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Updated: Aug 11, 2026
A Novel Procedure for Evaluating the Reinforcing Properties of Tastants in Laboratory Rats: Operant Intraoral Self-administration
Published on: February 6, 2014
Intake and behavioral responsiveness to taste stimuli in infant rats from 1 to 15 days of age
Insights
Infant rats show aversion to bitter tastes early on, but complex responses like chin scraping develop later. This indicates developmental immaturity in neural pathways, not taste detection, for these behaviors.
Area of Science:
- Neuroscience
- Developmental Biology
- Sensory Science
Background:
- Early life taste experiences shape feeding behaviors.
- Understanding the development of taste aversion is crucial for infant development research.
Purpose of the Study:
- To investigate the developmental timeline of taste aversion responses in infant rats.
- To determine if early detection of aversive tastes matures before complex motor responses.
Main Methods:
- Oral infusions of taste solutions (acid, quinine) administered to infant rats (1-15 days old).
- Observation and recording of intake and specific behavioral responses (gaping, flailing, chin scraping, paw treading).
- Experiments manipulated deprivation state and infusion site to assess their influence.
Main Results:
- Infant rats consistently suppressed intake and showed basic aversive responses (gaping, flailing) from day 1.
- Complex aversion behaviors (chin scraping, paw treading) emerged around 12 days of age.
- Deprivation state and infusion site did not significantly alter the emergence of these behaviors.
Conclusions:
- Infant rats can detect aversive tastes early in life.
- The delayed emergence of certain aversion behaviors is linked to neural immaturity, not taste perception.
- Developmental maturation of neural substrates underlies complex aversive responses.
Abstract:
Infant rats from 1 to 15 days of age received oral infusions of various taste solutions, and their intake of and behavioral responses to the infusions were observed. From 1 day of age on, pups responded to strong acid and quinine solutions with certain characteristic aversive responses and suppressed intake (Experiment 1). Although even very young (1- and 3-day-old) pups suppressed their intake of strong quinine and acid solutions, and rejected them by showing certain aversive responses (gaping and forelimb flailing), other components of the adultlike aversion response sequence (chin scraping and paw treading) did not appear until approximately 12 days of age. This suggests that the failure of pups to engage in chin scraping and paw treading prior to 12 days is not due to an inability to detect aversive solutions, but rather may be due to an immaturity in pups younger than 12 days of the neural substrates subserving these aversive responses. The emergence of chin scraping and paw treading to strong acid or quinine solutions was not influenced to any marked extent by either the deprivational state of the pup (Experiment 2a) or the site of the infusion (Experiment 2b).
