Mechanical Science: Fowles. Analytical Mechanics by Fowles and Cassiday 7th edition. Mathematics in Science and Engineering Fowles Solution Manual.Tonic activity in the retina is due to the excitatory neurotransmitter glutamate, not acetylcholine: a model study in the salamander.
The retinal ganglion cell layer of the eye of the black salamander spontaneously exhibits intense rhythmic activity and includes at least three distinct groups of cells: bursting cells, membrane depolarized cells (MDCs) and neuroglial-like cells. The bursting cells, originally described by Lampl and colleagues [Holt and Lampl (1970) Pflügers Arch 402:542-550], are the most conspicuous cells in the ganglion cell layer. They exhibit repetitive increases in membrane conductance, which, when brief, produce regular discharges of all-or-none spikes; the all-or-none spike is the hallmark of this discharge. The bursting cells exhibit tonic spikes which could conceivably result from excitatory synaptic transmission of glutamate onto the somas of the neurons. In the present investigation, it is shown that glutamate antagonists (D,L-2-amino-4-phosphonobutyrate (APB), 1-amino-phosphonopentanoate (AMP), and R,S-alpha-amino-3-hydroxy-5-methylisoxasole-4-propionate (AMPA)) do not block the bursting activity. The bursting activity is inhibited by the gamma-aminobutyric acid(A) (GABA(A)) antagonist picrotoxin; however, it is resistant to the GABA(B) antagonist T-phenylcyclohexyl-oxy-3-hydroxy-1-(2-pyridylethyl)indole (CGP 54626). The bursts of bursting cells occur throughout the day and night, indicating that the retinal ganglion cells are part of a self-sustaining system which could exhibit high-frequency oscillations independent of environmental cues. The bursting activity of retinal neurons resembles that of neurons in the isolated retina, but is distinct from the rhythmic activity of nonretinal neurons, such as the retinal ganglion cells of the leech. This work presents a possible model for future studies into the function of retinal ganglion cells.FTA: " 0b46394aab