Overview of Nature, Nurture, and the Nervous System

Interaction of Environment and Heredity

• Nature (Genetics, Biology)

• Nurture (Everything else)

• Language Acquisition (Noam Chomsky)

  • Reinforcement, punishment, social environment, learning, rewards.

  • Universal Grammar: Genetic factor distinguishing humans from other animals.

  • J.B. Watson: Culture influences behavior regardless of innate talents or ancestry.

Epigenetics

• Experiences and environment can alter genetics.

  • Rat licking studies shed light on the impact of nurture on nature.

  • Identical twins provide a genetic control by showing similarities in different environments.

Key Takeaways

1. Nature and Nurture interact; they do not work independently.

2. Epigenetics shows how environmental factors influence genetic expression.

Studies on Twins

• Identical Twins: Monozygotic, same DNA, similar when raised apart due to genetics.

• Fraternal Twins: Dizygotic, no more genetically similar than regular siblings.

• High vs. Low Lickers: Babies adopt behaviors from their mothers even when switched.

• Minnesota Twin Study: Extensive research showing that separated twins share many traits.

  • Enhanced LTP (Long-Term Potentiation) is influenced by enriched environments.

Heritability

• Variation among individuals attributed to genetics.

  • 62% of differences in intelligence linked to genetic factors.

  • Twin studies help assess the relationship between nature and nurture.

Overview of the Nervous System

• Somatic Nervous System: Communicates sensory information; includes sensory and motor neurons.

• Autonomic Nervous System: Involuntary functions;

  • Sympathetic: Fight or flight response (increases heart rate, blood circulation).

  • Parasympathetic: Rest and digest (calms the body).

Takeaway

• Human nervous system has several divisions, each with specialized functions.

The Neuron and Neural Firing

• Neurons are the basic building blocks of the nervous system. They communicate through electrical impulses, or action potentials.

• Types of Neurons:

  • Sensory neurons: Detect external stimuli.

  • Motor neurons: Control muscle movements.

• Glia Cells: Support neurons but also communicate chemically, affecting neural signals.

Spinal Reflex Arc

• Sensory neurons receive stimuli, interneurons process them, and motor neurons execute the response.

  • Reflects fast communication and interactions within the nervous system.

Important Functions of Neurons

• Dendrites: Receive messages.

• Axon: Carries messages away from the cell body.

• Electrical impulses travel down the axon, causing neurotransmitter release into the synapse.

Neurotransmitters

• Types:

  • Excitatory: Increase likelihood of neuron firing (e.g., Glutamate).

  • Inhibitory: Decrease likelihood of neuron firing (e.g., GABA).

• Synaptic Transmission proceeds from:

  1. Presynaptic neuron.

  2. Release of neurotransmitters.

  3. Neurotransmitters bind to receptors on postsynaptic neurons.

Myelin Sheath

• Fatty layer protecting axons, speeding up neural transmission. Damage can lead to conditions like Multiple Sclerosis.

Neurotransmitters and Their Effects

• Dopamine: Pleasure, movement; low levels linked to Parkinson's.

• Serotonin: Mood regulation; low levels associated with depression.

• Acetylcholine (ACh): Involved in movement and memory; reduced in Alzheimer's.

• Endorphins: Natural painkillers; can be triggered by intense exercise.

Drugs and Neurotransmitter Interaction

• Agonists: Enhance neurotransmitter action (e.g., opioids mimic endorphins).

• Antagonists: Block neurotransmitter action (e.g., Black Widow venom for ACh).

Brain Structures and Functions

Hindbrain

• Medulla: Controls autonomic functions (heart rate, breathing).

• Pons: Connects brainstem and cerebellum; involved in sleep coordination.

• Cerebellum: Manages balance and coordination, implicit memory.

Limbic System

• Thalamus: Processes sensory information.

• Hypothalamus: Regulates bodily drives (hunger, thirst, sexual motivation).

• Amygdala: Processes emotions like fear and aggression.

• Hippocampus: Essential for memory consolidation.

Cerebral Cortex

• Left and right hemispheres, each with distinct responsibilities.

  • Frontal Lobe: Decision-making, impulse control (includes Broca’s Area for speech).

  • Parietal Lobe: Sensory processing (sense of touch).

  • Temporal Lobe: Auditory processing.

  • Occipital Lobe: Visual processing.

Lateralization and Split Brain

• Split-brain procedure involves severing the corpus callosum to reduce epilepsy.

• Language functions are mainly lateralized to the left hemisphere, whereas face recognition is generally right.

Neuroplasticity

• The brain can reshape itself based on experiences.

  • Neurogenesis: Creation of new cells.

  • Long-term potentiation (LTP): Reinforces synaptic connections through repeated activation.

Brain Research Methods

• EEG: Measures electrical activity of the brain.

• fMRI: Shows brain activity by tracking changes in blood oxygen levels.

Case Studies and Plasticity

• Case study of Jody Miller illustrates high functional plasticity in young brains post-hemispherectomy.