older adults compared to the young adults. Pre to post waveform amplitudes had relatively lower LTP in the young adults compared to the older adults; however neither group showed signi cant LTP (p>0.05 for main e ect of pre versus post VEP amplitude). Conclusions: No correlation between AR and LTP was observed. AR was slower in older adults than in young adults. LTP was relatively greater in older adults compared with the young adult group. A decrease in GABA levels with older age, as most studies have found, alludes to an increase in ARs; however this was not the case in the present results. In contrast, while slower ARs suggests an increase in GABA levels, LTP was relatively greater in older adults suggesting a decrease in GABA levels. These data indicate that either AR or LTP, or both AR and LTP, are inadequate measures of GABA concentration or inaccurate measures of plasticity, or that GABA and LTP may not be directly related in the tested sample. Changes in neurotransmitter concentrations with age may lead to neural adaptations that alter the response to both rivalry and LTP in unexpected ways

The Frequency of Asymptomatic Sacroiliitis in Jordanian Patients with Crohn’s Disease. Assessment by Magnetic Resonance Enterography

Background: our aim was to assess frequency of asymptomatic sacroiliitis (SI) in patients with Crohns disease referred for magnetic resonant enterography (MRE) as a part of small bowel evaluation. Methods: this was a retrospective study of all patients with Crohns disease who were referred for MRE between January of 2016 to October of 2017 to Jordan University Hospital. All MRE were reviewed by an experienced radiologist and SI was diagnosed and graded based on predefined MRI criteria. All patients were contacted and assessed for symptomatic SI based on Assessment of SpondyloArthritis international Society (ASAS) criteria of 2009 for axial spondyloarthropathy. All patients were included in the final analysis.Results: a total of 60 patients were included, overall 18 (30%) showed evidence of SI, two patients were symptomatic and another two were diagnosed with ankylosing spondylitis as assessed by ASAS criteria. Those were excluded. Fourteen (23%) patients were included in the final analysis, with an average age of 36.7 years, 71% males. The average disease duration was 7.25 years. The percentage of ASA used by patients was 50%, Azathioprine 71%, Biologic agents in 36% in combination and single drug was used in 36% of patients.Conclusion: The prevalence of asymptomatic SI based on predefined MRI criteria was 23%, the importance of this finding and future course progression needs further studies

The understanding of Parkinson's disease through genetics and new therapies

Introduction: Parkinson's disease is one of the progressive neurodegenerative diseases from which people suffer for years. The mechanism of this disease is associated with a decrease in the number of dopaminergic neurons in the substantia nigra (SN) while Lewy bodies are still present. As a result, both motor-ridity, tremor, and bradykinesia-and non-motor symptoms such as anxiety and depression. Nowadays, it is well known that the cause behind Parkinson's disease is mainly environmental changes, genetic susceptibility, and toxins. Unfortunately, there is no cure for the disease but treatments. The replacement of lost neurons, alpha-synuclein and apomorphine, is currently being studied for new therapies. This article focuses on history, mechanism, factors causing Parkinson's disease as well as future therapies for the cure of the diseases. Methodology: Data were collected from medical journals published on PubMed, The Lancet, Cells, and Nature Reviews Neurology databases with a predefined search strategy. All articles considering new therapies for Parkinson's disease were considered. Results: The pathophysiology of Parkinson's disease is currently reasonably understood. However, there is no definitive cure so all the treatments focus mainly on reducing or limiting the symptoms. Current treatment studies focus on genetics, replacing lost neurons, alpha-synuclein and apomorphine. Conclusion: Parkinson's disease is the most common movement disorder worldwide because of the loss of dopaminergic neurons in the substantia nigra. Its symptoms include motor dysfunctions such as rigidity, tremor, and bradykinesia and non-motor dysfunctions such as anxiety and depression. Through genetics, environmental changes and toxins analysis, it is now known that future new therapies are working on replacing lost neurons, alpha-synuclein and apomorphine

Internet of Things in Agricultural Innovation and Security

The agricultural Internet of Things (Ag-IoT) paradigm has tremendous potential in transparent integration of underground soil sensing, farm machinery, and sensor-guided irrigation systems with the complex social network of growers, agronomists, crop consultants, and advisors. The aim of the IoT in agricultural innovation and security chapter is to present agricultural IoT research and paradigm to promote sustainable production of safe, healthy, and profitable crop and animal agricultural products. This chapter covers the IoT platform to test optimized management strategies, engage farmer and industry groups, and investigate new and traditional technology drivers that will enhance resilience of the farmers to the socio-environmental changes. A review of state-of-the-art communication architectures and underlying sensing technologies and communication mechanisms is presented with coverage of recent advances in the theory and applications of wireless underground communications. Major challenges in Ag-IoT design and implementation are also discussed

Extracting Names From Arabic Text For Question-Answering Systems

Tagging and extracting proper names is an important key for improving the effectiveness of questionanswering systems. The valuable information in the text usually is located around proper names, to collect this information it should be found first. By extracting proper names from the text we provide questionanswering systems with both the proper name found in the text, some information about it and where it was found. The proper names in Arabic do not start with capital letter as in many other languages so special treatment is needed to find them in a text. Little research has been conducted in this area; most efforts have been based on a number of heuristic rules used to find names in the text. In this paper we present a new technique to extract names from text by building a database and graphs to represent the words that might form a name and the relationships between them. First we mark the phrases that might include names, second we build graphs to represent the words in these phrases and the relationships between them, third we apply rules to find the names

Discovering Lexical Information by Tagging Arabic Newspaper Text

In this paper xve describe a system for building an Arabic lexicon automatically by tagging Arabic newspaper text. In this system we are using several techniques for tagging the words in the text and figuring out their types and their features. The major techniques that we are using are: finding phrases, analyzing the affixes of the words, and analyzing their patterns. Proper nouns are particularly difficult to identify in the Arabic language; we describe techniques for isolating them

The Poetry Café: An On-line Writing Workshop for Refugee and Newcomer Youth

The objective of this paper is to discuss the use of cross-disciplinary partnerships to design and implement a creative writing workshop for English-language learners (ELLs) in an online setting. The methodology utilized collaborative, cross-disciplinary feedback and revision cycles to identify key areas of consideration in facilitating the workshop. The findings revealed cultural and grammatical considerations, emotional nuance considerations, idiomatic language considerations, and internal translation and time considerations in the creative writing process for ELLs. In addition, a reflection, after the completion of the workshop, revealed that while the curriculum successfully implemented three scholarly fields of knowledge, the advances made by this cross-disciplinary partnership hit substantial obstacles when delivered over a virtual platform

Resonant Subwavelength and Nano-Scale Grating Structures for Biosensing Application: A Comparative Study

Resonant-based sensors are attractive optical structures due to the easy detection of shifts in the resonance location in response to variations in the analyte refractive index (RI) in comparison to non-resonant-based sensors. In particular, due to the rapid progress of nanostructures fabrication methods, the manufacturing of subwavelength and nano-scale gratings in a large area and at a low cost has become possible. A comparative study is presented involving analysis and experimental work on several subwavelength and nanograting structures, highlighting their nano-scale features’ high potential in biosensing applications, namely: (i) Thin dielectric grating on top of thin metal film (TDGTMF), which can support the excitation of extended surface plasmons (ESPs), guided mode resonance, or leaky mode; (ii) reflecting grating for conventional ESP resonance (ESPR) and cavity modes (CMs) excitation; (iii) thick dielectric resonant subwavelength grating exhibiting guided mode resonance (GMR) without a waveguide layer. Among the unique features, we highlight the following: (a) Self-referenced operation obtained using the TDGTMF geometry; (b) multimodal operation, including ESPR, CMs, and surface-enhanced spectroscopy using reflecting nanograting; (c) phase detection as a more sensitive approach in all cases, except the case of reflecting grating where phase detection is less sensitive than intensity or wavelength detection. Additionally, intensity and phase detection modes were experimentally demonstrated using off-the-shelf grating-based optical compact discs as a low-cost sensors available for use in a large area. Several flexible designs are proposed for sensing in the visible and infrared spectral ranges based on the mentioned geometries. In addition, enhanced penetration depth is also proposed for sensing large entities such as cells and bacteria using the TDGTMF geometry

Collect Meaningful Information about Stock Markets from the Web

Events represent a significant source of information on the web; they deliver information about events that occur around the world in all subjects and areas. These events can be collected and organized to provide valuable and useful information for decision makers, researchers, as well as for any person seeking knowledge. In this paper, we discuss an ongoing research to target stock markets domain to observe and record changes (events) when they happen, collect them, understand the meaning of each one of them, and organize the information along with meaning in a well-structured format. By using Semantic Role Labeling (SRL) technique, we have identified four factors for each event in this paper: verb of action and three roles associated with it, entity name, attribute, and attribute value. We have generated a set of rules and techniques to support our approach to analyze and understand the meaning of the events that take place in stock markets