How Psychologists Study the Brain

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					How Psychologists
 Study the Brain

Unit 2: Biology and Psychology
How Psychologists Study the Brain
• Mapping the brain has provided scientists with
  amazing information about the role of the brain in
• Psychologists who do this type of research are
  called Psychobiologists or Physiological
• There are 4 different methods they use to explore
  the brain:
    Recording
    Stimulating
    Lesioning
    Imaging
• Electrodes: wires that can be inserted into the brain
  to record electrical activity in the brain
    This allows for detection of minute electrical
     changes that occur when neurons fire
    The wires are connected to electronic equipment
     that amplifies the tiny voltages, even single
     neurons can be monitored
• EEG (Electroencephalograph): a machine used to
  record the electrical activity of large portions of the
    Wires from the machine are attached to the scalp
     so that millions of neurons can be monitored at
     the same time
                                    Psychologists have observed
                                    that the electrical activity of
                                    the brain rises and falls and
                                    that the pattern depends on
                                    whether a person is awake,
                                    drowsy, or asleep
                                    These rhythms, or brain
Probes are being placed on
this man’s head for an EEG
                                    waves, occur because the
Test.                               neurons in the brain tend to
                                    increase or decrease activity
                                    in unison
• Electrodes may be used to set off the firing of
  neurons as well as to record it
• Brain Surgeon Wilder Penfield stimulated the brains
  of his patients during surgery to determine what
  functions the various parts of the brain perform
    Penfield was then able to localize a
     malfunctioning part of the brain, for example in
     the case of epilepsy
• Some psychiatrists have experimented with
  methods that have allowed them to control violent,
  emotional behavior in uncontrollable patients
• Scientists sometimes create lesions by cutting or
  destroying part of an animal’s brain
• If the animal behaves differently after the surgery
  then they assume that the destroyed area is
  involved in that type of behavior
In one study, researchers removed a
portion of the temporal lobe of rhesus
monkeys, which are normally fearful,
aggressive and vicious. After the study
they became less fearful and less violent.
Leading to the assumption that that part of
the brain controlled aggression
• PET (Positron Emission Tomography): an image
  technique used to see which areas are being activated
  while performing tasks
    A slightly radioactive solution is injected into the
     blood. The active neurons will absorb more of the
     solution than non-active neurons
    The scan changes as the person does different tasks
• Computerized Axial Tomography: an image technique
  used to study the brain to pinpoint injuries and brain
    A moving ring passes X-Ray beams around and
     through a subject’s head
    The radiation is absorbed in different amounts
     depending on density of the brain tissue

    The above picture shows a brain CAT scan of a twenty year
    old with weakness on his right side. The red dots show that
    he's weak because there's destroyed brain tissue on that
    side - the black areas. The bones of the skull look like a
    white halo and normal brain tissues looks speckled gray.
• MRI (Magnetic Resonance Imaging): an imaging
  technique used to study brain structure and activity
    The MRI allows researchers to study both activity
     and brain structures. It combines the features of
     both CAT and PET scans
    A computer measures how the signals interact
     with brain cells and translates these signals into a
     detailed image of the brain
• There is a new technique, functional magnetic
  resonance imaging that allows them to observe the
  functions and structures