Behaviour Evolution, Brain Development, and Brain Plasticity

Behaviour and Brain Studies at Universitas Gadjah Mada

  • Focus Areas:

    • Behavioural Evolution

    • Brain Development

    • Brain Plasticity

Overview of Evolution

  • Definition: Change over time.

  • Steps of Evolution: physic → chemistry → biology

Evolution in Different Sciences

  • Physics Evolution:

    • Big Bang Theory by George Lemaitre.

      • Expansion of the universe leading to the formation of planets, including Earth.

  • Chemistry Evolution:

    -Organic compounds=a molecule (like a protein, sugar, fats) made of carbon, hydrogen, and oxygen

    -Primitive atmospheric gases: earth previous atmosphere that is mostly made up of gases like methane, ammonia, and hydrogen.

    -Amino acids(potential precursors to life): Amino acids are molecules that help build proteins, which are essential for life.

    • Abiotic Synthesis of Organic Compounds theory/Prebiotic Chemistry Theory, by Miller-Urey Experiment (1952):

      -uses electrical sparks (like lightning) to hit the gases in the air (methane, ammonia, etc.). This created organic compounds (like amino acids, potential precursors to life).

  • Biological Evolution:

    • Lamarckism/inheritance of acquired characteristics, by Jean Baptiste Lamarck:

      →theory that non-genetical traits can be passed down through generations

    • Natural selection and survival of the fittest, by Charles Darwin

    • Mutation theory, by Hugo Marie de Vries:

      *independent from Mendelian genetics

      →evolution happens through big, sudden genetic changes, not slow, gradual changes.

    • Neo-Darwinism theory:

      (merges Darwinian evolution with Mendelian genetics)

      →evolution happens because of natural selection, but the traits that are selected are determined by genetic inheritance

Behavioural Evolution

  • Approach: Evolutionary and functional explanations of behaviour.

  • Stimulus Types:

    • External Stimuli

    • Internal Stimuli

  • Behaviour Types:

    • Innate Behaviour: behaviours from birth

    • Learned Behaviour: behaviors from experience

Innate Behaviour Examples

  • Taxis: changes to a specific direction because of stimulus(towards/away)

  • Reflex: Automatic response (e.g., pulling hand from heat).

  • Kinesis: changes in speed because of stimulus (faster/slower).

  • Stereotyped Behaviour: Repetitive, predictable patterns.

  • Fixed Action Patterns (FAPs): automatic behaviors that has a set pattern, when triggered will be followed till the end?(e.g., geese retrieving eggs).

Learned Behaviour Examples

  • Habituation: Reduced response to non-threatening repeated stimuli.

  • Imprinting: Early-life attachments (e.g., baby birds).

  • Insight Behaviour: Problem-solving with prior knowledge.

  • Classical Conditioning: Learning through associating things (e.g., Pavlov’s dogs).

  • Operant Conditioning: Learning through rewards and punishments.

Altruistic Behaviour

  • Kin Selection: helping family members because they share your genes, and by helping them, you increase the chances of those shared genes being passed down to future generations

  • Reciprocal Altruism: Helping others with the expectation of receiving help later.

  • Group Selection: Mutual assistance increases survival in groups.

Brain Development

Early Development

-Homeobox genes=control the development of body structures by giving instructions to cells.

-Gastrulation=the process where an embryo’s cells arrange into layers that will become the different parts of the body;

  1. Ectoderm: Will become the skin and nervous system.

  2. Mesoderm: Will become muscles, bones, and the circulatory system.

  3. Endoderm: Will become internal organs like the digestive system.

  • Gastrulation: Critical for brain development; associated with homeobox genes.

  • Homeobox Genes: Regulate gene expression and anatomical development; mutations can lead to brain disorders.

CNS(central nervous system) Development Process

-CNS=part of the body that controls everything the body does(brain and spinal cord)

-neural tube=early structure that serves as the foundation for the central nervous system (CNS)

  • Begins at about 2 weeks of fetal age.

  • Formation of the neural tube, which differentiates into various brain structures.

Brain Weight Milestones

  • At birth: ~350 grams.

  • First year: ~1000 grams.

  • Adult weight: ~1200-1400 grams.

Neuron Development Stages

-neurons=a type of cell that helps with communicate information in the nervous system

-axon=part of a neuron that send messages/electric signals to other neurons

-dendrites=part of a neuron that recieve those messages/electric signals

-glial cells=non-neuronal cells in the nervous system that provide support and protection for neurons (nerve cells)

-myelin=fatty substance that wraps around the axons (long extensions) of some neurons to speeding up the transmission of electrical signals

-synapses=small gap where axon and dendrites send messages

  1. Proliferation: process of rapidlly making new neurons by dividing them during early development.

  2. Migration:process where neurons move from where they are created to where they are needed in the body using chemical cues.

  3. Differentiation: process of neurons growing/making axons and dendrites to communicate.

  4. Myelination: the process of glial cells making the myelin to speed up communication

  5. Synaptogenesis: the process of formation new synapses, ongoing throughout life.

Growth of New Neurons

  • Contrary to previous beliefs, new neurons can form in certain brain regions even in adulthood (e.g., hippocampus).

Axon Pathways and Chemical Cues

-chemical gradients=chemicals that are released in certain areas which form a gradient(acts as a map) exclusively for the axon to follow thus the axon can find the right end location

  • Axons navigate to their targets by following gradients of chemicals (Sperry's Research).

Vulnerability During Development

  • Early stages of brain growth are sensitive to malnutrition and toxic exposure, leading to potential lifelong issues.

Impact of Chemical Substances

  • Fetal Alcohol Syndrome (FAS): Caused by maternal alcohol consumption; leads to various developmental problems.

  • Effects include hyperactivity, attention difficulties, intellectual disabilities, and facial abnormalities.

Other Substances and Stress

  • Influences of cocaine and smoking during pregnancy negatively impact child development.

  • Maternal stress conditions have similar detrimental effects.

Brain Development Across Lifespan

  • Adolescence: brain still developing thus more likely to act in impulse, this is because some parts of the brain that control rewards and decision-making are developing at different speeds. with the reward system is super active, but the self-control part of the brain (prefrontal cortex) is still catching up

  • Old Age: Decline in memory and reasoning; structural brain changes occur, but cognitive compensation is possible through accrued knowledge.

Brain Plasticity

  • The brain can recover from damage through the growth of new connections and overall adaptability.

Causes of Brain Damage

  • Tumors, infections, degenerative diseases, injuries, and strokes.

Treatments and Recovery Methods

  • Rapid interventions, enhancing brain stimulation, regrowing axons, and behavioral therapy are crucial for recovery.