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Free keywords:
Animals
Female
GABA Antagonists/pharmacology
Grasshoppers/*physiology
Male
Membrane Potentials
Neurons, Afferent/*physiology
*Odorants
Olfactory Pathways/*physiology
Picrotoxin/pharmacology
Receptors, GABA/physiology
Sense Organs/physiology
Sensory Receptor Cells
Synaptic Transmission
gamma-Aminobutyric Acid/*physiology
Abstract:
Stimulus-evoked oscillatory synchronization of neural assemblies and temporal patterns of neuronal activity have been observed in many sensory systems, such as the visual and auditory cortices of mammals or the olfactory system of insects. In the locust olfactory system, single odor puffs cause the immediate formation of odor-specific neural assemblies, defined both by their transient synchronized firing and their progressive transformation over the course of a response. The application of an antagonist of ionotropic gamma-aminobutyric acid (GABA) receptors to the first olfactory relay neuropil selectively blocked the fast inhibitory synapse between local and projection neurons. This manipulation abolished the synchronization of the odor-coding neural ensembles but did not affect each neuron's temporal response patterns to odors, even when these patterns contained periods of inhibition. Fast GABA-mediated inhibition, therefore, appears to underlie neuronal synchronization but not response tuning in this olfactory system. The selective desynchronization of stimulus-evoked oscillating neural assemblies in vivo is now possible, enabling direct functional tests of their significance for sensation and perception.
