task 4 - method and techniques Flashcards
conventional x-ray photography
; x-ray beam is passed through and object and then onto a photographic plate. each molecule beam has passed through absorbs some of the radiation ⇒ only the unabsorbed portions of the beam reach the photographic plate
contrast x-ray techniques
; a substance is injected in a compartment of the body that absorbs x-rays either less or more than the surrounding tissue
cerebral angiography
; a contrast x-ray technique, a radio-opaque dye is infused into the cerebral artery to visualize the cerebral circulatory system during x-ray photography
aspiration lesion
→ cortical tissue is drawn off by suction through a handheld glass pipette
radio frequency lesions (RF)
→ subcortical regions are usually produced by passing electrical currents through a steel wire that is insulated except at its tip (destroys cell bodies at the region and axons that pass through the region)
excitotoxic lesions
→ a more selective way of producing lesions, namely by injecting an excitatory amino acid into the brain through a cannula, the amino acid stimulates the neurons in the region to death, leaving the axons that pass through the region alive
reversible brain lesion
→ disruption of brain activity of a particular region temporarily, can be caused by injecting an anesthetic (which blocks axons from leaving/entering a region) pr muscimol (stimulates GABA receptors and inactivates a brain region by inhibiting the neurons there) or cooling the target structure
positron emission tomography (PET)
measuring blood flow or energy consumption in the brain
small amounts of radioisotope is introduced into the blood and the brain carries it around, the radioisotope will show in the active parts of the brain
spatial: low
temporal: low
magnetic resonance imaging (MRI)
produce high-quality 3D image of organs and structures (non-invasive, no x-rays or other radiation) show structural abnormalities, how the develop and how they effect mental and emotional aspects
atoms swing back to align with the background field, that creates the signal that is picked up and converted into an image
spatial: high
temporal: low
functional magnetic resonance imaging (fMRI)
uses high-spatial resolution, non invasive imaging by detecting blood oxygen levels, BOLD signals,, compares brain activity under resting and active conditions
spatial: highest !!!!!!!!
temporal: low
computerized tomography (CT)
detect differences in structure or tissue type, such as tumors or bleeding, donut shape ring, directly opposite of the patients head is an x-ray detector → the x-ray beam passes through the patients head and the detector measures the amount of radioactivity that gets through it
spatial: medium
temporal: medium
transcranial magnetic stimulation (TMS)
can turn off an area of the cortex in a non-invasive way,, a way to prove the causality of brain activity to cognitive activity
spatial: low
temporal: high
magnetoencephalography (MEG)
magnetic fields patterns in the human brain can show the position and strength of activity in various regions of the brain, an array of cylinder-shaped sensors monitors the magnetic field pattern near the patients head → performed with neuromagnetometers (contain SQUIDS, superconducting detectors)
spatial: low (better than EEG)
temporal: high
EEG electroencephalography
measures the gross electrical activity of the brain in the form of a polygraph, dime sized and disk shaped electrodes are attached to the scalp → the scalp EEG signal reflects the sum of electrical signals from the skin, muscles, blood and eyes
spatial: low
temporal: high
diffusion tensor MRI
the movement of water molecules in bundles of white matter will not be random, but tend to be in a direction parallels to the axons that makeup the bundles
