Global Brain Activity Flashcards
What is the basic requirement for signal detection on EEG?
- A whole population of neurons must be active in synchrony to generate a large enough electrical field at the level of the scalp
- This population of neurons must be alligned in a parallel orientation so they summate rather than cancel out.
What kind of rhythm would you have for an awake person?
Alpha, 8-13 Hz awake but eyes closed
Which rhythm would you have if a person is mentally active and attentive eyes open?
Beta 14-60Hz
Which wave would you if you’re drowsy and sleepy or a pathological condition?
Theta waves 4-7 Hz
Which wave would you have in REM sleep?
Beta
Which wave would you have stage 1 non REM sleep?
Theta
What would you have in stage 2 non REM sleep?
Spindle and K complex
What would you have in stage 3 and 4 non REM sleep?
Delta
In REM sleep the modulation is?
Cholinergic
In waking state the modulation is?
Aminergic NE Seretonin and histamine
Why are CT used for brain scans?
Tumour diagnosis and haemorrhaging
Sequence of events for MRI?
Magnetic fields of protons initially random
Add external magnetic field and some protons align
Brief radio wave pulse orients them to 90 degrees to produce MR signal
Brain weight and oxygen consumption?
2%
20%
What does PET measure?
Change of blood flow to a region
What does fMRI measure?
Conc of oxygen into blood
Difference between PET and fMRI?
PET- radioactive tracer, fMRI no radioactivity
Temporal resolution for PET is 30” for fMRI is 1-4
Spatial resolution is 10mm vs 1mm
PET is sensitive to whole brain but for fMRI some brain parts are hard to image e.g near sinuses
BOLD signal?
Blood oxygen level dependent contrast, for oxy and deoxyhaemoglobin in blood
HRF?
Haemodynamic response function- describes changes of BOLD signal over time
