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• Our Genetic Inheritance • Neural Bases of Behavior • Nervous System Organization • A Tour Through the Brain

Chapter two Neuroscience and Biological Foundations

realworldpsychology

Things You’ll Learn in Chapter 2

Can our genes influence whom we vote for in presidential elections?

Why can spending the first few months of life in an orphanage lead to long-term problems in cognitive functioning?

How can a chemical in the brain lead rats to binge-eat M&Ms?

How can stem cell injections lead to restored vision and improved recovery from strokes?

Why are former NFL athletes at increased risk of depression, dementia, and suicide?

OUR GENETIC INHERITANCE

• The study of how heredity and environment affect us • Evolutionary psychology = the application of

principles of evolution to explain behavior and mental processes

• Genes control the transmission of traits • Modern research shows most human

characteristics are polygenic (controlled by multiple genes, not merely one dominant or two recessive genes)

Behavior Genetics

Most serious genetic disorders

are not transmitted by

dominant genes. Why?

realworldpsychology • Most people understand that genes affect

our health, such as potential for heart disease, diabetes, and cancer

• Genes also affect our personality traits, behavioral habits, sexual orientation, and psychological disorders

• Genes can even influence which political party we side with, and our views on death penalty, unemployment, and abortion (Hatemi & McDermott, 2012)

Can our genes influence whom we vote for in presidential elections?

• Environmental factors – both physical and psychological – also influence our characteristics

• Malnourished children may not reach their full potential genetic height or maximum intelligence

Gene-Environment Interaction

• Identical twins share all their genes, fraternal twins share about half of their genes (just like non-twin siblings)

• Twins raised together by birth parents share the same environment

• Identical twins should be more alike than fraternal twins (such as in intelligence)

• Research on adoptive children can trace characteristics to birth parents vs. adoptive parents

• Research shows many psychological traits (and disorders) run in biological families

Genes vs. Environment

How can psychologists

separate genetic causes from

environmental causes?

• Heritability = the percentage of variation in a population attributable to heredity – If no genetic influence, heritability would be 0% – If no environmental influence, heritability would

be 100%

• Heritability does NOT apply to INDIVIDUALS • Heritability does not trump environment

Heritability

• Many behaviors emerged and still exist because they helped our ancestors survive

• Natural selection = particular genetic trait gives an organism a reproductive advantage

• “Reproduction of the fittest,” not “survival of the fittest”

Evolutionary Psychology

NEURAL BASES OF BEHAVIOR

Building blocks of brain and nervous system: • Neurons = responsible for receiving, processing, and

transmitting electrochemical information • Glial cells = provide structure, nutrition and other

support to neurons

The Basics

• Dendrites = branching fibers that receive impulses from other neurons and send them to the cell body

• Cell body = AKA soma, contains cell nucleus

• Axon = long, tube-like structure that sends impulses away from cell body to other neurons (or to muscles, glands)

Parts of a Neuron

Action Potential

• Sequence of depolarization and repolarization moves the action potential from the cell body to the axon terminal buttons like the “wave”

Action Potential

• Electricity moves 36 million meters/second • Nerve impulses move 10 meters/second • Nerve impulses move 10x faster through

axons with myelin sheath

Speed of Thought

• Social isolation during early weeks/months of life (as for babies in orphanage) prevents proper growth of myelin, leading to long-term cognitive impairment

Why can spending the first few months of life in an orphanage lead to long-term problems in cognitive functioning?

• Communication WITHIN neuron is electrical, but communication BETWEEN neurons is chemical

• Sending neuron gets close to receiving neuron at synaptic gap, where neurotransmitters (chemicals) cross the gap to deliver the message

Communication Between

How Neurotransmitters Work

Reuptake

Lock and Key

Common Neurotransmitters

• Common neurotransmitter elevate mood, reduce pain • Opium-based drugs mimic the body’s natural

endorphins

Endorphins

• Endorphins affect memory, learning, appetite, and sexual activity. Rats injected with endorphins ate 5% of their body weight in M&Ms!

How can a chemical in the brain lead rats to binge-eat M&Ms?

• Endocrine system = network of glands located throughout the body that secretes hormones into the bloodstream

• Neurons send messages to certain receptors; hormone messages are carried by the blood to any cell that will listen

• Regulates and maintains long-term body processes, such as growth, sexual characteristics, digestion, and elimination

• Controls response to emergencies: adrenal glands release cortisol, epinephrine, and norepinephrine

Hormones & the Endocrine System

NERVOUS SYSTEM ORGANIZATION

• CNS is powerful, but fragile • Neuroplasticity = brain can reorganize its

functional structure due to usage and experience

Central Nervous System (CNS)

• Neurogenesis = lost cells can be replaced by neural stem cells (rare immature cells that can migrate and grow into any type of cell).

• No cell transplant for spinal cord injuries in humans, but animal research shows stem cell treatment leads to improvement in paralyzed limbs

How can stem cell injections lead to restored vision and improved recovery from strokes?

• Relays AND initiates vital information to other parts of the body

• Reflexes = automatic behavior in response to stimuli • Allows immediate action without delay of routing

through brain

Spinal Cord

What is the evolutionary benefit of the

reflex arc?

Newborn Reflexes

Rooting reflex – Lightly stroke the cheek and watch how the infant automatically (reflexively) turns toward the stimulation and attempts to suck

Grasping Reflex – Place your finger or an object in the infant’s palm and note the automatic grasp

Babinski Reflex – Lightly stroke the sole of the foot, and the big toe will move toward the top, while the other toes fan out.

• The part of the nervous system outside the brain and spinal cord

• Carries information to and from the CNS • Links brain and spinal cord to body’s sense

receptors, muscles and glands – Somatic nervous system (SNS): carries sensory

information to the brain and instructions back to skeletal muscles

– Autonomic nervous system (ANS): responsible for involuntary tasks like heart rate, digestion, and breathing

Peripheral Nervous System (PNS)

• Sympathetic division: mobilizes energy to respond to stressor (fight or flight)

• Parasympathetic division: calms body to conserve energy, returns body to normal functioning after stress

Autonomic Nervous System

A TOUR THROUGH THE BRAIN

Biological Tools for Research

Biological Tools for Research (cont.)

Forebrain

Limbic System – The interconnected group of forebrain structures involved with emotions, drives, and memory, as well as major physiological functions

Cerebral Cortex– The thin surface layer that regulates most complex behavior (i.e. sensations, motor control).

Limbic System

Hippocampus– Seahorse shaped part of the limbic system involved in forming and retrieving memories

Amygdala– Part of the limbic system that controls emotions, like aggression and fear.

realworldpsychology • Cerebral cortex = surface layer of the brain • Responsible for most complex behaviors and higher

mental processes • Damage to cerebral cortex linked to substance abuse,

dementia, and suicide

• Trauma is particularly common in contact sports, like football, ice hockey, boxing, and soccer

Why are former NFL athletes at increased risk of depression, dementia, and suicide?

Lobes

realworldpsychology • In 1848, 25-year-old railroad worker

Phineas Gage had a metal rod accidentally blown through the front of his face, destroying much of his brain’s frontal lobe

• Experienced drastic personality changes; became impatient and lacked concern for coworkers

• He eventually obtained a job driving a stagecoach, which required high motor, cognitive, and interpersonal skills

What does modern research about

neuroplasticity tell us about Gage’s possible

recovery?

• Each hemisphere controls the opposite site of the body

• Corpus callosum = thick band of nerves, connects the two hemispheres

• Although each side of the brain might have a specialty (like Broca’s area for speech in the left hemisphere), when specific regions of the brain are injured or destroyed their functions can be assumed by neighboring region – or even opposite hemisphere

Two Brains in One?

realworldpsychology • Popular myth says left brain is analytical and

right brain manages creativity • Research shows both hemispheres work

together in an integrated manner, like teammates playing soccer; each area might have specialties, but everyone knows what the other is doing and can help when needed

Slide Number 1
Slide Number 2
Our genetic inheritance
Behavior Genetics
Slide Number 5
Gene-Environment Interaction
Genes vs. Environment
Heritability
Evolutionary Psychology
Neural bases of behavior
The Basics
Parts of a Neuron
Action Potential
Action Potential
Speed of Thought
Communication Between
How Neurotransmitters Work
Lock and Key
Common Neurotransmitters
Endorphins
Hormones & the Endocrine System
Nervous system organization
Slide Number 23
Central Nervous System (CNS)
Spinal Cord
Newborn Reflexes
Peripheral Nervous System (PNS)
Autonomic Nervous System
A tour through the brain
Slide Number 30
Slide Number 31
Forebrain
Limbic System
Slide Number 34
Lobes
Slide Number 36
Two Brains in One?
Slide Number 38
Slide Number 39