Ingestion affected by the oral environment: The role of gustatory adaptation on taste reactivity in the rat

Intensity coding in the transient portion of the rat chorda tympani response.

“…However, in the rat and other mammalian preparations the tonic component does not return to baseline (Pfaffmann, 1955;Pfaffmann & Powers, 1964). In view of this, it has been suggested that changes in the peripheral neural response are not adequate to explain the effects of adaptation on preference behavior (Halpern, 1967;McCutcheon, 1971;Wilcove, 1973). In fact, Wilcove argued that central mechanisms of adaptation are required to account for alterations in preference behavior following prolonged stimulation.…”

“…Surgery. An oral cannula (Vance, 1970;Wilcove, 1973) was implanted in each animal by drilling a small hole through the nasal bone and hard palate under ether or Ketamine hydrochloride (75 mg/kg) anesthesia. A deep level of anesthesia was maintained by supplementary injection when Ketamine hydrochloride was used.…”

“…There has been some experimental evidence to support this latter view; for example, rats can discriminate gustatory quality within the duration of the transient phase of the response (Halpern & Tapper, 1971), which indicates that sufficient information for quality discrimination is present in the phasic component. In addition, continuous stimulation, which has its most obvious effect on the transient portion of the chorda tympani response in rats and cats (Smith & Frank, 1972;Wang & Bernard, 1970) although it also depresses the steady state (Smith, Bealer, & Van Buskirk, Note 1), reduces subjective taste intensity in humans (McBurney, 1966;McBurney & Pfaffmann, 1963), and alters taste-preference relationships in rats (McCutcheon, 1971;Vance, 1970;Wilcove, 1973) in a direction predicted by decreased sensitivity. These studies indicate that the transient response contributes a significant amount of sensory information to gustatory sensation.…”