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Brain & mental-health explorer
Lateral brain view
Tap any region to read about it. This is an educational illustration, not an anatomically exact scan.
Select a brain region
Tap any area on the brain, or pick one from the list below, to learn what it does and how it shows up in mental health.
All regions
Circuit view: how these regions connect
The brain works through circuits, not isolated parts. These diagrams show the key functional pathways behind each condition — arrows are connections, and color shows whether a structure runs hyperactive (warm) or hypoactive (cool) in this condition.
Depression: cortico-limbic & reward circuit
How this circuit works
Depression isn't a single "broken part" — it's a loop. A calming region at the front of the brain goes quiet just as an emotional-alarm region gets louder, the memory center loses its ability to file feelings into context, the reward pathway stops responding to things that used to feel good, and the stress-hormone system gets stuck partly "on." A network that runs when the mind is idle and turned inward (the kind of background thinking behind rumination) also gets stuck in overdrive.
Key connections
- dlPFC ↔ sgACC (BA25): Top-down regulation — weakened
- sgACC (BA25) ↔ Amygdala: Limbic-cortical loop — sgACC drives amygdala reactivity
- Amygdala ↔ Hippocampus: Emotional memory & contextual processing — impaired
- sgACC (BA25) ↔ PCC / precuneus: Default mode network hyperconnectivity — rumination
- Ventral striatum (NAcc) ↔ dlPFC: Fronto-striatal loop — reward-guided decision-making
- VTA → Ventral striatum (NAcc): Mesolimbic dopamine — blunted, drives anhedonia
- Raphe nuclei → Amygdala: Serotonergic projection
- Raphe nuclei → Hippocampus: Serotonergic projection
- Locus coeruleus → Amygdala: Noradrenergic projection
- Amygdala → Hypothalamus: Drives HPA activation
- Hypothalamus → Pituitary: CRH
- Pituitary → Adrenal gland: ACTH → cortisol
- Adrenal gland → Hippocampus: Cortisol — impaired negative feedback
Simplified: this collapses many DMN nodes (mPFC, PCC, precuneus, angular gyrus) into a single "PCC/precuneus" node, and shows only two monoamine nuclei explicitly (5-HT, NE) plus dopamine via the VTA — inflammatory and glutamatergic (ketamine-relevant) mechanisms aren't diagrammed.
Brain–body connection
Mental health lives in the body too. These are three of the pathways that link what happens in the brain to what you feel physically.
Stress Response (HPA Axis)
When you feel stressed, your brain sends a signal that releases the stress hormone cortisol. This affects your whole body.
- 🧠 Hypothalamus detects threat↓
- ⚛️ Releases CRH → Pituitary releases ACTH↓
- 💧 Adrenal glands release cortisol↓
- ❤️ Heart rate, blood pressure, digestion, immunity, sleep all affected
Anxiety & the Nervous System
When your brain's alarm center (amygdala) fires too often, it triggers your body's fight-or-flight response, causing the physical symptoms of anxiety.
- 🚨 Amygdala sounds the alarm↓
- ⚡ Sympathetic nervous system activates↓
- 💓 Racing heart, rapid breathing, sweating↓
- 💀 Muscle tension, stomach upset, dizziness
Depression & the Body
When brain chemicals like serotonin and dopamine are out of balance, it doesn't just affect your mood. It affects your energy, sleep, appetite, and even your ability to feel pleasure.
- 🔬 Serotonin & dopamine levels drop↓
- 💤 Sleep disrupted (too much or too little)↓
- 🍽️ Appetite changes (increase or decrease)↓
- 😔 Low energy, loss of motivation and pleasure
Neurotransmitter quick reference
The brain’s chemical messengers. Most mental health medications work by nudging one or more of these back into balance.
Serotonin (5-HT)
Helps regulate mood, sleep, appetite, and digestion. Often called the "feel good" chemical.
Dopamine (DA)
Drives motivation, reward, and pleasure. Makes you want to do things and feel good when you accomplish them.
Norepinephrine (NE)
Controls alertness, energy, and the body's "fight or flight" response. Helps you focus and respond to stress.
GABA
The brain's main "brake pedal." It calms neural activity and helps reduce anxiety, promote sleep, and prevent seizures.
Glutamate
The brain's main "gas pedal." It activates neural circuits, drives learning and memory formation, and helps the brain adapt.
Endorphins
Your body's natural painkillers and pleasure chemicals. Released during exercise, laughter, and social bonding. Create feelings of well-being.
A note on all of this
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