Reversal potentials (E~psp) of the inhibitory postsynaptic potential and the membrane resting potentials (E~r) of lobster muscle fibers were determined with intracellular recording under a variety of ionic conditions. ErPsP is solely dependent on the electromotive force of anionic batteries; i.e., on the electrochemical gradient for a "mobile" fraction of intracellular Cl (Cll) which is considerably smaller than the total intraceUular CL The active inhibitory membrane is more permeable to certain "foreign" anions in the order NOa > SCN > Br > CA. The membrane is impermeable to BrO3, isethionate, and methylsulfate, but is slighdy permeable to acetate and propiohate. The level of Cll appears to be determined in part by some active (pump?) process and most of the anions studied appear to interfere with the steady-state level of Cli.
Extracellular single-unit responses to odorants with various properties were recorded from mitral/tufted cells over large areas of the olfactory bulb of anesthetized rats. Each cell was exposed to one stimulus set consisting of five different odorants each at five concentrations. The resulting concentration-response profiles were compared. All mitral/tufted cells examined responded to two or more odorants, and the largest proportion of the cells were sensitive to all five odorants. Cells unresponsive to all five odorants regardless of concentration were not observed. Mitral/tufted cells sensitive to all three of the odorants that are known to evoke maximal electro-olfactograms in different regions of the olfactory epithelium were distributed widely throughout the olfactory bulb. There were no significant differences in latencies of odor responses either across recording sites or across odorants. A comparison of the concentration-response profiles suggested that all of the mitral/tufted cells were equally capable of responding to any odorant with their own distinctive pattern, but that the cells tended to show an identical pattern rather than variable pattern of response to different odorants. Five mitral/tufted cells isolated within 800 microns of one electrode track showed different concentration-response profiles. Of 18 simultaneously recorded spike pairs with different amplitudes and discharge patterns recorded incidentally through one electrode at different sites, 10 had different and 8 had identical response patterns to odorants. These results suggest that: (1) mitral/tufted cells are sensitive to a broad spectrum of odorants, but respond with their own patterns to odorants; (2) odor discrimination is not uniform in neighboring cells, and a discrimination unit is comprised of a single cell.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.