Love-struck moth seeks same. Odd number of antennas not a problem.
That could be the "personals" ad placed by an insect called Heliothis virescens, in a series of experiments reported March 22 in the British scientific journal Nature. Lead author is Neil J. Vickers, assistant professor of biology at the University of Utah.
Actually, the study was to discover the way that moths' brains process smells, because this may be analogous to methods other animals, including humans, use.
In one part of the study, a male moth would fly through a cloud of chemical attractant given off by female moths, called pheromones, carrying an extra antenna attached to its head.
Moth antennas function like noses and the extra had electrodes attached to measure electrical activity. Electrical impulses indicated that the antenna was sensing chemicals in the air.
Thousands of receptors, housed inside tiny hairs on the antenna, sense odors in the air. Sensory neurons in the antenna "have little cables that run down the length of the antenna and enter the brain," he said.
The spare antenna that the moth carried, rigged with electrodes to detect electrical activity, is called an electroantennogram. With the extra equipment, researchers released pheromone and "allowed the male then to sort of fly upwind as he normally would," Vickers said.
Recordings of the electrical changes from the spare antenna tell what the structure of the chemical plume is like. That can be correlated to how the moth flew, to give an idea of how it homed in on the attractant.
The study provided new details about "how the brain in part recognizes and discriminates different odors," Vickers said.
The chemical cloud was not continuous but varied in concentrations of attractants, and scientists were able to see how neurons fired in the moths' brains as they navigated through plumes of chemicals that changed in concentration.
"It gives us some idea of what kind of (chemical) structures the male encounters, in terms of the stimulation he's receiving," he said.
Biologists used a wind tunnel to waft the pheromones to the moths, discovering that the moths' brains reacted quickly to the scents. Earlier research had implied the brains responded with a pattern that later led to responses, but this study showed a much more immediate reaction.
Besides the experiments that measured flight and plume makeup, other trials used a miniscule probe to measure electrical activity inside the moths' brains, in the section called the antennal lobe. This is the insect equivalent to human brain's olfactory section.
"This is part of an ongoing effort to understand how the brain is organized to process the chemical world," he said. "There's a huge array of odors out there that animals of different kinds are sensitive to."
Vickers carried out the experiments while he was at the University of Arizona, Tucson. Co-authors of the report are Thomas A. Christensen and John G. Hildebrand of the University of Arizona and Thomas C. Baker of Iowa State University, Ames.
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