Motor Evoked Potential Recruitment Curves Indicate Neuroplasticity after Spinal Cord Injury

Motor Evoked Potential Recruitment Curves Indicate Neuroplasticity after Spinal Cord Injury Yasmina Zeineddine, Depts. of Biomedical Engineering and Anthropology, with Thibault Roumengous, Graduate Student in Biomedical Engineering, and Dr. Carrie Peterson, Dept. of Biomedical Engineering Introduction: Motor evoked potential (MEP) recruitment curves in response to transcranial magnetic stimulation across a range of stimulation intensities can provide insight into the condition of neural pathways to a muscle. Further, corticomotor reorganization associated with recovery of motor function may be reflected in changes in the MEP recruitment curve. At low TMS intensity, the MEP often consists of a single direct wave, whereas at higher stimulus intensities, the MEP amplitude increases due to recruitment of later indirect waves (I-waves). These late I-waves are thought to depend on trans-synaptic activation of corticospinal axons through excitatory interneurons. [1] In impaired patients, MEP recruitment curves can inform the development of individualized rehabilitation treatments, as curve irregularities can reveal specific deficits, and enhance our understanding of the neuroplastic changes that occur after injury. In comparing the biceps brachii recruitment curve of subjects with cervical spinal cord injury (SCI) to nonimpaired individuals, we hypothesized that individuals with SCI would have greater biceps excitability, and therefore greater RC slopes, due to the biceps cortical representation growing in response to triceps paralysis [2]. Materials and Methods: Ten nonimpaired (4 female, 6 male) and 5 impaired (3 female, 2 male) subjects consented to participate in the study. Subjects were seated and had their dominant arm positioned at a 90° elbow angle. EMG surface electrodes were placed on the biceps after being cleaned with alcohol wipes. The biceps cortical hotspot was determined as the area over the motor cortex where TMS evoked the largest MEP response. The resting motor threshold (RMT) was the lowest stimulus intensity required to elicit a 50μVpp MEP response in 3/5 trials. TMS was performed with a 126 mm diameter double cone coil and Magstim BiStim2 . MEPs were recorded from the BB and normalized by dividing by Mmax. Recruitment curves were recorded at stimulus intensities ranging from 80%- 160% of subject RMT in 10% increments. Pulse intensities were randomly administered with interstimulus intervals of 10 s. The data was recorded using Spike software and processed in Matlab. MEPs were excluded if they exceeded ±3 standard deviations of the mean response per intensity. Results and Discussion: The recruitment curve slopes for individuals with SCI, on average, were greater relative to the slopes of nonimpaired individuals. This was based on an analysis of MEPs between intensities of 100% and 140% RMT, wherein the slope was on average 5.13 across individuals with SCI, and 1.49 in the nonimpaired population. The greater slope in individuals with SCI suggests enhanced excitability of the biceps, which is consistent with previous studies showing greater cortical representation of non-paralyzed hand muscles relative to paralyzed muscles [2]. Conclusions: Our results indicate that cervical SCI promotes greater excitability in the muscles controlled by nerves rostral to the location of injury, and demonstrate neural plasticity following injury. The steeper slopes in individuals with SCI indicate greater recruitment of later I-waves. Whether increased recruitment of later I-waves is associated with greater cortical map area is unclear and will require further investigation.https://scholarscompass.vcu.edu/uresposters/1348/thumbnail.jp

Distributed Optimization of Multi-Cell Uplink Co-operation with Backhaul Constraints

We address the problem of uplink co-operative reception with constraints on both backhaul bandwidth and the receiver aperture, or number of antenna signals that can be processed. The problem is cast as a network utility (weighted sum rate) maximization subject to computational complexity and architectural bandwidth sharing constraints. We show that a relaxed version of the problem is convex, and can be solved via a dual-decomposition. The proposed solution is distributed in that each cell broadcasts a set of {\em demand prices} based on the data sharing requests they receive. Given the demand prices, the algorithm determines an antenna/cell ordering and antenna-selection for each scheduled user in a cell. This algorithm, referred to as {\em LiquidMAAS}, iterates between the preceding two steps. Simulations of realistic network scenarios show that the algorithm exhibits fast convergence even for systems with large number of cells.Comment: IEEE ICC Conference, 201

(Mis)Management of Syrian Refugees in Lebanon: Legal Informality and The Case Study of Jnah

Master's thesis in Migration and intercultural relationsThis thesis explores the management of Syrian refugees in Lebanon through the main lens of informality. The thesis is divided into two parts: 1. A policy analysis of the legal informality of Syrian refugees in Lebanon 2. An ethnographic study of the area of Jnah in Lebanon, where squatting Lebanese IDP’s live along with Syrian refugee

Madame Bandar\u27s Theatre of Love

Madame Bandar’s Theatre of Love, a comedic bildungsroman, follows the life of Omar Aladdine in the 1960s and ‘70s as he navigates the historic red-light district in downtown Beirut. At eighteen, Omar works at his father’s grocery store on Mutanabi Street, which is lined with brothels. He becomes enamored with the prostitutes at Madame Bandar’s Theatre of Love, where plays and musical performances are staged, and begins to write romantic plays for the brothel. But when civil war breaks out in the spring of 1975, Mutanabi Street is caught in the crossfire. The fate of Madame Bandar’s and all the prostitutes is at risk, as well as Omar’s newfound sense of home

Symmetric Weighted Odd-Power Variations of Fractional Brownian Motion and Applications

We prove a non-central limit theorem for the symmetric weighted odd-power variations of the fractional Brownian motion with Hurst parameter H< 1/2. As applications, we study the asymptotic behavior of the trapezoidal weighted odd-power variations of the fractional Brownian motion and the fractional Brownian motion in Brownian time Z_t:= X_{Y_t}, t >= 0, where X is a fractional Brownian motion and Y is an independent Brownian motion.Comment: 23 pages. arXiv admin note: text overlap with arXiv:1604.0315

An It\^o's type formula for the fractional Brownian motion in Brownian time

Let $X$ be a (two-sided) fractional Brownian motion of Hurst parameter $H\in (0,1)$ and let $Y$ be a standard Brownian motion independent of $X$. Fractional Brownian motion in Brownian motion time (of index $H$), recently studied in \cite{13}, is by definition the process $Z=X\circ Y$. It is a continuous, non-Gaussian process with stationary increments, which is selfsimilar of index $H/2$. The main result of the present paper is an It\^{o}'s type formula for $f(Z_t)$, when $f:\R\to\R$ is smooth and $H\in [1/6,1)$. When $H>1/6$, the change-of-variable formula we obtain is similar to that of the classical calculus. In the critical case $H=1/6$, our change-of-variable formula is in law and involves the third derivative of $f$ as well as an extra Brownian motion independent of the pair $(X,Y)$. We also discuss briefly the case $H<1/6$.Comment: 19 page