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The terminal nerve is an anterior cranial nerve that innervates the lamina propria of the chemosensory epithelia of the nasal cavity. The function of the terminal nerve is ambiguous, but it has been suggested to serve a neuromodulatory role. We tested this hypothesis by exposing olfactory receptor neurons from mudpuppies (Necturus maculosus) to a peptide,(More)
As we learn more about the neurobiology of olfaction, it is becoming increasingly clear that olfactory systems of animals in disparate phyla possess many striking features in common. Why? Do these features provide clues about the ways the nervous system processes olfactory information? This might be the case if these commonalities are convergent adaptations(More)
In this paper, the evolutionary origin of the vomeronasal system as a discrete sensory system separate from olfaction is examined. The presence of a discrete vomeronasal system appears to be a derived character in tetrapods, and its presence in larval amphibians indicates that the system did not arise as a terrestrial adaptation. The vomeronasal system has(More)
The vertebrate brain actively regulates incoming sensory information, effectively filtering input and focusing attention toward environmental stimuli that are most relevant to the animal's behavioral context or physiological state. Such centrifugal modulation has been shown to play an important role in processing in the retina and cochlea, but has received(More)
Animals must regulate their sensory responsiveness appropriately with respect to their internal and external environments, which is accomplished in part via centrifugal modulatory pathways. In the olfactory sensory system, responsiveness is regulated by neuromodulators released from centrifugal fibers into the olfactory epithelium and bulb. Among the(More)
Peripheral signal modulation plays an important role in sensory processing. Activity in the vertebrate olfactory epithelium may be modulated by peptides released from the terminal nerve, such as gonadotropin releasing hormone (GnRH). Here, we demonstrate that GnRH modulates odorant responses in aquatic salamanders (axolotls, Ambystoma mexicanum). We(More)
Many academics, clinicians and lay readers of science incorrectly assume that vomeronasal processing is equivalent to pheromone processing. We review the abundant data concerning the roles of both the olfactory and the vomeronasal systems in the processing of both pheromones and other odorants, demonstrating that this "equivalency hypothesis" is untenable.(More)
Glossary g0005 olfactory system The olfactory system in any animal is the primary sensory system that responds to chemical stimuli emanating from a distant source. g0010 pheromone A chemical cue that, when released by an individual, elicits specific behavioral or physiological responses from conspecifics. g0015 terminal nerve The most anterior cranial nerve(More)
We examined the anatomy of the nasal cavity and forebrain in the axolotl (Ambystoma mexicanum) to determine whether the olfactory and vomeronasal systems are present in this neotenic aquatic salamander. The current study was motivated by two considerations: (a) little is known of the anatomy of the vomeronasal system in aquatic vertebrates, and (b) the(More)