BIOLOGICAL BASIS OF BEHAVIOR

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BIOLOGICAL BASIS OF BEHAVIOR
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FORMS OF COMMUNICATION

• Nervous system
• Endocrine system

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FUNCTIONAL ORGANIZATION OF NERVOUS SYSTEM

• CENTRAL NERVOUS SYSTEM
• All neurons in the brain and spinal cord
• PERIPHERAL NERVOUS SYSTEM
• All the neurons forming the nerve fibers that
  connect the CNS to the body.

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CENTRAL NERVOUS SYSTEM

• Integrate and coordinate all bodily functions,
  process all incoming neural messages, and send
  out commands to different parts of the body
• CNS sends and receives neural messages from the
  spinal cord
• Isolated from the outside world

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PERIPHERAL NERVOUS SYSTEM

• Provide CNS with information from sensory
  receptors
• Composed of two sets of nerve fibers
• Somatic nervous system
• Regulates actions of bodys skeletal muscles
• Autonomic nervous system
• Sustains basic life processes
• On the job 24 hours a day

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• Autonomic nervous system
• Sympathetic nervous system
• Governs responses to emergency situations
• Parasympathetic nervous system
• Monitors the routine operation of the bodys
  internal functions

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THE NEURON

• Basic building block of the nervous system.
  Sends, receives and processes information.
• Discovered by Ramon y Cajal
• Not all neurons look the same
• Unipolar dorsal root ganglia
• Bipolar senses
• Multipolar the majority of neurons

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• One micrometer thick
• Soma about 10-25 micrometers
• Longest axon from spine to toes
• Giraffe running down entire neck
• Squid 0.5 to 1 millimeters thick, several
  centimeters long
• 100 billion neurons in the brain, each connected
  to about 7,000 other neurons, 3 year old, 1,000
  trillion connections, 100 to 500 trillion, in an
  adult

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• Dendrites
• Branchlike extensions of the neuron that detect
  information from other neurons
• Cell body or soma
• Contains the nucleus, region where information is
  processed
• Axon
• A long narrow outgrowth of a neuron by which
  information is sent to other neurons. Bundle of
  these make up nerves.
• Terminal buttons
• Small nodules (bumps) that contain chemicals

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• Schwaan cell (neurolemnocytes)
• Glial cell
• Form the myelin sheath in PNS
• Oligodendrocytes
• Glial cell
• Form myelin sheath in CNS
• Ten times more glial cells than neurons

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• Membrane
• Double layer of fatty molecules
• Lipids
• Semi-permeable
• Inside
• Intracellular fluid or cytoplasm
• Outside
• Extra-cellular fluid

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• TYPES OF NEURONS
• Sensory neurons
• A.k.a. afferent neurons
• Detect information from the outside world and
  sends it to the brain
• Motor neurons
• A.k.a. efferent neurons
• Sends messages from brain to muscles
• Interneurons
• Communicate only with other neurons within brain
  and spinal region

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HOW DOES A NEURON SEND A MESSAGE DOWN ITS AXON?

• A NEURON AT REST
• Resting Potential
• Ions
• Negatively (anion) or positively (cation) charged
  particles (gaining or losing electrons)
• Sodium (Na), chloride (Cl-), calcium (Ca),
  potassium (K)
• polarized
• Sodium potassium pumps
• A mechanism of the neuron that keeps the resting
  membrane at a constant voltage. K can come in
  but Na out!
• Fluid within more negative than fluid without
• 70/1000 of a volt inside or -70 milivolts

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• Pumps at work animation.1
• Pumps at work animation.2

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• A NEURON AT WORK
• Excitatory or inhibitory signals
• Fire or not to fire depolarization or
  hyperpolarization
• If enough depolarization, neuron will fire
• -55 to -50 millivolts
• Action Potential
• Axon hillock
• Gates (Ion channels) open
• Propagation down the axon, dominoes,
• 1/1000 of a second
• All or none law or principle (self-propagating)
• 10 centimeters per second to 200 meters per
  second

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• Spatial and temporal summation
• Spatial refers to number of simultaneous
  excitatory and inhibitory signals
• temporal refers to frequency of each type of
  signal
• Neural integration
• Signals all integrated in the axon hillock

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• Action Potential animation

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AFTER CELL FIRES

• Refractory Period
• Absolute refractory period
• Hyperpolarized, cell will not fire again despite
  excitatory signals
• Relative refractory period
• Somewhat hyperpolarized, will fire if given extra
  excitatory signals to fire.
• Takes about 5 milliseconds (5/1000 of a second)
  to return to resting potential

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• Speed is effected by myelin sheath
• Fatty material encases axons
• Gial cells
• Nodes of Ranvier (Louis-Antoine)
• 1878 (43 yrs. Old) discovered myelin and the
  nodes
• Saltatory conduction
• Multiple sclerosis
• Brain, spinal cord, optic nerve
• Muscular weakness, lack of coordination,
  impairment of vision and speech
• Early adult life
• Environmental and genetic factors
• Childhood in cool climates, rare in Gypsies and
  Asians

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• Guillain-Barre syndrome (Georges and Jean
  Alexandre)
• Peripheral nervous system
• From minor infectious diseases or illnesses
• Faulty immune system

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HOW DOES A NEURON COMMUNICATE WITH ANOTHER NEURON?

• Synapse or synaptic gap or synaptic cleft
• to clasp
• Greek word for junction
• Sir Charles Sherrington (1852-1952)
• English physiologist
• Space between neurons
• 20-40 nanometers (billionth of a meter)
• Otto Loewi and his dream (1920)
• Two dreams
• Nobel prize 1936
• Father of neuroscience
• Neurotransmitters
• Chemical substances that carry messages from one
  neuron to another

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• THE PROCESS
• Terminal buttons or synaptic knobs (presynaptic
  neuron)
• Calcium ions Ca
• Vesicles or synaptic vesicles
• Neurotransmitters
• More Ca more vesicles
• Each vesicle contains same amount of transmitters
• Roughly tens of thousands
• Release of several hundreds vesicles at a time
• Produced by the neuron cell body, transported
  down axon

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• Postsynaptic neuron (dendrites)
• Receptors
• Specialized protein molecules
• Ionotropic receptors aka chemically gated or
  ligand-gated ion channels
• Directly control the ion channel
• Metabotropic receptors
• Indirectly control the ion channel
• Receptors effect whether neurotransmitter is
  excitatory or inhibitory

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• WRAP-UP
• Reuptake
• Neurotransmitter is taken back up to its terminal
  button and repackaged into its vesicles
• pinocytosis
• transporters
• Enzyme deactivation aka degradation
• Neurotransmitter is destroyed by an enzyme
• Autoreceptors
• Neurotransmitter binds with its own receptor,
  signaling an excess.

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• How drugs effect neurotransmitters.
• Agonist
• Any drug that enhances the actions of a specific
  neurotransmitter
• Antagonist
• Any drug that inhibits the action of a specific
  neurotransmitter

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NEUROTRANSMITTERS

• Acetylcholine
• Responsible for motor control at the junction
  between nerves and muscles and are also involved
  in mental processes such as learning, memory,
  sleeping and dreaming.
• Curare
• Nucleus basalis
• Alzheimer's

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• MONOAMINES
• Synthesized from a single amino acid, involved in
  a variety of psychological activities
• Organic compound containing amino group NH2 and
  carboxyl group COOH.
• Epinephrine (adrenaline)
• Causes burst of energy in body

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• Norepinephrine (noradrenaline)
• States of arousal and vigilance

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• Dopamine
• Motivation, reward and motor control
• Substantia nigra
• Parkinsons disease
• Meso..
• schizophrenia

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• Serotonin
• Emotional states, impulse control and dreaming

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• AMINO ACIDS
• Act as neurotransmitters
• GABA (gamma-aminobutyric acid)
• Inhibitory neurotransmitter
• Valium
• Glutamate
• Excitatory neurotransmitter
• Learning and memory
• Astrocytes (glial cells)

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• PEPTIDES
• Two or more amino acids, act like
  neurotransmitters or modify quality of the
  partner neurotransmitter
• CCK (cholecystokinin)
• Cerebral cortex, learning, memory, pain
  transmission, exploratory behavior, also involved
  with the feeling of fullness from eating (discuss
  later)
• Endorphins
• Pain reduction and reward
• Substance P
• Pain perception

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NEUROANATOMY

• BASIC BRAIN STRUCTURES AND THEIR FUNCTIONS
• Spinal cord
• Hindbrain
• Midbrain
• Hind Mid Brainstem
• Forebrain

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SPINAL CORD

• Part of the central nervous system. A rope of
  neural tissue that runs inside the hollows of the
  vertebrae from just above the pelvis and into the
  base of the skull.
• Billion neurons
• Gray matter
• A segment of the spinal cord that is dominated by
  the cell bodies of neurons.
• White matter
• A segment of the spinal cord that consists mostly
  of axons and the fatty sheaths.

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• Spinal reflex
• Simplest behavior, conversion of sensation into
  action by a handful of neurons and the
  connections between them.
• Central pattern generator
• A circuit that, once activated, produces a
  rhythmic, recurring set of movements.
• Hind leg extensions, move up forelegs
• Fish can still swim, cats can walk

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HINDBRAIN

• A section of the bottom of the brain that houses
  the most basic programs of survival such as
  breathing, swallowing, vomiting, urination, and
  orgasm.
• Reflexes in the head
• Uses reflexes in the spinal cord as well
• Get animals to walk when stimulated, then trot,
  then gallop

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• Medulla (oblongata)
• Breathing, blood pressure, and the beating of the
  heart
• Coughing, vomiting, swallowing
• Pons
• bridge, initiates sleep, dreaming, integrates
  movements of and sensations from the face.
• Blow to the head can lead to unconsciousness
• Arousal
• Assists in Controlling Autonomic Functions
• Relays Sensory Information Between the Cerebrum
  and Cerebellum
• Sleep

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• Cerebellum (little brain)
• Essential for coordinated movement and balance.
• Damage can cause head tilt, balance problems,
  coordination of eyes and head movement, walking,
  limb coordination
• Very independent
• In additionautomatic psychological activities
• Reticular formation
• A large network of neural tissue within the
  brainstem (extends into cerebral cortex and basal
  ganglia) involved in behavioral arousal and
  sleep-wake cycles.

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• Autonomy of the brain stem
• Anesthetized animals can walk and
• Cats can still function.
• Walk around, direct attack at noises, eat food
• Kids even born like this

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MIDBRAIN

• mesencephalon
• Coordinating movement and relaying information
  from the senses
• Coordinating muscle movements with senses
• Reticular formation
• Tectum (roof)
• Located at the back of the midbrain, this brain
  structure helps guide orientation towards sounds
  or moving stimuli
• Tegmentum
• Ventricular mesocoelia
• Cerebral peduncles

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FOREBRAIN

• Huge, sits above and around the brainstem, site
  of all thoughts, detailed perceptions, and
  consciousnessin short, everything that makes us
  human!
• Cerebral hemispheres
• Two, symmetrical

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• Thalamus
• The gateway to the brain that receives almost all
  incoming sensory information before it reaches
  the cortex.
• Plays role in attention as well.

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• Hypothalamus
• Structure that is vital for temperature
  regulation, circadian rhythms, blood pressure and
  glucose level
• which then influences basic drivesemotion,
  sexual behavior, and motivation
• One of the most vital regions of the brain.
• Hippocampus (sea horse)
• Structure important for the formation of certain
  types of memory

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• Amygdala (almond)
• Serves a vital role in learning to associate
  things in the world with emotional responses and
  for processing emotional information.
• Enables organism to overrule instinctive
  responses by connecting the cortexs memories of
  things to the emotions they engender.
• Aids in responding to fear stimulus
• Limbic System

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• Basal ganglia
• A system of subcortical structures that are
  important for the initiation of planned movement.

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• Cerebral cortex
• The outer layer of brain tissue that forms the
  convoluted surface of the brain
• 1.5 to 4.5 mm thick
• 2.5 ft squared surface area
• Enables complex behaviors, think before we act

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• Occipital
• Parietal
• Temporal
• Frontal
• Named after the bones that cover the area
• Divided by the sulci
• Corpus callosum
• Thicker in women?

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• Each of the lobes have different areas
• Sensory areas
• Receive and interpret sensory impulses
• Motor areas
• Control muscular movement
• Association areas
• Integration functions

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• Occipital lobe
• A region of the cerebral cortex at the back of
  the brain that is important for vision.
• Primary visual area or cortex (sensory area)
• Receives information from the thalamus
• Topographically mapped and preserves spatial
  relationships
• Receives information concerning shape, color and
  movement
• Visual association area (assoc. area)
• Recognition and evaluation

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• Parietal lobe
• A region of the cerebral cortex lying in front of
  the occipital lobes and behind the frontal lobes
  that is important for the sense of touch and the
  spatial layout of an environment
• Primary somatosensory area/cortex or general
  sensory area (sensory area)
• Greek, bodily sense
• Receives nerve impulses sensory receptors for
  touch, proprioception, pain and temperature
• Somatosensory association area (assoc. area)
• Integrate and interpret sensations

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• Temporal lobes
• The lower region of the cerebral cortex that is
  important for processing auditory information and
  also for memory
• Primary auditory area/cortex (sensory area)
• The region of the temporal lobe concerned with
  hearing.
• Auditory association area (assoc. area)
• Wernickes area
• Differentiates sound, interprets meaning of speech

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• Frontal lobe
• The region at the front of the cerebral cortex
  concerned with planning and movement
• Primary motor area/cortex (motor area)
• The region of the frontal lobe concerned with
  movement
• Motor speech area (motor area)
• Brocas area
• Controls the muscles of speech
• Premotor area (assoc. area)
• Controls learned skilled movements, memory bank
  for the same
• Frontal eye field area (assoc. area)
• Voluntary scanning of the eyes

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• Prefrontal cortex
• A region of the frontal lobes, especially
  prominent in humans, important for attention,
  working memory, decision making, appropriate
  social behavior, and personality.
• 30 of brain in humans

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HOW IS THE BRAIN DIVIDED?

• The hemispheres can be separated.
• Corpus callosum
• Part way or complete
• Split brain
• Initially looked very normal

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• The separate hemispheres can be tested
• experiment

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• The hemispheres are specialized
• Left hemisphere
• Far superior in language than right
• Hopeless at spatial relationships
• Right hemisphere
• Rudimentary language comprehension
• Competent with spatial relationships
• Where the corpus callosum is cut has an effect
  also.

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• According to Michael Gazzaniga, the mind is a
  subjective interpreter
• Experiment
• Left brain propensity to construct a world that
  makes sense interpreter
• Strongly influences our view of the world
• compress experience
• Right brain just experiences the world, remembers
  with less distortion.
• Acts as a check to the left brain

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HOW DOES THE BRAIN CHANGE?

• Brain is extremely malleable
• Plasticity
• A property of the brain that allows it to change
  as a result of experience or injury.
• Reptiles vs. humans

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• The interplay of genes and the environment wires
  the brain.
• Chemical signals (chemical gradients) guide
  growing connections
• Signals from other cells and its surrounding
• What if you move some cells to a different area?
• Depends on when you do it.

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• Experience fine-tunes neural connections
• Major connections established by chemical
  signals
• detailed connections governed by experience
• Cats eye experiments
• Critical periods
• The time in which certain experiences must occur
  for normal brain development, such as exposure to
  visual information during infancy for normal
  development of the brains visual pathways.
• Orem Jr. High rats vs. Lakeridge rats

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• The brain rewires itself throughout life
• Change in the strength of connections underlies
  learning
• Preexisting connections are strengthened
• Like sledding
• Neurogenisis
• Hippocampus
• Environmental conditions effect neurogenesis

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• Changes in use distort cortical maps
• Monkey experiment
• What about phantom limbs?

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• The brain can recover from injury
• Better when younger than older
• Stem cell research

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ENDOCRINE SYSTEM

• A communication system that influences thoughts,
  behaviors, and actions. Uses hormones.
• Chemical substances released into the bloodstream
  by endocrine glands (ductless glands such as the
  pancreas, thyroid, and testes and ovaries).

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• Types of Hormones
• Steroids
• Synthesized from cholesterol
• Tissue repair and reproduction
• Amino acids and peptides
• Also function as hormones in endocrine system
• Focus on mode of communication not the substance
  itself.

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• Coordination of nervous and endocrine system
• Hypothalamus
• Releasing factor
• Pituitary gland
• Controls release of hormones from the rest of the
  endocrine glands

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• HORMONE ACTIONS
• Act in a gradual fashion
• Change intensity or probability of behavior
• Relationship between hormones and behavior is
  reciprocal.
• Each hormone has multiple effects on different
  tissue, organs and behaviors, single type of
  behavior can be effected by different hormones
• Produced in small amounts and secreted in bursts

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• Hormone levels vary throughout the day
• Hormones effect metabolic processes in most cells
• Hormones interact
• Chemical structure of hormones the same in all
  vertebrates
• Hormones only effect cells that possess
  appropriate receptor protein

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• NEURAL VS. HORMONAL COMMUNICATION
• Neural communication telephone hormonal
  communication TV
• Neural messages rapid hormonal slower
• Neural messages all-or-none hormonal graded
  in strength
• Voluntary control

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• SIMILARITIES IN NEURAL AND HORMONAL COMMUNICATION
• Neuron and endocrine gland both store and release
  respective chemical
• Both are stimulated to release chemicals
• Vast array of neurotransmitters and hormones.
  Some serve dual roles.
• Both neurotransmitters and hormones react to
  specific receptors on targets
• Hormones often trigger additional messages within
  a target cell to initiate change. This
  phenomenon is also found with neurotransmitters.

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PHYSIOLOGICAL TECHNIQUES

• INVASIVE TECHNIQUES
• Lesioned
• Destroyed in place
• Transecting
• Cutting relevant pathways
• Transcranial magnetic stimulation
• Creation of strong magnetic pulses at a
  particular location which causes a temporary
  disruption in a small brain region.

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• NEUROIMAGING TECHNIQUES
• EEG (electroencephalogram)
• Electrical activity of the entire brain is
  measured.
• Event-related potentials (ERPs)
• Averaging wave forms on successive EEG
  recordings, recording a specific stimulus event
  in which at least some of the electrical
  interference has been averaged out of the data
• Angiogram
• X-rays that provide some visual contrast when
  special dyes are injected into the blood vessels.

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• CT (computerized tomography) aka CAT scan, an
  abbreviation for computerized axial tomography
• X-rays of a brain area from different angles
  which are then constructed by a computer to
  provide a composite picture.
• MRI (magnetic resonance imaging)
• Strong magnetic field is passed through the brain
  (or whatever part of body is being studied).
  Orbits of nuclear particles changed. Different
  molecules react differently due to different
  compositions and environments. 3D picture
  created based on molecular variations
• Structural MRI
• Looks at static anatomical images
• Functional MRI (fMRI)
• Measures changes in the magnetic state of the
  blood as a function of oxygenation.

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• PET scan (positron emission tomography)
• Mildly radioactive glucose is injected and
  absorbed, more glucose is absorbed by more active
  parts of the brain, brain is scanned and
  researchers can see what areas are most active
  when participating in a certain activity.