Si. Cromarty et Cd. Derby, MULTIPLE EXCITATORY RECEPTOR TYPES ON INDIVIDUAL OLFACTORY NEURONS - IMPLICATIONS FOR CODING OF MIXTURES IN THE SPINY LOBSTER, Journal of comparative physiology. A, Sensory, neural, and behavioral physiology, 180(5), 1997, pp. 481-491
The aim of our paper was to investigate whether single olfactory recep
tor neurons (ORNs) of the spiny lobster Panulirus argus functionally e
xpress more than one type of receptor, examine the consequences of thi
s on coding of mixtures, and compare principles of odorant mixture cod
ing by spiny lobsters with that by the channel catfish, which has been
studied extensively using the same experimental and analytical proced
ures (Caprio et al. 1989; Kang and Caprio 1991). We examined responses
of individual taurine-sensitive ORNs to binary mixtures of excitatory
compounds, either competitive agonists (taurine, beta-alanine, hypota
urine> or non-competitive agonists (taurine, L-glutamate, ammonium chl
oride, adenosine-5'-monophosphate. Responses to mixtures were compared
to two indices: mixture discrimination index (MDI) and independent co
mponent index (ICI). Binary mixtures of competitive agonists had MDI v
alues close to 1.0, as expected for competitors. Mixtures of non-compe
titive agonists had ICI values averaging 0.83, indicating the effects
of the components are not independent. We conclude that individual olf
actory cells of spiny lobsters can express more than one type of recep
tor mediating excitation, one of which typically has a much higher den
sity or affinity, and that spiny lobster and catfish olfactory cells e
ncode mixtures of two excitatory agonists using similar rules.