Limitations of the Hodgkin-Huxley formalism : effects of single channel kinetics on transmembrane voltage dynamics

A standard membrane model, based on the continuous deterministic Hodgkin-Huxley equations, is compared to an alternative membrane model, based on discrete stochastic ion channel populations represented through Marlcov processes. Simulations explore the relationship between these two levels of description: the behavior predicted by the macroscopic membrane currents versus the behavior predicted by their microscopic ion channels. Discussion considers the extent to which these random events underlying neural signals mediate random events in neural computation

Within-Generation Morality of the Jack Pine Tip Beetle, \u3ci\u3eConophthorus Banksianae\u3c/i\u3e McPherson, in Michigan

(excerpt) The jack pine tip beetle (Conophthorus banksianae McPherson) is a shoot-infesting scolytid hat primarily attacks jack pine (Pinus banksiana Lamb.) in Michigan. The insect was previously thought to be a variant of C. resinosae Hopkins, which attacks cones and shoot tips of red pine. McPherson described C. banksianae as a new species, following life cycle and behavioral studies (McPherson, Wilson, and Stehr 1970; McPherson, Stehr, and Wilson 1970). Separating them by morphological features has been unsuccessful (Herdy 1963)

Grasshoppers Feeding on Red Pine Trees in Michigan (Orthoptera: Acrididae)

Very few North American grasshoppers are true feeders on conifers. The several species of the punctulatus species-group of the genus Melanoplus, as summarized and revised by Rehn (1946), have been reported as occurring on pine, juniper, and cedar, but few reports of actual feeding on conifers have appeared in the literature. Because of this paucity of information regarding the use of conifers as food for grasshoppers, we summarize here observations of several kinds of grasshoppers feeding on red pine (Pinus resinosa Aiton) in 1966 in Michigan

Biology, Injury, and Control of the European Needle-bending Midge (Diptera: Cecidomyiidae) on Scotch Pine in Michigan

Contarinia baeri is univoltine in Michigan. Adults emerge in spring, and females deposit eggs in small clusters in the sheaths of new-growth pine needles. Larvae hatch shortly thereafter and there are three larval instars. Larval feeding causes the needles to at first droop, discolor, and eventually drop, reducing the quality of Christmas trees and occasionally killing shoots. Larvae overwinter on the ground in cocoons, and pupate in spring. Adults were suppressed (\u3e 75% control) with formulations of Pydrin® (fenvalerate) and Tempo® (cyfluthrin) applied within a week after adult emergence

Episodic neurologic disorders: syndromes, genes, and mechanisms.

Many neurologic diseases cause discrete episodic impairment in contrast with progressive deterioration. The symptoms of these episodic disorders exhibit striking variety. Herein we review what is known of the phenotypes, genetics, and pathophysiology of episodic neurologic disorders. Of these, most are genetically complex, with unknown or polygenic inheritance. In contrast, a fascinating panoply of episodic disorders exhibit Mendelian inheritance. We classify episodic Mendelian disorders according to the primary neuroanatomical location affected: skeletal muscle, cardiac muscle, neuromuscular junction, peripheral nerve, or central nervous system (CNS). Most known Mendelian mutations alter genes that encode membrane-bound ion channels. These mutations cause ion channel dysfunction, which ultimately leads to altered membrane excitability as manifested by episodic disease. Other Mendelian disease genes encode proteins essential for ion channel trafficking or stability. These observations have cemented the channelopathy paradigm, in which episodic disorders are conceptualized as disorders of ion channels. However, we expand on this paradigm to propose that dysfunction at the synaptic and neuronal circuit levels may underlie some episodic neurologic entities