title: Unconditioned oromotor taste reactivity elicited by sucrose and quinine is unaffected by extensive bilateral damage to the gustatory zone of the insular cortex in rats.
abstract: Rats display stereotypical oromotor and somatic responses to small volumes of intraorally infused taste solutions. These behaviors, known as taste reactivity, are categorized by their association with ingestion or rejection and are thought to reflect the palatability of the stimulus. Because supracollicular decerebrate rats display normal taste reactivity responses, it would appear that forebrain structures are not necessary for generating them. However, because moving the plane of transection rostrally, or damaging or manipulating specific ventral forebrain sites disrupts normal taste reactivity behavior, lesions of the gustatory cortex, a region that has been suggested to be involved with palatability processing, may do the same. In the current study, rats received two injections of either ibotenic acid (N=12) or vehicle (N=8), targeting the conventionally defined gustatory cortex in each hemisphere, and were implanted with intraoral cannulae. Following recovery, their responses to intraoral infusions (0.23ml in 1min) of dH2O, sucrose (1.0M and 0.1M), and quinine hydrochloride (3mM and 0.3mM) were video recorded. Analysis of brains with sufficient bilateral lesions (N=10) revealed that, on average, approximately 94% of the gustatory cortex was destroyed. These extensive bilateral lesions had no significant effect on taste reactivity; the numbers of ingestive and aversive responses to sucrose and quinine were similar between groups. Though these findings do not rule out involvement of the gustatory cortex in palatability processing, they make evident that the region of insular cortex destroyed is not necessary for the normal expression of unconditioned affective behavioral responses to taste stimuli.
authors.affiliation: Department of Psychology, Stetson University, DeLand, FL, USA. Electronic address: cking@stetson.edu.
authors.forename: Camille Tessitore
authors.initials: CT
authors.lastname: King
authors.affiliation: Department of Morphological and Physiological Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan; Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, FL, USA. Electronic address: coji@kumamoto-u.ac.jp.
authors.forename: Koji
authors.initials: K
authors.lastname: Hashimoto
authors.affiliation: Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, FL, USA.
authors.forename: Ginger D
authors.initials: GD
authors.lastname: Blonde
authors.affiliation: Department of Psychology & Program in Neuroscience, Florida State University, Tallahassee, FL, USA. Electronic address: spector@psy.fsu.edu.
authors.forename: Alan C
authors.initials: AC
authors.lastname: Spector
mesh_terms: D000818:Animals; D002408:Catheters, Indwelling; D002540:Cerebral Cortex / Q000293:injuries / Q000502:physiology*; D004327:Drinking Behavior / Q000502:physiology*; D007051:Ibotenic Acid; D011803:Quinine / Q000008:administration & dosage*; D017207:Rats, Sprague-Dawley; D013395:Sucrose / Q000008:administration & dosage*; D013649:Taste / Q000502:physiology*; D055697:Taste Perception / Q000502:physiology*; D014867:Water / Q000008:administration & dosage
chemical_list: D014867:Water; D007051:Ibotenic Acid; D013395:Sucrose; D011803:Quinine
keywords: Cortex; Hedonic; Motivation; Palatability; Taste reactivity