Methods of Studying Biological Functions and Structures

Question 1

What is Phrenology?

4

Answer 1

Bulges and depressions in the skull = specific brain areas => specific behaviors

• -skull shape has little to do with brain anatomy
• • based on individuals

Question 2

What are Neuroanatomical Techniques?

6

Answer 2

• The gross examination of the brain
  – does not allow study of cell structure or connectivity
  + reveals locations and directions
  + locate specific neurons and neurotransmitters
• uses: Histological Procedures: Brian slices are selectively stained and viewed under a microscope

Question 3

Describe 3 Staining techniques:

7

Answer 3

Different stains = specific anatomical structures

1. Cell body stain/ Nissl Stains = cresyl violet reveal cell bodies in brain tissue
2. Myelin Stains = selectively colours the myelin sheath => observing bundles if myelinated nerve fibers
3. Membrane Stains = silver: interacts with axon membrane => dendrites, dendritic spines etc

Question 4

What are Immunocytochemical Techniques?

2

Answer 4

• uses selective artificial antibodies to bind to particular proteins
• takes advantage of normal immune reactions

Question 5

What are the problems with techniques that involves parts of the brain being removed?
(1)

Answer 5

Doesn’t tell much about living brain processes

Question 6

What is Computerized (Axial) Tomography (CT/ CAT Scans?

6

Answer 6

• X-rays create 2D images of the brain
• the whiter the image the denser the tissue
• used to diagnose: tumours, strokes, blood clots and neural degeneration

Question 7

What is Magnetic Resonance Imaging (MRI)?

6

Answer 7

• uses powerful magnet to observe magnetic radiations from hydrogen atoms which are present in all cells, varying in concentration
• Produces images on all 3 anatomical planes

Question 8

What is Functional Magnetic Resonance Imaging (fMRI)?

6

Answer 8

• uses similar process like MRI but demonstrates Structure and Function
• Measures Heamodynamic Responses (metabolic activity) like consummation of oxygen = happens when an area is active

colder colours = less activity
warmer colours = greater activity

Question 9

What is Positron Emission Tomography (PET)?

6

Answer 9

• Radioactive glucose injected in the patient which is taken up by metabolising/ active cells
• Rest and activity (eg: Cognitive tasks)
  Observe which areas are involved in specific mental operations
• Healthy brain and diseased brain:
  Observe which areas are in decline and relate them to behavior

Question 10

What are the advantages and disadvantages of Brain Imaging?

9

Answer 10

+ Non invasive ( CAT/ MRI/ fMRI)
+ Good special resolution: Structure (MRI/ CAT)
Function (fMRI/ PET)
+ Can be used for comparison

• -Risk from X-ray (CAT) and Radioactivity (PET)
• -Poor temporal resolution (linking events to image changes)
• • Noisy, claustrophobic and scary (MRI/ fMRI)
• -very expensive
• • Lots of equipment
• • Not portable

Question 11

Why is recording electrical activity helpful?

1

Answer 11

Tells what structures are used in particular functions

Question 12

What are the advantages and disadvantages of Micro-electrodes?

Answer 12

• they are implanted in the brain to record neural activity

+ monitor activity of individual neurons

• • Highly invasive
• • non suitable for humans
• • can neglect neural integration because it is very specific

Question 13

What are the advantages and disadvantages of Macro-electrodes/ electroencephalogram (EEG)

Answer 13

Active electrodes attached to scalp in areas of expected neural activity
Indifferent electrodes attached to neutral areas

+ fairly invasive
+ differentiation between neurological conditions and behavioral states
–time consuming
– lots of equipment
–interpretation requires considerable evidence
–crude measures = averaging activity of many neurons cannot establish

Question 14

What are EEG waves?

4

Answer 14

• EEG waves represent different sleeping/ wakefulness/ arousal states:

1. Beta 14-30 Hz: actively attending to events, awake and aware
2. Alpha 9-13 Hz: Awake but it is not actively processing information: relaxed/ daydreaming
3. Theta 4-8 Hz: light sleep: easily awakened
4. Delta 1-3 Hz: deep sleep

Question 15

What are the advantages and disadvantages of Experimental brain studies?
(6)

Answer 15

+ Damage is controlled and specifically localised to brain areas associated to specific behavior => if behaviour altered = area involved in that behaviour

• -Brain is interconnected => lesion in one part could damage another function
• • Generalising artificial damage to natural damage
• • ETHICS

Question 16

What are the advantages and disadvantages of human studies?

5

Answer 16

– Not ethical
+ Natural damage can be very insightful = function/ behaviour rarely known before damage
– Unethical to administer neurotoxins although some people do it willingly = + behaviour can be assessed

Question 17

What are the advantages of Nervous Endocrine System Activity measurements?
(3)

Answer 17

+ less invasive
+simpler equipment
+can be used in everyday settings

Question 18

Describe 2 examples of Nervous Endocrine Activity measurements:
(4)

Answer 18

1. Sympathetic Nervous System: Heart rate and blood pressure => they go up with sympathetic activity
   Galvanic Skin Response (GSR): Sympathetic activity increases perspiration: levels of sweat can be measured
2. Endocrine System: Hormones can be sampled in saliva and blood