R D Hadley

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Isolated neurons from adult central ganglia of the snail Helisoma were cultured in vitro in modified Liebowitz L-15 medium. Such neurons displayed electrical excitability comparable to that in acutely dissected ganglia. Isolated neurons remained spherical in defined medium throughout culture durations up to 2 weeks. This static morphology was contrasted by(More)
A major obstacle to understanding the mechanism of long-term change in the vertebrate nervous system has been the inability to observe the same nerve cell at different times during the life of an animal. The possibility that changes in neural connectivity underlie the remarkable flexibility of the nervous systems of mammals has therefore not been tested by(More)
We describe a means of visualizing the same neuron in the superior cervical ganglion of young adult mice over intervals of up to 3 months. The dendrites of these neurons change during this interval; some branches retract, others elongate, and still others appear to form de novo. Thus, neuronal dendrites in this part of the nervous system are subject to(More)
Identified neurons of the snail, Helisoma, undergo extensive remodeling in response to axotomy, including the formation of specific sets of novel electrical connections. This communication addresses the question of why, under the conditions employed, some neurons readily form new connections with a single "test" neurons, whereas others do not. The present(More)
Our previous experiments have suggested the hypothesis that conjoint active neuronal outgrowth may be necessary for formation of new electrical synapses between identified neurons of adult Helisoma buccal ganglia. This growth dependence hypothesis now has been tested by examining the responses of individual pairs of neurons in isolation from the influences(More)
An in vitro organ culture system for buccal ganglia of the adult snail, Helisoma, is described. The system supports: (1) maintenance of characteristic electrophysiological parameters of identified neurons over seven days of culture; (2) choline metabolism including uptake and synthesis over the same duration; (3) sprouting and growth of neurons in response(More)
The electrically coupled buccal ganglion neurons 4R and 4L of the snail, Helisoma, display predictable plasticity. The strength of the electronic synapse between them increases significantly following axotomy. Synaptic strength was assayed by measurements of electrical coupling coefficients and by assessment of dye coupling (passage of dye into the(More)
Helisoma neurons require a factor(s) present in conditioned medium (CM), for successful neurite outgrowth in vitro. A approximately 300 kDa Helisoma extracellular matrix (ECM) protein has been identified in CM and is necessary for neurite initiation. Here we show that purified approximately 300 kDa ECM protein supports outgrowth. Furthermore, anti-(More)
The response of populations of neurons to axotomy has traditionally been studied by crushing or sectioning whole nerve trunks. The present communication describes a technique by which single neurons can be reliably and selectively axotomized in the absence of damage to other axons and non-neuronal cells within the nerve. To obtain selective axotomy,(More)