Dynamics of Fast and Slow Inhibition from Cerebellar Golgi Cells Allow Flexible Control of Synaptic Integration

SummaryThroughout the brain, multiple interneuron types influence distinct aspects of synaptic processing. Interneuron diversity can thereby promote differential firing from neurons receiving common excitation. In contrast, Golgi cells are the sole interneurons regulating granule cell spiking evoked by mossy fibers, thereby gating inputs to the cerebellar cortex. Here, we examine how this single interneuron class modifies activity in its targets. We find that GABAA-mediated transmission at unitary Golgi cell → granule cell synapses consists of varying contributions of fast synaptic currents and sustained inhibition. Fast IPSCs depress and slow IPSCs gradually build during high-frequency Golgi cell activity. Consequently, fast and slow inhibition differentially influence granule cell spike timing during persistent mossy fiber input. Furthermore, slow inhibition reduces the gain of the mossy fiber → granule cell input-output curve, while fast inhibition increases the threshold. Thus, a lack of interneuron diversity need not prevent flexible inhibitory control of synaptic processing

Developing the ERP Pre-Mortem Framework: Addressing the Debate Over Organizational Learning

Organizational learning (OL) is a major weakness for ERP project implementation. Exploratory research interviews of ERP managers/consultants support this finding. Many organizations do not implement proper procedures that effectuate valid learning experiences from failures endured. The literature suggests that effective OL involves complex ongoing processes requiring pervasive knowledge management and organizational memory systems (Jennex and Olfman, 2002). One example of an OL failure is FEMA’s experience with the pre-Katrina “Hurricane Pam” exercise. Alternatively, an example of OL success is found in the U.S. Navy’s methods and procedures. There is considerable similarity between managing ERP systems and managing high reliability system environments like those of FEMA and the US Navy. Given both the failures and successes in the area of OL, it is evident that further research is required if the phenomena is to be more fully understood

The Computer-Controlled Oculometer: A Prototype Interactive Eye Movement Tracking System

One kind of eye movement tracking device which has great potential is the digital computer-controlled Oculometer, an instrument which non-invasively measures point of regard of the subject, as well as pupil diameter and blink occurrence. In conjunction with a computer-generated display which can change in real time as a function of the subject's eye motions, the computer-controlled Oculometer makes possible a variety of interactive measurement and control systems. Practical applications of such schemes have had to await the development of an instrument design which does not inconvenience the subject, and which conveniently interfaces with a digital computer (see ref. 1). This report describes an Oculometer subsystem and an eye-tracking/control program designed for use with the PDP-6 computer of the MIT Project MAC Artificial Intelligence Group. The oculometer electro-optic subsystem utilizes near-infrared light reflected specularly off the front surface of the subject's cornea and diffusely off the retina, producing a bright pupil with an overriding corneal highlight. An electro-optic scanning aperture vidissector within the unit, driven by a digital eye-tracking algorithm programmed into the PDP-6 computer, detects and tracks the centers of the corneal highlight and the bright pupil to give eve movement measurements. A computer-controlled, moving mirror head motion tracker directly coupled to the vidissector tracker permits the subject reasonable freedom of movement. Various applications of this system, which are suggested by the work reported here, include; (a) using the eye as a control device, (b) recording eye fixation and exploring patterns, (c) game playing, (d) training machines, and (e) psychophysiological testing and recording

The status of shark and ray fishery resources in the Gulf of California: applied research to improve management and conservation

Seasonal surveys were conducted during 1998–1999 in Baja California, Baja California Sur, Sonora, and Sinaloa to determine the extent and activities of artisanal elasmobranch fisheries in the Gulf of California. One hundred and forty–seven fishing sites, or camps, were documented, the majority of which (n = 83) were located in Baja California Sur. Among camps with adequate fisheries information, the great majority (85.7%) targeted elasmobranchs during some part of the year. Most small, demersal sharks and rays were landed in mixed species fisheries that also targeted demersal teleosts, but large sharks were usually targeted in directed drift gillnet or, to a lesser extent, surface longline fisheries. Artisanal fishermen were highly opportunistic, and temporally switched targets depending on the local productivity of teleost, invertebrate, and elasmobranch fishery resources. Major fisheries for small sharks ( 1.5 m, “tiburón”) were minor components of artisanal elasmobranch fisheries in Sonora and Sinaloa, but were commonly targeted during summer and early autumn in Baja California and Baja California Sur. The pelagic thresher shark (Alopias pelagicus) and silky shark (Carcharhinus falciformis) were most commonly landed in Baja California, whereas a diverse assemblage of pelagic and large coastal sharks was noted among Baja California Sur landings. Rays dominated summer landings in Baja California and Sinaloa, when elevated catch rates of the shovelnose guitarfish (Rhinobatos productus, 13.2 individuals/vessel/trip) and golden cownose ray (Rhinoptera steindachneri, 11.1 individuals/vesse/trip) primarily supported the respective fisheries. The Sonoran artisanal elasmobranch fishery was the most expansive recorded during this study, and rays (especially R. productus) dominated spring and summer landings in this state. Seasonal catch rates of small demersal sharks and rays were considerably greater in Sonora than in other surveyed states. Many tiburón populations (e.g., C. leucas, C. limbatus, C. obscurus, Galeocerdo cuvier) have likely been overfished, possibly shifting effort towards coastal populations of cazón and rays. Management recommendations, including conducting demographic analyses using available life history data, determining and protecting nursery areas, and enacting seasonal closures in areas of elasmobranch aggregation (e.g., reproduction, feeding), are proposed. Without effective, enforceable management to sustain or rebuild targeted elasmobranch populations in the Gulf of California, collapse of many fisheries is a likely outcome. (PDF contains 243 pages

John Stevens Wade Correspondence

Entries include a typed letter presenting the book Gallery for the Maine Author Collection and a lengthy typed biographical sketch of the author C.J. Stevens, contributed as John Stevens Wade, his pseudonym

Incidence and public health burden of sunburn among beachgoers in the United States.

The beach environment creates many barriers to effective sun protection, putting beachgoers at risk for sunburn, a well-established risk factor for skin cancer. Our objective was to estimate incidence of sunburn among beachgoers and evaluate the relationship between sunburn incidence and sun-protective behaviors. A secondary analysis, of prospective cohorts at 12 locations within the U.S. from 2003 to 2009 (n = 75,614), were pooled to evaluate sunburn incidence 10-12 days after the beach visit. Behavioral and environmental conditions were cross-tabulated with sunburn incidence. Multivariable logistic regression was used to estimate the association between new sunburn and sun-protective behaviors. Overall, 13.1% of beachgoers reported sunburn. Those aged 13-18 years (16.5%), whites (16.0%), and those at beach locations along the Eastern Seaboard (16.1%), had the highest incidence of sunburn. For those spending ≥5 h in the sun, the use of multiple types of sun protection reduced odds of sunburn by 55% relative to those who used no sun protection (Odds Ratio = 0.45 (95% Confidence Interval:0.27-0.77)) after adjusting for skin type, age, and race. Acute health effects of sunburn tend to be mild and self-limiting, but potential long-term health consequences are more serious and costly. Efforts to encourage and support proper sun-protective behaviors, and increase access to shade, protective clothing, and sunscreen, can help prevent sunburn and reduce skin cancer risk among beachgoers

Driver Assessment with Measures of Continuous Control Behavior

This paper reviews past research on stimulus/response analysis methods in continuous control tasks, and describes procedures for specifically measuring driver behavior in a car following task. Example driving simulator data is given for drivers with disease impairments. The data processing methods are summarized and example results are given to demonstrate the data analysis approach. Analysis of driver steering and speed control behavior have been used to identify normal highway operations and effects of various impairments, including drugs, alcohol, fatigue and medical conditions. Typical measures might include characteristics of control (steering, throttle, brake) activity, such as control reversals and expected values such as mean and standard deviation. More powerful time series analysis methods look at the relationship between stimulus and response variables. Fourier analysis procedures have been used to carry out stimulus/response relationships, such as steering response to wind gusts and roadway curvature, and speed response to lead vehicle speed variations. These methods allow the analysis of driver time delay in responding to stimulus inputs, and the correlation of driver response to the stimulus input. Typically, driver impairments lead to responses with increased time delay and decreased correlation

Characterization of bacterial lipooligosaccharides by delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption ionization (MALDI) with a time-of-flight analyzer has been used to analyze bacterial lipooligosaccharides (LOS). Crude LOS preparations from pathogenic strains of Haemophilus influenzae and Haemophilus ducreyi and a commercial preparation of lipopolysaccharide from Salmonella typhimurium were treated with hydrazine to remove O-linked fatty acids on the lipid A moiety. The resulting O-deacylated LOS forms were water soluble and more amenable to cocrystallization with standard MALDI matrices such as 2,5-dihydroxybenzoic acid and 1-hydroxyisoquinoline. Under continuous extraction conditions, O-deacylated LOS yielded broad peaks with abundant salt adducts as well as forming prompt fragments through β-elimination of phosphoric acid, that is, [M-H3PO4-H]. However, when a time delay was used between ionization and extraction (“delayed extraction”) a significant improvement was seen in both mass resolution and the stability of the molecular ions against β-elimination of phosphoric acid, especially in the negative-ion mode. Both an external two-point calibration and an internal single-point calibration were used to assign masses, the latter of which provided the highest degree of accuracy (better than 0.01% in most cases). At higher laser powers, the LOS molecules cleave readily between the oligosaccharide and lipid A moieties yielding a number of prompt fragments. Postsource decay (PSD) analysis of selected molecular ions provided a set of fragments similar to those seen in the linear spectra, although they were more limited in number because they were derived from a single LOS-glycoform. Both the prompt and PSD fragments provided important structural information, especially in assigning the phosphate and phosphoethanolamine substitution pattern of the lipid A and oligosaccharide portions of LOS. Last, with the addition of ethylenediaminetetraacetic acid followed by pulsed sonication, the relatively insoluble (and impure) LOS preparations yielded MALDI spectra similar to the O-deacylated LOS, although these intact LOS preparations required higher laser powers to ionize and were generally more affected by competing impurities