Brain and Mind: Historical Perspectives

• The brain can be thought of as hardware, and the mind as the software it produces, studying the brain reveals how we see, feel, remember and act.

Historical Perspectives

• Aristotle thought the heart did the thinking because he couldn't dissect humans
• Aristotle believed the heart was the center of sensation and thought, not the brain and assigned roles to the Heart (passionate soul), Brain (rational soul), Liver (appetitive soul) and was limited by inability to dissect human bodies
• Galen shifted focus to the brain, attributing thought to ventricles (fluid-filled spaces), suggesting ventricles send signals to the body, ideas persisted for over 1,000 years due to limited technology
• Andreas Vesalius established the brain as the source of thoughts, feelings, and actions, rejected ventricles as the key mechanism but didn't fully explain how the brain worked
• Luigi Galvani discovered the brain uses electricity to function and introduced neurostimulation and the concept of neurons communicating electrically
• Franz Gall developed phrenology, the idea that specific brain areas control specific functions, but skull bumps were nonsense
• Phineas Gage survived a prefrontal cortex injury and personality changes suggested frontal lobes influence behavior and thinking
• Pierre Paul Broca studied stroke patients with language loss and right-side paralysis and founded cognitive neuropsychology by studying brain damage effects

Philosophical Perspectives

• Dualism (René Descartes, 1600s): Brain and mind are separate, connected via a gland in the brain
• Monism/Materialism states the brain and mind are the same thing; the mind is what the brain produces through activity
• Functionalism (William James): The mind is what the brain does, while the brain is the hardware enabling those functions
• Most scientists lean toward monism: everything you think or feel comes from your brain

Psychology Milestones

• Wilhelm Wundt (1879) Established the first psychology lab to study thought experimentally
• Hermann Ebbinghaus (1885) Conducted early memory studies
• William James (1890) Wrote the first psychology textbook, linking mind and brain functions

Computer Science Influence

• Computers inspired the idea that the brain works like a machine with inputs and outputs
• Metaphor: Mind as a computer-psychology and neuroscience borrow from computing, and vice versa

Brain Function Concepts

• Localization is where some brain parts have special jobs, and specific brain areas have specific jobs
• Distributed is where big tasks (like understanding a sentence) need lots of brain parts working together and complex tasks involve multiple brain areas working together
• Think of it like a kitchen: One person chops veggies (local), but making a meal needs everyone (distributed).

Key Brain Areas

• Broca's Area is responsible for speech production (damage = trouble speaking)
• Wernicke's Area is responsible for language comprehension (damage = fluent but nonsensical speech)
• Geschwind's Area connects language areas for coordinated function

Modern Techniques

• Cognitive Neuropsychology studies brain damage (lesions) to understand healthy brain function
• Neuroimaging (Past 30-40 Years) examines brain anatomy while alive or observes brain activity during tasks (e.g., EEG measures electrical signals)

Studying the Brain

• Looking at people with brain damage (like Phineas Gage or Broca's patients) shows us what different brain parts do
• Limitation: Everyone's brain is a bit different, and damage might mess up more than one thing.
• Old days: No dissections or scans, so ideas were guesses and technology drives progress
• Now: Tools like EEG (tracking brain electricity) or neuroimaging (seeing the brain work live) let us test ideas and build models of how the mind works.

Themes of the Lecture

• The brain is not like other organs because it's full of neurons (cells) that talk to each other all the time
• This chatting makes you think, feel, and move and no other organ does this networking thing
• Everyone's brain is different, like a fingerprint, built from your genes (DNA from your parents) plus everything you've lived through
• Even identical twins can end up with different brains because of their experiences The brain keeps changing (plasticity) rewire itself, happening fast (even during a lecture!) and slows down as you age, but it never stops
• Genes and environment team up

Amazing Adaptability and the "Normal" Brain

• Some people live normal-ish lives with huge brain chunks missing
• Flatworms regrow heads! Psychedelics can rewire your brain in one go
• There's no standard brain-yours is different from mine, but we still act pretty similar most of the time

What makes the brain special?

• Unique Features:
  • Unlike the heart or liver, the brain's neurons connect and communicate in networks
  • No such thing as a "normal brain"-every brain is different, shaped by genes and environment
  • Behavior can be similar across people despite brain differences
• Constant Change:
  • The brain rewires itself all the time
  • This adaptability is called plasticity-highest in youth but present throughout life

Factors Shaping the Brain

• Genes:
  • Half from mom, half from dad; mutations can occur but don't always cause disease
  • No single gene for disorders like autism or schizophrenia-just risk factors
• Pre-Prenatal Factors (Before Birth): Events during pregnancy affect the baby's brain via hormones
• Generational Effects:
  • Rat Study: Male rats given alcohol for 8 weeks, then mated after sobriety. Human relevance: Your grandparents' experiences might subtly shape your brain
• Everything Affects the Brain: Daily experiences, stress, learning-everything rewires your brain, making it uniquely yours

Research Methods

• You want to understand the strengths and limitations of each method, and choose the right one for a research question

Manipulation Methods

• Techniques to actively change brain activity
• Manipulation is like flipping switches in the brain to see what happens (e.g., damaging an area or stimulating it)
  • Brain Damage ('Spontaneous' or 'Induced')
  • Direct Stimulation (Electrical or Magnetic)
  • Drug Injections (Systemic or Local)

Imaging/Measurement Methods

• Techniques to observe brain activity
• Measurement is like watching the brain's dashboard to see what lights up when you do something (e.g., EEG, fMRI)
  • Microscopic Imaging
  • Electrical Imaging (EEG)
  • Magnetic Imaging (MRI & (f)MRI)
  • Chemical Imaging (PET)

Brain Damage

• Studying the brain by observing/creating lesions in specific areas of the brain
• Spontaneous: Naturally occurring damage (e.g., strokes, accidents, tumors) where scientists study patients who already have this kind of damage to see how it affects their behavior or abilities
• Induced: Deliberate damage in research (usually animals) to understand the role of specific brain areas
• Advantages: Identifies roles of specific brain areas (e.g., hypothalamus regulates hunger) and precise lesions in animals overcome messy human damage
• Disadvantages: Human lesions are large, affecting multiple areas-hard to isolate functions, rare to find identical lesions for consistent studies and electrical lesions damage nearby fibers; chemical lesions are more precise (spare fibers)

Direct Stimulation

• Zapping the brain with electricity or magnets to activate/inhibit neurons
• Deep Brain Stimulation (DBS): Invasive electrodes implanted in the brain and is used for Parkinson's (tremors, rigidity) when drugs fail
• Transcranial Magnetic Stimulation (TMS): Non-invasive magnetic pulses on scalp, targets cortical areas (2-3 cm deep), temporary effects
• Lateral Hypothalamus: Damage → rats eat less (red line vs. blue line for normal)
• Ventromedial Hypothalamus: Damage → rats eat more
• Finding: Lateral = "eat more" signal; Ventromedial = "stop eating" signal
• Advantages:
  • DBS: Relieves severe symptoms (e.g., Parkinson's movement issues)
  • TMS: Reversible, can target specific areas, non-invasive
• Disadvantages:
  • DBS: Highly invasive, risky, only for extreme cases
  • TMS: Affects all cells in the area (not selective), limited to cortical regions

Drug Injections

• Using drugs to alter brain activity, either throughout the body (systemic) or in specific areas (local)
• Advantages: Targets specific chemical processes (e.g., neurotransmitters)
• Disadvantages: Systemic drugs hit everywhere, not just the brain and local injections need precision-hard to do perfectly

Imaging/Measurement Methods

• Microscopic Imaging: Examining brain cells under a microscope, often post-mortem
• Advantages: Very high spatial resolution (can see tiny details, like individual neurons)
• Disadvantages: Only after death-no real-time activity data, misses dynamic changes (e.g., neurons firing) and can't link to live behavior (e.g., emotions, decisions)
• Electrical Imaging (EEG): Electroencephalogram (EEG) measures electrical activity via electrodes on the scalp (sometimes inside the brain)
• Advantages: Extremely fast (high temporal resolution, detects changes in nanoseconds) and easy to measure multiple brain regions at once (synchrony)
• Disadvantages: Low spatial resolution (measures average activity of millions of neurons) and mostly limited to cortical regions

Magnetic Imaging (MRI & (f)MRI)

• Structural MRI: Looks for physical changes in the brain (e.g., lesions)
• Functional MRI (fMRI): Measures brain activity based on oxygen levels (blood oxygen level dependent)
• Advantages:
  • Good spatial resolution (around 1.5 mm³)
  • Can measure both structure (MRI) and function (fMRI)
• Disadvantages:
  • Poor temporal resolution (4-5 seconds, though improving)
  • Only shows correlations, not causation or neurotransmitter activity

Chemical Imaging (PET)

• Positron Emission Tomography (PET) uses radioactive compounds to measure brain chemistry
• Advantages:
  • Can measure changes in brain chemistry (e.g., neurotransmitter activity)
  • Reasonable spatial resolution Disadvantages:
  • Expensive and requires radioactive ligands
  • Low temporal resolution
  • Works with relatively weak radioactive compound

Resolution Summary

• High Spatial: Microscopic, MRI (~1.5 mm³)
• Low Spatial: EEG (broad averages)
• High Temporal: EEG (nanoseconds)
• Low Temporal: fMRI (seconds), PET

Why it Matters

• High spatial = exact location (e.g., where a lesion is)
• High temporal = fast changes (e.g., during a seizure)

Brain Development & Plasticity

• Key Processes:
  • Neurogenesis: Neuron formation (starts week 3, mostly done by birth)
  • Gliogenesis: Glial cells form (regulate fluids, form myelin sheaths)
  • Synaptogenesis: Synapses (connections) form, mostly after birth
  • Myelination: Myelin coats axons for faster signals (finishes in prefrontal cortex ~20s)
  • Synaptic Pruning: Removes unused synapses to save energy and reduce noise

Key Scientists

• Roger Sperry: Studied split-brain patients (epilepsy treatment); researched axon pathfinding in lizards (Nobel Prize 1981)
• Rita Levi-Montalcini: Discovered Nerve Growth Factor (NGF) for neuron growth (Nobel Prize 1986)

Brain Development Timeline & Basics

• Starts 2-3 weeks after conception (embryo forms neural groove → neural tube)
• 3 weeks: Brain splits into forebrain, midbrain, hindbrain
• Birth: Most neurons formed (~300g brain weight)
• 1 year: Brain grows to ~1000g (near adult size)
• 20-25 years: Development mostly complete (e.g., prefrontal cortex myelination)
• Sensory First: Sight/hearing develops before behavior/integrative systems
• Driven By: Genes initially, then the environment shapes it post-birth

DNA, Genetics & Heredity

• Key Scientists:
  • Gregor Mendel laid the foundation for genetics with pea plant experiments
  • James Watson & Francis Crick discovered DNA's double-helix structure (1953)

Mendel's Contributions - Heredity

• Before Mendel, people thought kids were a mushy mix of mom and dad
• Mendel used peas to show it's more like picking cards-one from each parent
• Some cards (alleles) are loud (dominant) and hide the quiet ones (recessive)
• You've got 23 pairs of chromosomes-like filing cabinets-holding all these trait cards (genes)
• Pre-Mendel: No clear idea of how traits were inherited; "blending theory" (mix of parents) was popular but flawed-kids sometimes resembled one parent or grandparents
• Mendel's Work: Studied pea plants with traits in two forms

Key Principles

• Two alleles (elements of heredity) per trait-one from each parent
• Dominant: One allele can mask the other
• Recessive: Masked allele only shows if paired with another recessive
• Homozygous: Two identical alleles
• Heterozygous: Two different alleles

DNA

• Definition: Structures in cells carrying genes; humans have 23 pairs (46 total)
• Role: Genes on chromosomes determine inherited traits

DNA Structure

• Components: Made of 6 elements: sugar, phosphate, and 4 bases (nucleotides): Adenine (A), Thymine (T), Cytosine (C), Guanine (G)
• Double-helix structure
• Self-Replication: Splits and copies itself to produce two identical strands during cell division

How DNA Affects Cells

• Transcription:
  • DNA → RNA (messenger molecule)
  • RNA uses 4 bases: A, U (Uracil replaces T), C, G
• Translation:
  • RNA → proteins (building blocks of cells)
  • Code: 3 DNA/RNA bases (codon) = 1 amino acid (protein unit)
• Outcome: Proteins determine cell functions (e.g., enzymes, structural components)

Mutations vs. Epigenetic Changes

• Genetic Mutations Definition is permanent change in DNA sequence (e.g., G → A)
• Epigenetic Changes Definition is changes in gene expression without altering DNA sequence
• Mechanism for Epigenetic Changes:
  • All cells have the same DNA, but different cells (e.g., brain vs. kidney) "turn on" different genes via RNA Alters protein's 3D structure (qualitative change), changing its function Effect is changes protein quantity (quantitative change), not type
• COMT Val158Met polymorphism-affects dopamine breakdown, linked to behavior/cognition differences
• Most mutations directly cause mental health conditions (rare); most increase risk (e.g., schizophrenia):
• DNA itself changes → new protein Key Difference: DNA stays same → more/less protein
• DNA in the Nucleus: Size: DNA is ~2 meters long but fits in a tiny nucleus (~0.006 cm³) Size is wound around positively charged histones (DNA is negative), forming chromosomes Environment interacts with genes (e.g., stress worsens genetic risk for depression) - Environment (e.g., stress) can tighten/loosen DNA, with effects lasting or passing to offspring
• Human behavior evolved over millions of years, shaped by survival needs: Mental conditions (e.g., anxiety) may reflect adaptive traits gone awry