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Neurobiology: The Brain Study Guide
A. Tools of Discovery
- Clinical observations have revealed general effects of damage to various areas of the
brain.
- Scientists can electrically, chemically, or magnetically stimulate various parts of the
brain and note the effects or surgically lesion tissue in specific brain areas.
o EEG (electroencephalogram): amplified reading of brain waves; reveals brain
activity
o PET (positron emission tomography) scan: visual display of brain activity;
detects where glucose goes when brain performs a task
o MRI (magnetic resonance imaging): uses magnetic fields and radio waves to
produce computer images, allowing scientists to see structures within the
brain
o fMRI (functional magnetic resonance imaging): reveals blood flow and brain
activity; shows brain function
B. Older Brain Structures
- Brainstem: brain’s oldest and
innermost region; begins where
spinal cord swells at it enters skull;
responsible for automatic survival
functions
- Medulla: base of brainstem;
controls heartbeat and breathing
- Reticular Formation: inside
brainstem, between ears; controls arousal
- Thalamus: brain’s sensory switchboard on top of brainstem; receives info from all
the senses (except smell) and sends them to brain regions dealing with the other 4
senses
- Cerebellum: extends from rear of brainstem, “little brain”; processes sensory input;
coordinates movement and balance
- Limbic System: associated with emotions like fear and aggression, as well as drives
for food and sex
o Hippocampus: processes memory
o Amygdala: linked to emotion
o Hypothalamus: directs several maintenance activities, helps govern
endocrine system via pituitary gland, linked to emotion
C. Cerebral Cortex
- The body’s ultimate control and information processing center
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The brain hemisphere is divided into four lobes:
o frontal lobes: behind forehead; involved in speaking and muscle movements
and making plans and judgments
o parietal lobes: at the top and the rear; receives sensory input for touch and
body position
o occipital lobes: back of head; receives visual information from the opposite
visual field
o temporal lobes: side of head, above ears; receives auditory info primarily
from opposite ear
Sensory Cortex: area of front of parietal lobes that registers and processes body
touch and movement sensations
Association Areas: not involved in primary motor or sensory functions; involved in
higher mental functions such as
learning, remembering, thinking,
and speaking
Damage to any one of the several
cortical areas can caused aphasia:
impaired use of language
Broca’s Area: controls language
expression; area of frontal lobe, in
left hemisphere; directs muscle
movements involved in speech
Wernicke’s Area: controls
language reception; involved in
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language comprehension and expression; left temporal lobe
- Plasticity: the brain’s ability to modify itself after some types of damage
D. Divided Brain
- Clinical evidence has shown that the brain’s two sides have different functions
o Left hemisphere: “dominant” or “major” hemisphere
o Right hemisphere: “subordinate” or “minor”
- Corpus Callosum: large band of neural fibers connecting two brain hemispheres and
carrying messages between them
- Split Brain: two hemispheres of the brain are isolated by cutting the connecting
fibers between
them
o In most people, the left hemisphere is more verbal and right hemisphere
excels in visual perception and recognition of emotion
o Almost all right-handed people process speech in left hemisphere
o Remainder of left-handers process language in right hemisphere or in both