L5 - Ways to measure brain function Flashcards
Which cranial nerves do not connect to brainstem?
CN1 and2 - Olfactory and optic nerve
What happens when light (which is focused on a specimen) meets the tissue? What does the lens do?
It gets diffracted out. The lens collects all the diffracted light, brings it back together and that light interferes (additively/subtractively) to form the contrast that makes the image.
Why can you record brain activity by placing electrodes on the scalp of the head
A lot of neurons are orientated radially (90 degrees to the surface of the scalp) with respect to the head. They tend to fire together making it easier to record.
When you are awake and at the beginning of sleep (Stage 1 non REM sleep) EEG is quiet or noisy? High or low amplitude and frequency? What kind of rhythms?
Noisy, low amplitude, high frequency – alpha and beta rhythms
As you progress deeper into sleep, what is the EEG like? What kind of rhythm?
Brain behaves more coherently, delta rhythms *Loss of consciousness also shows more coherence
EEG has poor or rich spatial resolution?
Poor
Magnetoencephalography:
Measures the normal (tiny) magnetic fields (billion times smaller than Earth’s magnetic field) associated with brain activity. The most sensitive magnetic detectors (semi quantum interference devices - SQUIDS) need to be cooled to the temperature of liquid helium to detect these tiny fields. It is expensive and needs to be kept cold, hence not readily available
- Good temporal, poor spatial resolution
- Not invasive
As MEG provides no structural information, the MEG data are combined with MRI or CT maps.
Patch clamp electrode
2-5 um tip that is fire polished which leads to formation of a tight seal (GigOhm - covalent bond) with membrane.
Visible light wavelengths limited the maximum achievable resolution to about ___ nm.
250
In stimulated emission depletion (STED) methods, how is super resolution achieved?
super resolution is achieved by narrowing the point spread function of the diffraction disc (Airy disc) by using a laser to precisely deactivate the outmost portion of the disc
In stochastic optical reconstruction (STORM) the random switching of fluorescence of individual molecules allows
their individual contributions to be imaged: single molecules, which are stochastically switched on, imaged and localized, and then switched off. Many cycles of this allows the centre of these discs to be calculated and the image is constructed from millions of locations.
