lecture 13

Question 1

head direction cell

Answer 1

dont fire in a place but fire when head is looking at a direction

Question 2

place by direction

Answer 2

fire when head is aiming in a particular direction

Question 3

grid cell

Answer 3

fire in regular grid pattern

Question 4

place cell

Answer 4

fire when animal is in specific place in environment (hippocampus)

Question 5

computed tomography

Answer 5

x ray beam passes through brain at different angles
images combined to create 3D image
high resolutioncannot distinguish gray and white matter
ventricles show up as black because less dense
bone is white

Question 6

pros and cons of CT

Answer 6

pros- fast and cheap, resolution better than Xray

cons- difficult to distinguish specific tissues, involves ionizing radiation which is invasive

Question 7

magnetic resonance imaging

Answer 7

strong magnetic fields produce highly detailed brain images

- aligns rotational axis of protons to sum electric activity by measuring time it takes to recover

Question 8

diffusion tensor imaging

Answer 8

detects directional movement of water molecules to image nerve fiber pathways in the brain
- detect abnormalities like MS

Question 9

Magnetic resonance spectroscopy (MRS)

Answer 9

MRS uses H proteins in remaining 20% of tissue to image chemical composition by showing metabolite concentraions it can distinguish cell types

Question 10

functional MRI

Answer 10

activity increase causes increase in oxygen

• alters magnetic properties of water in blood
• good spatial resolution but temporal resolution is lower because bloowf low takes a long time

Question 11

fMRI issues

Answer 11

1. false positives- what do activation pixels actually mean
2. key assumption: neural activity is coupled with increased blood flow
3. dont know fi excitatory or inhibitory

Question 12

optical tomography

Answer 12

functional near-infrared spectroscopy (fNIRS)

• fraction- light injected and reflected to be captured by a detector on scalp surface
• oxygenation affects blood abrosption differently

Question 13

pros/cons of optical tomography

Answer 13

pros: easy, convinient, cheap and non-invasive
cons: spatial resolution is okay and only surface data

Question 14

positron emission tomography

Answer 14

tracks the flow of radioactive isotopes throughout the brain

- assumes increase in blood flow = increase neural activity

Question 15

how does PET work

Answer 15

injects radioactive isotope into bloodstream that releases positron then collides with electrons in brain

• emits photons at right angles which are picked up by detectors
• computer constructs image of brain

Question 16

pros/cons of PET

Answer 16

pros: infor on chemical events, image receptors activity, used in oncology and dementia-related disorders
cons: low resolution, same downsides as MRI and more invasive

Question 17

microdialysis

Answer 17

determine chemical constituents of extracellular fluid

• detect increase in NT during reward task
• place semipermeable membrane in brain and fluid flows, extracellular molecules diffuse across the membrane

Question 18

epigenetics

Answer 18

genex expressed can change dramatically in response to environment and experience, can persist for generations
ex. chronic stress, traumatic events, drugs, culture, disease