The Brain: Our Three Pound Universe The Biological Basis of Behavior: Unit II

I. The Three Brains A. Hindbrain – part of the brain at the rear base of the skull, involved in the basic processes of life 1. Oldest part 2. Responsible for automatic and survival functions 3. Three parts Medulla Pons Cerebellum

B. Midbrain – small part of the brain above the pons that relays sensory information upward (vision & hearing). Reticular activating system C. Forebrain – the most highly developed part of the brain responsible for the most complex aspects of behavior and mental life. 1. Covers the brain’s central core 2. 4 parts Thalamus Hypothalamus Limbic System Cerebrum

Brain Lobes (Each hemisphere of the brain is divided into 4 lobes.) Occipital (back) Temporal (side, behind ears) Wernicke’s Area Broca’s Area Parietal (top and rear) Frontal (behind forehead)

Major parts of the brain and their functions Forebrain Thalamus “inner chamber”-relay station for sensory stimulation Relays messages from sense organs for interpretation Hypothalamus “under”-vital functions, regulates body temp., storage of nutrients, motivation, and emotion Hunger, thirst, sexual behavior, caring for offspring, and aggression Cerebrum “brain”- 70% of brain’s weight Receives sensory info. and transmits motor info. Cerebral cortex “bark”-wrinkled surface, part that “thinks” Memory, language, emotions, complex motor functions, perception, etc. Corpus callosum-connects two brain hemispheres of cerebral cortex

Limbic System Inner fringe of cerebrum Learning and memory Emotion Hunger Sex Aggression *Evolutionary Psy*

Major parts of the brain and their functions (contd.) Midbrain Reticular Activating System-stretches from hindbrain through midbrain, to lower part of forebrain Coordinates basic movements with sensory info. Attention Sleep Arousal (heart rates/blood pressure) Alcohol lowers activity

Major parts of the brain and their functions (contd.) Hindbrain Medulla-heart rate and breathing, blood pressure, vital life functions Pons-coordinates left & right sides of body, regulates body movement, attention, sleep alertness, & facial expressions Cerebellum-balance and coordination, fine motor movements Affected by alcohol (DUI test)

Brain Lobes (sensory & motor areas) Occipital (back) Primary visual area Temporal (side, behind ears) Hearing/auditory area Wernicke’s Area Language function, puts together sounds & sights Damage-difficulty understanding written/spoken lang. Can speak quickly & easily but speech often makes no sense Broca’s Area Language function/speech production Damage-can comprehend written/spoken lang. but difficulty speaking Damage to areas causes “aphasia” Trouble understanding, producing language

Brain Lobes (condt.) Parietal (top and rear) Skin senses (integrates sensory systems) touch, temperature, pressure Frontal (behind forehead) Motor skills & problem solving Making plans & decisions, core of working memory, speech, learning, thinking

II. The Cerebral Hemispheres: Left and Right A. corpus callosum – a connection of nerve bundles that carry messages between our two brain hemispheres B. each hemisphere controls the opposite side of the body

C. laterization – specialization of the two cerebral hemispheres (L&R) for particular functions 70% of lefties are left hemisphere dominant for language Left Hem.-usually handles verbal processing, language, speech, reading, & writing Right Hem.-usually handles nonverbal processing, spatial, musical, and visual Primary sensory & motor areas are symmetrical.

III. Split Brain Patients Study Split Brain Patients- those who due to severe epilepsy, have their corpus callosum cut. Epilepsy-seizures due to neuron misfires that can spread from hem. to hem. Roger Sperry-won Nobel Prize in physiology/medicine.

Testing the Divided Brain

Accidents Phineas Gage Story 3.5 ft. iron rod Personality changed after the accident. What does this tell us? That different parts of the brain control different aspects of who we are. Damaged his frontal lobes

Neuroimaging Techniques 1. Computerized axial tomography (CAT Scan) X-rays beam around the head (3D view) Pinpoints injuries and brain deterioration

2. Position Emission Topography (PET Scan) Can see which areas of the brain are activated when performing tasks A radioactive solution is injected into the body Shows activity vs snapshot

3. Magnetic Resonance Imaging (MRI) Can see structures in detail, hard to see areas Magnetic fields and radio waves More powerful than CAT scan, “slice images”

4.Electroencephalograph (EEG) Measures electrical activity of brain using small electrodes pasted to your scalp Rhymic patterns produced are “brain waves”

Chapter 3 Main Points (exam review) Divisions of the Nervous System Parts/functions of neuron Parts/functions of brain Endocrine glands and hormones Heredity/genes/chromosomes Nature vs. Nurture