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How hunger, hormones, and brain wiring make animals switch between parenting and aggression.

Episode Summary: Dr. Johannes Kohl explains instinctive behaviors in mice, focusing on how hunger and estrous cycle hormones interact in the hypothalamus to toggle between parental care and pup-directed aggression in virgin females; he also details how pregnancy hormones rewire the medial preoptic area for robust maternal behavior before birth, revealing multi-timescale neural integration of internal states.

About the guest: Jonny Kohl, PhD is a group leader at the Francis Crick Institute in London, heading the State-Dependent Neural Processing Lab.

Discussion Points:

• Instincts are pre-wired, robust yet modifiable by experience and states like hunger.
• AGRP “hunger neurons” in the hypothalamus regulate hunger state and respond to environmental cues related to food.
• Hunger regulates parental care neurons in medial preoptic area (MPOA) via inhibitory peptides.
• Estrous cycle (4-5 days) in mice comes with fluctuations in estradiol & progesterone; their ratio, not absolute levels, gates aggression probability.
• Hormone ratio sensed in MPOA neurons via nuclear receptors altering gene expression of HCN ion channels, changing excitability.
• Pregnancy (20 days) boosts parental circuits in MPOA via hormone surges before pregnancy ends, enabling instant care at birth.
• Hormone fluctuations enable adult brain plasticity.
• Humans disrupt natural cycles (e.g., hormonal contraceptives, GLP-1 drugs) that have broad, poorly understood brain effects.

Reference Paper:

• Study: Integration of hunger and hormonal state gates infant-directed aggression

Related Episode:

• M&M 89: Neuroscience of Aggression, Sex, Behavior, Hormones, Emotion & Consciousness | David Anderson

*Not medical advice.

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