Quiz 3 Study Guide Psychology

Epigenetics

Definition: The study of changes in gene expression that do not involve changes to the DNA sequence. These changes can be influenced by environmental factors (e.g., diet, stress, toxins).

Nature vs. Nurture: Epigenetics shows that while genes provide a blueprint, the environment can alter gene expression. This bridges the gap between nature (genetics) and nurture (environment).

Key Takeaway: Our genetic make-up is not static; environmental influences can turn genes "on" or "off."

Genetic Predisposition

Definition: An increased likelihood of developing a condition based on genetics, but environmental factors still play a role.

Examples from Lecture:

Alcoholism: Some people have genetic markers that make them more susceptible, but environment (peer pressure, culture) also plays a role.

Depression: A family history increases risk, but life experiences influence whether it manifests.

Nature vs. Nurture Debate & Twin Studies

Answer to the Debate: It’s not one or the other—both genetics (nature) and environment (nurture) shape us.

Twin Studies:

Identical twins share 100% of their DNA. If raised apart, any similarities suggest genetic influence, while differences suggest environmental influence.

Example: Studies show that identical twins separated at birth often have similar intelligence levels, supporting nature, but also have different interests, supporting nurture.

Brain Plasticity

Definition: The brain's ability to change and adapt in response to experience, learning, or injury.

Three Ways It Happens:

1. Developmental Plasticity – Changes during early life as the brain matures.

Example: Babies learning language through exposure.

2. Adaptive Plasticity – The brain reorganizing itself after injury.

Example: Stroke patients relearning how to speak using different brain regions.

3. Experience-Dependent Plasticity – Changes due to learning and skill development.

Example: Musicians have a larger motor cortex controlling finger movements.

Prefrontal Cortex

Location: Front part of the frontal lobe.

Major Functions:

Decision-making

Impulse control

Planning and reasoning

Social behavior

Effects of Damage:

Poor judgment, impulsivity, personality changes.

Example: People with prefrontal cortex damage may struggle with following social norms.

Phineas Gage

Who was he?: A railroad worker who survived a severe brain injury (iron rod through his skull).

Why Important?: His personality drastically changed, showing that the prefrontal cortex is involved in impulse control and personality.

Relevance Today: His case helped scientists understand brain function localization.

Corpus Callosum

Definition: The bundle of nerve fibers connecting the brain’s two hemispheres.

Function: Allows communication between the left and right hemispheres.

Example from Lecture (Shoe-Lace Activity): Demonstrated how each hemisphere controls different functions and the importance of coordination between them.

Split Brain Procedure

What is it?: Surgical severing of the corpus callosum to treat severe epilepsy.

Effect on Communication: The two brain hemispheres can no longer share information directly.

Behavioral Effects:

Right hand (controlled by left brain) might not know what the left hand (controlled by right brain) is doing.

Example: A patient might see an object in their left field of vision but be unable to name it, since the right hemisphere (which processes the left visual field) cannot communicate with the left hemisphere (which controls speech).

Hemispherectomy

What is it?: Surgical removal of one hemisphere of the brain, usually to treat severe epilepsy.

Who Receives It?: Mainly children, because their brains have greater plasticity.

What It Shows About Brain Plasticity: The remaining hemisphere can often take over many functions of the removed one.

Major Brain Regions

Hindbrain: Controls basic vital functions.

Midbrain: Processes sensory information and controls reflexes.

Forebrain: Involved in mental processes

-Cortex and Subcortex