lecture 13 Flashcards
head direction cell
dont fire in a place but fire when head is looking at a direction
place by direction
fire when head is aiming in a particular direction
grid cell
fire in regular grid pattern
place cell
fire when animal is in specific place in environment (hippocampus)
computed tomography
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
pros and cons of CT
pros- fast and cheap, resolution better than Xray
cons- difficult to distinguish specific tissues, involves ionizing radiation which is invasive
magnetic resonance imaging
strong magnetic fields produce highly detailed brain images
- aligns rotational axis of protons to sum electric activity by measuring time it takes to recover
diffusion tensor imaging
detects directional movement of water molecules to image nerve fiber pathways in the brain
- detect abnormalities like MS
Magnetic resonance spectroscopy (MRS)
MRS uses H proteins in remaining 20% of tissue to image chemical composition by showing metabolite concentraions it can distinguish cell types
functional MRI
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
fMRI issues
- false positives- what do activation pixels actually mean
- key assumption: neural activity is coupled with increased blood flow
- dont know fi excitatory or inhibitory
optical tomography
functional near-infrared spectroscopy (fNIRS)
- fraction- light injected and reflected to be captured by a detector on scalp surface
- oxygenation affects blood abrosption differently
pros/cons of optical tomography
pros: easy, convinient, cheap and non-invasive
cons: spatial resolution is okay and only surface data
positron emission tomography
tracks the flow of radioactive isotopes throughout the brain
- assumes increase in blood flow = increase neural activity
how does PET work
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
pros/cons of PET
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
microdialysis
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
epigenetics
genex expressed can change dramatically in response to environment and experience, can persist for generations
ex. chronic stress, traumatic events, drugs, culture, disease
