Journal of Neuroscience, Vol 16, 313-324, Copyright © 1996 by Society for Neuroscience
High-speed optical imaging of afferent flow through rat olfactory bulb slices: voltage-sensitive dye signals reveal periglomerular cell activity
DM Senseman
Division of Life Sciences, University of Texas at San Antonio 78249, USA.
Fast, multiple-site optical recording and video imaging techniques were
combined to visualize the olfactory processing stream as it flowed through
rat olfactory bulb slices stained with the voltage-sensitive dye RH155. A
464 element photodiode detector array was used to record the
voltage-sensitive dye signals. Focal electrical stimulation of the
olfactory nerve layer evoked relatively large optical responses in the
olfactory nerve and glomerular layers but only small responses within the
external plexiform layer. With paired-pulse stimulation, glomerular
attenuation was evident in signals recorded from the glomerular and
external plexiform layers but not from the olfactory nerve layer. At very
high recording speeds ( < 0.2 msec/frame), the presynaptic component of
the olfactory processing stream could be followed as it flowed through the
olfactory nerve layer and into the glomerular layer, where its amplitude
rapidly declined. This decline was followed by a reciprocal rise in a
postsynaptic depolarization that was largely restricted to the glomerular
layer. Spatiotemporal interactions between overlapping afferent streams
within the glomerular layer were observed and partially characterized. The
optically recorded glomerular layer response was largely resistant to bath
application of GABAA receptor antagonists but was sensitive to
manipulations of external chloride concentration and to bath application of
a stilbene derivative, 4-
acetamido-4'isothiocyanatostilbene-2,2'-disulfonic acid known to block Cl-
conductances. It is suggested the the voltage-sensitive dye signals
recorded from the glomerular layer reflect activity in periglomerular cells
and that Cl- efflux through non-GABAA chloride channels contributes to the
postsynaptic depolarization of these cells after olfactory nerve
stimulation.
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