neuroscience - imaging

Question 1

describe the clinical or neuropsychological assessment for studying the brain

Answer 1

• non invasive
• correlates impairment of function with damaged area of the brain
• diagnosis, understanding nature of brain injury, measuring change over time

Question 2

describe stimulation methods for studying the brain

Answer 2

• invasive
• electrical current briefly applied to part of brain to study effect
• patients describe subjective experience
• roles of speech and language areas have been identified

Question 3

describe brain imaging to study the brain

Answer 3

• imaging techniques show relationship between brain structures and their functions

Question 4

describe the process of electroencephalography

Answer 4

• electrodes on scalp detect voltage fluctuations in the brain
• signals recorded by machine and observed by doctor
• allows monitoring of the depth of anaesthesia during surgery
• provides information about normal electrical activity

Question 5

what are the advantages of using an EEG scan

Answer 5

• non invasive
• cheap
• fast

Question 6

what are the disadvantages of using an EEG scan

Answer 6

• not exact as it is hard to figure out where the electrical activity is coming from in the brain

Question 7

describe the process of a computerised tomography scan

Answer 7

• many x-ray images taken from different angles and combined
• x-rays from beams detected after passing though the body and their strength measured
• less dense tissue produces strongest beams
• can detect tumours, brain injuries and blood clots…

Question 8

what are the advantages of using CT scans

Answer 8

• more detailed information
• more readily available in the UK than MRI scans
• whole. body scan can be done in seconds

Question 9

what are the disadvantages of using CT scans

Answer 9

• involves doses of radiation
• very expensive
• requires cooperation or sedated patients

Question 10

describe the process of a magnetic resonance imaging scan

Answer 10

• uses strong magnetic fields to align protons in water molecules
• monitored as they move through following a pulse of radio waves
• produces detailed images of soft tissues and organs

Question 11

what are the advantages of using MRI scans

Answer 11

• no ionising radiation involved
• no known side effects
• non invasive
• better soft tissue contrast that CT
• 3D data

Question 12

what are the disadvantages of using MRI scans

Answer 12

• very expensive
• cannot scan patients with metallic implants
• unsuitable for claustrophobic or obese patients

Question 13

describe how an MRI scan may be used to assess brain damage.

Answer 13

• patients head placed in magnetic field
• computer measures differences in strength of magnetic fields
• computer produces images of internal structure of brain
• images show slices of the brain
• areas of brain respiring
• little respiration in areas that are damaged

Question 14

what are the advantages of fMRI scans

Answer 14

• no ionising radiation
• no know side effects
• non invasive
• better soft tissue contrast that CT scan
• 3D data

Question 15

what is the process of a positron emission tomography scan

Answer 15

• injection of small amount of radioactive isotope
• shows use of radioactive glucose in 3D map of brain
• active areas release more radioactive glucose so show as yellow and red
• can detect biochemical changes in the brain before anatomical changes occur

Question 16

what are the advantages of using a PET scan

Answer 16

• usually painless
• helps diagnose, treat or predict outcomes for a range of conditions
• shows how different parts of the body work and can detect problems early

Question 17

what are the disadvantages of using a PET scan

Answer 17

• exposure to gamma rays
• radioactive materials can cause reactions in some people
• scanners can cause people to feel claustrophobic

Question 18

define neuroplasticity

Answer 18

brains ability to change and adapt over time by forming new connections between neurones

Question 19

define developmental plasticity

Answer 19

neurones in the young brain rapidly sprout branches and form synapses

Question 20

why is the critical period important

Answer 20

• brain must receive certain sensory inputs in order to develop properly
• when this period has ended it becomes hard to learn new noises

Question 21

what is synaptic pruning

Answer 21

• large drop in number of connections after critical period ends
• ones that remain are the ones used the most
• occurs during adolescence

Question 22

what is epigenetics

Answer 22

study of chemical reactions that can turn genes on or off and the factors that influence them

Question 23

what is cortisol

Answer 23

hormone released from the adrenal glands in response to stress

Question 24

outline the stages of cortisol production

Answer 24

• production controlled by hippocampus
• when stressed, the hippocampus sends impulses to the hypothalamus, which releases corticotrophin-releasing hormone and arginine vasopressin
• these hormones stimulate the pituitary gland which then releases adrenocorticotrophic hormone into the blood
• cells of adrenal glands release cortisol when they take up this hormone

Question 25

what is the process of cortisol production an example of and why

Answer 25

• negative feedback
• as cortisol circulates in the bloodstream it binds to glucocorticoid receptors in the hippocampus, which responds by sending impulses to the hypothalamus, inhibiting it
• this stops us from being constantly overstressed

Question 26

what does it mean about the feedback loop when adults who have had a traumatic childhood and are consequently stresses produce too much cortisol

Answer 26

the negative feedback loop is not working and they could have fewer receptors or release more hormone leading to higher cortisol production