BioPsych

Inflammation Hypothesis

• Depression = inflammatory illness

• Immune activation → changes in brain chemistry

• Affects:

  • Neurotransmitters

  • Brain structure (amygdala, hippocampus)

Pathogens Linked to Depression

Parasite: Toxoplasma gondii

• Infects ~30% of world population

• Forms cysts in:

  • Brain

  • Muscle

Effects on Brain:

• Amygdala → fear

• Hypothalamus → sexual behavior

• ↑ Dopamine

• ↓ Serotonin (via immune response)

👉 Linked to:

• Schizophrenia

• Personality changes

• Suicide risk

Gut Microbiome

• Brain ↔ gut communication (bidirectional)

• Changes in microbiome → changes in:

  • Emotion

  • Behavior

  • Brain activity

Viruses

• Example: Borna Disease Virus (BDV)

• May influence brain and mood disorders

Human Endogenous Retroviruses (HERVs)

Key Concept:

• Ancient viral DNA in human genome (~8%)

Balance Model

• Trauma + infection → activates HERVs

• Effects:

  • Pathogenic (inflammation, damage)

  • Protective (neurotrophic effects)

👉 Depression risk = balance between these effects

 Key Takeaways

• Depression is not just “chemical imbalance”

• It may involve:

  • Immune system

  • Infection

  • Genetics + environment

Aggression & the Brain

Brain Regions:

• Amygdala → emotion, fear, aggression

• Prefrontal Cortex (PFC) → control, inhibition

👉 Aggression = imbalance:

• Overactive amygdala

• Underactive PFC

 MAOA Gene (“Warrior Gene”)

MAOA-L variant:

• ↓ brain volume in:

  • Amygdala

  • Cingulate cortex

• ↑ emotional reactivity

• Altered connectivity with PFC

👉 Associated with:

• Aggression (especially in certain environments)

Criteria for Criminal Responsibility1. Act Requirement

• Must be:

  • Intentional

  • Conscious behavior

Mens Rea (Mental State)

• Intention

• Recklessness

• Negligence

What doesn’t excuse crime

• Genetics (G×E) does NOT excuse crime automatically

👉 Stephen Morse:

• “Causation is not an excuse”

What can effect sentencing

• Genetics can:

  • Mitigate (reduce blame)

  • Aggravate (increase perceived risk)

👉 “Knife that cuts both ways”

Predicting Recidivism (Kent Kiehl)

Go/No-Go Task:

• Measures impulse control

Finding:

• Low ACC activity → higher chance of reoffending

Key Takeaways

• Biology influences behavior—but law focuses on:

  • Rationality

  • Control

• Courts evaluate individual cases, not genetic groups

What is Neuroethics?

• Study of:

  • Ethical

  • Legal

  • Social implications of neuroscience

Why is the Brain Special?

Raises questions about:

• Identity

• Consciousness

• Personhood

• Morality

 Neurogenethics

• Combines:

  • Genetics

  • Brain science

  • Ethics

Technologies Driving the Field

• fMRI (brain imaging)

• TMS (brain stimulation)

• Genomics

Gene Therapy in the Brain

Current Status:

• Parkinson’s trials (Phase I/II)

• No major safety issues yet

Ethical Issues:

• Patient understanding vs. autonomy

• Access to treatment

• Risk vs. benefit

Brain Organoids (“Mini-Brains”)

What they are:

• Lab-grown 3D brain models

Uses:

• Study development

• Study disease

Organoid Intelligence (OI)

Combining:

• Brain cells

• Artificial intelligence

Example:

• “DishBrain” (neurons learning Pong)

 Ethical Concerns on brain organoids

• Consciousness?

• Moral status?

• Human–animal chimeras

• Consent

• Regulation

Neurogenethics Problem Space

Covers:

• Molecules → behavior → society

• Issues:

  • Personhood

  • Stigma

  • Safety

  • Regulation

Odds of a second depressive episode: 

80%

% of positive studies published: 

100%

Why inflammation alone is insufficient:

 Inflammation doesn’t explain:

why specific brain regions are affected

why some people get depression and others don’t

Which does NOT belong?

Ghost glowworm

Bifidobacteria infantis

reduces stress reactivity in mice

It’s a gut microbiome bacterium

Linked to lower stress responses → supports gut–brain connection

Is HIV is associated with depression? 

True
HIV is associated with:

• immune activation

• inflammation

• BUT important nuance:

  • HERV model says HIV alone doesn’t explain depression fully

Best support for inflammatory hypothesis 

Depressed patients show increased inflammatory markers, and anti-inflammatory add-on treatments improve symptoms in some studies. 

Statistically significant but not clinically meaningful 

• Statistical significance = math says “real effect”

• Clinical significance = actually meaningful improvement

👉 If patients are still depressed → not clinically meaningful

Recklessness vs Negligence 

Recklessness vs Negligence 

subjective; objective

• Recklessness = subjective

  • person KNOWS the risk

• Negligence = objective

  • person SHOULD have known