Sensory tuning

The carnivorous fish all have diets which are reasonably similar in chemical composition. The herbivorous species in our study has a diet completely unlike any previously studied species. By taking a comparative approach, we hope to examine the concept of "sensory tuning" and the way in which selection of diet is regulated by sensory control. 

Chemosensory neurons of the vomeronasal system are narrowly tuned to specific chemical cues, and utilize a unique mechanism of sensory transduction 824... 

The sensory neuron from the tail makes a synapse with the modulating neuron, known as an intemeuron. Its job is to fine-tune the response of the sensory neuron to stimulation. Note that the intemeuron synapses with both the cell body and the presynaptic terminal of the sensory neuron. The neurotransmitter released by the intemeuron into these synapses is serotonin (also a key neurotransmitter in the human nervous system). The net effect of the serotonin release is to strengthen the connection between the sensory neuron and the motor neuron. It remains to explain how this happens that, too, has been tracked down in molecular detail. 

An important anatomical feature of the LC is the rich innervation by afferents from the sensory systems. This puts the LC in the position to monitor the internal and external environments. The widespread LC efferents in turn then lead to an inhibition of spontaneous discharge in the target neurons. Therefore, the LC is thought to be crucial for fine-tuning the attentional matrix of the cortex and the activity in limbic structures. Anxiety disorders may be due to perturbations of this system. 

The sensitivity and selectivity of olfaction and contact chemosensation are due (1) in the brain, to the existence of a neuronal network of neurons tuned to a specific chemical stimulus, and (2) in the periphery, to the existence of olfactory/ chemosensory receptor neurons housed in sensory microorgans called sensilla. The sensilla can best be viewed as simple cuticular porous extrusions that increase the surface that captures airborne odorants or chemicals dissolved in water droplets. They contain the receptive olfactory or chemosensory structures (Schneider, 1969). The olfactory sensilla are most numerous on the antennae and mediate the reception of sex pheromones and plant volatiles, as well as other odorants. Low volatility pheromones may also be detected by contact chemoreceptors on... 

Many insects have in addition to a large number of sexually isomorphic glomeruli also sex-specific glomeruli with specialized functions. The best studied are the male-specific MGCs, that receive input from sensory neurons tuned to components of the conspecific sexual pheromone, or to allospecific compounds inhibiting sexual behavior. These glomeruli can readily be identified and the innervation is stereotyped with respect to input, i.e. each compartment of the MGC is innervated by a specialized type of neuron (Hansson el al., 1992 Hansson and Christensen, 1999). 

This story has a happy ending, however. Taking advantage of the retardation of PET in neutral systems in solvents of lower polarity, we were able to tune the sensory performance of both (14) and (18) to very respectable levels in terms... 

Luecke, H., Schobert, B., Lanyi,J. K., Spudich, E. N., and SpudichJ. L. (2001). Crystal structure of sensory rhodopsin II at 2.4 angstroms insights into color tuning and transducer interaction. Science 293, 1499-1503. 

Dunten, P. Koshland, D. E., Jr. (1991). Tuning the responsiveness of a sensory receptor via covalent modification. J. Biol. Chem. 266, 1491-1496. 

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