To test the hypothesis that different odorants are likely to cause distinctive changes in the ongoing electrical activity of populations of olfactory cells, we investigated field potentials (FP) in the Helix brain and their alterations by odorants as seen by semimicroelectrodes in an isolated preparation of the rostrum with its olfactory organ and whole central nervous system. Five pure chemica...

Behavioral studies of olfactory discrimination and stimulus generalization in many species indicate that the molecular features of monomolecular odorants are important for odor discrimination. Here we evaluate how features, such as carbon chain length and functional group, are represented in the first level of synaptic processing. We recorded antennal lobe ensemble responses in the moth Manduca...

Response times provide essential subthreshold perceptual data that extend beyond accuracy alone. Behavioral reaction times (RTs) were used to characterize rats' ability to detect individual odorants in a series of complimentary binary odorant mixture ratios. We employed an automated, liquid-dilution olfactometer to train Fischer 344 rats (N = 8) on an odor identification task using nonreinforce...

To simulate the occurrence of masking phenomena with the aid of an air dilution sensory (ads) test, two types of odorant mixtures were prepared: (1) M(2) with two individual odorants [H(2)S and acetaldehyde (AA)] and (2) M(6) with six individual odorants (H(2)S and five aldehydes). The test results derived for samples containing single individual odorants at a wide range of concentrations are i...

The gradient of activity produced along the olfactory mucosa by odorant stimulation was measured by the ratio (the LB/MB ratio) of the summated neural discharges recorded from two branches of the olfactory nerve, a lateral branch (LB) supplying a mucosal region near the internal naris and a medial branch (MB) supplying a region near the external naris. Twenty-four frogs "sniffed" sixteen differ...

The perception and discrimination of thousands of different odorants by the vertebrate olfactory system results from the activation of specific olfactory neurons within the olfactory epithelium of the nose (reviewed in Buck, 2000; Firestein, 2001). Activity from these cells is then interpreted by the brain to discern the molecular identity of a given odorant stimulus. How is this process of mol...

Using a conditioning paradigm, the olfactory sensitivity of four spider monkeys, three squirrel monkeys and three pigtail macaques to four thiols and two indols, substances characteristic of putrefaction processes and faecal odours, was assessed. With all odorants, the animals significantly discriminated concentrations below 1 p.p.m. (part per million) from the odourless solvent, and in several...

Animals perceive their olfactory environment not only from odors originating in the external world (orthonasal route) but also from odors released in the oral cavity while eating food (retronasal route). Retronasal olfaction is crucial for the perception of food flavor in humans. However, little is known about the retronasal stimulus coding in the brain. The most basic questions are if and how ...

Recent studies have pointed to olfactory system beta oscillations of the local field potential (15-30 Hz) and their roles both in learning and as specific responses to predator odors. To describe odorant physical properties, resultant behavioral responses and changes in the central olfactory system that may induce these oscillations without associative learning, we tested rats with 26 monomolec...

Although odorants are known to activate olfactory receptor neurons through cAMP, the long-term effects of odorant detection are not known. Our recent findings indicate that there is also a delayed and sustained cAMP response, with kinetics sufficient to mediate long-term cellular responses. This cAMP response is mediated by cGMP through activation of adenylyl cyclase by protein kinase G (PKG). ...