Brain transections selectively alter ingestion and behavioral activation in neonatal rats

Area of Science:

• Neuroscience
• Developmental Biology
• Animal Behavior

Background:

• Neonatal rats ingest milk when food-deprived, showing behavioral activation.
• The neural control of infant rat ingestion and activity is not fully understood.

Purpose of the Study:

• To investigate the neuroanatomical basis of ingestion and behavioral activation in food-deprived neonatal rats.
• To determine if brain mechanisms for ingestion and activation are distinct.

Main Methods:

• Surgical transections were performed along the neuraxis of 2-day-old rats, from olfactory bulbs to anterior pons.
• Following a 24-hour deprivation period, rats received intraoral milk infusions.
• Milk intake and locomotor activity were measured in relation to transection level.

Main Results:

• Diencephalic transections severely reduced milk intake.
• Transections anterior or posterior to the diencephalon resulted in normal or slightly decreased intake.
• Locomotor activity decreased as transection level moved caudally.

Conclusions:

• Ingestion and behavioral activation in infant rats can be neuroanatomically separated.
• Distinct brain mechanisms likely control ingestive responses: one in the diencephalon, another caudal to the mesencephalon.
• Behavioral activation appears to involve a more widespread neural network across the neuraxis.