Animals neurophysiology

In view of the universal role of the area postrema (AP) in emesis among animal species, including man [54], an analysis of this structure in terms of receptors, neurotransmitters and neurophysiological responses is indicated. The AP has also been implicated in several other functions (cardiovascular, caloric intake, osmotic water balance) unrelated to emesis [55], The reader is referred to general and comprehensive references on this neuronal structure [36, 37, 56],... 

Land animals exploit the odorsphere, the world of vapors around them. In any given locale, they move in an odorscape, a landscape of volatiles. Even in fish we speak of odors because neurophysiologically the olfactory system is involved, even though water-soluble stimulants are not necessarily volatile. We expect vertebrates to have taken advantage evolutionarily of the physicochemical characteristics of their environment first to select and then to optimize chemical communication. The chemical communication system of a cold-water fish differs vastly from that of a tropical bat. Despite similar biological functions, each system has been shaped by, and is adapted to, a distinct set of environmental circumstances. 

The Neurophysiology Sensory Evoked Potentials test guideline (OPPTS 870.6855) is designed to detect and characterize changes in the sensory aspects of nervous system function that result from exposure to chemical substances. The techniques involve neurophysiological measurements from adult animals and are sensitive to changes in the function of auditory, somatosensory (body sensation), and visual sensory systems. 

Animals continually exposed to concentrations between 100 and 600 ppm developed signs of peripheral neuropathy after 4-8 weeks in cats, the conduction velocity of the ulnar nerve was less than one-half of normal after exposure for 7-9 weeks. In these animals, histologic examination revealed focal denudation of myelin from nerve fibers with or without axonal swelling. In rats and monkeys, adverse effects on neurophysiological indicators of nervous system integrity were found with 9-month exposures to 100 ppm, 6 hours/day, 5 days/week. MBK neuropathies, however, occurred only after 4-month exposure at 1000 ppm. Four months of intermittent respiratory exposure of rats to 13 00 ppm caused severe symmetric weakness in the hind limbs. ... 

The first is that the activity of chemically specific cell groups correlates more strongly than any other brain measure with REM sleep vs. waking neurophysiology in animals (and hence, by implication, with dreaming vs. waking consciousness in humans). 

The primary approach currently used to detect and characterize potential neurotoxicants involves the use of animal models, particularly rodents. Behavioral and neurophysiological tests, often similar to the ones used in humans, are typically administered. The sensitivity of these measures to neurotoxicant exposure is widely accepted. Although it is often not possible to test toxicant effects on some higher behavioral functions in animals (e.g., verbal ability, cognitive flexibility), there are other neurobehavioral outcomes such as memory loss, motivational defects, somatosensory deficits, and motor dysfunction that can be successfully modeled in rodents. These behaviors are based on the ability of the nervous system to integrate multiple inputs and outputs, thus they cannot be modeled adequately in vitro. Although the bulk of neurotoxicity data has been collected in rodents, birds and primates are also used to model human behavioral outcomes. 

Anatomically, the chemosensory cells of these animals share a unifying set of characteristics they are bipolar neurons with ciliated dendrites closely apposed to the environment and axons that project into the central nervous system from a peripherally located cell body. This is a cellular bodyplan that is characteristic of chemosensory cells from a broad range of metazoan phyla, so much that has been learned by the study of crustacean chemosensory neurophysiology has been of heuristic value to the understanding of chemoreception in other organisms. 

Downs, R. M., and Liben, L. S. (1987). Children s understanding of maps. In P. Ellen and C. Thinus-Blanc (eds.), Cognitive processes and spatial orientation in animal and man, vol. 1 Neurophysiology of spatial knowledge and developmental aspects (pp. 202-219). Dordrecht, Holland Martinius Nijhoff. 

In this report the neurophysiology of mammalian taste systems is reviewed with especial attention to stimulus chemistry. The neurophysiology described is primarily that from our laboratory, since we have been among the few neurophysiologists concerned with stimulus chemistry. The animals that have been investigated in detail are the cat, dog, goat and rat. Work on other animals is included where comparisons are viable. 

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