THE BIOLOGY OF THE MIND

BIOLOGICAL PSYCHOLOGYUNDERSTANDING SLEEP, DREAMS, DEPRESSION, HUNGER, STRESS,

& SEX

• Everything psychological is simultaneously biological• Thoughts, emotions,

memories, intelligence, and creativity are based on biological processes

• To understand our behavior, we need to study how biological, psychological and social systems interact.

THE NERVOUS SYSTEM

It starts with an individual nerve cell called a NEURON.

Sensory neurons Carry incoming messages from the body’s tissues and

sensory organs inward to the brain and spinal cord, for processing

Motor neurons Carry outgoing information from the brain and spinal cord to

the body’s tissues, muscles, glands

Interneurons Neurons within the brain and spinal cord that communicate

internally between sensory inputs and motor outputs

NEURAL COMMUNICATION

WHEN DO NEURONS TRANSMIT MESSAGES?

Stimulated by: Signals from senses Chemical signals from neighboring

neurons

Action potential Brief electrical charge that travels down

axon

Threshold – minimum intensity Excitatory signals – stimulate

Increase likelihood neuron will fire

Inhibitory signals – calm Decrease likelihood neuron will fire

http://www.youtube.com/watch?v=cNaFnRKwpFk

HOW NEURONS COMMUNICATE

• Synapse• Meeting point between neurons

• Neurotransmitters• Chemical messengers

• Acetylcholine (Ach)• Best-understood neurotransmitter• Messenger between motor neuron and skeletal

muscle• Released = muscle contraction• Blocked = paralysis

http://science.education.nih.gov/supplements/nih2/addiction/activities/lesson2_neurotransmission.htm

Neurotransmitter

Function Examples of Malfunctions

Acetylcholine (Ach)

Enables muscle action; excretion of certain hormones; anger, aggression, sexuality

ACh producing neurons deteriorate – lack of ACh leads to Alzheimer’s disease

Dopamine

Controlling movement and posture; Impacts mood, learning, attention, and emotion

Excess dopamine - linked to schizophrenia. Starved of dopamine = brain produces tremors, decreased mobility and muscle rigidity (Parkinson’s disease)

SerotoninRegulation of body temperature; Affects mood, hunger, sleep, and arousal

Undersupply linked to depression; Prozac raises serotonin levels

Neurotransmitter

Function Examples of Malfunctions

Norepinephrine

Helps control alertness and

arousal

Undersupply can depress mood

GABA(Gamma-

aminobutyric acid)

Major inhibitory neurotransmitter

Undersupply linked to seizures, tremors,

and insomnia

GlutamateMajor excitatory

neurotransmitter; involved in

memory

Oversupply can overstimulate brain, produce migraines or seizures (why some avoid MSG)

DRUGS & NEUROTRANSMITTERS

• When flooded with opiates, morphine or heroin, brain may stop producing natural opiates• Causes intense discomfort - withdrawals

• Drugs and other chemicals affect brain chemistry at synapses – amplifying or blocking neurotransmitters

• Examples:• Agonist - Black widow venom – floods synapses with ACh• Violent muscle contractions, convulsions, possible death

• Antagonist – Botulin – causes paralysis by blocking ACh release• Botox – smooth wrinkles by paralyzing underlying facial

muscleshttp://thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_par/i_03_m_par_cocaine.html#drogues

THE NERVOUS SYSTEM

• Central Nervous System• Brain• Spinal Cord• Connects peripheral nervous system to brain

• Peripheral Nervous System• Somatic (skeletal) – controls voluntary muscles• Autonomic – controls involuntary muscles

• Glands and muscles of internal organs• Heartbeat, digestion, etc.

• Sympathetic – Arouses and expends energy• You become alarmed or enraged• Increases heartbeat and raises blood pressure

• Parasympathetic – Conserves energy• Stress subsides • Decreased heartbeat, lowering of blood sugar

THE BRAIN

AM I LEFT OR RIGHT BRAIN DOMINANT?

• Recent studies have revealed no evidence of a stronger left or right-sided brain network• Example: Language• Left hemisphere specializes in picking out the sounds that form words • Right hemisphere is more sensitive to the emotional features of language

• It is true that some functions occur in one side or the other of the brain• Language tends to be on the left (Sounds that form words)• Attention more on the right (Emotional features of language)

Left-BrainLogical

LanguageAnalytic

Right-BrainIntuitive

ExpressiveCreative

CEREBRAL CORTEX

CEREBRAL CORTEX

FRONTAL LOBE

• Associated with:• Reasoning• Motor skills• Higher level cognition• Expressive language

• If damaged:• Changes in socialization

and attention; increased risk-taking

• Example - Used when planning a road trip

CEREBRAL CORTEX

• Example – Figuring out if car will fit into parking spot

PARIETAL LOBE• Associated with:• Processing tactile sensory

information• Pressure, touch, pain

• Processing mathematical, spatial information

• If injured:• Problems with verbal

memory• Problems with language

CEREBRAL CORTEX

OCCIPITAL LOBE• Home to the primary

visual cortex• Associated with:• Interpreting visual

stimuli and information

• If injured:• Visual problems• Difficulty recognizing

objects, identifying colors or recognizing words

• Example – Ability to see a stop sign

CEREBRAL CORTEX

• Example – Responding to another driver honking

TEMPORAL LOBE

• Home to the:• Primary auditory cortex • Interpreting sounds and

language

• Hippocampus• Formation of memories

• If injured:• Problems with memory,

speech perception, and language skills

STORY OFHOW YOU USE YOUR LOBES

• Instructions:• Construct a short story detailing how you use your lobes•Must include reference to all four

•Write story on back page of your brain book

THE BRAINSTEMTHE BRAIN’S BASEMENT

• Brain’s oldest and innermost region

• Brain stem acts as crossover point• Regulates involuntary functions

• Midbrain • Helps to relay information for vision

and hearing• Also associated with motor control,

alertness, and temp. regulation

• Pons• Helps coordinate movement

• Medulla• Controls heartbeat and breathing

THE BRAIN

Cerebellum• “Little brain”• Regulates voluntary

motor movements• Posture, balance,

coordination, speech

Corpus Callosum

• Wide band of axon fibers connecting two brain hemispheres• Carries messages between

←Cerebellum

THE SPLIT BRAINAssists researchers in studying hemispheric

specialization

• 1961 - Neurosurgeons predict epileptic seizures caused by amplified abnormal brain activity between the two hemispheres

THE LIMBIC SYSTEM

• Hypothalamus – controls maintenance• Helps keep the body’s internal environment in a steady state• Hunger, thirst, body temperature, sexual behavior

• Controls the pituitary gland “master gland”• Regulates and releases important hormones

• Hippocampus• Responsible for memory

creation and retention

• Amygdala• Linked to emotion• Influence aggression and fear• Processing of emotional

memories

• Thalamus• Brain’s sensory

switchboard• Relays all sensory

information• Except for smell

THE ENDOCRINE SYSTEM

• Glands secret hormones, chemical messengers

• Travel through bloodstream affecting other tissues

• Influence our interest in sex, food, and aggression

THE ENDOCRINE SYSTEM

• Pituitary Gland• “Master gland”• Located near core of brain• Controlled by hypothalamus

• Releases hormones that influence growth

• Secretes hormones that control output of hormones by other endocrine glands• Triggers sex glands to release

sex hormones

THE ENDOCRINE SYSTEM

•Adrenal gland• Located on top of

kidneys

• Release epinephrine and norepinephrine• Adrenaline and

noradrenaline

• Hormones increase heart rate, blood pressure, and blood sugar• Provide surge of energy

THE ENDOCRINE SYSTEM

• Thyroid gland• Produces thyroxine• Too little – feel lazy, lethargic

• Hypothyroidism

• Too much – overactivity• Hyperthyroidism

• Sex glands• Testes• Produce sperm and

testosterone

• Ovaries• Produce eggs and estrogen

and progesterone

STUDYING THE BRAIN

CAT SCAN

• Computerized axial tomography scan• CAT scan or CT scan

• Combines series of X-ray views taken from different angles to create cross-sectional images

• Can be reformatted into multiple planes or even used to generate three-dimensional images

• Provide great detail of soft tissues and blood vessels

(EEG) - ELECTROENCEPHALOGRAM

Amplified read-out of waves of electrical activity

that sweep across the brain’s surface

• Process:• Stimulus presented regularly• Computer filters out brain

activity unrelated to stimulus• Able to identify electrical wave

evoked by stimulus

• Used in identifying:• Epilepsy• Other brain disorders

PET SCAN(PET) - POSITION EMISSION TOMOGRAPHY

• Shows how the brain and its tissues are working• Depicts brain activity by showing each brain area’s

consumption of its chemical fuel, sugar glucose• Radioactive glucose

• Useful in looking for cancer, disease, or injury to the brain

PET SCAN

• Shows which brain areas are most active during:• Math calculations• Looking at images of faces• Daydreaming

(MRI)MAGNETIC RESONANCE IMAGING

• MRI has revealed:• Larger neural area in left hemisphere of

musicians with perfect pitch• Enlarged fluid-filled brain areas in patients

experiencing schizophrenia

• Head inserted into strong magnetic field

• Allows us to see structures in the brain• Signals provide detailed

picture of brain’s soft tissues

• fMRI (functional MRI)• Can reveal brain function and structure• Comparison of MRI scans taken less than a second

apart• Reveals blood flow – “lights up”

• Person performs different mental functions• Example: • Person looks at scene• fMRI detects blood rushing to back

of brain• Processing of visual information

fMRI – FUNCTIONAL MRI