Brain Scan, Longitudinal + Cross Sectional Studies

Question 1

Types of brain scan

Answer 1

Electroencephalogram (EEG)
Computed Axial Tomography (CAT scan)
Positron Emission Tomography (PET scan)
Magnetic Resonance Imaging (MRI scan)

Question 2

Electroencephalogram

Answer 2

Record electric signal
Attach electrodes to scalp
Signal produced move instrument attached with pen to trace brain wave in graph papers

Dement + Kleitman
-during rapid eye movement in sleep brain wave rapid, usually slow for sleep

Adv:
-measure impulse changes over split second of time
-show what state a person is in (awake, sleep, anaesthesia)

Disadv:
-does not brain structure + not tell which area of brain active

Question 3

Computed Axial Tomography

Answer 3

Using series of x-ray
-form 2 D picture of area scanned
-usually dye injected as contrast material

Johnstone et al - schizo brain ventricle larger than non schizo

Adv:
-useful to reveal abnormal brain structure or damages
-better quality than traditional x ray

Disadv:
Use more radiation than normal x ray
Can’t use on pregnant

Question 4

Positron Emission Tomography

Answer 4

Observe blood flow or metabolism
-radioactive glucose injected
-area of brain cells more active absorbed more glucose
-scan detect absorption of radioactivity
-detect which area of brain more active - absorption level separated by colour

Raine et al

Adv:
-reveal chemical info other can’t (benign or malignant tumours)
-shows brain during action

Disadv:
-costly
-contain radiation (can’t have multiple in short session)
-less precise than MRI

Question 5

Magnetic Resonance Imaging

Answer 5

Use magnetic + radio wave
-sit in large cylinder shape magnet
-have moves nuclei out of place
-when nuclei back into place = send radio wave
-machine pick up = form cross sectional slice

Adv:
More detailed than PET scan
Can be used repeatedly for multiple short session - no radiation

Disadv:
-take long time to do = uncomfortable for patient

Question 6

Longitudinal study

Answer 6

Observe participant over long period of time
-often use repeated measure (same audience)
-ask participant to be researched on multiple occasion
-can be used in case study

Adv:
-participant variables control (environment, upbringing)

Disadv:
-attrition rate; some participant might leave since last too long= can’t gain back so sample size small = less generalisable
-biased: those left could share similar characteristics (unhappy, do less well)
-participant aware of study - demand characteristics/ artificial behaviour
-time consuming

Question 7

Cross sectional study

Answer 7

One group of participant represent 1 group of society (young) compare to another group (old)
-compare differences or influence between 2 groups

Adv:
-quicker to do than longitudinal study

Disadv:
-participant variables - may not be social difference causing difference could be participants themselves (IQ not age)
-cohort effect the difference between could be due to other factors (malnutrition in WW1 rations cause brain to not fully develop = lower IQ)