Transcript brain research methods 1-10

By Marli Andrew
Done when the participant in completely awake and engaged so changes in
responses and behavior to certain stimuli may be observed.
Involves using a device to stimulate the brain with a weak electrical current
by activating or disrupting the normal activity of neurons in a specific brain
area, therefore being able to identify functions of certain parts of the brain.
There are two types studied:
-Electrode stimulation
-Transcranial magnetic stimulation
In the 1940’s to 1960’s Wilder Penfield (18911976), an American neurosurgeon, used a
technique involving inserting into or placing
an electrode into a specific area of the brain,
this electrode was able to send a precisely
regulated electric current to the brain,
directly stimulating a specific brain area.
These observations found that when certain
parts of the brain were stimulated, the body
reacted in certain ways without the
participant controlling them.
For example, when Penfield shifted the
electrode to stimulate the primary motor
cortex at the rear of the frontal lobe, he
found that his patients responded by moving
specific body parts.
✔ Largely assisted in the production of
‘mapping’
✔Provides information about the
function and structure of the brain.
✔Gave a lot of useful information to
future neurosurgeons and
psychiatrists.
✘Highly invasive procedure
✘No longer completely necessary
with new technologies
✘Imposes risks that, by today’s
ethical standards, would be
considered unacceptable
✘There are difficulty's generalizing
the results
http://www.youtube.com/watch?v=FiUL7pm4w3A
There are two types:
-Single pulse TMS or Nonrepetitive TMS
-Repetitive TMS (rTMS)
A direct brain stimulation technique that
involves delivering a magnetic field pulse
through the skull, temporarily activating or
disrupting the normal activity of neurons in
that specific area of the cerebral cortex. The
magnetic field used is completely harmless
and is transmitted through a small copper
electromagnetic coil that is enclosed in plastic
and placed next to the scalp. The pulses
caused by the electrical current only affects
the part of the brain that lies directly below
the skull beneath the coil and goes about 2 to
3 centimeters into the brain.
It works by activating the neurons and they
send a burst of neural impulses (electrical
activity) to adjacent neurons, activating them
which in turn, activates other neurons.
✔Non-invasive and completely
harmless
✘Although rare, TMS carries a risk of
inducing seizures
✔Provides information about
the function of the brain
✘May cause headaches or
discomfort
✔May be used successfully for
the treatment of depression
✘Can not be used on individuals with
any metal or implanted devices in
their body of if they have a history of
seizures.
✔Gives the ability to
temporarily simulate brain
damage.
✘Can only be used for the part of the
brain that lies directly below the
skull, not parts below the cerebral
cortex
An EEG is a device that detects,
amplifies and records general
patterns of electrical activity in
the brain. The activity of neurons
in the cerebral cortex can be
detected outside the skull so
small electrodes are attached to
the surface of the scalp at the
tops and sides of the head, thus
picking up the activity.
✔Non-invasive and completely
harmless
✔Provides information about
the function of the brain
✔Provides genereal information
about brain activity
✔Gives the ability to
temporarily simulate brain
damage.
✔Cost effective
✔Can be used while a
participant in completing long,
complex tasks
✘Only provides basic information
✘It is difficult to pinpoint the specific
part of the brain that is the source of
brainwave activity
✘The strength of the electrical
activity at its source is reduced after
having traveled through the thick
structure of the skull
Also called Computerized axial tomography (CAT).
A neuroimaging technique that produces a computer-enhanced image of a cross
section (‘slice’) of the brain from X-rays taken at different angles. The process involves
moving an X-ray source in an arc around the head while a computer compiles different
‘snapshots’ of the brain.
Can only be performed by a specialist doctor called a radiologist.
The participant needs to be injected with a dye that highlights the blood vessels in the
brain and assists the radiologist in interpreting the X-rays.
✔Doesn’t involves the use of
potentially harmful invasive
procedures and rarely has any
side affects
✔Useful for indentifying the
precise location and extent of
damage to or abnormalities in
various brain structures or areas
✔Shows brain structure
✔Can be used to identify the
size and location of tumors
✘Does not provide information
about the activity of the brain
✘Costly