THE BRAINTHE MIRACLE OF THE BRAIN-YOUTUBE

OVERVIEW--NERVOUS SYSTEM

THE BRAIN

HypothalamusThalamus

Pons

Reticular FormationSpinal Cord

Medulla

Brain stem

Spinal Cord

“Old” Brain

“New” Brain

“OLD” BRAIN• 1-Cerebellum: located at the rear of the brain & controls

coordination, posture, balance, muscle tone, & control over body movement

• 2-Reticular Activating System (a.k.a. formation): monitors the general level of activity in the hindbrain & maintains a state of consciousness; Essential for the regulation of waking & sleeping

• Part of brain stem; alerts cerebral cortex to sensory input

• 3-Thalamus: relays & translates information from all of the senses, except smell, to higher levels in the brain

• Relays sensory impulses to cerebral cortex

• 4-Hypothalamus: plays a major role in the regulation of motivated behavior (hunger, thirst) & controls homeostasis (internal conditions/body temperature)

• 5-Medulla: the oblong structure at the top of the spinal cord that controls many vital life-support functions such as breathing, waking, heart rate, & blood pressure

• 6-Pons: located above the medulla; connects spinal cord with lower brain, & lower brain with higher brain regions

• Helps regulate sensory information & facial expressions

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“NEW” BRAIN

• Cerebrum: regulates higher cognitive & emotional functions• Cerebral cortex: outer gray covering of the cerebral hemispheres• Cerebral Hemispheres: right & left halves of the cerebrum, covered by the cerebral cortex

& connected by the corpus collosum• Hemispheric lateralization: specialization of one of the cerebral hemispheres to handle a

particular function• Left hemisphere: controls right side of body; coordinates complex movements; speech

& language in 95% of right handers & in 62% of lefties• Right hemisphere: controls left side of body; visual-spatial perception; nonverbal

behavior• Corpus Callosum: mass of nerve fibers that connect the right & left cerebral

hemispheres• Split-brain operation: corpus callosum is cut, separating

cerebral hemispheres (done in cases of severe epilepsy to reduce frequency of grand mal seizures)

“NEW” BRAIN• Left Handedness

• Right hemisphere more developed

• Corpus callosum 11% thicker with 25 million more nerve cells

• 12 times more likely to stutter & have learning disabilities (esp. dyslexia)

• 2.5 times more likely to have allergies & migraines

• lefties overrepresented in the following professions: art, music, engineering, math, major-league baseball player

• Split-brain operation = corpus collosum is cut, separating cerebral hemispheres (done in cases of severe epilepsy to reduce frequency of grand mal seizures)

• Contains four major lobes:

• Frontal lobe: controls voluntary movement & includes the motor cortex

• Broca’s area: controls physical production of speech sounds

• Parietal lobe: contains the primary somatosensory area that manages skin senses

• Somatosensory cortex

• Occipital lobe: located in the back of the head & contains the visual cortex

• Temporal lobe: located on each side of the head above the temples & contains the auditory cortex

• Wernicke’s area: comprehend spoken word; formulate (cognitively) speech & written language

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OTHER PARTS

• Limbic System = group of structures in the brain that are collectively involved in emotion, memory, & motivational urges

• Amygdala: emotion, aggression, formation of emotional memory

• Hippocampus: acquisition of explicit (conscious) memory

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BRAIN MONITORING

• PET Scanning (positron emission tomography): creates a visual image of functioning in various parts of the brain by tracing radioactivity emitted by cells

• MRI (magnetic resonance imaging): provides clear pictures of the structural anatomy & chemistry of the brain by passing a strong magnetic field & radio waves through the person’s head

• CAT (computerized axial tomography) scan: presents a picture of the human brain by passing X-ray beams through the head at various angles

• EEG (electroencephalograph): records the electrical activity of the brain

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