Search PubMed⌕ Search

Biomedical subjects

M R Burke

Publications and source records attributed to M R Burke.

7 recordsLinked to original sources
PubMed2006

Quantitative differences in smooth pursuit and saccadic eye movements.

Recently it has been suggested that smooth pursuit (SP) and saccadic (SAC) eye movements share many common brain substrates in the planning and control of eye movements (Krauzlis in J Neurophysiol 91:591-603, 2004). Evidence is mounting that these two types of eye movements may also share similar mechanisms used to drive both reactive and predictive eye movement responses (Missal and Keller in J Neurophysiol 88:1880-1892, 2002, Keller and Missal in Ann NY Acad Sci 1004:29-39, 2003). The objective of this study was to quantify these similarities by establishing whether the behavioural response properties of human eye movements to predictive (PRD) and randomized (RND) conditions are quantitatively similar for both SP and SAC in directly comparable paradigms. Two previous studies have attempted to evaluate the coordination and motor preparation time of SP and saccadic eye movements (Erkelens in Vis Res 46:163-170, 2006; Joiner and Shelhamer in Exp Brain Res, Epub ahead of print, 2006). However, no previous study has quantitatively evaluated PRD and RND conditions to discretely presented SP and SAC tasks. We used simple SAC and SP paradigms in blocks of PRD and RND presentations, with eye movements monitored throughout using an IR-limbus eye-tracking system (Skalar). Twelve normal subjects (aged between 20 and 39 years) participated in the study which took place over two recording sessions, on two separate days. Data were analysed for two main comparable descriptive statistics: latency and eye velocity/displacement gain. The results presented here support the notion that SP and SAC share common brain substrates/mechanisms in the generation of responses to PRD and RND visual targets but differ in the movement preparation time.

Adult↗
PubMed2004

Touch responses made to remembered and visual target locations in the dark: a human psychophysical study.

UNLABELLED: Saccadic eye movements made to remembered locations in the dark show a distinct up-shift in macaque monkey, and slight upward bias in humans (Gnadt et al. 1991). This upward bias created in the visual spatial mapping of a saccade may be translated downstream in a hand/touch movement. This error could possibly reveal (a) information about the frames of reference used in each scenario and (b) the sources of this error within the brain. This would suggest an early planning stage if they are shared, or a later stage if the errors are distinct. METHODS: Eight human subjects performed touch responses to a touch screen monitor to both visual and remembered target locations. The subjects used a high-resolution touch-screen monitor, a bite bar and chin-rest for restricting head movements during responses. All target locations were 20 degrees vectors from the central starting position in horizontal, vertical and oblique planes of motion. RESULTS: Subjects were accurate to both visual and remembered target locations with little variance. Subject means showed no significant differences between control and memory trials; however, a distinct asymmetry was observed between cardinal and oblique planes during memory trials. Subjects consistently made errors to oblique locations during touches made to the remembered location that was not evident in control conditions. This error pattern revealed a strong hypermetric tendency for oblique planes of touches made to a remembered location.

Adolescent↗
PubMed1997

The scientific rationale and development of an optimized stannous fluoride dentifrice, Part 1.

Stannous fluoride has been recognized as an effective anticavity therapeutic agent since the early 1950s. There has recently been a resurgence in activity to discover ways to fully exploit its documented antimicrobial activity. Through the use of targeted in vitro methodology to predict in vivo efficacy, a highly optimized stannous fluoride dentifrice has been developed. Careful selection of stabilizing agents formulated into a unique system has resulted in a Colgate Optimized Stannous Fluoride (COSF) dentifrice that has been proven to simultaneously help control supragingival plaque, gingivitis, supragingival calculus, and caries. Furthermore, the COSF dentifrice has been clinically shown not to cause the traditional stannous fluoride staining of dentition.

Bacteria↗
PubMed1994

Anal fissure.

Explore the source record for details and available documents.

Fissure in Ano↗
PubMed1987

Parvodicin, a novel glycopeptide from a new species, Actinomadura parvosata: discovery, taxonomy, activity and structure elucidation.

An extensive taxonomic investigation identified strain SK&F-AAJ-271 as a new species, designated Actinomadura parvosata. Fermentations of this organism produce a complex of acidic, lipophilic glycopeptide antibiotics, the parvodicins. Structures for seven of the isolated components were derived from a combination of mass spectral, high-field NMR and chemical techniques. The O-acetyl functionality present in two of the isolated components is a structural feature unique among the known members of this class of antibiotics. The parvodicins are active in vitro against a range of Gram-positive bacteria. The most active parvodicin, C1, produces high serum levels in vivo and has the potential for a long duration of action.

Animals↗