THE following six papers derive from a satellite symposium held at the 23rd annual meeting of the Society for Neurosci- ence in Washington, D. C. on November 7, 1993. All articles in this meeting report were updated for currency and were subjected to peer review.T!~e purpose of the symposium Be- havioral, Neural and Pharmacological Aspects of Palatabil- ity: Current Research on Taste Reactivity, was to inform investigators of recent advances in the assessment of palat- ability by the taste reactiviity test, devised by Grill and Nor- gren in (4,5). In his introduction to the symposium, Ralph Norgren referred to a single sentence in a grant proposal writ- ten about 20 years ago that proposed the use of a behavioral measure of orofacial reactions to assess the of tastants. Shortly thereafter, Harvey Grill came to work in Norgren's laboratory at Rockefeller University where he de- veloped the taste reactivity test. Palatability is a difficult concept to define (15) but seems to be a hypothetical construct that is useful from a theoretical point of view (e.g.,16). Whether one partitions this concept into an intrinsic component (ingestant) and an associational component (ingestor) as suggested by Kissilef (11), or as a hedonic response to a taste stimulus based on an integration of taste, organism state, and prior associations (3), it is useful to have a metric which provides information about the mo- mentary behavioral reaction of the animal to the stimulus. The taste reactivity test serves as a tool for directly assess- ing the palatability of a flavored solution on the basis of operationally defined and quantifiable behavioral responses. By means of a permanently implanted intraoral cannula, a flavored solution is delivered across a rat's tongue while its orofacial and somatic responses are videotaped. On the basis of an extensive series of investigations, Grill and Norgren (4) determined that tastants that are normally preferred, such as sucrose solution, elicit iingestive reactions such as tongue protrusions (lateral and forward), mouth movements and paw licking. On the other hand, tastants that are normally avoided, such as quinine solution, elicit aversive reactions such as gaping, chin rubbing, paw treading, forelimb flailing and head shaking. Finally,. examination of the relationships between taste reactivity responses and intake measures in rats (17) has validated the importance of these behaviors in inges- tion. The taste reactivity test has been employed by a number of laboratories to directly index palatability. This methodologi- cal approach has been successfully used in both neural (e.g., 5-7) and pharmacological (e.g., 14) examinations of the con- trols of ingestive behavior. The taste reactivity methodology has several distinct attributes that make it well-suited for an analysis of (8). First, the experimenter has explicit control of the stimulus delivery parameters. Second, taste re- sponsiveness can be measured in nondeprived animals. Third, the taste reactivity test can be used with a variety of neurologi- cal manipulations that render animals aphagic and adipsic (e.g., chronic decerebrate rats). Fourth, small volumes of the taste stimulus can be used to minimize the influence of postin- gestive events. Fifth, changes in behavior can be quantified past the point when animals would cease ingesting the stimu- lus fluid during an intake test. Finally, actual behavior is measured as opposed to the quantification of only the conse- quences of behavior (i.e., amount ingested). The symposium began with an introduction to the tech- nique by Ralph Norgren. This was followed an historical reflection on the development and refinement of the taste reactivity methodology by Harvey Grill and an overview of the importance of examining individual components of taste reactivity by Paul Breslin. The papers presented at this sympo- sium described the research of various investigators in North America (1,2,9,10,12,13) that are currently employing the taste reactivity test in their research programs. The goal of the symposium was to provide a forum for the discussion of collective research involving the taste reactivity methodology. The articles that follow represent the spirit of that discussion and offer broad range of insights into the psychobiological aspects of taste reactivity. In some ways the symposium seD'ed as an assessment of our progress in the conceptualization taste-elicited consummatory behavior. At least one fact re- mains clear. Since its inception as a systematic behavioral technique two decades ago, the taste reactivity methodology has repeatedly demonstrated its power as an anlytical tool that can promote a better understanding of both and the neural control of ingestive behavior. Klaus-Peter Ossenkopp University of Western Ontario, London, Ontario, Canada Linda A. Parker University of Waterloo, Waterloo, Ontario, Canada, Alan C. Spector University of Florida, Gainesville, FL, USA 87
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Mar 17, 2010
Winfried Rief + 3
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