Perception mammals

The local dynamics of tire systems considered tluis far has been eitlier steady or oscillatory. However, we may consider reaction-diffusion media where tire local reaction rates give rise to chaotic temporal behaviour of tire sort discussed earlier. Diffusional coupling of such local chaotic elements can lead to new types of spatio-temporal periodic and chaotic states. It is possible to find phase-synchronized states in such systems where tire amplitude varies chaotically from site to site in tire medium whilst a suitably defined phase is synclironized tliroughout tire medium 51. Such phase synclironization may play a role in layered neural networks and perceptive processes in mammals. Somewhat suriDrisingly, even when tire local dynamics is chaotic, tire system may support spiral waves... 

In mammals, the main olfactory system is the work horse in the perception of odors. Excellent detailed reviews of the mammalian olfactory system are available elsewhere. In brief, the olfactory epithelium is located on a portion of the scroll bones (endoturbinales and posterior part of nasoturbinales F ig. 5.4), in humans it is located about 1 cm beneath the bridge of the nose. Olfactory reception is affected by several factors, such as the size, shape, or wetness of the nasal passages. In the dog, the olfactory membrane extends over 75-150 cm depending on body size, while in humans it is only 2-4cm. It consists of three... 

Bunger MK, Wilsbacher LD, Moran SM et al 2000 Mop3 is an essential component of the master circadian pacemaker in mammals. Cell 103 1009—1017 Cermakian N, Sassone-Corsi P 2002 Environmental stimulus perception and control of circadian clocks. Curr Opin Neurobiol 12 359—365... 

Olfactory perception translates abstract chemical features of odorants into meaningful neural information to elicit appropriate behavioral responses (Shepherd, 1994 Buck, 1996). Specialized bipolar olfactory sensory neurons (OSNs) are responsible for the initial events in odor recognition. These have ciliated dendrites exposed to the environment, and a single axon that extends into the brain and forms synapses with second order projection neurons (PNs) (Shepherd, 1994 Buck, 1996). In arthropods and mammals, the first olfactory synapse is organized into glomeruli, spherical structures in which afferent olfactory neuron axons synapse with projection neuron dendrites (Hildebrand and Shepherd, 1997). 

The same conclusions were also recorded for vertebrate herbivores. For example rabbits (Cuniculus europaeus) and hares (Lepus europaeus) clearly prefer the sweet plants and leave the bitter plants almost untouched, at least as long as there is an alternative food source. In conclusion, although taste perception in mammals and insects differs in many aspects, there also some similarities both in anatomy and in the function of the bitter taste perception. A comparison of the effects of alkaloids, as well as of other bitter compounds, will be assisted by further advances in the knowledge of the structure of taste genes and receptors. 

Olfaction, like visual and taste perception, is an ancient process. Olfaction plays a role in sexual arousal. The olfactory system in mammals is remarkable with respect to the number of receptors engaged in monitoring odours. There are several thousand hepta-helical G-protein-coupled receptors in the olfactory epithelium and the nasal organ of a dog, and still about 1000 receptors in the corresponding human organs. It has been estimated that nearly 1% of all genes code for olfactory receptors alone. 

Conte C, Ebeling M, Marcuz A, Nef P, Andres-Barquin PJ (2003) Evolutionary relationships of the Tas2r receptor gene families in mouse and human. Physiol Genomics 14 73-82 Dulac C (1997) Molecular biology of pheromone perception in mammals. Semin Cell Dev Biol... 

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