Stereo Smelling

In 2003, two British artists Leslie Hill and Helen Paris, in an artistic exploration of the connections between smell and memory, created an art installation in London that evoked everyday smells.

In 2003, two British artists Leslie Hill and Helen Paris, in an artistic exploration of the connections between smell and memory, created an art installation in London that evoked everyday smells. They a lot of time with Indian olfactory researcher and computational neuroscientist Upinder Bhalla at his laboratory at the National Centre of Biological Sciences NCBS in Bangalore8212;to understand how the brain processes smell inputs.

Dr Bhalla8217;s computational neuroscience lab is one of those at the forefront of efforts to study the brain8217;s computing ability. 8216;8216;Using slow electrical events and still slower chemical processes the brain achieves computations beyond the reach of supercomputers,8221; he says. 8220;We study three aspects of these computational functions: representation, processing, and information storage.8217;8217;

Unlike vision, just two primary regions of the brain are involved in processing smell. Its strong association with memory also makes smell one of the most viable inputs for studying the brain8217;s computational abilities, according to Bhalla.

In a significant recent scientific finding relating to the process of smell, Bhalla and his colleagues, in a paper published in the journal Science in February, proved a long-standing hypothesis that rats and other mammals don8217;t just hear in stereo8212;they also smell in stereo.

Through experiments in their laboratory Bhalla and his colleagues Raghav Rajan and James P Clement reported that rats locate an odor source within a split second using multiple information inputs like concentration differences in the smell and differences in the time the smell reached the olfactory epithelium. 8216;8216;There have been hints in this direction, what we have done is provide concrete evidence,8217;8217; says Bhalla.

Nearly 50 years ago Georg von Bekesy, who won a Nobel Prize for his work on hearing, first suggested that humans smell in stereo. Whether or not people actually smell in stereo however remained unproven.

8216;8216;Stereo means you simultaneously sample an odor from two locations and compare the signals from those locations, as in stereo hearing,8217;8217; Bhalla explains. NCBS researchers exposed rats to different smells and used electrical probes to record the responses in their olfactory bulbs8212;the part of the brain that processes odors.

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Incidentally, rats are suited for olfactory and brain studies since scientists can efficiently monitor the precise moment of intake of an odor and its resultant brain response using electrical probes. The rats showed behavioural evidence of using stereo cues. Depending on whether a smell was sniffed through the right or left nostril the rats correctly licked a right water spout lick for sniffs through the right nostril and vice-versa. The experiments with rats could be extrapolated for humans, but the human capability to smell in stereo would be lower and much slower.

In a way, the NCBS work so far may also have proven why rats, human and most mammals have two nostrils instead of just one8212;for stereo effect.