Lecture II Flashcards
MRI
Hydrogen atoms respond to magnetic fields and radiofrequency pulses by emitting energy.
Diffusion tensor imaging/DTI
Measures diffusion of water molecules in brain tissue.
Comparing responses to magnetic fields in different directions.
Combine this information into neural fiber bundles.
Following fibers allows to map connections between areas in health and disease.
Structural/anatomcial MRI
image depends on structures like white and grey matter; analyze tissue changes in health and disease.
fMRI
Measures blood flow and oxygenation changes in brain areas.
Low temporal resolution, high spatial resolution.
Active brain areas consume more oxygen, which … the amount of …
To compensate, … is supplied …
Increases the amount of deoxyhemoglobin.
Oxyhemoglobin is supplied more.
Magnetic resonance of … is higher than …
This is measured in the …
Oxyhemoglobin higher than deoxyhemoglobin.
Blood oxygenation level dependent (BOLD) flow.
Active brain areas (5):
Use more oxygen. Increase deoxyhemoglobin. More oxyhemoglobin supply. Magnetic resonance oxyhemoglobin higher. Seen in BOLD response.
2 types of neural activity:
Neural firing/APs = neural output
Synaptic activity/LFPs = neural processing
BOLD signal reflects …, not itself, but the anticipation on …
Synaptic activity, upcoming changes in neural metabolism.
Excitatory NTs cause…
Vasodilation
Inhibitory NTs cause…
Vasoconstriction
BOLD signals arise from NT release and modulate oxyhemoglobin supply:
Excitatory NTs like glutamate cause…
Inhibitory NTs like GABA cause…
Excitatory NTs cause widening of blood vessels (vasodilation) - leading to more oxyhemoglobin to reach the area in which the NT is released.
Inhibitory NTs cause narrowing of blood vessels (vasoconstriction) - leading to less oxyhemoglobin to reach the area in which the NT is released.
Reduction of information occurs through…
Detecting signal changes in image and disregarding constant parts.
Receptor cells
Consist of rods and cones, which convert light to neural activity that is passed onto the middle cell layers.
Middle cell layers
Consist of horizontal, bipolar, and amacrine cells - compress information by interacting with each other and detecting signal changes while ignoring constant parts.