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A Novel Procedure for Evaluating the Reinforcing Properties of Tastants in Laboratory Rats: Operant Intraoral Self-administration
Published on: February 6, 2014
Olfactory influences on the ingestive behavior of infant rats
Insights
Infant rat pups aged 3-9 days show behavioral activation and increased intake in response to milk odor, demonstrating early olfactory learning. This response is specific to milk and influenced by factors like deprivation.
Area of Science:
- Neuroscience
- Developmental Psychology
- Olfactory Learning
Background:
- Early life experiences shape sensory processing and behavior.
- Infant mammals rely heavily on olfactory cues for survival, particularly for locating nourishment.
- Understanding the ontogeny of olfactory responses is crucial for developmental studies.
Purpose of the Study:
- To investigate the behavioral responses of infant rats to milk odor.
- To determine the developmental trajectory of olfactory responsiveness to milk.
- To examine the specificity and influencing factors of milk odor-induced behaviors.
Main Methods:
- Exposure of infant rats (1-12 days old) to milk odor with and without oral infusions.
- Testing responses to various odors to assess specificity.
- Manipulating deprivation and ambient temperature to observe effects on odor response.
Main Results:
- Infant rats (3-9 days old) exhibited behavioral activation (mouthing, probing) to milk odor.
- Increased intake of solutions was observed in the presence of milk odor in 6- and 9-day-old pups.
- Responsiveness to milk odor was absent in 1-day-old pups and diminished by 12 days.
- Milk odor elicited a more specific and intense response compared to other tested odors.
- Deprivation and ambient temperature modulated responses to milk odor.
Conclusions:
- Infant rats develop a specific behavioral and ingestive response to milk odor between 3 and 9 days of age.
- This olfactory learning is influenced by developmental stage, nutritional status (deprivation), and environmental conditions.
- The findings highlight the critical role of olfactory cues in early life development and feeding behaviors.
Abstract:
Twenty-four-hour deprived infant rats from 1 to 12 days of age were exposed to the odor of milk, either by itself or accompanied by oral infusions of water, sucrose, quinine, or milk (Experiment 1). Pups from 3 to 9 days of age became behaviorally active, and mouthed and probed in response to the odor of milk, even in the absence of oral infusions. Six- and 9-day-old pups also increased their intake of various test solutions in the presence of milk odor. This responsiveness to milk odor was not seen in 1-day-old pups, and waned by 12 days of age. Other stimulus odors that were presented in the same context (Experiment 2) failed to elicit such intense behavioral activation, indicating that there was some degree of specificity in the responsiveness to milk odor. Finally, 2 manipulations that influence pups' ingestion of milk, deprivation and ambient temperature, were found to influence pups' responses to milk odor (Experiment 3).
