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 Cerebellum pons

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 cerebral cortex corpus callosum

Brain Lobes (Each hemisphere of the cerebral cortex in divided into 4 lobes.)

Occipital (back) Temporal (side, below ears)

Wernicke’s Area Broca’s Area

Parietal (top and rear) Frontal (behind forehead)

Limbic System

Inner edge of cerebrumLearning and memoryEmotion HungerSexaggression

Major parts of the brain and their functions Forebrain

Thalamus-relay station for sensory stimulation Relays messages from sense organs for interpretation

Hypothalamus-vital, regulates body temp., storage of nutrients, motivation, and emotion

Hunger, thirst, sexual behavior, caring for offspring, and aggression Cerebrum- 70% of brain’s weight

Cerebral cortex-wrinkled surface, part that “thinks” Memory, language, emotions, complex motor functions, perception,

etc. Corpus callosum-connects two brain hemispheres of cerebral

cortex

Major parts of the brain and their functions (contd.) Midbrain

Reticular activating system-stretches from hindbrain through midbrain, to lower part of forebrain

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 functions

Pons-coordinates left & right sides of body, body movement, attention, sleep alertness

Cerebellum-balance and coordination

Brain Lobes (sensory & motor areas) Occipital (back)

Primary visual area Temporal (side, below ears)

Hearing/auditory area Wernicke’s Area

Language function, puts together sounds & sights Broca’s Area

Language function Damage to areas causes “aphasia”

Trouble understanding, producing language Parietal (top and rear)

Skin senses Frontal (behind forehead)

Motor skills, executive center Solve problems, make plans & decisions, core of working memory

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

III. Split Brain Patients Study

A. Split Brain Patients- those who due to epilepsy, have their corpus callosum cut.

Testing the Divided Brain

B. Accidents

Phineas Gage Story Personality changed

after the accident.What does this tell

us? That different part

of the brain control different aspects of who we are.

Neuroimaging Techniques 1. Computerized axial

tomography (CAT Scan) a) x-rays beam around the

head (3D view) b) pinpoints injuries and brain

deterioration

2. Position Emission Topography (PET Scan)

a) can see which areas of the brain are activated when performing tasks

b) a radioactive solution is injected into the body

Shows activity vs snapshot

3. Magnetic Resonance Imaging (MRI) a) can see structures in detail, hard to see areas b) magnetic fields and radio waves c) more powerful than CAT scan