The relation between stimulus and response in olfactory receptor cells of the tiger salamander.

Abstract

1. Olfactory receptor cells were isolated from the adult tiger salamander Ambystoma tigrinum and the current in response to odorant stimuli was measured with the whole-cell voltage-clamp technique while odorants at known concentrations were rapidly applied for controlled exposure times. 2. Three odorants, cineole, isoamyl acetate and acetophenone, were first applied at 5 x 10(-4) M. Out of forty-nine cells tested, 53% responded to one odorant only, 22% to two odorants and 25% to all three odorants. 3. The amplitude of the current in response to a given odorant concentration was found to be dependent on the duration of the odorant stimulus and reached a saturating peak value at 1.2 s of stimulus duration. 4. The current measured at the peak of the response for odorant steps of 1.2 s as a function of odorant concentration was well described by the Hill equation for the three odorants with Hill coefficients higher than 1 and K1/2 (odorant concentration needed to activate half the maximal current) ranging from 3 x 10(-6) to 9 x 10(-5) M. 5. It is concluded that olfactory receptor cells are broadly tuned and have a low apparent affinity for odorants, integrate stimulus information over time, and have a narrow dynamic range.

Distinct signaling of Drosophila chemoreceptors in olfactory sensory neurons

“…The dose-response relationship was approximately linear at its foot (Fig. 1D, Left, Inset) but was supralinear overall (Hill coefficient, 1.7 for this cell), broadly similar to the behavior of vertebrate OSNs (27,28). As expected from OSNs expressing different Ors, the sensitivity to butyl acetate varied widely across randomly recorded Or-expressing OSNs, with a half-saturating concentration of 0.6-17 mM (10 cells; 3.7 mM in Fig.…”

Intensity coding in two-dimensional excitable neural networks

“…Experimental results show that individual receptor neurons have a small dynamical range [1,2]. Given a properly defined stimulus intensity r (e.g.…”

“…In other words, the dynamical range roughly measures the number of decades over which the stimulus can be properly discriminated 1 , discarding stimuli too faint to be considered "detected" (r < r 10 ) or too close to saturation (r > r 90 ). In olfactory receptor cells of the tiger salamander [1] and the frog [2], ∆r ∼ 1 log unit (10 dB). The psychophysics literature, on the other hand, shows that our ability to discriminate external signals of different kinds covers a large dynamical range [3].…”

“…light intensity for rods in the retina, or odorant concentration for sensory neurons in the olfactory epithelium), the response f (r) of a single neuron (e.g. the spike frequency) saturates at a value f max for sufficiently large values of r. Defining r 10 and r 90 as the stimulus values for which the response attain 10% and 90% of f max , the dynamical range ∆r is usually defined [1] as ∆r = log 10 r 90 r 10 ,…”

Gap junctions in olfactory neurons modulate olfactory sensitivity

“…Subsequent studies further demonstrate that ORN input is responsible for, or partially responsible for, the diverse spatial and temporal dynamics observed in glomeruli [5,6]. These results are in sharp contrast to those from single isolated ORNs in which the dose-response relationships are typically saturated within a log unit [7,8]. The difference appears irrelevant to the techniques used.…”