Nano Bio Technology

All the complexity of the olfactory system in insects is regulated by a single giant interneuron. The sense of smell is crucial for eating the matching and survival, so it is important that the olfactory system is fully operational at all times. A few years ago identified a backup stem cells that can repair severe damage to the nerves responsible for the sense of smell.

Neuron Controls

This reserve is usually located close to functional neurons, doing nothing, but when neighboring cells die, the stem cells into action. The cells then act as a fail-safe to ensure continued function of the sense of smell, which encode complex patterns of olfactory signals.

Machinery for the codification of odors in the locust

In the real world, the smells are not presented as a blow at the time. Animals move and adrift columns distorted odor molecules (such as smoke), changing direction as the wind scatters them. Short time ago revealed that, in locusts, the brain encodes these patterns using curved and complex machinery that contains few groups neurons.

Olfactory neurons and the principle of coding efficiency

The principle of efficiency of the code is the adaptation of sensory neurons to the statistical characteristics of natural stimuli. In study made a few years ago, states that the moth neurons process stimuli better occur more frequently, this is evidence that the system follows the principle of coding efficiency.

The odor receptors:

The ability to discriminate odors depends on receptor cells expressing different patterns of receptor genes, regardless of which each cell has the same genes. A few years ago demonstrated the receivers are controlled by patterns in DNA sequences found in a certain position on the receptor genes.

The locust control interneuron:

Now, scientists at the Max Planck Institute for Brain Research in Frankfurt, have found a neuron in the brain of locusts that allows the adaptive regulation of olfactory codes. It is a giant interneuron leading real-time track of the activity of tens of thousands of neurons in the olfactory center and feedback to all to maintain its collective output within an appropriate regime. In this way the representation is fixed to the extent that the intensity of the input or the complexity vary.

In insect olfactory data are sent to antennal lobes where they are processed and some regions of the brain called mushroom bodies, the neurons of these bodies are called Kenyon cells. Each average Kenyon cell is connected to half of all potential presynaptic cells of the antennal lobes. The interneuron, which is highly branched, is activated by all Kenyon cells and that inhibits them, forming a feedback loop negative.

This single interneuron may, in real time, processing an average kind of information of all neurons Kenyon, instead it would take hundreds of thousands of individual neurons.

Vertebrates may have a similar mechanism coding

The interneuron, in turn, is controlled by another inhibitory neuron, which allows the network activity is enhanced or attenuated, in addition to being able to adjust the sensitivity of the feedback loop. This is important for brain regions such as the mushroom bodies, which are not only responsible for processing olfactory but also of learning and memory. In the mushroom bodies odors can be associated with other sensory modalities, allowing the formation of complex representations.

In vertebrates the analogue of the mushroom bodies is piriform cortex. “It is quite possible that mammals have similar mechanisms of control in cortical circuits or other. Interneurons may not be unique, but inhibitory neuron populations with means to attach their responses and actions” Gilles Laurent is leading the research team. “Insect’s brain never stops giving us data on neural computation, and gives us elegant solutions if you know where to look and have some luck”.