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Published on: June 10, 2013
Developmental neurobiology of the rat attachment system and its modulation by stress
Reto Bisaz1, Regina M Sullivan
1Emotional Brain Institute, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, New York, NY 10962, USA ; Child & Adolescent Psychiatry, New York University School of Medicine, 215 Lexington Avenue, New York, NY 10016, USA ; Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA.
Insights
Infant rats learn to approach maternal odor, but stress hormone corticosterone later shifts this to fear learning. Mother
Area of Science:
- Neurobiology
- Developmental psychology
- Stress research
Background:
- Stress profoundly impacts brain development and function.
- Early life stress increases risks for mental and physical health issues.
- The infant rat's maternal odor learning system is crucial for survival.
Purpose of the Study:
- Investigate the neurobiology of infant rat odor learning.
- Examine corticosterone's role in modulating odor approach learning during development.
- Understand how stress responses shape attachment behaviors.
Main Methods:
- Studied infant rat odor approach learning.
- Assessed the impact of corticosterone on learning across development.
- Observed changes in amygdala activity and fear learning.
Main Results:
- Infant rats initially show odor approach learning, supported by sensory stimuli.
- Maturation leads to stress-induced corticosterone release, terminating approach learning.
- Corticosterone emergence shifts learning to amygdala-dependent fear/avoidance.
- Maternal presence suppresses pup corticosterone and amygdala activity, restoring approach learning.
Conclusions:
- Developmental changes in stress responsiveness are critical for adapting attachment systems.
- Maternal influence can mitigate stress effects on pup behavior.
- Stress hormones and learning systems interact to shape adaptive behaviors in early life.
Abstract:
Stress is a powerful modulator of brain structure and function. While stress is beneficial for survival, inappropriate stress dramatically increases the risk of physical and mental health problems, particularly when experienced during early developmental periods. Here we focus on the neurobiology of the infant rat's odor learning system that enables neonates to learn and approach the maternal odor and describe the unique role of the stress hormone corticosterone in modulating this odor approach learning across development. During the first nine postnatal days, this odor approach learning of infant rats is supported by a wide range of sensory stimuli and ensures attachment to the mother's odor, even when interactions with her are occasionally associated with pain. With maturation and the emergence of a stress- or pain-induced corticosterone response, this odor approach learning terminates and a more adult-like amygdala-dependent fear/avoidance learning emerges. Strikingly, the odor approach and attenuated fear learning of older pups can be re-established by the presence of the mother, due to her ability to suppress her pups' corticosterone release and amygdala activity. This suggests that developmental changes in stress responsiveness and the stimuli that produce a stress response might be critically involved in optimally adapting the pup's attachment system to its respective ecological niche.
