A new study has shown that mice which do not have a receptor in the olfactory centre can easily distinguish similar smells than mice without genetic manipulation.
The researchers in Professor Dr. Thomas Kuner's team at the Institute of Anatomy and Cell Biology at Heidelberg University Medical School and Dr. Andreas Schäfer at the Max Planck Institute for Medical Research directly attributed the above behaviour to inhibitor loops between adjacent nerve cells.
The Heidelberg researchers have for the first time confirmed "lateral inhibition" for the olfactory system, from the molecular level to behaviour. dours attach to receptors of olfactory cells in nasal mucosa, where they trigger nerve signals.
These signals are processed in what is known as the olfactory bulb, a part of the brain.
In the neuronal network, the incoming signal is converted to a specific electrical pattern that is transmitted to the cerebral cortex and other areas of the brain and is recognized there.
The researchers have now shown for the first time how neuronal processing of olfactory stimuli directly affects the behaviour of test animals.
"We manipulated information processing very specifically in the olfactory bulb and then measured the effect of this genetic manipulation based on reaction time. We were thus able to prove that the test animals, due to localized inhibitor loops, could distinguish very similar odor combinations much faster, yet very reliably," explained Kuner.
Inhibition via interneurons acts as a kind of filter by amplifying strong stimuli and further weakening weak stimuli, which makes the essential information easier to recognize.
In the test animals, reaction time was reduced by about 50 ms. The time needed by test animals to learn various odors and their memory capability remained unaffected. Recognition of simple odors was also unchanged.
The results of the study were published in the prestigious journal 'Neuron'.