McGill University

About: McGill University is a education organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 72688 authors who have published 162565 publications receiving 6966523 citations. The organization is also known as: Royal institution of advanced learning & University of McGill College.

Unmyelinated tactile afferents signal touch and project to insular cortex

Abstract: There is dual tactile innervation of the human hairy skin: in addition to fast-conducting myelinated afferent fibers, there is a system of slow-conducting unmyelinated (C) afferents that respond to light touch. In a unique patient lacking large myelinated afferents, we found that activation of C tactile (CT) afferents produced a faint sensation of pleasant touch. Functional magnetic resonance imaging (fMRI) analysis during CT stimulation showed activation of the insular region, but not of somatosensory areas S1 and S2. These findings identify CT as a system for limbic touch that may underlie emotional, hormonal and affiliative responses to caress-like, skin-to-skin contact between individuals.

Analytical distributions for stochastic gene expression

Abstract: Gene expression is significantly stochastic making modeling of genetic networks challenging. We present an approximation that allows the calculation of not only the mean and variance, but also the distribution of protein numbers. We assume that proteins decay substantially more slowly than their mRNA and confirm that many genes satisfy this relation by using high-throughput data from budding yeast. For a two-stage model of gene expression, with transcription and translation as first-order reactions, we calculate the protein distribution for all times greater than several mRNA lifetimes and thus qualitatively predict the distribution of times for protein levels to first cross an arbitrary threshold. If in addition the fluctuates between inactive and active states, we can find the steady-state protein distribution, which can be bimodal if fluctuations of the promoter are slow. We show that our assumptions imply that protein synthesis occurs in geometrically distributed bursts and allows mRNA to be eliminated from a master equation description. In general, we find that protein distributions are asymmetric and may be poorly characterized by their mean and variance. Through maximum likelihood methods, our expressions should therefore allow more quantitative comparisons with experimental data. More generally, we introduce a technique to derive a simpler, effective dynamics for a stochastic system by eliminating a fast variable.

A Neurolinguistic Theory of Bilingualism

Abstract: This volume is the outcome of 25 years of research into the neurolinguistic aspects of bilingualism. In addition to reviewing the world literature and providing a state-of-the-art account, including a critical assessment of the bilingual neuroimaging studies, it proposes a set of hypotheses about the representation, organization and processing of two or more languages in one brain. It investigates the impact of the various manners of acquisition and use of each language on the extent of involvement of basic cerebral functional mechanisms. The effects of pathology as a means to understanding the normal functioning of verbal communication processes in the bilingual and multilingual brain are explored and compared with data from neuroimaging studies. In addition to its obvious research benefits, the clinical and social reasons for assessment of bilingual aphasia with a measuring instrument that is linguistically and culturally equivalent in each of a patient’s languages are stressed. The relationship between language and thought in bilinguals is examined in the light of evidence from pathology. The proposed linguistic theory of bilingualism integrates a neurofunctional model (the components of verbal communication and their relationships: implicit linguistic competence, metalinguistic knowledge, pragmatics, and motivation) and a set of hypotheses about language processing (neurofunctional modularity, the activation threshold, the language/cognition distinction, and the direct access hypothesis).

Dysferlin, a novel skeletal muscle gene, is mutated in Miyoshi myopathy and limb girdle muscular dystrophy

Abstract: Miyoshi myopathy (MM) is an adult onset, recessive inherited distal muscular dystrophy that we have mapped to human chromosome 2p13. We recently constructed a 3-Mb P1-derived artificial chromosome (PAC) contig spanning the MM candidate region. This clarified the order of genetic markers across the MM locus, provided five new polymorphic markers within it and narrowed the locus to approximately 2 Mb. Five skeletal muscle expressed sequence tags (ESTs) map in this region. We report that one of these is located in a novel, full-length 6.9-kb muscle cDNA, and we designate the corresponding protein 'dysferlin'. We describe nine mutations in the dysferlin gene in nine families; five are predicted to prevent dysferlin expression. Identical mutations in the dysferlin gene can produce more than one myopathy phenotype (MM, limb girdle dystrophy, distal myopathy with anterior tibial onset).

Some Tools for Functional Data Analysis

Abstract: Multivariate data analysis permits the study of observations which are finite sets of numbers, but modern data collection situations can involve data, or the processes giving rise to them, which are functions. Functional data analysis involves infinite dimensional processes and/or data. The paper shows how the theory of L-splines can support generalizations of linear modelling and principal components analysis to samples drawn from random functions. Spline smoothing rests on a partition of a function space into two orthogonal subspaces, one of which contains the obvious or structural components of variation among a set of observed functions, and the other of which contains residual components. This partitioning is achieved through the use of a linear differential operator, and we show how the theory of polynomial splines can be applied more generally with an arbitrary operator and associated boundary constraints. These data analysis tools are illustrated by a study of variation in temperature-precipitation patterns among some Canadian weather-stations.