RESEARCH METHODS 2

RESEARCH METHODS 2

1. CT SCANS (COMPUTERISED AXIAL TOMOGRAPHY)

   • BIOLOGICAL MATERIAL VARIES IN DENSITY, DIFFERENT TISSUE TYPES ABSORB DIFFERENT AMOUNTS OF X RAY RADIATION
     • HIGH DENSITY MATERIAL (BONE) ABSORBS MORE X-RAY RADIATION
   • 1) INJECT DYE TO BLOOD (INC CONTRAST IMAGE)
   • 2) X-RAYS PASSED THROUGH BRAIN, DIFFERENT ANGLES
   • 3) RADIATION NOT ABSORBED BY TISSUE RECEIVED BY DETECTORS
   • 4) FORMS 3D IMAGE
   • ADVANTAGES
     • PRECISE LOCATION/EXTENT OF DAMAGE/ABNORMALITIES
       • STRUCTURAL/TUMOUR/PSYCHOLOGICAL DISORDERS
     • BETTER DETAIL THAN X-RAYS
     • LOW INTRUSIVENESS
   • DISADVANTAGES
     • RISKS: RADIATION, ALLERGIC TO DYE
     • LOW SPATIAL RES: CAN'T DISCRIMINATE OBJECTS LESS THAN 0.5CM APART!
     • LOW TEMPORAL RES (ONLY STATIC STRUCTURES, NOT ACTIVITY)

2. MRI SCAN

   • HARMLESS MAGNETIC FIELDS & RADIO WAVES THAT VIBRATE HYDROGEN ATOMS IN NEURONS
   • 1) MRI > POWERFUL MAGNETIC FIELD
   • 2) HYDROGEN PROTONS ORIENT IN DIRECTION PARALLEL TO MAGNETIC FIELD
   • 3) RADIO FREQUENCY PULSE APPLIED = KNOCKS PROTONS BY 90DEG MAKING DETECTABLE CHANGES IN MAG FIELD
   • 4) PROTONS BACK TO RESTING STATE
   • 5) REPEATED TO EXCITE DIFFERENT SLICES IN TURN
   • ADVANTAGES
     • DETERMINES DAMAGE/ABNORMALITIES IN CERTAIN AREAS
       • BETTER IMAGE THAN CT
     • LOW INTRUSIVENESS ( NO RAYS/SUBSTANCES)
     • HIGH SPATIAL RES
   • DISADVANTAGES
     • CAN'T BE USED ON THOSE WITH INTERNAL MAGNETIC DEVIDES
     • LOW TEMPORAL RES (LIKE CT)
     • CLAUSTROPHOBIA

3. EEG

   • RECORDS ELECTRICAL ACTIVITY IN BRAIN
     • RECORDS GROUPS OF NEURONS FIRING AT SAME TIME
       • DETECTED BY ELECTRODES ON SCALP
   • EEG TO ERP
     • EEG NOT SENSITIVE TO DISTINGUISH BETWEEN FINE CHANGES IN MENTAL ACTIVITY
       • ERP = TIMINGS
   • ADVANTAGES
     • CHEAP EQUIPMENT
     • WIDE RANGE P'S
     • STUDY ACTIVITY OVER TIME
     • LOW INVASIVENESS
     • HIGH TEMPORAL RES
   • DISADVANTAGES
     • SIGNALS CONTAMINATES (BLINKS)
     • ONLY ALLUDES TO WHICH AREAS ACTIVE
     • ERP - LARGE NO. TRIALS
     • LOW SPATIAL RESOLUTION