Hormones & Instincts: Hunger, Aggression & Parenting Behavior | Jonny Kohl | 262

Wide release date: November 7, 2025.

Episode Summary: Dr. Johannes Kohl explains instinctive behaviors in mammals, emphasizing how states like hunger and hormonal cycles modulate actions such as parental care; they discuss hypothalamic circuits, hormone integration, and pregnancy-induced brain changes, highlighting the balance between motivations like feeding and nurturing offspring.

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:

• Instinctive behaviors: Pre-wired actions like escaping predators or parental care enable survival without learning, yet remain modifiable by experience and internal states.

• Internal states: Defined as slowly changing conditions (minutes to weeks) like hunger or hormonal fluctuations that influence brain processing and behavior prioritization.

• Hunger regulation: Hypothalamic AGRP neurons detect caloric deficits, creating motivational discomfort relieved by food anticipation, operating on multiple timescales via neurotransmitters and peptides.

• Parental care: Virgin mice show variable pup-directed behaviors; hunger increases aggression, modulated by estrous cycle hormone ratios (estradiol/progesterone).

• Hormone-brain interactions: Steroid hormones like estradiol and progesterone diffuse into the brain, altering gene expression, neuronal excitability, and circuit plasticity over short and long timescales.

• Integration of states: In the medial preoptic area (MPOA), hunger signals inhibit parental neurons, with estrous cycle hormones converging on ion channels to fine-tune excitability and behavior.

• Pregnancy adaptations: Late pregnancy rewires MPOA circuits via surging hormones, preparing robust maternal behavior before birth, showing anticipatory brain plasticity.

• Broader implications: Disrupting natural hormone cycles (e.g., via contraception) may have unintended brain effects; calls for more research on hormone-selective interventions.

Practical Takeaways:

• Recognize hunger’s impact: Mild food deprivation can heighten irritability or aggression, which can affect social interactions.

• Consider hormonal influences: Cyclical hormone changes affect mood and motivation; tracking cycles may help predict and manage behavioral shifts.

• Prioritize self-care in parenting: Sleep and nutrition deficits mimic hunger states, potentially reducing patience; ensure rest and meals to support nurturing behaviors.

• Question chronic hormone use: Long-term interventions like birth control or testosterone can alter brain function; weigh benefits against potential side effects with medical advice.

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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• Episode transcript below.

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Episode Chapters:

00:03:26 Dr. Kohl Intro
00:08:19 Defining Behavioral State
00:13:08 Hunger Circuitry & AGRP Neurons
00:18:16 Hunger vs Parental Behavior in Virgin Females
00:20:44 Estrous Cycle & Hormone Fluctuations
00:28:54 Hunger-Hormone Integration in MPOA
00:35:51 Ion Channels & Multi-Timescale Signaling
00:43:12 Pregnancy Rewires Parental Circuits
00:48:55 Balancing Hunger & Maternal Care
00:53:28 Hormonal Contraception & Brain Effects
00:57:16 Future Directions & Closing

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Full AI-generated transcript below. Beware of typos & mistranslations!