week 14

Question 1

name: types of neuroimaging (4)

Answer 1

1. electrical recordings
2. brain stim.
3. structural imaging
4. dynamic (functional) imaging

Question 2

name: types of electrical recordings

Answer 2

• single cell recording
• electroencephalography (EEG)
• event-related potentials (ERP)
• magnetoencephalography (MEG)

Question 3

name: types of brain stimulation

Answer 3

• intracranial brain stim.
• transcranial magnetic stimulation (TMS)

Question 4

name: types of structural brain imaging

Answer 4

• conventional radiography
• pneumoencephalography (PEG)
• angiography
• computed tomography (CT)

Question 5

name: types of functional (dynamic) brain imaging

Answer 5

• positron emission tomography (PET)
• magnetic resonance imaging (MRI)
• functional magnetic resonance imaging
  (fMRI)
• magnetic resonance spectroscopy (MRS)
• diffusion tensor imaging (DTI)

Question 6

explain: single cell recording

Answer 6

• type of electrical recording
• invasive
• recording activity of one neuron
• insert microelectrode into/near cell to record activity
• continuous and spont. recording

Question 7

explain: electroencephalography (EEG)

Answer 7

• type of electrical recording
• non invasive
• cap w/ many electrodes to record diff. locations
• awake = beta rhythm
• relaxed = alpha waves

Question 8

question: would an EEG be good for detecting seizures?

Answer 8

• no
• normal activity resumes after seizure
• would need EEG cap on for a long time to detect a change

Question 9

explain: event-related potentials (ERP)

Answer 9

• type of electrical recording
• non invasive
• detects changes in elec. sig. in resp. to a sensory stim.
• stim. presented repeatedly -> responses get averaged
• provides info on location and time of processing
• P component = positive
  ⤷ attention, perception, memory
• N component = negative
  ⤷ sees/hears stim.

Question 10

explain: magnetoencephalography (MEG)

Answer 10

• type of electrical recording
• non invasive
• uses magnets to detect electrical field around neurons
• creates map to show spots of higher magnetic intensity

Question 11

explain: intracranial brain stim.

Answer 11

• type of brain stim.
• invasive
• surgical procedure to treat mvt. disorders
  ⤷ ex. parkinson’s
• implants medical device (neurostimulator)
• helps modulate abnormal neural activity
• excites brain regions w/ electrical signals

Question 12

explain: transcranial magnetic stimulation (TMS)

Answer 12

• type of brain stim.
• stim. brain using magnetic stimulator
• non invasive
  ⤷ but can cause nausea
• current is passed through coil -> magnetic field around coil
  ⤷ causes neurons around coil to fire

Question 13

explain: conventional radiography

Answer 13

• type of structural imaging
• X-rays absorbed to diff. degrees by diff. tissues
  ⤷ dense = white (absorb more X-rays)
  ⤷ soft = shades of gray
  ⤷ ventricle = black
• helps w/ seeing fractures + brain abnormalities

Question 14

explain pneumoencephalography (PEG)

Answer 14

• type of structural imaging
• small amount of CSF removed from subarachnoid space
  ⤷ replaced by air or gas
• X-rays taken as air moves upwards and into ventricles
  ⤷ shows struc. of vent.
• not common bc painful + can get similar results from other techniques

Question 15

explain: angiography

Answer 15

• type of structural imaging
• uses X-rays to image blood vessels
  ⤷ inject substance that absorbs X-rays into bloodstream (ex. iodine)
• taking many images allows dynamic view

Question 16

explain: computed tomography (CT)

Answer 16

• type of structural imaging
• uses X-rays + computer processing to create cross sectional images of the body
• also known as CAT (computed axial tomography)
• gives good diagnostic info
• visualizes internal struc., organs, tissues in great detail
• might be more costly
  ⤷ but more precise info

Question 17

explain: positron emission tomography (PET)

Answer 17

• type of dynamic imaging
• inject radioactive substance into blood
• shows areas of high vs low blood flow
  ⤷ activity lvl shown through blood flow
  ⤷ does not directly measure activity
• radioactive substance breaks up + emits positrons to stabilize
• positrons get eliminated bc contact w/ free e-
  ⤷ releases photons
• photons are detected by machine
• usually expensive (more for research)
• take a control + do many stim. rounds and take the difference

Question 18

question: what does increased blood flow shown in PET mean?

Answer 18

• more blood flow = more activity
• more unstable substances breaking up -> more positrons -> more photons released + detected by machine

Question 19

explain: magnetic resonance imaging (MRI)

Answer 19

• type of dynamic imaging
• uses magnets to detect H molecule relaxation
  1. first magnetic field orients H atoms in one direction
  2. second larger magnetic field changes their orientation
  3. stopping second magnetic field (pulse) allows H atoms to return to their first orientation
  4. calculate relaxation time
  ⤷ time it takes for atoms to align w/ first magnetic field after magnetic pulse is gone

Question 20

explain: functional magnetic resonance imaging (fMRI)

Answer 20

• type of dynamic imaging
• Hb carries O2 in blood
• fMRI detects blood O2 lvls in tissue
  ⤷ more deO2 blood in active areas (bc increased use of O2 + increased blood flow)]

**active areas have more deO2 bc using more O2 but get more O2Hb bc higher requirement (contradictory)
⤷ depends on ratio of O2:deO2 Hb (need info about both)

Question 21

explain: magnetic resonance spectroscopy (MRS)

Answer 21

• type of dynamic imaging
• detecting biochemical metabolites
  ⤷ choline = cell mem.
  ⤷ creatine = E metabolism
  ⤷ inositol + glucose (sugars)
  ⤷ N-aspartate, alanine, lactate = tumours
• differentiates nerve cells from others
• active areas breakdown molecules -> metabolites are created

Question 22

explain: diffusion tensor imaging (DTI)

Answer 22

• type of dynamic imaging
• MRI method that views fiber pathways
  ⤷ brain connections
• detects directional mvt. of water molecules