Geniculate ganglion system

The sensation of pleasant is postulated on the basis of cat neurophysiology and human psychophysics. The pleasant sensation is assumed to arise from the stimulation of a. small fiber geniculate ganglion system. The stimuli eliciting the pleasant sensation are lactones and other carbon-oxygen compounds (23). 

Pleasant is associated with the small fibre geniculate ganglion system and is evoked by lactones and similar carbon-oxygen compounds. Umani is a Japanese word used to describe the sensation elicited by the amino acid monosodium glutamate and the nucleotides sodium inosinate and sodium guanylate. The metallic sensation is produced by certain salts such as silver... 

Table I Summary of Neurophysiological Investigations on Mammalian Geniculate Ganglion Taste Systems.

Studies on human taste sensations confirm and extend our understanding of the types of chemical signals measured by these oral chemoreceptor systems. There are, for instance, several distinct sensations elicited by chemical stimulation of fungiform papillae innervated by the geniculate ganglion, indicating that a neural functional complexity similar to that described above for... 

Salt Responsive Units. One of the neural groups with the simplest stimulus chemistry is the GG salt system found only in the geniculate ganglion of the rat and goat. These units are only responsive to sodium or lithium salts. When a series of Cl salts with different cations are examined, only those with Na and Li elicit large responses (Fig. 3). Na and Li are effective with other anions as well, although responses are largest with I and F (6). 

The fungiform papillae taste systems consist of taste bud receptors distributed on the fungiform papillae which are located on the anterior surface of the tongue and the peripheral sensory neurons in the geniculate ganglion of the facial nerve. These neurons collect sensory information relevant to the chemical nature of food substances in the mouth. This chemosensory information is encoded into a series of pulses and transmitted to the central nervous system over nerve fibers that stretch from the tongue to the central nervous system (Figure 3). These pulse trains can be measured electrically with microelectrodes in the... 

By flavor chemistry is meant the chemistry of the total complement of sensory responses elicited by a food or a food component. In human sensory research, the sensory responses are psychophysical sensations, whereas in neurophysiological studies the responses are measured from neurons. The flavor chemistry of the geniculate ganglion fungiform papillae taste systems would then consist of a description of the neural responses to foods and to the types of compounds present in food. The neural responses of both the dog and the cat have been examined with respect to the excitability of many of the compounds found in vertebrate tissues. The cat has been tested with more compounds than the dog, but the results will also apply in large part to the dog, since the two species are so similar with respect to the majority of the compounds considered. 

Off-flavor or bitterness is usually reported for compounds such as creatine, creatinine and nucleotide bases. A mixture of several different types of compounds has been reported necessary to reconstruct meat flavors. This chemical complexity suggests that different sensory systems are being activated. Many of these compounds appear to exert their effects through human geniculate ganglion taste systems others obviously stimulate other oral chemoresponsive systems. 

Human hearing arises from airborne waves alternating 50 to 20,000 times a second about the mean atmospheric pressure. These pressure variations induce vibrations of the tympanic membrane, movement of the middle-ear ossicles connected to it, and subsequent displacements of the fluids and tissues of the cochlea in the inner ear. Biomechanical processes in the cochlea analyze sounds to frequency-mapped vibrations along the basilar membrane, and approximately 3,500 inner hair cells modulate transmitter release and spike generation in 30,000 spiral ganglion cells whose proximal processes make up the auditory nerve. This neural activity enters the central auditory system and reflects sound patterns as temporal and spatial spike patterns. The nerve branches and synapses extensively in the cochlear nuclei, the first of the central auditory nuclei. Subsequent brainstem nuclei pass auditory information to the medial geniculate and auditory cortex (AC) of the thalamocortical system. 

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