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Sparing of function after infant lesions of selected limbic structures in the rat
Insights
Early limbic system lesions in rats impact adult weight gain and learning. Infant-accrued lesions show task-specific recovery, suggesting functional reorganization in the developing brain.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Behavioral Neuroscience
Background:
- The developing brain exhibits plasticity, allowing for potential compensation following early injury.
- Understanding the long-term effects of early-life insults to limbic structures is crucial for developmental neuroscience.
Purpose of the Study:
- To investigate the long-term effects of early-life limbic system lesions on adult behavior in Wistar rats.
- To compare the impact of infant versus adult lesioning on weight gain and learning.
Main Methods:
- Bilateral lesions were induced in the amygdala, septum, posteroventral hippocampus, anterodorsal hippocampus, or frontal cortex of infant (10 days) or adult (60 days) male Wistar rats.
- Weight gain, conditioned emotional response (CER), and conditioned avoidance response (CAR) acquisition were measured in adulthood.
- Control groups included normal and anesthetized rats.
Main Results:
- Amygdala and septal lesions, regardless of timing, disrupted weight gain.
- Adult amygdala and posteroventral hippocampus lesions impaired CER acquisition.
- Adult septal and posteroventral hippocampus lesions facilitated CAR acquisition.
- Infant amygdala lesions impaired CER acquisition, while infant septal lesions facilitated CAR acquisition.
- Anterodorsal hippocampus and frontal cortex lesions had no significant effects.
Conclusions:
- Early-life limbic lesions can have lasting effects on behavior, with some recovery observed in infant-operated animals.
- Task-specific recovery in early-lesioned rats suggests potential functional reorganization of neural circuits.
- The timing of limbic system insult significantly influences behavioral outcomes in adulthood.
Abstract:
The effects, in adult animals, of limbic lesions produced in infancy were studied in 273 male Wistar rats using weight gain and conditioned emotional response (CER) and conditioned avoidance response (CAR) acquisition as the critical measures. Subjects received bilateral lesions of the amygdala, septum, posteroventral hippocampus (PH), anterodorsal hippocampus (AH), or frontal cortex either as infants (at 10 days of age) or as adults (at 60 days). Normal and anesthetized control groups were also used. Frontal cortical lesions, AH lesions, and anesthetization had no effect on weights or on CER and CAR acquisition. Both infant and adult amygdala and septal lesions significantly disrupted normal weight gain. Adult-accrued amydala and PH lesions significantly retarded CER acquisition, and adult septal and PH lesions significantly facilitated CAR acquisition. Infant-accrued amygdala lesions significantly retarded CER acquisition but had no effect on CAR acquisition. Infant septal lesions significantly facilitated CAR acquisition, and infant PH lesions had no effect on either task. The results were interpreted to mean that the observed task-specific recovery in early-operated animals may have been due to some form of functional reorganization.