Concerning the need for more sophisticated animal models in sensory behavioral toxicology.

It is necessary but not sufficient to develop laboratory animal models in sensory behavioral toxicology for screening toxic substances and for the analysis of sensory impairment at threshold levels of stimulation. It is important to develop more thorough and quantitative tests of impairment which in their greater complexity more accurately reflect the conditions and environmental demands of day-to-day life. Such greater complexity in stimulus conditions and behavior may also aid in monitoring not merely the state of the receptor organ but more central nervous processes which are the focus of assault by many known toxic substances. Techniques are described for studying such acoustic behaviors as intensity discrimination and frequency selectivity in guinea pig and monkey by use of operant conditioning procedures coupled with sensory testing (psychophysical) methods. Impaired auditory selectively and discrimination is shown to be correlated with histopathological changes in the inner ear. Slight modification of these procedures in animals may be used to investigate acoustically more intricate behaviors such as sound localization and the perception of frequency modulated acoustic signals as elements of speech and communication sounds.